[RBW] Re: Stem Strength
When we tested bikes for heavy front loads, we found that the flex of a quill stem did cause some trouble. There was a slight lag of the fork after the steering input. This was with 30 lbs. on a porteur rack... In normal riding, even with fully loaded front low-rider panniers (which are much closer to the steering axis than a porteur rack), I haven't felt this, and I doubt it would be an issue even for a strong rider. The front fork and wheel of most bikes has too little inertia to make itself felt that way. The flex of the stem does not appear to be the problem - my Grand Bois Urban Bike is equipped with a very flexible Alex Singer stem. The stem flexes so much that my hands touch the load as I torque (slightly) on the handlebars. However, because the stem clamps directly to the steerer tube, the handling is lag-free even with a heavy front load. It's the quill in the steerer that appears to be the cause of the flex that causes the lag in the steering. (We had four testers ride the bikes without sharing their experiences until after the testing was over, and all commented on this, so it's not a placebo effect.) However, I'd like to stress that this is an issue only with heavy front loads. For a porteur bike, I feel that a clamp-on stem is preferable to a traditional quill stem. Otherwise, I don't see much advantages one way or the other. Jan Heine Editor Bicycle Quarterly http://www.bikequarterly.com Follow our blog at http://janheine.wordpress.com/ -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Stem Strength
Ok, so the steel stem has a larger OD AND a stiffer modulus. Staying on the back of an envelope, the ratio of 31.6^2 to 22.2^2 is about 2. In which case your calc requires the ratio of moduli to be about 5. For steel it's about 30,000 ksi and for aluminum it's about 10,000 ksi. Not bad, for the back of an envelope, and no finite element work!! On Sat, May 7, 2011 at 1:15 AM, James Valiensi valie...@mac.com wrote: Hey, My back of the envelope calc's indicate a standard aluminum quill stem will deflect about ten times more than a steel stem. This is with equal extensions lengths and loads, and the aluminum stem has a solid 22.2mm diameter extension, and the steel stem is 31.8mm OD w/ 25.4mm ID extension. The extension into the fork vs. clamping on the outside of the fork are not significant here. By the way, neither stem deflects that much. If you really want a stiff stem, use a short extension, and big diameter. And steel too. And you know why they went to 31.8mm diameter handle bars? Because of the stinking cable grooves. The grooves make the bar section too flexible, the bigger diameter overcame this. Cheers! James Valiensi, PE Northridge, CA H818.775.1847 M.818.585.1796 On May 6, 2011, at 6:44 PM, Philip Williamson wrote: When I got my Quickbeam, I tried a couple of stems, including the stock Technomic Deluxe and the Nitto Dirt Drop. Both flexed noticeably more than the Salsa welded stem I ended up with. The Dirt Drop not as much as the Technomic Deluxe, but the quill was bottomed out in the steerer. Philip On May 6, 9:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- Ken Freeman Ann Arbor, MI USA -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Stem Strength
Actual, the polar moment of inertia is to the 4th power: PI()(D^4-d^4)/32. Cheers! James Valiensi, PE Northridge, CA H818.775.1847 M.818.585.1796 On May 7, 2011, at 5:29 AM, Ken Freeman wrote: Ok, so the steel stem has a larger OD AND a stiffer modulus. Staying on the back of an envelope, the ratio of 31.6^2 to 22.2^2 is about 2. In which case your calc requires the ratio of moduli to be about 5. For steel it's about 30,000 ksi and for aluminum it's about 10,000 ksi. Not bad, for the back of an envelope, and no finite element work!! On Sat, May 7, 2011 at 1:15 AM, James Valiensi valie...@mac.com wrote: Hey, My back of the envelope calc's indicate a standard aluminum quill stem will deflect about ten times more than a steel stem. This is with equal extensions lengths and loads, and the aluminum stem has a solid 22.2mm diameter extension, and the steel stem is 31.8mm OD w/ 25.4mm ID extension. The extension into the fork vs. clamping on the outside of the fork are not significant here. By the way, neither stem deflects that much. If you really want a stiff stem, use a short extension, and big diameter. And steel too. And you know why they went to 31.8mm diameter handle bars? Because of the stinking cable grooves. The grooves make the bar section too flexible, the bigger diameter overcame this. Cheers! James Valiensi, PE Northridge, CA H818.775.1847 M.818.585.1796 On May 6, 2011, at 6:44 PM, Philip Williamson wrote: When I got my Quickbeam, I tried a couple of stems, including the stock Technomic Deluxe and the Nitto Dirt Drop. Both flexed noticeably more than the Salsa welded stem I ended up with. The Dirt Drop not as much as the Technomic Deluxe, but the quill was bottomed out in the steerer. Philip On May 6, 9:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- Ken Freeman Ann Arbor, MI USA -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
[RBW] Re: Stem Strength
I suspect that the introduction of carbon fiber bars had something to do with the introduction of 31.8 mm bars as well. Bill On May 6, 10:15 pm, James Valiensi valie...@mac.com wrote: Hey, My back of the envelope calc's indicate a standard aluminum quill stem will deflect about ten times more than a steel stem. This is with equal extensions lengths and loads, and the aluminum stem has a solid 22.2mm diameter extension, and the steel stem is 31.8mm OD w/ 25.4mm ID extension. The extension into the fork vs. clamping on the outside of the fork are not significant here. By the way, neither stem deflects that much. If you really want a stiff stem, use a short extension, and big diameter. And steel too. And you know why they went to 31.8mm diameter handle bars? Because of the stinking cable grooves. The grooves make the bar section too flexible, the bigger diameter overcame this. Cheers! James Valiensi, PE Northridge, CA H818.775.1847 M.818.585.1796 On May 6, 2011, at 6:44 PM, Philip Williamson wrote: When I got my Quickbeam, I tried a couple of stems, including the stock Technomic Deluxe and the Nitto Dirt Drop. Both flexed noticeably more than the Salsa welded stem I ended up with. The Dirt Drop not as much as the Technomic Deluxe, but the quill was bottomed out in the steerer. Philip On May 6, 9:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Stem Strength
With carbon fiber, all the old standards are thrown out! James Valiensi, PE Northridge, CA H818.775.1847 M.818.585.1796 On May 7, 2011, at 7:01 AM, Bill M. wrote: I suspect that the introduction of carbon fiber bars had something to do with the introduction of 31.8 mm bars as well. Bill On May 6, 10:15 pm, James Valiensi valie...@mac.com wrote: Hey, My back of the envelope calc's indicate a standard aluminum quill stem will deflect about ten times more than a steel stem. This is with equal extensions lengths and loads, and the aluminum stem has a solid 22.2mm diameter extension, and the steel stem is 31.8mm OD w/ 25.4mm ID extension. The extension into the fork vs. clamping on the outside of the fork are not significant here. By the way, neither stem deflects that much. If you really want a stiff stem, use a short extension, and big diameter. And steel too. And you know why they went to 31.8mm diameter handle bars? Because of the stinking cable grooves. The grooves make the bar section too flexible, the bigger diameter overcame this. Cheers! James Valiensi, PE Northridge, CA H818.775.1847 M.818.585.1796 On May 6, 2011, at 6:44 PM, Philip Williamson wrote: When I got my Quickbeam, I tried a couple of stems, including the stock Technomic Deluxe and the Nitto Dirt Drop. Both flexed noticeably more than the Salsa welded stem I ended up with. The Dirt Drop not as much as the Technomic Deluxe, but the quill was bottomed out in the steerer. Philip On May 6, 9:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
[RBW] Re: Stem Strength
I was out riding today and thinking about this issue. Now today I had the lugged Nitto steel stem on my Rando bike , about 7cm of quill showing. If there is some flex, I sure can't tell. But, similarly on the Ram with a Nitto Pearl and about 6cm to center of stem there was still Nothing. As I was climbing out of the saddle, I was analyzing my technique. I learned a long time ago that you let the bike move and you keep your body steady. That way there is little force on the stem and bars to make them deflect. ~mike On May 7, 2:06 pm, Ken Freeman kenfreeman...@gmail.com wrote: OHH! I knew that, once upon a time! Cheers, back! On Saturday, May 7, 2011, James Valiensi valie...@mac.com wrote: Actual, the polar moment of inertia is to the 4th power: PI()(D^4-d^4)/32.Cheers! James Valiensi, PENorthridge, CAH818.775.1847 M.818.585.1796 On May 7, 2011, at 5:29 AM, Ken Freeman wrote: Ok, so the steel stem has a larger OD AND a stiffer modulus. Staying on the back of an envelope, the ratio of 31.6^2 to 22.2^2 is about 2. In which case your calc requires the ratio of moduli to be about 5. For steel it's about 30,000 ksi and for aluminum it's about 10,000 ksi. Not bad, for the back of an envelope, and no finite element work!! On Sat, May 7, 2011 at 1:15 AM, James Valiensi valie...@mac.com wrote: Hey, My back of the envelope calc's indicate a standard aluminum quill stem will deflect about ten times more than a steel stem. This is with equal extensions lengths and loads, and the aluminum stem has a solid 22.2mm diameter extension, and the steel stem is 31.8mm OD w/ 25.4mm ID extension. The extension into the fork vs. clamping on the outside of the fork are not significant here. By the way, neither stem deflects that much. If you really want a stiff stem, use a short extension, and big diameter. And steel too. And you know why they went to 31.8mm diameter handle bars? Because of the stinking cable grooves. The grooves make the bar section too flexible, the bigger diameter overcame this. Cheers! James Valiensi, PE Northridge, CA H818.775.1847 M.818.585.1796 On May 6, 2011, at 6:44 PM, Philip Williamson wrote: When I got my Quickbeam, I tried a couple of stems, including the stock Technomic Deluxe and the Nitto Dirt Drop. Both flexed noticeably more than the Salsa welded stem I ended up with. The Dirt Drop not as much as the Technomic Deluxe, but the quill was bottomed out in the steerer. Philip On May 6, 9:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To
[RBW] Re: Stem Strength
Definitely. I weigh 245 and raise my stem to the max insertion line (never beyond). And this is with the Nitto Dirt Drop; not a flimsy cheap stem. And, since I believe Nitto tests the hell out of their products, the fact that my stem flexes a little sometimes doesn't bother me in the slightest. (It might bother me if it wasn't in a good steel fork's steerer.) On May 6, 5:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
[RBW] Re: Stem Strength
Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
[RBW] Re: Stem Strength
Is he he sure it's the stem that's moving? Based on the forces that are applied rididng out of the saddle and the different cross sectional areas, I would think that the bar is what's moving the most. Both move some amount. I've never usd the taller Nitto Technomic stems ( if that's what your son has) but on the Pearl model I've never felt stem flex and I'm also larger than your son. ~mike On May 6, 6:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael- Hide quoted text - - Show quoted text - -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
[RBW] Re: Stem Strength
Mike, I can say without question that it is my Tech Delux that moves around under torque loads. I have the same RM013 bars on bikes with both different styles of stems. On my Rawland with the threadless setup you can feel the spring in the drops rotating primarily around the about the same axis as the bar tops. But on the Roado I have flex in the stem along the front to back axis of the stem extension before the bars start to give. Enough that you can see it moving around on steep climbs. I have been looking for an economical (read deal on Ebay) welded or lugged stem to compare, but most are either really short on extension, beat up or Rob - http://oceanaircycles.com/ On May 6, 7:13 am, Michael_S mikeybi...@rocketmail.com wrote: Is he he sure it's the stem that's moving? Based on the forces that are applied rididng out of the saddle and the different cross sectional areas, I would think that the bar is what's moving the most. Both move some amount. I've never usd the taller Nitto Technomic stems ( if that's what your son has) but on the Pearl model I've never felt stem flex and I'm also larger than your son. ~mike On May 6, 6:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
[RBW] Re: Stem Strength
I use Noodles on 3 bikes with 3 different stems. The flex characteristics out on the hoods is different for all three. The Tech DLX 11cm extension feels the flexiest. It feels a lot less flexy now that I have it about 3/4 below min insertion. The Nitto Pearl 11 is less flexy still, which I attribute to the still shorter quill. Least flexy of the three is the Nitto lugged, which is also the shortest extension of the three, a mere 9cm. None of the three would I call objectionably stiff, nor would I call any of the three objectionably flexy. I have zero concerns about the strength of any of the three. On May 6, 8:33 am, rperks perks@gmail.com wrote: Mike, I can say without question that it is my Tech Delux that moves around under torque loads. I have the same RM013 bars on bikes with both different styles of stems. On my Rawland with the threadless setup you can feel the spring in the drops rotating primarily around the about the same axis as the bar tops. But on the Roado I have flex in the stem along the front to back axis of the stem extension before the bars start to give. Enough that you can see it moving around on steep climbs. I have been looking for an economical (read deal on Ebay) welded or lugged stem to compare, but most are either really short on extension, beat up or Rob -http://oceanaircycles.com/ On May 6, 7:13 am, Michael_S mikeybi...@rocketmail.com wrote: Is he he sure it's the stem that's moving? Based on the forces that are applied rididng out of the saddle and the different cross sectional areas, I would think that the bar is what's moving the most. Both move some amount. I've never usd the taller Nitto Technomic stems ( if that's what your son has) but on the Pearl model I've never felt stem flex and I'm also larger than your son. ~mike On May 6, 6:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
[RBW] Re: Stem Strength
On May 6, 7:24 am, Bill M. bmenn...@comcast.net wrote: The quill stem was allowing the bars to twist, the new one wasn't. That's my experience, too. I have 12 bikes and only 2 of them have clamp-on stems. When I ride those two bikes, I'm always struck by how much the stem doesn't twist (ie.: is torsionally stiffer). I think what's really happening with the quill stems is that the threaded steel tightening bolt, that pulls up on the wedge, is twisting. In therory, there should be a small gap between the wedge and the tapered end of the stem, which would allow that much movement, and a small steel rod is pretty easy to twist. Expander bolt - style quill stems might be differerent, but I don't own any and can't comment. The big question is why it would matter, though. Its not in danger of breaking, and it probably provides a bit of shock deadening to high- frequency lateral twisting (shimmy? I'm speaking beyond my level of enegineering expertise and vocabulary here) in the front wheel and fork. And that's a GOOD thing, just like a handlebar that flexes a bit. I can't imagine that it sucks any measureable power out of most riders. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
[RBW] Re: Stem Strength
When I got my Quickbeam, I tried a couple of stems, including the stock Technomic Deluxe and the Nitto Dirt Drop. Both flexed noticeably more than the Salsa welded stem I ended up with. The Dirt Drop not as much as the Technomic Deluxe, but the quill was bottomed out in the steerer. Philip On May 6, 9:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
Re: [RBW] Re: Stem Strength
Hey, My back of the envelope calc's indicate a standard aluminum quill stem will deflect about ten times more than a steel stem. This is with equal extensions lengths and loads, and the aluminum stem has a solid 22.2mm diameter extension, and the steel stem is 31.8mm OD w/ 25.4mm ID extension. The extension into the fork vs. clamping on the outside of the fork are not significant here. By the way, neither stem deflects that much. If you really want a stiff stem, use a short extension, and big diameter. And steel too. And you know why they went to 31.8mm diameter handle bars? Because of the stinking cable grooves. The grooves make the bar section too flexible, the bigger diameter overcame this. Cheers! James Valiensi, PE Northridge, CA H818.775.1847 M.818.585.1796 On May 6, 2011, at 6:44 PM, Philip Williamson wrote: When I got my Quickbeam, I tried a couple of stems, including the stock Technomic Deluxe and the Nitto Dirt Drop. Both flexed noticeably more than the Salsa welded stem I ended up with. The Dirt Drop not as much as the Technomic Deluxe, but the quill was bottomed out in the steerer. Philip On May 6, 9:24 am, Bill M. bmenn...@comcast.net wrote: Back in 1991 I bought a Cannondale (very stiff frame) that came with a standard quill stem. I swapped it out for a hollow, welded stem that had a much larger diameter extension. The first time I stood up and cranked the bike up a short steep rise I was astonished at how much stiffer the front end of the bike felt. The quill stem was allowing the bars to twist, the new one wasn't. That may or may not be seen as a good thing, but I have no doubt that typical threadless stems are stiffer in torsion than traditional quill stems. Bill On May 6, 3:58 am, MichaelH mhech...@gmail.com wrote: The new RR contains an article by GP outlining his believes about various aspects of bike strength, comfort, weight, and comfort. There wasn't much new there for anyone who has followed him for a few years, including why he prefers threaded headsets and stems, but it did trigger this question from me. My son, who is 39 years old and a very muscular 170 lbs claims that he experiences stem flex while climbing with a traditional quill stem. I am always disinclined to challenge people's subjective experience but I have never experienced this and suspect it is in his imagination. Has anyone here felt their stem flex and has anyone ever broken a stem? michael -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en. -- You received this message because you are subscribed to the Google Groups RBW Owners Bunch group. To post to this group, send email to rbw-owners-bunch@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
