Originally Posted by
vesteroid
I have a giant defy advanced and the wife has a trek 5.2 and both have ultegra cranks on them, and neither has an outboard bearing...so I assume they are bb30....does that just mean they have an adapter?
Originally Posted by
Campag4life
Yup...they are BB30. An Ultegra crank is one of the most popular and effectively adapted external bearing crank that will adapt to BB/PF30.
Most bike makers use Wheel Mfg. spacers...which space radially from 24mm spindle to 30mm BB30 ID and outboard to take up axial distance between bearing being mounted inside aka BB30 versus outside the shell as is the case with outboard bearings.
vesteroid, Campag4life is spot on with Ultegra cranksets fitting into BB30 bottom brackets with the use of adapters (c.f.,
http://wheelsmfg.com/complete-crankset-bb-adapter-guide). But just to clarify and correct what seems to be an honest mistake,
AFAIK neither road bikes mentioned by you use BB30 bearings. (And the more knowledgeable ones, please correct me if I'm wrong.)
The Giant Defy Advanced uses BB86 press fit bearings, while the Trek 5.2 uses BB90 slip fit bearings. The difference is BB86 (like PF30) uses internal cups while BB90 (like BB30) uses integrated races. Both BB86 and BB90 will natively accomodate the 24 mm spindle of the Ultegra crankset without the need for adapters. The graphic table below is a helpful guide in thinking about this.
vesteroid, the discussion of internal cups versus integrated races is really what's being debated about extensively in this thread. The other minor debate going on in this thread is external bearings versus internal bearings. It's a very lively thread, and quite educational for me as well. I especially like reading those posts from people who seem to have had many years of firsthand experience working on the different kinds.