Specialized BB30 with Shimano Dura Ace SRM

I'm using a Shimano Dura Ace Compact SRM with my Specialized Tarmac SL3.  The bike came equiped with the Specialized S-Works BB30 crank set.  To get the Shimano crank to work with the BB30 frame requires an adapter.  I've seen four different styles of adapters.

1.  A pressed in threaded piece that allows you to use an Italian threaded bottom bracket.
2.  A pressed in adapter that uses standard outboard BB cartridge bearing with a couple of 5mm spacers on either side.
3.  A pressed in cartridge Shimano BB that also requires spacers.
4.  An adapter that is pressed into the standard BB30 bearings.

I have used 2, 3, and 4.  My Transition TT bike uses number 2 and I've used 3 and 4 on my SL3.

To use the adapter you need to take the Specialized crank off.  I stripped it completely down and this is what the bottom bracket shell looks like:

From BB30

The Specialized BB consists of this press in bearing holder and the BB30 bearing.

From BB30
The Shimano cartidge insert is shown next.  Also included is the BB shell insert that comes with the bike.

From BB30

The four, 2mm spacers (two on each side) that come with the Shimano cartridge are not enough.


This combination of spacers worked well.  One 5mm on each side.  I also added an extra 2mm spacer on the drive train side to get the chain line to work better.

From BB30

But since I had stolen those two 5mm spacers from my Transition I ordered the BB30 adapter from Enduro.  Here are the parts (again included the Specialized part)

From BB30

The bearing and adapter put together.

From BB30

Another view:

From BB30

I used a headset press to press it all together.

From BB30


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