Need help with my bottom bracket


New Member
I have Boardman Team Carbon road bike with FSA Crankset


and I want to make an upgrade, so I bought a full SHIMANO 105 R7000 groupset.

now I have a problem with the bottom bracket size, so I have to buy an adapter to fit the new 24 mm crankset with the bottom bracket or an entire bottom bracket.
Now I’m confused, I see two different numbers, the one on the bearing say “BB30” and the one on the bottom bracket say “B3155”, so correct me if I’m wrong, if I’m gonna buy an adapter then I’ll get the one which compatible with BB30, but if I’m gonna buy an entire bottom bracket then I’ll choose B3155 / PF30?


Legendary Member
Accra, Ghana
Its a pressfit right? I think Shimano is a different diameter crank so you'll need the correct BB. You'll need a press to put the new one in but you can cobble something together with threaded bar and washers. Have a look on YouTube for videos.
Last edited:
  • Like
Reactions: C R


Legendary Member
It's a PF30. No special tools required to remove, just judicious brute force, although a proper tool is available.

You can either press in 30 --> 24mm adaptor cups or, more permanently, press in an adaptor sleeve to make it a normal ISO threaded shell, then use Shimano cups. You should use a headset press for either option.


Legendary Member
Accra, Ghana
This will always happen when you change inboard for outboard bearings. The difference is minimal and hasn't made any difference to the way the gearing behaves on my Specialized AWOL after going from square taper to Hollowtech 2.


Über Member
Thanks. 23mm overall or 11mm each side seems initially to be a big jump.
I've just found another thread on here talking about the same conversion, and they also reckon no problem.
Top Bottom