First - Thanks to all who have responded.
Originally Posted by
JohnDThompson
Why replace a perfectly good crank and bottom bracket? If the rings are worn, just buy new rings in the sizes you want.
I'm replacing the crankset for 2 reasons - wear and also to lower the gearing to help with local short but steep climbs. The smallest ring I can fit on my current 130 BCD crank is a 39. I want to go to a 110 BCD crank so I can use smaller rings.
Originally Posted by
HillRider
I don't know if a 36T chainring would fit the old crank. If the bolt circle is the common 130mm it won't. I also wonder if the change from 39T to 36T is worth the expense. Why not get a "compact" (50/34) and get a usefully lower low gear?
I ride rolling terrain in North Texas with some short but steep punchy climbs that I want to start including in daily rides. I can climb them now, but lower gearing would make the experience more pleasant! The difference in gear ratio between a 36X28 and a 34X28 is only .08. But I like to use the big ring also on flats and the back side of rollers and I'd lose some top end in my favorite 17, 19 and 21 cogs if I drop to a 50 versus a 52.
Originally Posted by
JohnDThompson
Good point. Depending on what compact crank is used, the OP may "get lucky" and be able to retain the old bottom bracket, but it's not given.
I'll make sure that any replacement crankset I get will fit the BB that I have now whether it's a compact or semi-compact.
Originally Posted by
Phil_gretz
I agree. Who needs a 52T chainring, if they're not racing?
I haven't pinned on a number in 25 years, but I still like to go fast and push the pace as much as I can.
Originally Posted by
zacster
Um, no. The bearings used today will last a lot longer than that. They are much more likely to be damaged by doing "repair" than by just riding them. Overtightening, undertightening, tapping them out, tapping them in, not seating properly are all much worse for bearings than spinning the pedals. If they are smooth there is no reason at all to replace them.
I agree and have pretty much decided to retain the current bottom bracket when I replace the crankset. Plus, in almost 40 years of "serious" riding, including commuting, racing and touring both road bikes and mtn bikes I've never had a BB seize up so bad that I couldn't make it home. Any issues I've ever had with bottom brackets were developed over time with plenty of warning to rectify the issue before it became a "show stopper."