BB and Crankset confusion

paulc

Needing to replace the standard BB and crankset but having a whole lot more trouble choosing then I thought.

Old BB is sized 68 112 and a square taper, been looking at external BBs, But unsure about axle length and if I would be ok with axle same length as old or would a longer axle be needed.

Then there's octolinks are they better than square or just a weight saver.

All square taper cranks are just cranks and arms, but do octolinks cranks have axles fitted to them so will fit any octolink BB... Reason I ask is when looking non have axles In pics so if they don't come supplied how do I choose the right axle for for external BB

Just fitted shimano hg51 cassette and hg50 chain so hoping to match up with a crankset.


Thanks for any help

nicklouse

external dont have different axle lengths

octalink are the same as square taper in that you need to get the correct BB for the arms.

if going external the BB shell will need facing.

paulc

Would there be possible clearance issues with external bb rubbing on crankset, or would the axle allow for the crankset to be clear or is it dependant on the crankset.

I know about matching bb to crankset but is there any real advantage between square and octolinks.


Not sure what you you mean by facing an external bb

nicklouse

paulc wrote:

Would there be possible clearance issues with external bb rubbing on crankset, or would the axle allow for the crankset to be clear or is it dependant on the crankset.

no idea what you mean. thy just fit.

I know about matching bb to crankset but is there any real advantage between square and octolinks.

octalink a bit stiffer but bearings a little smaller

Not sure what you you mean by facing an external bb

see the FAQs or read parktools