Bicycle Mechanics - Change to compact crank

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Dominae
05-13-10, 11:23 AM
I currently have a standard Ultegra cranset (6600) and the bike has the corresponding Ultegra bottom bracket. I want to switch to an Ultegra compact crankset (6650), but it is unclear if I would need a new bottom bracket to accomodate a compact crankset. Does anyone know whether a new bottom bracket would be required?

krazygl00
05-13-10, 11:36 AM
Both are hollowtech, correct? Should not require a BB change.
Dominae
05-13-10, 11:46 AM
Yes, both are Hollowtech.

elader
05-14-10, 06:32 PM
Yes, both are Hollowtech.

you will have to shorten your chain and seriously move the front derailleur. I did this and learned all about adjusting front DA derailleur in the process. :lol:
MudPie
05-14-10, 07:12 PM
The bottom bracket (actually two outboard bearings) is the same for the 6600 and 6650. However, depending on the age/condition of the current BB, you might want to get a new bearing set. I just bought a Shimano 6600 outboard bearing set for $15 from:
http://www.competitivecyclist.com/road-bikes/product-components/2009-shimano-ultegra-10-speed-fc-6600-bottom-bracket-1264.314.0.html