What's the typical life of a bottom bracket?

pigeontoes

I've got a Scott S35 speedster which came with a Truvativ 07BB 68/108 bottom bracket which needs replacing after about 1500 miles. The symptoms are a knocking at the same point of rotation of the cranks when they are under pressure, although there is no obvious play in the BB.

How long does a bottom bracket typically last and what sort of reputation do Truvativ components have?

I've looked on the internet and can't find anywhere I can buy a like for like replacement and having had a similar experience with a Truvativ BB on a mountain bike, I'd prefer to choose a different brand if possible but haven't got a clue what would be suitable.

The bike's got a Truvativ TOURO C 2.1 34/50 T chain set, if I choose a different brand BB, will I need to replace this as well?

Don't know whether it is relevant to choosing a replacement but the shifters are Tiagra front and 105 9-speed rear.

Any help welcome - please provide any answers in simple terms as I am a bit of numpty on the maintenance side of things.

smidsy

If there is no play you could strip it and repack with grease to see if that cures it (no harm done if you are replacing it anyway).

You can fit any make of BB as long as it is the same type/fitment e.g BB30 or English thread external bearing (i.e Hollogram) etc.

Shifters etc have no relevance to the choice.

pigeontoes

Thanks for the advice. Do you think 1500 miles is the life I should expect in the future?

tiredofwhiners

My BB from my PX bike is on about 10,000 miles and completely silent (touches wooden table)

bikermart

pigeontoes wrote:

Thanks for the advice. Do you think 1500 miles is the life I should expect in the future?

It can be a bit of a lottery!

My son's bike has Shimano 105 and he is on his second BB in about 1000 miles. (I refuse to be drawn on the quality of Shimano :evil: )

I have always had Campag on my bikes and the good old square taper BB has been as good as gold and lasted for years.

simon_masterson

I'm pretty sure that the BB on my favourite bike is the original; from when my dad bought it in the early '80s. I know I'd probably benefit from changing it. At some point I will.

I've only actually killed one; I sheared the fixed cup. That bike is also old, but more like mid '80s vintage.

kettrinboy

The original Ultegra 6600 BB on my Scott CR1 has done 13,000 miles so far, but then its hardly got properly wet over 6 yrs odd which seems to kill a lot of BB,s prematurely.

CYCLESPORT1

I had mine fitted to my old bike when the Tour de France was on the south coast, it's now on my new bike and thats 5 years old.

Wulz

I managed about 2000 ish miles on the standard bb that came with my 2010 trek 1.5. Folk at bike shop rekoned that that was short but lots of winter/wet/mud work as its on commuter duties.

Shop recommended going to a sealed unit. All good so far with about 2000 miles on now.

majormantra

smidsy wrote:

If there is no play you could strip it and repack with grease to see if that cures it (no harm done if you are replacing it anyway).

You can't strip and repack a sealed cartridge bottom bracket. Once it's done, it's done. Or did you just mean reinstall it? (Which won't do anything.)

It's probably easiest to buy the same BB again. 1500 miles is terrible though - it should have lasted far longer than that.

In general, if you are replacing a standard BB you need to know the BB shell width (68mm is typical on road bikes), the axle length, the type of thread (English 1.37x24TPI is by far the most common) and the type of spline/taper that the cranks fit onto.

smidsy

I do not know the specifics of that particular BB and just assumed it could be re-packed...ho hum, sorry.

Hoopdriver

The BB - a Shimano UN72 - on my Thorn eXp touring bike is original from 1999 and has God knows how many thousands of miles on it. I have a Phil Wood BB on my custom Enigma tourer and I certainly expect to get many years out of it.

Fifteen hundred miles seems a pretty short life to me - less than two months' riding in the summer! But then I favour the old square-taper BBs and I do think they last a lot longer.

drlodge

I think these modern cartigide based bottom brackets will have a shorter life than a well adjusted cup bearing, mainly because I think the design of modern BB's isn't that good - they rely on some kind of bearing pre-load which is not accurate, and in the case of Campag Ultra Torque, is iffy with that wavy washer.