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I mean if you use a normal, regular length crank you can get problems with 42mm chain line. Therefore the frame isn’t suitable for a 42mm chain line.
A 109mm Campag taper gives a 42mm chainline on my (10 year old) primato cranks.
Otp bikes using Miche used to use the Campag 111mm. Not sure if that’s still the case.
miro_o-
I know we have used 107mm Shimano (and other jis) bbs with them at work and we have done so with cranks that’d have been made when the stock bb was the unflanged one that was (I think) iso taper and with newer crank sets for which the stock bb would be the far better, flanged jis one.
I have no idea what length those unflanged iso bbs were but we have still got them in the smallest bikes so could measure one.
I can’t be sure but I think the new flanged Miche B.B. is 107mm so all points to there having been no change in the crank when they changed B.B. taper.
Re chainline: I’d say it sounds like 42mm chainline is possible but only with selected cranksets, guess that’s the price you pay for large tyre clearance plus 120mm rear end (and the q factor etc that comes with that) minus lots of money being spent on things like design and manufacturing tolerances.
M_V
I think the cranks stay the same anyway.
I guess maybe where the chainring sits in relation to the taper might have changed?
Does anyone know if the stock bb length changed when they changed taper spec?
When you say “Pomps don’t seem to have the claimed 42mm chainline”... it’s be teaching you suck eggs to tell you that a frame doesn’t determine the chainline right?