When should I care about hops and flat spots for a "PBP wheel"? I just built up a rear wheel with a Velocity Aerohead OC rim. The spokes are all very evenly tensioned, and the wheel is horizontally true, but I decided that 1/2 mm out of round is "good enough." Getting from 1 mm out of round to 1/2 mm required a lot of back-and- forth to get the spoke tensions evened up again, at the same time going around and re-truing horizontally, while not at the same time making the vertical true worse. Is 1/2 mm "good enough for government work" (as government contractors say)? Or would you look at that wheel and say I should either do another round of truing or start over for PBP quality?
Thanks, Nick On Oct 1, 9:50 am, Peter Jon White <[EMAIL PROTECTED]> wrote: > The job of the wheelbuilder is to build a round wheel. To build a > round wheel, you need to start with a round rim. Of course I try to > determine if the rim isn't round before starting the build, but very > often the irregularities don't show up clearly until you have tension > on the spokes. It's not that the rim starts out round, it's that the > rim isn't round, but for whatever reason you can't see the problem. > > There's only one shape of an untensioned rim that I want to recreate, > and that's the shape of a round untensioned rim. > > On Oct 1, 1:43 am, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> > wrote: > > > > > Well, Swan is clear in what I quoted. and in the rest of his > > post.http://search.bikelist.org/getmsg.asp?Filename=classicrendezvous.1080... > > that the non-concentricities are there, and are best ignored because > > they are hard to correct. He earlier claims that the job of the > > wheelbuilder is to build a tensioned wheel which well recreate the > > shape of the untensioned one. > > > I know, PJW, that you have been building wheels for many years. Have > > you tried, say with Sun rims, to identify these flat spots and hops > > before the building begins? I know you've posted about them at your > > webpage? Again, I'm asking whether you have tried to identify and > > quantify the out-of-roundnesses ahead of time. > > > Harry Travis > > Washington, DC > > > On Sep 30, 11:17 pm, Peter Jon White <[EMAIL PROTECTED]> wrote: > > > > If the out of roundness in a rim is small enough to have no effect on > > > the performance of the wheel, yes, you should ignore them and get the > > > spoke tension as even as possible. But you can be faced with a > > > difficult choice when the rim isn't quite round. If you're using an > > > inexpensive rim because you're just riding the bike a few miles back > > > and forth to work, you would be silly to start all over when you find > > > that the rim isn't perfect. You rarely find these flaws before you've > > > spent a lot of time lacing and tensioning the wheel, so do you want to > > > start all over with another rim which may be no better than the first? > > > > On the other hand, if you're building wheels for PBP, your standards > > > need to be quite a bit higher. > > > > On Sep 30, 9:23 pm, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> > > > wrote: > > > > > Jamie Swan offered this opinion to a first-time amateur wheel builder > > > > over at Classic Rendezvous (bikelist.org). He has trued over 400,000 > > > > wheels. > > > > > _____________________________ > > > > > The big issue is: are those hops and/or flat spots the true shape of > > > > the rim or did you put them there as you applied tension to the > > > > spokes? If those minor eccemtricites are the actual shape of the rim > > > > then you shouldn't try to change them. You should just support them > > > > with uniform spoke tension. > > > > > Jamie Swan > > > > Centerport Cycles Inc. > > > > Northport, New York, USA > > > > ___________________________________ > > > > > Any opinion here from other wheelbuilders? Is it feasible for amateurs > > > > to mark non-concentricities in rims against a perfectly drawn circle, > > > > and so not make mistakes in trying to correct them? Or are they too > > > > subtle to see? > > > > > Harry Travis > > > > Washington, DC USA- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Bicycle Lifestyle" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/bicyclelifestyle?hl=en -~----------~----~----~----~------~----~------~--~---
