scottz123

2015 Ridley Orion
FSA Omega Crank w/ FSA MegaExo BB-4000 (says "BC 1.37" x 24t" on it)

I will be installing some type of Hollowtech crank on it (105?)

My question is:
As far as the BB is concerned, is it basically as simple as swapping out MegaExo for Shimano SM-BB5700?

Is SM-BB5700 the right replacement for the BB-4000?

Thanks in advance

Sangetsu

Sounds like a standard British-thread bottom bracket. There are three measurements you need to be aware of, first is the type of thread (which is British), the next is the width (measure the width of the bottom bracket shell), and next is the chain line. For my bike it is 68mm by 113mm. The chain line for hollow tech bottom brackets can be adjusted with spacers. A couple millimetres of error one way or the other won't make much difference. There are some good videos on Youtube which can show you how to do the conversion.

jimc101

If you have a 2015 bike what do you anticipate in gaining by swapping the BB?

For the one you have suggested, the SM-BB5700 is obsolete, this has been replaced by the BBR60 which covers the 105/Ultegra level groupsets, it's smaller & lighter than the old version, and looks better to

#Sangetsu mentions chainline, for road external BB's, this is fixed with HT2 BB's so no need to think/worry about it.

scottz123

I am under the impression that the ID for that BB is 19mm. (OD for Omega cranks is 19mm?)
For $20 or so, i would like to have all the parts lined up, if FSA BB does not work.
Seems like some peeps do not like FSA BB for longevity compared to Shimano, even if it does fit HT2.