Re: [RBW] Re: Yet another post on shimmy
To Jims point, is it shimmy or vibration coming from the dynohub? The latter does happen to me sometimes but only at certain speeds, someone way smarter could tell why due to harmonics and magnetic polarity. I would think going back to tje original front wheel would be a good place to start. On Apr 22, 2013 1:50 AM, "Cyclofiend Jim" wrote: > Well, there are definitely a few variables in that equation... > > Let's work backward a bit - > > Shimmy should show up at specific speeds. Or under specific speeds and > weight distributions. There are a number of things which tend to amplify > this, and there have been long threads here and on the iBob list about the > general topic of shimmy. Anyone new to the general topic can get some info > here - http://sheldonbrown.com/brandt/shimmy.html > > Jan H also has a good video of the condition here - > http://www.youtube.com/watch?feature=player_embedded&v=8pzc2aYVFEg > > From your post, you say you never got shimmy before, but then also say it > "almost never happened" with the original setup - so, it sounds like you > did get shimmy before, and now it happens much more frequently. Is that > the case? > > I'd actually just swap back your old front wheel to start with, and see > what that does. There could be some hesitation in that hub which is > exacerbating things. > > I'd also remove the saddlebag and see what that does. One variable at a > time! > > I don't know if going from 35 Panaracers to 33.3 JB's would do it, but I'd > consider the possibility of tire pressure being a variable as well. I'd > also try to get a fix on the speed at which it occurs. > > best of luck in tracking down the issues. > > - J > > Jim Edgar / cyclofiend.com > > > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to rbw-owners-bunch+unsubscr...@googlegroups.com. > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > Visit this group at > http://groups.google.com/group/rbw-owners-bunch?hl=en-US. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
On Mon, 2013-04-22 at 08:32 -0400, Peter Morgano wrote: > To Jims point, is it shimmy or vibration coming from the dynohub? Vibration from a dynohub doesn't feel like shimmy. It's a very high frequency, low amplitude buzz. It doesn't make the bike shake or turn the bars from side to side, and it's definitely not frightening. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
My own experience with shimmy has fortunately been limited and occured mostly with the '95 custom Road. After years of riding it without any sign of shimmy, moderate shimmy started happening at about 18-20 mph. I have no idea what caused it and, after a few weeks, it went away. No major build changes, but continual minor changes in this, that and the other -- loads, manner of carrying loads, seatpost, saddle, brakes, gearing. I personally think it has to do with your astrological sign and the phase of the moon, but I could be wrong. > > On Sunday, April 21, 2013 7:46:47 PM UTC-7, john wrote: >> >> Hello All. >> >> I thought I'd get some ideas on a recent shimmy development. Here is the >> scenario: >> >> Rider specs: >> John >> Height: 5'11" >> Weight: 150 soaking wet >> PBH: 88.9 >> SH: apprx 78.5 cm >> >> I ride a 60 cm. Sam HIll. >> >> I Never experienced shimmy with the stock build: Shimano deore front and >> rear hubs, Velocity synergy wheels, (35 cm panaracer pasella tires), noodle >> handlebars, SKS Longboard fenders, etc. >> I ride with a nitto mini front rack, nitro rear rack (the one for >> saddlebag support, not panniers). I ride with a Baggins "Adam" saddlebag. >> No front bag as yet because I haven't found one to fit the distance between >> the front rack and handlebars (I'm not particularly interested in buying a >> nitro F-15 rack, but instead covet a Berthoud rando bag - yet I don't know >> if the 28cm size will fill the gap. ) >> >> Nothing unusual for a Rivendell. >> >> Now, for the recent developments: >> Swapped the old wheel (Velocity Synergy) for a newly built Velocity >> Synergy with dynohub (Shimano Alfine). Have a lightweight B&M Cyo light >> attatched to the right (rider's right while riding) of the rack. Switched >> from 35cm Panaracers to 33.3 Jack Brown Greens. Got the JBs to fit under >> Hono because I had issues with the Longboards on two different sets: >> (rubbing, chattering, due to inherent fleibility) . I also shortened the >> stem just a hair, to see if doing so would help alleviate some forearm >> discomfort I'd been having. (The old setup was stem height equidistant to >> saddle height.) Now the stem height is slightly below saddle height. >> That's it. >> >> >> Now: experiencing some shimmy (and less overall feeling of stability) >> while riding no hands sitting upright. This does not occur all the time, >> but it's noticeable. The "response" doesn't happen all the time, but still, >> it's there, and unnerving when it does. >> >> This "response" almost never happened with my old, original setup. >> Frustrating! Because I much prefer dyno lighting for any number of reasons, >> and wanted to run narrower tires to better fit underneath Honjo fenders, >> which I much prefer to Longboards. My "upgrades" were plenty expensive, >> too! And a pain in the neck, and time away from the bike. Still, I want >> what I want: the best Riv ride possible. Is there an inherent compromise >> here? Am I missing something? And if it is the new developments, where is >> the problem? Stem height? Wheel weight? Tire width? >> >> Any comments? Clues? Suggestions? I'll continue to ride and see how it >> goes, but honestly, as much as I like the changes I've made (except for the >> need to run thinner tires with is not optimal for me), I'd go back to the >> original set up if it meant the end to shimmy. I do not like to shimmy! >> >> Yes, obviously I will start with the easy stuff first. As in, I'll raise >> the stem and see what happens (or doesn't). After that, I'm frustrated. >> Very frustrated. >> >> Suggestions would be appreciated. Thanks. >> >> John >> > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to rbw-owners-bunch+unsubscr...@googlegroups.com. > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > Visit this group at > http://groups.google.com/group/rbw-owners-bunch?hl=en-US. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- http://resumespecialties.com/index.html patrickmo...@resumespecialties.com __ -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
On Mon, 2013-04-22 at 07:32 -0700, john wrote: > > 1. I got shimmy so infrequently with the original set up that it isn't > really worth mentioning (In my opinion). This occured while I sat > upright going down a long hill at considerable speed. But as I said, > it seldom occured, and a slight pinching of the top tube with my knees > would stop it. That sounds more like speed wobble than shimmy. > > 2. Now, the shimmy occurs at very low speed, again while sitting > upright, and on the flats. So yes, I did not get shimmy at all often > before, now much more often, and at much lower speeds, on flat road. I > don't remember every getting shimmy on a flat road with the old set > up. I missed part of the back story here. Are you doing anything different with front load now? -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Steve: I don't currently load the front. I never have, in fact. On Monday, April 22, 2013 7:58:13 AM UTC-7, Steve Palincsar wrote: > > On Mon, 2013-04-22 at 07:32 -0700, john wrote: > > > > 1. I got shimmy so infrequently with the original set up that it isn't > > really worth mentioning (In my opinion). This occured while I sat > > upright going down a long hill at considerable speed. But as I said, > > it seldom occured, and a slight pinching of the top tube with my knees > > would stop it. > > That sounds more like speed wobble than shimmy. > > > > > > 2. Now, the shimmy occurs at very low speed, again while sitting > > upright, and on the flats. So yes, I did not get shimmy at all often > > before, now much more often, and at much lower speeds, on flat road. I > > don't remember every getting shimmy on a flat road with the old set > > up. > > I missed part of the back story here. Are you doing anything different > with front load now? > > > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Shimmy is a seemingly mysterious thing, except it isn't really. With shimmy the bike is acting as a vibrating spring, anchored at the wheel contact patches with the ground and the rider's contact points. The headset allows the front end mass (bars, stem, fork, wheel, fender, bar bag, rack, lights, whatever is attached to the fork) to swing in the opposite direction of the mass of the rest of the bike. That's why a headset with more friction, such as a roller bearing headset, tends to reduce shimmy. I think, but don't know for sure, that lateral flexibility in the rear wheel also contributes (suggesting that a high-dish wheel may increase the risk for shimmy). Shimmy is usually most pronounced when coasting because the various loads on the bike are consistent and allows the sine wave to develop and amplify; shimmy is less pronounced when pedaling because of the shifting mass of the rider and the effects of pedaling causing frame flex, etc. I've seen one exception to that, a Lightspeed titanium frame one of the master's racers hereabouts used to ride. Shimmied like the dickens when he pedaled which is unnerving in a peloton... Something has to start the shimmy. You have perhaps seen the shimmy videos of the coasting rider whacking the handlebar to start the shimmy. Road surface irregularities, an imperfectly mounted tire, a cold and shivering rider, a death grip on the bars (which transmits our body's natural tremor to the bike- the same tremor that blurs hand-held photos with slow shutter speeds), etc. If your tire was out of round on the rim, that might have been enough to start the shimmy. Back in my racing days, a teammate of mine had terrible problems with a shimmy. None of the bike shops in town could find the problem and fix it, and even when he had the opportunity to consult with pro team mechanics about it they were unable to diagnose or fix it either. The problem was so bad that he couldn't descend hills at more than than about 20 miles an hour. This was a handicap in races. One day he changed the front tire and the shimmy went away. I don't know whether it was something about that particular tire or about how the tire was mounted to the rim, but that solved the problem. By the way, if your bike is shimmying, standing on the pedals and rising a tiny bit from the saddle will almost always stop it. Usually just reducing your weight on the saddle is enough. Your weight is one of the things driving a shimmy. Tim On Apr 22, 2013, at 6:48 PM, john wrote: > Well, here's an interesting situation! > > I decided to take on the wheel issue first. I rode a very shallow hill at > perhaps 10 mph, no handed, sitting up. The shimmy was pronounced. Enough so > that I turned around, went back up the gentle grade, and tried again. Once > again, as the bike picked up a bit of speed, the shimmy returned. I turned > around, rode back up, did it again. And the shimmy returned. > > So I rode home, took the new tire off the new wheel, and installed it on my > old wheel. I went back to the same spot and tried again. The first time down, > at the same pace, on the same road, same lack of wind: no shimmy. I tried it > again: no shimmy. And again: no shimmy. > > Eureka! I thought. It must be the wheel. Well, this being my day off, I took > a good long flat ride on mixed terrain with that old wheel. Fantastic few > hours out on the bike. I'm really loving the Jack Browns - surprisingly, as > much or more so off pavement as on. > > This late afternoon, the wind had picked up considerably. Just to make sure I > had solved the riddle, I removed the tire, installed it on the new wheel, > went back to the same spot, and tried the test again: no shimmy. I did it > once, twice, three times. No shimmy. Went to different areas which were a bit > less windy: no shimmy. > > So now I can't reproduce the shimmy. Maybe the tire wasn't seated as well as > it could have been on the first trial? Maybe riding in wind has something to > do with it? > > I'll try again tomorrow morning. Hopefully the wind will have abated. > > On Monday, April 22, 2013 10:55:24 AM UTC-7, Dave Rivbike wrote: >> >> Hi John, If it's only happening when going no hands... the problem might be >> not ENOUGH weight (you) on the front of the bike. Your body is the engine, >> but it's also part of the steering and suspension. It's like taking the >> shock absorbers off your '64 Impala lowrider and bouncing around at >> inersections >> >> On Sunday, April 21, 2013 7:46:47 PM UTC-7, john wrote: >>> >>> Hello All. >>> >>> I thought I'd get some ideas on a recent shimmy development. Here is the >>> scenario: >>> >>> Rider specs: >>> John >>> Height: 5'11" >>> Weight: 150 soaking wet >>> PBH: 88.9 >>> SH: apprx 78.5 cm >>> >>> I ride a 60 cm. Sam HIll. >>> >>> I Never experienced shimmy with the stock build: Shimano deore front and >>> rear hubs, Velocity synergy wheels, (35 cm panaracer
Re: [RBW] Re: Yet another post on shimmy
Wheel balance on bikes is a red herring. The mass differences are too small and the RPMs of a bike wheel are too slow. I have another anecdote that I don't have time to write at this time (at work, should be working...) which should help demonstrate this. On Apr 23, 2013, at 8:35 AM, Will wrote: > I've always felt that shimmy was related to an unbalanced wheel. We > routinely balance our automobile wheels, why would a bike be different? > > I think as we move to fatter tires (more mass) we will need to address the > balance issue. I think the frame discussion is irrelevant. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Well, after removing the tire from the new wheel, remounting the tire to ensure a perfect seal, and matching up the valve to the label for future testing, and ensuring that the wheel was perfectly centered in the fork, I got out for some more testing. One thing that has changed since my initial tests: I no longer provoke shimmy at a slow speed, only a decent clip. However, when descending a hill at moderate speed or fast speed, if I'm sitting upright with hands off the bars, my Sam Hillborne will dance. Frustrating. Of course, Charlie is right: I could just right with my hands on the bars. But for me, riding no-handed down hills not only is relaxing, but a great joy. So at least for me, it's not an option. Or at least not one I'm willing to consider at this time. And as others have suggested, i could ride without a saddlebag. But after using saddlebags for 20 years, I wouldn't even know how to ride without my beloved saddlebag. (And furthermore, although I'm sure a weighted saddlebag is a factor, I have not had any significant weight in my saddlebag throughout this discovery process. Not to mention when I ride the old wheel with the same saddlebag, I experience no shimmy.) How to explain the initial shimmy at slow speeds and now only at higher speeds on a steeper hill? Perhaps the tire is seated better than initially. Perhaps the rubber of the tire has expanded over the course of a day. Who knows? I guess the worst case scenario is I go back to my old wheel with fantastic new Jack Brown Greens. Wow, I love those tires! I was anticipating a let down, going from 35c Panaracer Pasellas to a "skinny" JB 33.3c. To the contrary, I'm really loving the tires and don't notice the width as being a factor. Time will tell about puncture resistance. But as far as ride quality, much improved on the JBs. Thanks for everyone for sharing his opinions and anecdotes. Much, much appreciated. I will update this thread if and when I am able to solve the riddle. But I suspect I will just swap back to my old wheel for the time being and quit worrying about it. If any of you out there is interested in a new Shimano Alfine generator hub on a new Syngery Velocity 32 spoke wheel, I may just be willing to part with it. thanks again for sharing. John On Tuesday, April 23, 2013 7:12:08 AM UTC-7, Tim McNamara wrote: > > Wheel balance on bikes is a red herring. The mass differences are too > small and the RPMs of a bike wheel are too slow. > > I have another anecdote that I don't have time to write at this time (at > work, should be working...) which should help demonstrate this. > > On Apr 23, 2013, at 8:35 AM, Will > > wrote: > > > I've always felt that shimmy was related to an unbalanced wheel. We > routinely balance our automobile wheels, why would a bike be different? > > > > I think as we move to fatter tires (more mass) we will need to address > the balance issue. I think the frame discussion is irrelevant. > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
I dunno... Jan Heine has this to say: http://janheine.wordpress.com/2012/01/30/the-downsides-of-wide-tires/ Will On Tuesday, April 23, 2013 9:12:08 AM UTC-5, Tim McNamara wrote: > > Wheel balance on bikes is a red herring. The mass differences are too > small and the RPMs of a bike wheel are too slow. > > I have another anecdote that I don't have time to write at this time (at > work, should be working...) which should help demonstrate this. > > On Apr 23, 2013, at 8:35 AM, Will > > wrote: > > > I've always felt that shimmy was related to an unbalanced wheel. We > routinely balance our automobile wheels, why would a bike be different? > > > > I think as we move to fatter tires (more mass) we will need to address > the balance issue. I think the frame discussion is irrelevant. > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Shimmy is typically very speed dependent. When ride-buddy JimG was diagnosing his issue on a non-RBW bike, it shimmied in a very predictable pattern when using a front bag, rear load and unloaded. ). They were not equivalent speeds - 15, 18 and 21 mph IIRC. It's also extremely center of gravity dependent. I've seen it more with lighter, taller riders, and by sitting back and up, you are taking what little mass you have up off the pedals and pitching it back and behind. You might experiment slightly with the angle of your hips when you go no handed. The reason I mention this is that I've found minor differences in how I sit makes a great deal of difference in where the COG is located. It's not important on my RBW bicycles, but I have an older fixed-gear bike where weight distribution is a lot more critical. My suggestion for removing the saddlebag was really one of identifying variables. As far as differing speeds on differing hills: I'd go back to COG. The steeper hill does effectively move it forward. On the Jack Browns, after I got my first pair, I had to really force myself to go back and use up the old Paselas... - Jim On Tuesday, April 23, 2013 11:02:51 AM UTC-7, john wrote: > > Well, after removing the tire from the new wheel, remounting the tire to > ensure a perfect seal, and matching up the valve to the label for future > testing, and ensuring that the wheel was perfectly centered in the fork, I > got out for some more testing. > > One thing that has changed since my initial tests: I no longer provoke > shimmy at a slow speed, only a decent clip. However, when descending a hill > at moderate speed or fast speed, if I'm sitting upright with hands off the > bars, my Sam Hillborne will dance. Frustrating. > > Of course, Charlie is right: I could just right with my hands on the bars. > But for me, riding no-handed down hills not only is relaxing, but a great > joy. So at least for me, it's not an option. Or at least not one I'm > willing to consider at this time. > > And as others have suggested, i could ride without a saddlebag. But after > using saddlebags for 20 years, I wouldn't even know how to ride without my > beloved saddlebag. (And furthermore, although I'm sure a weighted saddlebag > is a factor, I have not had any significant weight in my saddlebag > throughout this discovery process. Not to mention when I ride the old wheel > with the same saddlebag, I experience no shimmy.) > > How to explain the initial shimmy at slow speeds and now only at higher > speeds on a steeper hill? Perhaps the tire is seated better than initially. > Perhaps the rubber of the tire has expanded over the course of a day. Who > knows? > > I guess the worst case scenario is I go back to my old wheel with > fantastic new Jack Brown Greens. Wow, I love those tires! I was > anticipating a let down, going from 35c Panaracer Pasellas to a "skinny" JB > 33.3c. To the contrary, I'm really loving the tires and don't notice the > width as being a factor. Time will tell about puncture resistance. But as > far as ride quality, much improved on the JBs. > > Thanks for everyone for sharing his opinions and anecdotes. Much, much > appreciated. I will update this thread if and when I am able to solve the > riddle. But I suspect I will just swap back to my old wheel for the time > being and quit worrying about it. > > If any of you out there is interested in a new Shimano Alfine generator > hub on a new Syngery Velocity 32 spoke wheel, I may just be willing to part > with it. > > thanks again for sharing. > John > > > On Tuesday, April 23, 2013 7:12:08 AM UTC-7, Tim McNamara wrote: >> >> Wheel balance on bikes is a red herring. The mass differences are too >> small and the RPMs of a bike wheel are too slow. >> >> I have another anecdote that I don't have time to write at this time (at >> work, should be working...) which should help demonstrate this. >> >> On Apr 23, 2013, at 8:35 AM, Will wrote: >> >> > I've always felt that shimmy was related to an unbalanced wheel. We >> routinely balance our automobile wheels, why would a bike be different? >> > >> > I think as we move to fatter tires (more mass) we will need to address >> the balance issue. I think the frame discussion is irrelevant. >> > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Check the spoke tension, trueness and roundness. You can check relative tension by plucking the spokes like a harp. In a front wheel all the spokes should ring out at the same pitch and should not be a dull thud- it should be a fairly bright note. Tension can be checked with a tensiometer, as well, but an experienced wheelbuilder could check without very quickly. Put the wheel in a truing stand or in the fork and sight along the brake pads as a guide to trueness and roundness as you spin it slowly. Tim On Apr 24, 2013, at 9:38 AM, john wrote: > > Is there a way to test the wheel? Test the hub? A set of criteria a mechanic > can focus on which would say: "yes, this hub - or wheel - isn't quite right"? > > On Tuesday, April 23, 2013 8:57:12 PM UTC-7, Reid wrote: > I once replaced a front wheel with a similar "professionally built" wheel on > a road bike with 27" wheels. Suddenly the bike shimmied. After much > aggravation, I found that the newly built wheel had "settled in," meaning it > had become the tiniest bit "flexy." Another wheel builder tightened it up to > spec and all was well. > > Reid > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
OK, the first shimmy anecdote of which I have two from personal experience. I used to own a Gunnar Crosshairs, which after I stopped racing was set up as a randonneuse. I rode that bike in the Alps and on PBP. I tried mounting my Nitto mini front rack on it one day, since it had rack braze-ons on the upgraded Waterford fork. The bike immediately developed a disconcerting shimmy while pedaling and coasting even with no load at all on the rack; removing the rack made the shimmy go away; putting the rack back on returned the shimmy and loading the rack with a couple of pounds made the shimmy much worse. This was with 700 x 28 tires. I decided this bike was a "rear loader" and used a saddlebag instead. The second shimmy anecdote was back in my racing days. I had a Bianchi Reparto Corsa which had the typical short chainstays and long top tube, which meant the bike popped wheelies on steep hills while climbing in the saddle. It also meant the bike felt like it was plowing through corners. I had two of those bikes and they were just not good-handling bikes; my Ritchey Road and my All-Rounder are much better handling bikes (and so was the Gunnar, which I used for road races and crits in between the Bianchis and the Ritchey). Anyway, that Bianchi scared the hell out of me when I was descending the High Bridge in St. Paul in a full aero tuck with my butt hanging way off the back of the saddle (there was a little trend for this started by Marco Pantani when he was descending that way and everyone thought "if a pro is doing it, it must be the way to descend"). The shimmy felt different and I determined later that it was probably the 9 speed rear wheel shimmying- I had so much weight over it (I am 6'4" and was a "skinny" 200 lbs in my racing days) that I reduced the spoke tension to much too low in the load affected area between the contact patch and the hub, destabilizing the wheel. When I got my weight forward, the shimmy stopped. A 9 speed wheel has so much dish that only the drive side spokes are supporting the vertical load- the non-drive side spokes are nearly slack. So, only two to four of the 16 spokes on that side were predominantly carrying my weight at any given time. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
On Wed, 2013-04-24 at 12:42 -0500, Tim McNamara wrote: > > Anyway, that Bianchi scared the hell out of me when I was descending > the High Bridge in St. Paul in a full aero tuck with my butt hanging > way off the back of the saddle (there was a little trend for this > started by Marco Pantani when he was descending that way and everyone > thought "if a pro is doing it, it must be the way to descend"). The > shimmy felt different and I determined later that it was probably the > 9 speed rear wheel shimmying- I had so much weight over it (I am 6'4" > and was a "skinny" 200 lbs in my racing days) that I reduced the spoke > tension to much too low in the load affected area between the contact > patch and the hub, destabilizing the wheel. When I got my weight > forward, the shimmy stopped. This is pretty clearly not shimmy, but rather speed wobble. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
What is the difference? On Wed, Apr 24, 2013 at 2:19 PM, Steve Palincsar wrote: > > > This is pretty clearly not shimmy, but rather speed wobble. > > -- http://resumespecialties.com/index.html patrickmo...@resumespecialties.com Albuquerque, NM -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
On Wed, 2013-04-24 at 14:33 -0600, PATRICK MOORE wrote: > What is the difference? http://www.cyclingtips.com.au/2011/03/speed-wobble-when-the-bike-shakes-its-head/ This is NOT the sort of thing you sometimes read about in BQ reviews, hands off at a particular speed, that Jan suggested curing with a roller bearing headset. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
On Apr 24, 2013, at 3:19 PM, Steve Palincsar wrote: > On Wed, 2013-04-24 at 12:42 -0500, Tim McNamara wrote: >> >> Anyway, that Bianchi scared the hell out of me when I was descending >> the High Bridge in St. Paul in a full aero tuck with my butt hanging >> way off the back of the saddle (there was a little trend for this >> started by Marco Pantani when he was descending that way and everyone >> thought "if a pro is doing it, it must be the way to descend"). The >> shimmy felt different and I determined later that it was probably the >> 9 speed rear wheel shimmying- I had so much weight over it (I am 6'4" >> and was a "skinny" 200 lbs in my racing days) that I reduced the spoke >> tension to much too low in the load affected area between the contact >> patch and the hub, destabilizing the wheel. When I got my weight >> forward, the shimmy stopped. > > This is pretty clearly not shimmy, but rather speed wobble. A shimmy is a shimmy. One was a front end shimmy, the other was a back end shimmy. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Hilarious that the slang terms "shimmy" and "speed wobble" invite a discussion of semantics. We may require some more exact language. On Wednesday, April 24, 2013 4:38:45 PM UTC-5, Tim McNamara wrote: > > On Apr 24, 2013, at 3:19 PM, Steve Palincsar wrote: > > On Wed, 2013-04-24 at 12:42 -0500, Tim McNamara wrote: > >> > >> Anyway, that Bianchi scared the hell out of me when I was descending > >> the High Bridge in St. Paul in a full aero tuck with my butt hanging > >> way off the back of the saddle (there was a little trend for this > >> started by Marco Pantani when he was descending that way and everyone > >> thought "if a pro is doing it, it must be the way to descend"). The > >> shimmy felt different and I determined later that it was probably the > >> 9 speed rear wheel shimmying- I had so much weight over it (I am 6'4" > >> and was a "skinny" 200 lbs in my racing days) that I reduced the spoke > >> tension to much too low in the load affected area between the contact > >> patch and the hub, destabilizing the wheel. When I got my weight > >> forward, the shimmy stopped. > > > > This is pretty clearly not shimmy, but rather speed wobble. > > A shimmy is a shimmy. One was a front end shimmy, the other was a back > end shimmy. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
On Wednesday, April 24, 2013 10:29:21 AM UTC-7, Tim McNamara wrote: > > Check the spoke tension, trueness and roundness. You can check relative > tension by plucking the spokes like a harp. In a front wheel all the > spokes should ring out at the same pitch and should not be a dull thud- it > should be a fairly bright note. Tension can be checked with a tensiometer, > as well, but *an experienced wheelbuilder could check without very quickly > *. Put the wheel in a truing stand or in the fork and sight along the > brake pads as a guide to trueness and roundness as you spin it slowly. > Not being the complete mechanic, an experienced wheelbuilder is what worked for me. Reid -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Well... I hate to be pedantic about semantics, but words is all we've got here. I think it's helpful if we agree that "Shimmy" is what Jobst describes - specific oscillation of the front end of the bicycle - "the lateral oscillation of the head tube about the road contact point of the front wheel" which causes spontaneous steering oscillation of the front wheel. There are certainly enough variables in the motion of the bicycle that causes shudders - having a wheel out of round will cause it to oscillate, and out of true causes side-to-side vibration. These tend to be speed-specific, but are different phenomena than what is being discussed here. - J -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
I have two road bikes and they both shimmy, so I sort of feel like a crash test dummy for the shimmy phenomena. Wind seems to makes things worse as do imperfections in the road surface. My racing bike has tried to kill me on occasion. My Rivendell scares me when it starts to shimmy, but it doesn't approach the level of violence that my racing bike exhibits. I can keep riding my Rivendell at the same speed when it starts to shimmy and not crash. Although, with both bikes the shimmy scares me enough that I rapidly scrub speed until the shimmy stops. On my racing bike that usually means scrubbing speed from ~40mph to under 15mph while I hang on for dear life. I ride large frames and I attribute the shimmy to the greater flex in the longer tubes. Based on my experiences, I believe tubes need to be stiffer as frames get larger. Using the same tube set on a 56cm and a 65cm frame seems problematic to me. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
I ride where it is very windy (a lot of cross winds) and do get what you are describing, but its not so much a shimmy as it is an "unsteadiness"--damn I wish there was some book of bicycle verbiage out there! On Thu, Apr 25, 2013 at 1:59 AM, samh wrote: > I have two road bikes and they both shimmy, so I sort of feel like a crash > test dummy for the shimmy phenomena. Wind seems to makes things worse as > do imperfections in the road surface. My racing bike has tried to kill me > on occasion. My Rivendell scares me when it starts to shimmy, but it > doesn't approach the level of violence that my racing bike exhibits. I can > keep riding my Rivendell at the same speed when it starts to shimmy and not > crash. Although, with both bikes the shimmy scares me enough that I > rapidly scrub speed until the shimmy stops. On my racing bike that usually > means scrubbing speed from ~40mph to under 15mph while I hang on for dear > life. > > I ride large frames and I attribute the shimmy to the greater flex in the > longer tubes. Based on my experiences, I believe tubes need to be stiffer > as frames get larger. Using the same tube set on a 56cm and a 65cm frame > seems problematic to me. > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to rbw-owners-bunch+unsubscr...@googlegroups.com. > To post to this group, send email to rbw-owners-bunch@googlegroups.com. > Visit this group at > http://groups.google.com/group/rbw-owners-bunch?hl=en-US. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
On Wed, 2013-04-24 at 22:59 -0700, samh wrote: > I have two road bikes and they both shimmy, so I sort of feel like a > crash test dummy for the shimmy phenomena. Wind seems to makes things > worse as do imperfections in the road surface. My racing bike has > tried to kill me on occasion. My Rivendell scares me when it starts > to shimmy, but it doesn't approach the level of violence that my > racing bike exhibits. I can keep riding my Rivendell at the same > speed when it starts to shimmy and not crash. Although, with both > bikes the shimmy scares me enough that I rapidly scrub speed until the > shimmy stops. On my racing bike that usually means scrubbing speed > from ~40mph to under 15mph while I hang on for dear life. The usual cures for speed wobble involve getting your butt up off the saddle a little, and clamping the top tube with your knees. Have you ever tried those remedies? -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Crosswinds are a different animal. Probably deserve a separate thread. I was actually working on a blog post about that, following the very windy ride of a couple weeks ago. Overheard several conversations which included advice on how to deal with crosswinds that was at best wrong, at worst dangerous. - J On Thursday, April 25, 2013 8:43:23 AM UTC-7, Peter M wrote: > > I ride where it is very windy (a lot of cross winds) and do get what you > are describing, but its not so much a shimmy as it is an > "unsteadiness"--damn I wish there was some book of bicycle verbiage out > there! > > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
I went out today hell-bent on proving a theory: namely, that my new wheel was the cause of shimmy. Unfortunately, I discovered something else again - perhaps my theory is incorrect. I set out with my old wheel and new tire. Saddlebag loaded with the usual suspects: (mini U-lock, tool kit, a few toe straps and bungees, a couple spare tubes). The saddle bag isn't light (Baggins Adam). I'm guessing the bag plus goods weighs roughly 5 pounds. Could be more, I dunno. Never weighed the kit, never wanted to. Climbed a good 1000' hill in my neck of the woods, to the top of my immediate valley. Thence, the descent. I wanted to see if I could reproduce the shimmy I'd experienced yesterday with the new wheel, but this time, with the old wheel. As a matter of fact, I did reproduce shimmy in the old wheel. Doggawnit! The shimmy was not nearly as fierce as that with the new wheel (which is rater scary), but it is subtly present. As in, I need to grab the top tube with my knees to make things right. With the new wheel, i need to grab the wheel with my knees to make things partly right, then grab hold of the bars with my hands. I have been very happy with my Sam HIll. But If there were one thing I would change about it, I'd ditch the 6% upsloping top tube. This is purely from aesthetical considerations. However, I'm wondering now if samh doesn't have something right when he speaks of large frames needing extra stiffness to ward off shimmy. Maybe (and I hope I'm wrong) my 60 cm frame, with very tall head tube, is flexy enough to produce shimmy when a skinny guy like me descends a steep hill, sitting up, without weight over the front of the bike. Tomorrow I'm going out again, with the old wheel, new tire, and no saddlebag. That is to say, no additional weight of any kind, other than my 150#, front and rear racks, Zefal pump, and a couple of water bottles. Oh, and an "under saddle" bag which I usually just toss nonchalantly in my capacious saddlebag because why not? Maybe I'll not be able to produce shimmy? I doubt it, but I can hope. I really don't want the bike's fleeciness and height to be the cause of this problem. (Granted, the shimmy with the old wheel is not severe, and it's something I can live with, but I'd much rather not.) On Thursday, April 25, 2013 6:03:48 PM UTC-7, Cyclofiend Jim wrote: > > Crosswinds are a different animal. Probably deserve a separate thread. > > I was actually working on a blog post about that, following the very windy > ride of a couple weeks ago. Overheard several conversations which included > advice on how to deal with crosswinds that was at best wrong, at worst > dangerous. > > - J > > On Thursday, April 25, 2013 8:43:23 AM UTC-7, Peter M wrote: >> >> I ride where it is very windy (a lot of cross winds) and do get what you >> are describing, but its not so much a shimmy as it is an >> "unsteadiness"--damn I wish there was some book of bicycle verbiage out >> there! >> >> >> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
On Thu, 2013-04-25 at 23:25 -0700, john wrote: > > I have been very happy with my Sam HIll. But If there were one thing I > would change about it, I'd ditch the 6% upsloping top tube. This is > purely from aesthetical considerations. However, I'm wondering now if > samh doesn't have something right when he speaks of large frames > needing extra stiffness to ward off shimmy. Maybe (and I hope I'm > wrong) my 60 cm frame, with very tall head tube, is flexy enough to > produce shimmy when a skinny guy like me descends a steep hill, > sitting up, without weight over the front of the bike. There's no Rivendell that's anywhere near as flexible as my 60 cm MAP Randonneur (8/5/8 std diam tubing vs OS Riv tubing) and the MAP does not shimmy. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
I'm sorry to hear you are having this experience with your Sam H. I too am a 60cm Sam owner. In fact, I've had two: first an orange single tt canti version, and now a double tt blue side pull variant. I have never experienced any shimmy or wobble on either. Actually, my experiencd has always been the opposite. The Sam H's have been the smoothest, stable-est, most wonderful bikes to ride that I have ever had the pleasure to ride. However, I have only ever had small saddle bags with light loads in them. One of my greatest pleasures during a ride is the ability, on a descent, to momentarily take my hands off the bars to open and take a pull from my bottle. I'm always struck by the frames stability at those times. In crosswinds even! No matter... I wonder if its possible that your particular frame could have an alignment issue develop for one reason or another? Maybe worth considering if you can't solve it moving things around. Maybe have your LBS check it out. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Years ago some dude on here had a shimmying Rambouillet. He apparently solved the problem by installing a thick, heavy thorn-resistant tube in his front tire. At the time, I thought he was a kook, but you never know. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
I ride three largish Rivendells, a road custom (61.5cm), Legolas (62), and a Quickbeam (60). None shimmy, not one bit. A fourth early Allrounder (58cm for 26 inch wheels) is super flexible made from Reynolds 753 tubing. It doesn't shimmy either. The Quickbeam has a front basket and the Allrounder most often carries a front Acorn bag. Still no shimmy. Shimmy is mysterious but med-high trail designs such as Rivendells tend to limit shimmy. Back in The Day I raced on a Dave Moulton Fuso 58cm frame (for sale, make an offer! http://www.flickr.com/photos/79695460@N00/400396875/in/set-72157607471577085 ). Dave claimed his high trail design and short top tubes eliminated shimmy on his frames. It has always been rock solid. Jan Heine has posited that stiff chainstays in relation to flexible top tubes help minimize shimmy. On Friday, April 26, 2013 7:51:39 AM UTC-6, Jim Thill - Hiawatha Cyclery wrote: > Years ago some dude on here had a shimmying Rambouillet. He apparently > solved the problem by installing a thick, heavy thorn-resistant tube in his > front tire. At the time, I thought he was a kook, but you never know. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
William: You know, I did have an alignment issue: I was hit by a car. I got a new fork from Rivendell to replace the original, which was bent. The new fork is for side pull whereas my original was a canti fork. I actually never thought of this until now, because with the new fork, the bike has ridden fine. (I've been riding the new fork for about a year.) I guess it could be that small imperfections in the rest of the frame may actually be causing the shimmy. I certainly hope not, but it could be. Another interesting story: My first Sam H. (2009 I think, first generation green) was a fun bike, but I always felt it was running slightly off true. I consulted with Riv and they said, "try riding on a windless day on a flat road without significant coping, eyes closed, and see how it feels" and etc. They suggested I remove saddlebag, any excess, to see if I still felt the alignment issue (it veered to the right). Well, I did all those things, and it still felt off. I eventually returned it to Riv so they could take a look-see. Turns out it was out of alignment. Great thing about Riv, they apologized and sent me a new bike - this one the new orange. I mention this because something one can't necessarily see with the naked eye can have such a profound effect on a bike's handling. With the first Sam, I just knew there was something off, although I couldn't place what it was (I'm no mechanic). I rode that bike for about 3 months, and came back from most rides feeling that it was a great bike, but...And since it was a new bike, I couldn't imagine it could be defective - especially coming from Riv. When I rode the orange Sam, it immediately felt wonderful. It was a real Ahaa! moment. "So I wasn't crazy after all, this is how it's supposed to feel." I want that feeling back. I'm going to keep digging. I seriously hope that wreck had nothing to do with this issue, but I guess I ought to be a consideration. It honestly never occurred to me until reading your post because in other ways, it rides like a dream. By the way, I'd be curious to know if you notice a different ride sensation between the single TT and double TT? John On Friday, April 26, 2013 5:23:52 AM UTC-7, William R. wrote: > > I'm sorry to hear you are having this experience with your Sam H. I too am > a 60cm Sam owner. In fact, I've had two: first an orange single tt canti > version, and now a double tt blue side pull variant. I have never > experienced any shimmy or wobble on either. Actually, my experiencd has > always been the opposite. The Sam H's have been the smoothest, stable-est, > most wonderful bikes to ride that I have ever had the pleasure to ride. > However, I have only ever had small saddle bags with light loads in them. > One of my greatest pleasures during a ride is the ability, on a descent, to > momentarily take my hands off the bars to open and take a pull from my > bottle. I'm always struck by the frames stability at those times. In > crosswinds even! No matter... I wonder if its possible that your particular > frame could have an alignment issue develop for one reason or another? > Maybe worth considering if you can't solve it moving things around. Maybe > have your LBS check it out. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
While you're investigating frame alighnment, it might not hurt to try a new headset. The standard issue Hillborne headsets are not the greatest. I don't think you need to hunt down an obsolete needle bearing headset, though. Something with cartridge bearings would be nice. Ask your lbs to face the head tube before installation. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
I repeat my suspicion of the head set. If it doesn't need adjustment and you want a new one, I highly recommend the Cane Creek. On Friday, April 26, 2013 10:47:44 AM UTC-4, Jim Thill - Hiawatha Cyclery wrote: > > While you're investigating frame alighnment, it might not hurt to try a > new headset. The standard issue Hillborne headsets are not the greatest. I > don't think you need to hunt down an obsolete needle bearing headset, > though. Something with cartridge bearings would be nice. Ask your lbs to > face the head tube before installation. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Thanks for the suggestion Michael. I'll be looking into the headset early next week. On Friday, April 26, 2013 9:32:20 AM UTC-7, Michael Hechmer wrote: > > I repeat my suspicion of the head set. If it doesn't need adjustment and > you want a new one, I highly recommend the Cane Creek. > > On Friday, April 26, 2013 10:47:44 AM UTC-4, Jim Thill - Hiawatha Cyclery > wrote: >> >> While you're investigating frame alighnment, it might not hurt to try a >> new headset. The standard issue Hillborne headsets are not the greatest. I >> don't think you need to hunt down an obsolete needle bearing headset, >> though. Something with cartridge bearings would be nice. Ask your lbs to >> face the head tube before installation. > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Hi John. Sounds like you have a lot of things you can try this weekend to try to solve your issue. In addition to considering getting your alignment checked, I would also suggest the headset too. The headset that Riv sent with my frame went indexed steering on me in short order. I wasn't comfortable taking my hands off the bars until I put a King headset on. Smooth sailing. Getting back to you on the single tt vs double tt: there are some nuances that I've noticed. Mostly it is a small degree stiffer. I run my tires a bit softer because of that. It's not issue-worth-mentioning really. On the plus side I find the bike easier to portage with the lower tt. The bike is more balanced as I run or walk with it. It's a nice feeling with the bike on my shoulder just holding the stem lightly with the same hand. The other hand free for balance while crossing un-rideable obstacles and such. The biggest deal for me was the brakes. I really didn't like messing with the canti's on the original. It seemed like every time I touched them it took me an hour to get them back into adjustment! I pined for one of Rivs bikes with the silver brakes on them. When Grant had that initial special on the "bleu" Sams I jumped at it. All is well now. I hope you can get everything set up to your liking with yours. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Miche and Velo Orange both offer 1" threaded needle bearing headsets, if it comes to that. On Friday, April 26, 2013 7:47:44 AM UTC-7, Jim Thill - Hiawatha Cyclery wrote: > > While you're investigating frame alighnment, it might not hurt to try a > new headset. The standard issue Hillborne headsets are not the greatest. I > don't think you need to hunt down an obsolete needle bearing headset, > though. Something with cartridge bearings would be nice. Ask your lbs to > face the head tube before installation. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
As does a certain company in Walnut Creek - http://www.rivbike.com/product-p/hsrd.htm On Friday, April 26, 2013 3:26:33 PM UTC-7, William wrote: > > Miche and Velo Orange both offer 1" threaded needle bearing headsets, if > it comes to that. > > > On Friday, April 26, 2013 7:47:44 AM UTC-7, Jim Thill - Hiawatha Cyclery > wrote: >> >> While you're investigating frame alighnment, it might not hurt to try a >> new headset. The standard issue Hillborne headsets are not the greatest. I >> don't think you need to hunt down an obsolete needle bearing headset, >> though. Something with cartridge bearings would be nice. Ask your lbs to >> face the head tube before installation. > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
How are those headsets different from the standard headsets supplied by Riv? On Friday, April 26, 2013 4:26:33 PM UTC-6, William wrote: > > Miche and Velo Orange both offer 1" threaded needle bearing headsets, if > it comes to that. > > > On Friday, April 26, 2013 7:47:44 AM UTC-7, Jim Thill - Hiawatha Cyclery > wrote: >> >> While you're investigating frame alighnment, it might not hurt to try a >> new headset. The standard issue Hillborne headsets are not the greatest. I >> don't think you need to hunt down an obsolete needle bearing headset, >> though. Something with cartridge bearings would be nice. Ask your lbs to >> face the head tube before installation. > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Standard headsets typically use round ball bearings on both the upper and lower races. Depending upon the design, the others use needle bearings on both the top and bottom or just on the bottom. The description on the RBW page does a pretty good job of describing the differences. - J On Monday, April 29, 2013 4:32:05 PM UTC-7, samh wrote: > > How are those headsets different from the standard headsets supplied by > Riv? > > On Friday, April 26, 2013 4:26:33 PM UTC-6, William wrote: >> >> Miche and Velo Orange both offer 1" threaded needle bearing headsets, if >> it comes to that. >> >> >> On Friday, April 26, 2013 7:47:44 AM UTC-7, Jim Thill - Hiawatha Cyclery >> wrote: >>> >>> While you're investigating frame alighnment, it might not hurt to try a >>> new headset. The standard issue Hillborne headsets are not the greatest. I >>> don't think you need to hunt down an obsolete needle bearing headset, >>> though. Something with cartridge bearings would be nice. Ask your lbs to >>> face the head tube before installation. >> >> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
That's a fairly new item at RBW, no? -J -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
IMO, the needle beating headsets were an improvement when they came on the scene (in the age of crummy headsets), but in this day and age, I don't know why anybody would bother. I believe Cane Creek, King, FSA, VO, and perhaps others, all make/sell cartridge bearing headsets. The Shimano 105/Ultegra/DA headsets discontinued a few years ago are excellent and still floating around. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Needle bearing headsets have quite a lot of drag, even when adjusted perfectly. For that reason alone, needle bearing headsets are a pretty common remedy for shimmy. I don't have first hand experience curing shimmy with one. This type of front end shimmy is usually considered a harmonic oscillator, which is modeled in math as a spring/mass/damper. The wikipedia page on Damping has the math. Moderate to severe shimmy on a bicycle will continue indefinitely until you grab the bars or squeeze the top tube with your knees, which is typical of an underdamped system. The ways to get out of that are to change the frequency of your oscillation (difficult and/or confusing guesswork) or add damping. Your hands on the bars adds damping. A steering damper adds damping. A headset with some drag adds damping. There are many anecdotal reports out there that "my bike shimmied like crazy on my ride to the shop, where we installed a needlebearing headset. The ride home on the identical bike I could not make it shimmy". The model that Riv sells is only half-needle bearing. Maybe that's enough damping. It's an empirical question. On Tuesday, April 30, 2013 8:50:27 AM UTC-7, Jim Thill - Hiawatha Cyclery wrote: > > IMO, the needle beating headsets were an improvement when they came on the > scene (in the age of crummy headsets), but in this day and age, I don't > know why anybody would bother. > > I believe Cane Creek, King, FSA, VO, and perhaps others, all make/sell > cartridge bearing headsets. The Shimano 105/Ultegra/DA headsets > discontinued a few years ago are excellent and still floating around. > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
For those of you all who are still interested in my quest for perfection, I've got some news to report. I finally got the bike over to my ace mechanic for some evaluation. He performed several steps in the discovery process: 1. checked the new front wheel for dish, true, tension. Discovered that the wheel was very slightly out of tension. Fixed it. 2. Checked the rear wheel. It was perfect. 3. Checked the old front wheel. It too, was perfect. 4. Popped open the cockpit, removed the headset, inspected. It looked good to him. Although he has needle bearing headsets, he suggested we just try re-facing the one I had. So that's what he did. I am happy to report that when I descended my local volcanic plug dome today (my testing grounds as it's close to home and provides a long hill with swooping turns), I got no shimmy with either the old wheel, or the new wheel. Rode like the Riv. of old! However, this was with no saddlebag. In investigating the possible causes of the shimmy, I've taken everyone's advice, and yes, I've resorted to trying the bike without the saddlebag. It turns out, the saddlebag, with a typical load, weighs 6.5#. The under saddle tube-an d-tool bag, just 1#. Tomorrow morning I will head out once more, this time with my typically loaded saddlebag. First with the new wheel. If there's no shimmy, it ought to tell me one of two things. Either the wheel was the problem, or the headset needed re-facing. Either way, I will be a happy camper. If the bike shimmies, I'll swap to my old wheel, and try again, and see if there's a difference. John On Tuesday, April 30, 2013 9:32:35 AM UTC-7, William wrote: > > Needle bearing headsets have quite a lot of drag, even when adjusted > perfectly. For that reason alone, needle bearing headsets are a pretty > common remedy for shimmy. I don't have first hand experience curing shimmy > with one. > > This type of front end shimmy is usually considered a harmonic oscillator, > which is modeled in math as a spring/mass/damper. The wikipedia page on > Damping has the math. Moderate to severe shimmy on a bicycle will continue > indefinitely until you grab the bars or squeeze the top tube with your > knees, which is typical of an underdamped system. The ways to get out of > that are to change the frequency of your oscillation (difficult and/or > confusing guesswork) or add damping. Your hands on the bars adds damping. > A steering damper adds damping. A headset with some drag adds damping. > There are many anecdotal reports out there that "my bike shimmied like > crazy on my ride to the shop, where we installed a needlebearing headset. > The ride home on the identical bike I could not make it shimmy". > > The model that Riv sells is only half-needle bearing. Maybe that's enough > damping. It's an empirical question. > > On Tuesday, April 30, 2013 8:50:27 AM UTC-7, Jim Thill - Hiawatha Cyclery > wrote: >> >> IMO, the needle beating headsets were an improvement when they came on >> the scene (in the age of crummy headsets), but in this day and age, I don't >> know why anybody would bother. >> >> I believe Cane Creek, King, FSA, VO, and perhaps others, all make/sell >> cartridge bearing headsets. The Shimano 105/Ultegra/DA headsets >> discontinued a few years ago are excellent and still floating around. >> > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
My 1998 LongLow has always shimmied on descents - yes, I like to take my hands off the bars, but it was also sensed with hands on - and so I thought a set of the new hotness needle roller bearings would be a good thing to try. Placed an order, and coincidentally dropped the forks out today to get the canti boss fixed (by Ed Litton, in Richmond CA). Loe and behold... what do I see at the bottom of my headseat, but a needle roller bearing, with a brinnelled race. I'll look at it all more closely this weekend. - Andrew, Berkeley -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
Re: [RBW] Re: Yet another post on shimmy
Andrew, I'd be interesting in hearing about your project. As for me, after a couple weeks of fiddling about with this, that, and the other, I've come to some conclusions. 1. My Sam shimmies down hills either with a dynohub wheel or a non-dyno wheel. 2. My Sam shimmies with a rear load or without a rear load, although it's more pronounced with a rear load. 3. In attempting to solve the riddle, my ace mechanic checked all wheels (front, back, dyno, non-dyno) for true, dish, tension. He checked frame alignment, he re-faced the headset. It is his opinion that a roller bearing headset is not necessarily a panacea, and that it may or may not help. 4. Still, the bike shimmies on descents. 5. Although the bike shimmies, I can quiet her down with knees locked around top tube or a hand on the bars. 6. I noticed if I mount my Baggins Adam saddlebag to the front rack the stability is much improved. (Bag+goods = 6.5#) Perhaps this is heavier than I ought to, but I'm now thinking I can try a front loading bag (I want a Berthoud 28, their tallest) and see how it goes. Thanks to all for encouragement in solving the riddle. In the end, i'm not sure why the Sam shimmies. In the end, I still love the bike. I'd just love it more without the shimmy. On Wednesday, May 1, 2013 8:43:23 PM UTC-7, BSWP wrote: > > My 1998 LongLow has always shimmied on descents - yes, I like to take my > hands off the bars, but it was also sensed with hands on - and so I thought > a set of the new hotness needle roller bearings would be a good thing to > try. Placed an order, and coincidentally dropped the forks out today to get > the canti boss fixed (by Ed Litton, in Richmond CA). Loe and behold... what > do I see at the bottom of my headseat, but a needle roller bearing, with a > brinnelled race. > > I'll look at it all more closely this weekend. > > - Andrew, Berkeley > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
