Author Topic: Bottom Bracket Life  (Read 2407 times)

Socialist Clarion Call

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Bottom Bracket Life
« on: December 01, 2018, 08:33:07 pm »
A piece string question I guess. However what life expectancy should I expect get from an FSA Square Taper Bottom Bracket?
Is it worth paying more, would that improve the life expectancy ?
The reason I'm asking is I purchased a new FSA 103 Bottom Bracket in Jan of this year, for work reasons the bike Dolan FXE has not done much mileage, max I guess 3000 mls!
Boots an Spurs

zigzag

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Re: Bottom Bracket Life
« Reply #1 on: December 01, 2018, 09:24:54 pm »
i'd expect 10k or more miles from square taper bb, the shimano ones have good reputation

Re: Bottom Bracket Life
« Reply #2 on: December 20, 2018, 08:08:43 am »
I have no idea of milage, but I got 12 years of regular use on my Sugino 75 BB and it's still going strong.

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Bottom Bracket Life
« Reply #3 on: December 20, 2018, 08:50:19 am »
My Shimano square taper has just died. I don’t know it’s history before I bought it 6 years ago.

I’d like to say I’m disappointed with its lack of longevity but I’m more gutted that it’s stuck tight to the bike

Re: Bottom Bracket Life
« Reply #4 on: December 20, 2018, 10:53:08 am »
When/if you get it out, use plenty of copperslip on the threads when fitting the new one so you can get that one out the day it finally retires.
Duct tape is magic and should be worshipped

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Bottom Bracket Life
« Reply #5 on: December 20, 2018, 11:26:34 am »
When/if you get it out, use plenty of copperslip on the threads when fitting the new one so you can get that one out the day it finally retires.

Thanks. I thought that I had but obviously not enough :( “Fortunately” the bike has an EBB so, whilst not sacrificial is low cost compared to some other option

Re: Bottom Bracket Life
« Reply #6 on: December 31, 2018, 09:52:46 am »
Some FSA BBs fail very early.  I think there's a kind of bathtub curve and the crap ones show up within a few hundred miles.
Never tell me the odds.

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Bottom Bracket Life
« Reply #7 on: December 31, 2018, 12:38:16 pm »
When/if you get it out, use plenty of copperslip on the threads when fitting the new one so you can get that one out the day it finally retires.

Thanks. I thought that I had but obviously not enough :( “Fortunately” the bike has an EBB so, whilst not sacrificial is low cost compared to some other option

By way of an update (because I know you were all perched on the edge of your saddles for this) both my LBS and local motor mechanics admitted defeat. Fortunately I managed to get a used one for £20.

I suppose a New Year’s resolution should be to modify my maintenance régime.

Re: Bottom Bracket Life
« Reply #8 on: December 31, 2018, 08:48:07 pm »
I’d suggest that an over-tight chain, or a transmission with tight spots due to dodgy sprockets or chainrings will significantly shorten the life of a bottom bracket bearing. A poor chain line wouldn’t help either.

When working at 6days and other track races I was initially quite surprised how slack the best mechanics set the ( always 1/8) chains.

Re: Bottom Bracket Life
« Reply #9 on: January 01, 2019, 04:18:59 pm »
Keirin chains are often blowing in the wind, too.  However, the consequences of an unshipped chain on a track are not as serious as when you're on the road, going downhill at 150rpm, with an impatient car driver up your arse, which is a daily occurrence for me.

As tight as possible without binding is what I aim for.  The "without binding" is important.  It also pays to buy decent chainrings and sprockets, and to centre the chainring on the crank properly - this enables you to get the chain tighter throughout its rotation.  With cheap sprockets and chainrings, you often end up with a very slack spot just to avoid binding at the tightest spot.  Bigger cogs (e.g. 48 x 18, or even 52 x 20) are more forgiving of concentricity errors than smaller ones (e.g. 42 x 16, or 39 x 14 like I used to run on an MTB conversion).

If you want real insurance (HEALTH WARNING - DO THIS VERY CAREFULLY AND USE A TOOL RATHER THAN YOUR FINGER IF YOU'RE ACCIDENT-PRONE), turn the pedals slowly when the chain is at the slackest spot and try to derail it as it feeds onto the chainring.  If you can't manage this, the chain is tight enough for safety, at least until it wears a bit and gets slacker.
Never tell me the odds.

Re: Bottom Bracket Life
« Reply #10 on: January 01, 2019, 04:28:22 pm »
We used to spin the pedals then hold the bike sideways 90 degrees to upright) and shake it a bit.

Re: Bottom Bracket Life
« Reply #11 on: January 01, 2019, 05:53:44 pm »
Absolutely. The chain needs to have a little slack at its tightest point. That counts as "tight", but not "taut". Not sloppy, but very far from the point where it's binding.

To answer the OP's other question: if you spend more, then yes, the BB will last longer. But not in proportion. I tried it: spending twice as much on a BB got  me 50% longer life, spending four times as much got almost double the life. The rest of the cost is in the (tiny) weight reduction. Unless you're a weight weenie, buy the basic model and treat as a consumable.

Another factor is rider weight. I used to weigh 95 kg and got through a veloce BB every 10,000 km. Now I weigh 70 kg and BBs last much longer. ISO taper spindles are hard to find now, my current one is a Tifosi, widely regarded as made of cheese, but it is still good at 30,000 km.
Quote from: tiermat
that's not science, it's semantics.

Re: Bottom Bracket Life
« Reply #12 on: January 03, 2019, 03:29:31 am »

I suppose a New Year’s resolution should be to modify my maintenance régime.

Mine consists of lubing the chain spring & fall and checking the brake cable once a year. What else do you need to do?

Re: Bottom Bracket Life
« Reply #13 on: January 05, 2019, 09:31:01 am »
The chain needs retightening two or three times over the winter, I find.  A little wear causes a lot of slack.
Never tell me the odds.

Socialist Clarion Call

  • Age Is Just A Number Just Wish By Body Agreed
  • Age but a number,which grows ever larger.
Re: Bottom Bracket Life
« Reply #14 on: January 05, 2019, 07:41:53 pm »
Thanks all I weigh 72kg, chainline is within0.5mm chainring/cog 48/19 or 48/20, concentricity is off but as close as I can get . Tried Sheldon Browns trick of tapping chain with chainring bolts nipped up.
I've swapped BB now and returned old one to Wiggle (awaiting there response).
Guess I'll just have to see what happens now.
Boots an Spurs