Originally Posted by
paulie.reklama
Hi everyone, I started working on converting a Dahon Espresso (Pininfarina) to a road bike. I bought a second-hand Shimano FC-4550 (Sora/Tiagra around 2011) 175mm crankset and a Shimano Tiagra BB-RS501 68mm bottom bracket. The problem is that the right crank is max 1mm away from the frame and the left crank is already touching the frame. Can anyone give me some advice and experience with this? I'm not very familiar with Hollowtech bottom brackets, I don't know if there are any spacers that can be put in without negatively affecting the attachment of the left crank? The chainring is also close to the frame, but unlike the cranks, it's not completely touchable.
I´ve tried to write to Schocca about his excel parts list that he posted here for his fantastic road conversion, but unfortunately he doesn't come here anymore. Does anyone have that list from him to shere? I know that he probably had a very similar crank there, but I don't know why it doesn't work for me.
Thanks a lot.
I did a 2X crank conversion for my Dahon Speed (turned out fantastic), with a generic brand Hollowtech II copy crank, 50/34; Even with "road" Q-factor, crank arms have plenty of clearance. HOWEVER... because of the FAT seat tube plus thick front derailleur adapter plus large front derailler inner lip, I couldn't get it to shift to the smaller chainring. So I spaced the right crankarm out 4mm; Was able to shift but frequently dropped the chain when downshifting, AND, 4mm less clamping length on the left crank arm/shaft spline, made that come loose after a week. Removed spacers, and took a grinder and ground off the WAY excessively wide FD inner lip, only in the area of interference; Cage was still plenty strong and stiff as material was also thick. Chainline was 43.5 mm as designed, shifts perfect.
So no, don't space the crank out on a hollowtech II. Get a crank with either a longer spindle (but this may mess up the chainline), or a mountain crank with a larger Q-factor (pedal spacing), as fat frame tube interference was the reason for mountain bike crank arms being spaced further out.
You could dent the chainstays where they interfere, but those welds tell me that is an aluminum frame, so don't, and I'd even be careful with a steel frame unless there was no other option.