Evening,

External BBs come in 3 bits: the 2 ends which hold the bearings and the tube thingy that connects them.

So, how important is the tube thingy? Any reason to be worried about not having one?

I think its just there to keep the crankset secure.

Its there only to prevent water from inside of the frame to go into the bearings

I never used to put them in as I thought it was packaging!

Then I realised it was meant to keep water in the frame out of the bearings, after I read some instructions, years later.

If you look at the internal side of the bearing they are often very poorly sealed. The tube seals one side against the other helping keep water out of the bearings. Some frames seem to fill up with water others are fine. Depends on where the holes are I guess.

I probably wouldn’t fit one on my road bike to save weight 😉 but on my winter ss it would be a good idea.

As others have said the centre tube is there to seal the internal side of the cups. You may get away without it but you may also experience faster bearing wear.

Thanks, yep, makes sense..

jonba, they’re plastic and must weigh around 5g max 8)