Originally Posted by
pgoat
I just don't know how much work it is to swap out BBs on this frame - seems like every 3-4 yrs the standard sizes change; since this bike has a gruppo towards the end of its lifespan, would a newer BB fit the frame?
Yeah, if it'll take Octalink it'll take other standards too. If you're going with a Shimano compact crank, I recommend the
Tiagra BB for $20-$25 since there's no meaningful difference among the different "levels" of Shimano outboard-bearing BBs.
Oh, and to go with that, Tiagra 4500 or 4600 cranks would be a good value if weight's not a priority. If weight's an issue, watch Ebay for Ultegra SL or Ultegra 6650. You may want to switch to narrower 10-speed chains to reduce chain rub on the big ring when using the small ring.
You've probably thought this through already, but the large jump in chainring sizes on compacts can be annoying. Punching down from the big ring and having to counter-shift the rear three gears for your next ratio is not a trait I personally like. But your alternate poison is a wide-range cassette with bigger cog-to-cog jumps that demand a wider "powerband" from your legs.