The strangest question about press fit bottom brackets you'll probably ever get

Does anyone else go through press fit bottom brackets really fast? I’m talking 6-9 months before the they need to be repacked or replaced?

I have a weird theory that because I’m a heavy sweater, and the shape of most bottom bracket areas with flush press fit BBs channels the sweat almost directly into the area where the bottom bracket bearings sit.

When I have threaded bottom brackets, because the cups are a little bit outside of the BB and there are threads, the sweat instead runs along the side of the cups.

I ride my MTB in all sorts of terrible conditions, rarely wash it, and the cranks spin super freely, whereas it feels like my road bike bearings go bad super quickly.

Sure could be an issue. We know how corrosive sweat can be, so getting it right on the bearings and seals may lead to penetration and early death of the bearings inside.

Could be worth a bit of hack work to make a sweat diverter that acts as a dam to prevent the sweat from rolling over the side of the BB. Something as simple as a bead of silicone around the Outside Diameter of the widest part of the BB/Frame, could direct the sweat around the BB, roll to the underside and drop from there.

Might be tough to make given the space on your example, but could be worth a try.
image

1 Like

That’s what I was thinking. I have some black sugru so I might give that a shot

1 Like

Might be something simpler

If the sleeve you’re pressing the bearings into is out of true (even slightly) then it can and will wear out super fast

I had something similar

Replaced with a CBear modular item - highly recommend- solved it

Good luck
:+1:t2:

1 Like

How are your BB bearings failing? Are they starting to creak or are they getting rough and grinding?

rough and grinding

Ok, then on the trainer I would just slather on a bunch of extra lithium based grease where the BB is exposed ie between the dustcap, crankshaft and bearing seals

there is an instagram page about ‘your bike hates you’ that you should post to.

1 Like

I don’t even use it on the trainer, that’s the thing!

Hmm I’m surprised you are even dripping much sweat onto this area then. I’d still slather a bunch of extra grease in there as a water barrier, I do this for my CX bike and it seems to extended their life for a couple races

1 Like

I just had a problem with my rotor PF30 BB, one bearing has become rough after less then 5.000km. After some research I pressed in two NTN 6806 LLU bearings yesterday. These have a little more resistance, but are fully sealed. This was important to me, I drive it in the rain and snow.

I’ll bet the housing is out of true. If you can bear his childish delivery then Hambini explains it well.

1 Like

Give me threads or give me death!

:wink:

1 Like

I’d rather have my toenails removed with pliers than read or listen to anything from Hambini, regardless of how correct he may or may not be.

2 Likes

That grating opening shout “Hello, Hambini fans!” lol!

A good amount of spacers there, I think. Anyone have an external BB cup conversion?

Are you sure that’s sweat? Could it be a bottle leak? It’s interesting to see sweat drip like that on my down tube. The only marks I have are from dripping water bottles. Of course, mine are all heavily loaded with sugar, so it leaves a sticky mess that I need to wash with soap and water after each ride, as well as rubbing with my hands to get the syrup off.

2 Likes

21000 miles on my year round roadie (I bought used), haven’t touched the BB yet.

Normally press fit doesn’t work because the frame is out of spec.

1 Like