Why does my BB only last 3 months ?

Possibly you are overtightening the cranks so you are squashing the bearings? The preload in the crank should only be just tight enough to remove any play once the crank is done up tight.

If it was just the CX season I'd understand it, the filth of CX is death to so many parts, especially if jetwashed as well (sometimes several times a race!) but then if it's the same in the road season that is a bit poor. Sounds like a misalignment somewhere, but I thought the Hope thing should sort that.

You don't say how many miles the Scandal does - and consequently how many revs in comparison, but devils advocate - 600 miles a month, 1800-2000 miles between bearings. 100-150 hours of riding at 80 rpm = 36 million revs. Is that so bad? You then have the tools, it's a 10 minute job, a pair of bearings is a tenner, it's fractions of a penny and time per mile towards what's an expensive hobby..... I wouldn't oversweat it, it just 'is'

What about trying some fancy ceramics?

Is the BB faced?

Re bearings, from what I can tell, it's best to avoid max variants (extra balls) and LLU is better than 2RS. (LLU is full contact seals)

I've never bothered with stainless bearings.

The hope bottom bracket use enduro bearings whilst visibly the same as they've always been they judtvdont seem to last its the same story with hope btm headset bearings ,again enduro and don't last .
What rs replacement bearings are you using

Can you measure the diameter of the inside of the bb shell in a couple of places? I had a giant tcr Al which got progressively worse and I think it ended up slightly ovalised.

If so, some suitable loctite will cure it for a while, and in my case I completely cured it with a new frame.

Possible over tightening of the crank axle in the bb would be my guess or slight out of tolerance bb...

I'm a Hope PF46 user so the 73mm shell. The PF46 takes me down to a 24mm Shimano axle.

My first set of bearings went rough very quickly and were clicky while pedalling and slightly rough when first installed on the drive side. Should have realised then.

On the second or third set (and out of Hope warranty on the bb) they still clicked from installation. Popped the bearings back out then ran some very fine wet and dry round the bearing seat in the BB a few times as I had a suspicion it was right on the edge of tolerance and a smidge tight. Bearings went back in (i.may have repeated this a few times) and it ran smooth and didn't click at all. Those bearings seem to be lasting better. I wouldn't do this in warranty period though. 🙂

Probably misalignment issues but

I always use ss 2rs bearings

as said above, try non-stainless bearings and LLU seal spec if they're used in winter conditions. Won't fully solve the short period of use you're getting but they should be more durable than stainless 2RS.

Push fit BB's in my old Camber Carbon lasted 6 month if they were lucky whereas I got a year out of SRAM DUB on my Cotic.

I then changed to a shorter crank which was Shimano and found out that the Hope ceramic BB from my ancient HT was still fine. It must have covered 10k now (across a number of bikes), bought in 2009.

Push fit BB, a solution looking for a problem IME.

Push fit BB, a solution problem looking for a problem solution IME.

 

i never really got on with the fancier BBs.
Especially push fit. THe cheaper shimano push fit BBs have plastic carriers and seemed to last much longer. I always put it down to the plastic being able to take up some intolerances in manafacture or funny loading while in use.
No point in putting a well machined BB with a high end bearing in a wobbly aluminum BB shell. If youve been pushing metal BBs in and out a few times, it could well be a bit worn too.

Possibly you are overtightening the cranks so you are squashing the bearings? The preload in the crank should only be just tight enough to remove any play once the crank is done up tight.

+1 @thegingerone, assuming it's definitely the bearings and not the cups creaking in the frame (which tbh is more likely with press fit...).

Shimano spec for the HT2 preload cap is 0.8-1.2nm.

When you remove the BB is there water in the BB shell? Spray off the back wheel seeps down the seat tube and kills bearings, plus spray off the front wheel. Smothering them in marine grease and fitting mudguards in winter might help.

https://www.hambini.com/giant-tcr-roasted-more-crap-quality-control/

I'd try angular contact bearings, better for anything you need to preload a bit.

https://www.wychbearings.co.uk/MRA-2437-LLB-ABEC5-Enduro.html

Because it is press fit?

Fit a square taper BB/Crankset? It'll last a decade withut being touched...

is there a way to do that in a pressfit shell (inserts or something) - I've used a Praxis on one of mine, and that has been good but it's still effectively HT type solution with 2 cups, on the plus side it's easy to remove and access the bearings to knock out and replace.

Whats the actual mode of failure?

EDIT: Never mind, let's keep on topic.

Thanks for the replies - to answer some of the above the hope bb adaptor is a screw through unit which should eliminate any allignment issues. Around 3 months in the bearings start to click when pedalling up hill and a strip down usually shows the non drive side is stiff and notchy and the drive drive side not quite as bad. Popping the seals and a re grease works as a stop gap but the bearings will have lost there smooothness and replacements are ordred. I know i put on a fair few miles on the bike but as a 11 stone racing snake i would expect a longer service life. Yes i could be over tightening the pre tension. I will pay more attention when my new bearings arrive. I will try some llu sealed bearings next time (around August 😁)

I had this issue on a aluminium Norco Search with a PF BB. The original Shimano plastic cupped BB lasted about 90 miles before it started to creak. Being on the larger and heavier end of the scale (193 cm and 90 ish kg), I though that i'd just killed it as it was cheap and made of plastic, I replaced it with a Hope PF41, creaking gone - all good. Or so I thought. The Hope bearings lasted a lot longer but then the drive side went rough and notchy. Tried cleaning and regressing the bearing but then it went rough and notchy shortly.

I decided to take the BB completely out and get the BB shell measured, the drive side cup was very tight but came out. Turns out that the drive side end of the BB shell was out of tolerance, both over and undersize - it was oval. This resulted in the bearings not being aligned in the shell and causing them to wear prematurely and also some slight wear on sections of the crank axle where the bearing contacts it. The frame is still under warranty so i've submitted a claim.

Going on what the OP has said my bet is that the BB shell is out of tolerance in some way. The Hope PF BB with its screw together design helps stop the cups creeping in the shell but it doesn't eliminate alignment issues. I would get the BB shell measured to determine if its in tolerance or not.

What does the crank axle look like? I'm guessing there will be some evidence of wear from the misalignment where the bearings contact the axle.

Have you measured the ID of the BB shell? EG for a press fit 41 Park do a 40.98 reamer, I have had frames in as tight as 40.6, Whilst loose fits cause creaking and movement, excessively tight fits crush the frame bearings and you get premature wear/failure.

Out of round is not uncommon either, measuring alignment is more difficult.

If the frame is round but undersized, and cannot be reamed you can turn the OD of the cups down to achieve the correct fit.