Jan, It was not my intention to dis your crank. I'm sure it's very nice > and I might even buy one when my checkbook is healthier. Nonetheless, I > think you have almost made my point. Of course poorly made cranks fail, > that's not what we're discussing. Lots of cheap center pull brakes were > made and lots of people drew the wrong conclusion that center pull brakes > are no good. We both know better. >
I have a White VBC crank, which is CNC mfg process, on my Rambouillet. I have no expectation that it will ever fail. I also have an Alpina, cold forged crank on my Marinoni, which I don't ever expect to fail. The VBC crank weighs 655 grams, the Alpina 640, and yours is 540. That 100 gram advantage is not a lot of material = to 3 ozs of water! And I suspect that much of the weight advantage is in your rings which clearly use less material than the White rings. But both your rings and the White rings are CNC machined! In the last addition of BQ you argued, quite convincingly, that a bike with 650 b wheels weighing 21 ozs more than the same bike with 700c tubulars would not be any slower; so the 100 oz disadvantage of the White crank is not "a lot of material". The same holds true for Paul's brakes, the possible weight saving by forging the arms is insignificant. In the real world these CNC products have outstanding records. blessings, Michael My touring tandem also has a CNC machined crank, sold by DaVinci and also made by White Ind. I bought the crank used and have no idea how many miles there are on it, but I do know that fully loaded the bike weighs well over 400 lbs. The cranks work just fine. > > I am glad you agree with us on many things... If your only bone with > us is that we use a more expensive manufacturing process for our > products than you deem necessary, then that isn't too bad! > > Cranks do fail from fatigue - otherwise, they would fail the first > time you pedal very hard. > > Cold-forging is stronger than CNC machining. That is a simple fact, > which does not need to be discussed. Is cold-forging necessary for a > bicycle crank? It probably depends on the crank design and on the > rider. We know that a CNC-machined crank will fail the EN fatigue > test, unless it uses a huge amount of material. > > In the 1990s, there were large numbers of lightweight CNC-machined > cranks for mountain bikes. Remember Kooka, Topline and all the others? > Very few of the companies exist any longer. Their cranks had high > failure rates, and once this became an issue after these cranks had > been out for a few years, most of the makers folded. > > The René Herse crank is a lightweight design, with material only where > it is needed. Cold-forging is more expensive, but I cannot imagine > sending out cranks to customers without being confident that they are > safe to ride. > > Jan Heine > Compass Bicycles > http://www.compasscycle.com/ > > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To view this discussion on the web visit https://groups.google.com/d/msg/rbw-owners-bunch/-/ZbX32Kb4E04J. 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.
