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post #1 of 8 (permalink) Old 28-03-2015, 13:38 Thread Starter
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Life Expectancy - Bottom Bracket

A question for any experienced cyclists on the forum.

What kind of life expectancy should I be looking from for a new BB fitted to my Cyclocross bike late September 2014.

The bike has done 945 steady away commuting miles since then, the vast majority of which were in fair weather and the BB is shot.

I did around 3000 similar use miles in the previous 2.5 years on the original BB and my local bike shop that fitted the BB during a service, tell me that they can go as early as after just 3 months ??

Ken.
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post #2 of 8 (permalink) Old 28-03-2015, 13:46
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Depends almost entirely on the bearings used.

Good quality sealed SKF, NSK, Fafnir or similar will probably last you out, but anything unsealed that gets dirt inside will fail rather quickly, especially the cheap Chinese bearings.

Failure after 3 months is quite possible for cheap bearings.

Peter
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post #3 of 8 (permalink) Old 28-03-2015, 14:16 Thread Starter
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Thanks Peter,

Part of the problem is that I don't know what quality bracket they fitted, but I was told it was sealed.

They are a reputable shop and it's a decent bike, so I trusted them to fit like for like, however I've got an appointment with the owner on Monday to sort it out.

Ken.
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post #4 of 8 (permalink) Old 02-04-2015, 04:11
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Quote:
Originally Posted by Blizzard View Post
A question for any experienced cyclists on the forum.

What kind of life expectancy should I be looking from for a new BB fitted to my Cyclocross bike late September 2014.

The bike has done 945 steady away commuting miles since then, the vast majority of which were in fair weather and the BB is shot.

I did around 3000 similar use miles in the previous 2.5 years on the original BB and my local bike shop that fitted the BB during a service, tell me that they can go as early as after just 3 months ??

Ken.

What BB do you have ?

External or internal ?

External Shimano should last for YEARS of abuse.

Internal should last YEARS of abuse.


My last internal BB on my roadbike commuter lasted 6000 miles and 4 years. Im a 100 kg rider, and very heavy on the pedals.

My shimano external BB has lasted for numerous years of Mountain biking madness.

945 miles..... it should only be ridden in by now.
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post #5 of 8 (permalink) Old 02-04-2015, 07:21
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Just replaced the bearings on my wife's MTB ,the BB is a Hope titanium square taper.I wouldn't have said she had done a lot of miles but I couldn't believe the amount of crap that was in there when I removed it,they were sealed bearings but totally shot.I changed to Shimano XT hollowtech about 4-5 years ago and they still feel fine.It really depends how much you spend,the cheaper models will not last as long as the dearer ones.Shimano XT is worth the money but XTR is just is just a bit expensive.
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post #6 of 8 (permalink) Old 02-04-2015, 07:27 Thread Starter
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Quote:
Originally Posted by robbosps View Post
What BB do you have ?

External or internal ?

External Shimano should last for YEARS of abuse.

Internal should last YEARS of abuse.


My last internal BB on my roadbike commuter lasted 6000 miles and 4 years. Im a 100 kg rider, and very heavy on the pedals.

My shimano external BB has lasted for numerous years of Mountain biking madness.

945 miles..... it should only be ridden in by now.
Shimano 105, which replaced the original 105 and after totting my miles up correctly, that one had actually done just over 4000 miles.

I've got a higher spec carbon road bike that has covered some decent miles and is running as smooth as when new.

My old Scott GZero mountain bike was sold 2 years ago with its original BB, which was over 12 years old, so I'm not best impressed with this recent failure.

I've authorised the bike shop to replace the 105 with a better quality Hope BB, which should last a lot longer.

Checking around the Internet there are a fair few examples of BBs going after a few months, so I'm letting it go on this occasion
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post #7 of 8 (permalink) Old 02-04-2015, 08:29
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It could be that the BB fitted had been assembled without being greased - hence the unacceptable early failure. Not fit for purpose. It should have been good for many thousands of miles. Get the shop to fit a new one (of your choice) and you only pay for the price difference of the unit. Tell them to keep the failed BB and break it open when you pick up the bike - this will show how/why it failed.

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post #8 of 8 (permalink) Old 02-04-2015, 08:38
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I once worked as a temp for a very reputable bearing company. Lunchtimes invariably involved playing football with the bearings, throwing them back into the bin when we finished the game. Could this be why some have a shorter life than others?
Alan
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