Bottom Bracket Lifespan


Über Member
Durham City, UK
At the end of September last year I had my Cube crosser overhauled with new 105 group set fitted after the original stuff gave up the ghost after over 4000 all weather miles.

I've just had to replace the bottom bracket after only 6 months and 945, mostly dry miles and was expecting it being being replaced under warranty, to be told that they can go after as little as 3 months !!

I bit the bullet on this occasion and forked out for an upgrade, but was I expecting too much from the 105 ?


Kilometre nibbler
My SRAM GXP BB seized after only 2-2.5k (often wet and filthy) miles and I was miffed.


I had a UN26 fail after three months, but my present UN55 has been in a fair time and done a high mileage, including right through the winter.

In the bad old days when bikes were rubbish and not made from carbon fibre, bottom brackets had loose balls, and many bikes had a little hole in the BB shell where a few drops of oil could be injected. Fit new balls and adjust, then oil periodically and the BB assembly could easily last many years before needing stripping and overhaul. I cannot deny that modern cartridge types are a lot easier to install though.


I've had many thousands of miles out of the old style loose bearing BBs, through all year round commuting. Occasionally they develop a little play, but so far tightening up the adjustable cup a fraction has fixed things perfectly.

My new commuter has a cartridge bearing that's seen 4000 miles or so - it was starting to make an alarming noise, but the LBS were able to tighten things up (I lack the tools to do the modern ones myself) and it's still going strong.

I guess there is a large amount of variability in BB life, some due to product variability (insufficient grease in bearings?) and most due to the conditions they're ridden in.
I've had some go for no good reason after a couple of hundred miles, and some (much more abused) examples, last for years and many thousand miles. They just seem to be very random in their quality.


Legendary Member
I'm amazed to hear that a shop has claimed 'some go after only 3 months'. No they don't. Not unless there's something badly wrong with them. That's outrageous. The Sale of Goods Act says goods have to be 'fit for purpose'. I'd be happy to argue the toss with anyone trying to tell me that a BB's 'purpose' has been fulfilled if it manages to get through 'nearly' 1000 miles. And for anyone to tell you that about 105 gear! Astonishing.

Personally there's no way I'd take that on the chin. I'd write to Shimano, explaining what happened, and what you were told, and ask them whether they consider that a 105 BB that's given up the ghost after less than 1000 miles is acceptable. You might if you felt inclined drop a hint that your many friends on one of the UK's most popular cycle sites are looking forward to hearing their thoughts....
I like sweet pea's advice.

I had to replace my boardman's bottom bracket after about 8000 all weather, all condition miles (day to day commuting whatever the weather), and the Focus is at about 4000 dry miles at the moment and hasn't needed a change.

I would not be happy with under 1000 dry miles, and with a company the size of Shimano and a component of 105 quality would certainly be meeting them know...
Blimey! What are you guys doing? I cannot remember a bottom bracket failing in under 20,000 miles, certainly my fixed went 30,000 before needing replacement and that gets more abuse and wear than a geared bike. Headsets and bottom brackets do not last anywhere near as long on bikes ridden in all weathers without decent mudguards, but then this is somewhat contradicted by a few posts that say they are failing after just dry miles. Strange, I would be taking them back.


Legendary Member
There's only one reason why a BB bearing will fail prematurely: water and degreaser ingress washing out the grease.


Still wavin'
Ovver 'thill
There's only one reason why a BB bearing will fail prematurely: water and degreaser ingress washing out the grease.
Or incorrect preload when fitting, or a lack of grease to start with, or crap bearing shields, or seals. But I agree, they do need looking after, eespecially the outboard type. They aren't fit and forget.
My Dyna-Tech has a Campagnolo Chorus BB & Chainset, that was fitted when the bike was new in 1994 (as an exchange item, as the shop couldn't get the Ultegra cranks in the length I wanted at that time)
Until its retirement 18 months ago, plus it had been used solely as a winter/commuter for the past 5 years, it still span perfectly & had never been touched

Years ago, when I had my Pace Research RC100 (1990 - 1995), that had grease-nipples (car type) on the head-set & BB shell (press-fit cartridge bearings, & BullsEye cranks - one-piece right crank spindle), & that never gave any problems

Plus, the predecessor of the Aheadset/steerer-tube set up we see today

The stem was the steerer, & was clamped into a split fork-crown, with individually replaceable fork-legs

Pics aren't of mine, but it's the identical model

Pace Research RC100. 3.jpg Pace Research RC100. 8.jpg Pace Research RC100. 9.jpg Pace Research RC100. 10.jpg


Legendary Member
The same doubt that millions of car owners should be feeling when they've just shelled out for a "service". I used to service my Landy and would only change things like brakes and filters when they were worn or dirty. The only item that got changed regardless was the engine oil because you can't judge its condition easily.


Well-Known Member
Had a BB completely collapse on the rear BB on our Tandem. Balls split in half - complete failure after 250 dry miles. This was on a new professionally built tandem. Unheard of with the 'old style' BB. My guess is. - it was a faulty BB when it left the factory
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