When I look at a disk equipped wheel and I am less distressed by asymmetry of dish and am more concerned about the builder's resolution of which are inbound versus outbound spokes now that the hub is stopping the wheel under braking intend of the rim. The dearth of asymmetrically drilled rims seems to support that. I give more gravity in Rich's comments to his concerns for inbound/outbound assignment.
Despite the increasing use of the low spoke count wheels, used on OEM bikes, I still see the spoked wheel as a dynamic rather than static engineering structure. It is a construction of parts that by selection (of material, design and gauge) distribute stresses of rider input (braking, pedaling and steering) and surface input. Not too dissimilar from all the city bridges around here...and I will tell you that they do move under load. More easily sensed from a bike. <https://lh3.googleusercontent.com/-b07GcDgir2g/UgTJs21XUHI/AAAAAAAAB5s/7Lkxek7VC3wwUSALEC4od23VM9DbDCB6wCKgB/s1600/DSC01094.JPG> Steve's observation of a rider in his group breaking a spoke on one of those wheels, a Trek 720 disk by his description, parallels my experience. A fellow rider popped a spoke on low count, girder-like rim proprietary wheel, and no one (LBS mech, bike company, component mfgr.) could give him a spoke, source, tool for the nipple or specification of tension, only an address for warranty service. OEM, but unsatisfactory. I want my bike wheels to share those forces and not imply more of the structure to a single one (or type, like spokes). The net result is a wheel that has response to those surges of input rather than direct transmission of them to you via the frame. I can't speak for Rich, but his concern for assembling the spokes of a disk hub so as to account for the dynamic operating stresses and response. Common rim-braked wheels have the same dynamic considerations. Spokes pulling under the implied rotating force exerted by rim braking caused distortion of overall structure, deflecting the rim, resulting in this brake wear pattern in the anodization: <https://lh3.googleusercontent.com/-R4tFhNrztxk/VfQYTCobcnI/AAAAAAAADQk/gWhruxgbEoAlWFwGsZOhDi2xqkdBBogmQCKgB/s1600/Screen%2BShot%2B2015-09-12%2Bat%2B7.46.40%2BAM.png> Jobst Brandt's excellent diagrammatic of the same: <https://lh3.googleusercontent.com/-fkfYIfepHdo/VfQYEGY_L0I/AAAAAAAADQM/ZNnQzh9fODsLz0wOolmxfy8PrAtCXmqAACKgB/s1600/Screen%2BShot%2B2015-09-12%2Bat%2B7.51.52%2BAM.png> Bottom line is that I haven't seen or heard this amount of insight and attention to detail being discussed regarding disk brake wheel spoking patterns or discussions about contrasting views or designs supporting the alternate views. My quiet inspections of rear disk wheels in shops hasn't indicated a consensus either (PJW built my SON28 centerlock front hub and Synergy 36° rim with 14g pulling spokes inbound, symmetric). Andy Cheatham Pittsburgh On Friday, May 20, 2016 at 4:55:43 PM UTC-4, masmojo wrote: > > Well, I've personally built several disk wheels & a couple of those were > fronts and will be building 2 or 3 more shortly. (On top of that I have > probably built a couple dozen non disk wheels) No disrespect to Rich but > the front disk hubs I have used required no dish at all! Typically, (from > what little I've seen) the manufacturers relocate the non braking side > flange further inboard so that no dishing of the wheel is needed and while > I prefer not having any dish in the wheel I am not sure whether I wouldn't > prefer it to the loss of triangulation that results from moving the flanges > in to compensate for the disk. > I used the term sprung weight mearly as a counterpoint to the rolling > weight and because a better term did not come to mind. It was not the > significant point of the topic anywayz. The main point that you obviously > missed was that less rotating mass is preferable to less weight in the > frame. AND not to be argumentative or go into too much pointless > explanation, but a bicycle frame on spoked wheels would be considered > sprung weight! > Your friends Trek probably just got a bum wheel, my XO-1s front wheel > broke several spokes when I first got it, tore it down rebuilt it, no > further problems. > The average rider probably doesn't break too many spokes regardless of > configuration, which was part of the point of what I was making. If you > break a lot of spokes you need a new wheel builder. > > My experience with trying to straighten pieces of metal like brake rotors > is that typically you do more harm then good. The tolerances on disks are > so small that a wobble of less then a millimeter effects whether it will > rub or not and by extension how good it will work. I have seen people > "shrink" metal, using a torch/heat, but again I might cause more harm then > good. > -- 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 https://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
