Bottom Bracket worn out again!

simbob3
simbob3 Posts: 12
edited May 2012 in Workshop
I've got a Giant Rapid 1 with Shimano Tiagra Double chainset, 34/50 with external Bottom Bracket. I noticed the other day a lot of movement in the crank - yet again! Tightening up doesn't solve anything. I've only had it 14 months and am looking a third new Bottom Bracket, the second has lasted less than 6 months! I ride approx 100 miles per week, is this an expected norm? I didn't replace the BB on my last bike in 3 years.

Has anyone else experienced this with a similar set up? is it because it's a double rather than triple chainset (heavier loadings?), is there a better (more hard wearing) BB i could replace it with? Is it possible to replace just the bearings?

Comments

  • ugo.santalucia
    ugo.santalucia Posts: 28,325
    It's not far off average... Shimano Hollowtech II BBs don't last very long...
    You might have a misaligned shell and want to have it checked/faced by a decent bike shop... other than that, 5000 miles with a BB is kind of average these days
    left the forum March 2023
  • estampida
    estampida Posts: 1,008
    reface bb, and get a hope or similar bb......
  • jermas
    jermas Posts: 484
    Avoid spraying the bottom bracket area with degreaser, muc off, detergents and lubes (wd40 etc). Also try not to spray hose pipe directly at bearings as they aren't particularly well sealed.
  • ride_whenever
    ride_whenever Posts: 13,279
    Check the shell has been faced properly and fit a hope SS or ceramic one.
    Neeermad
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  • cycleclinic
    cycleclinic Posts: 6,865
    Kind of why I like square tasper BB's. But like everyone else I have to run external BB's now, well I don't have to but I do as I want modern groupsets.

    If you want relioability then get something like a Miche crankset or one of TA cranks. Both do square taper cranks new.
    http://www.thecycleclinic.co.uk -wheel building and other stuff.
  • simbob3
    simbob3 Posts: 12
    jermas wrote:
    Avoid spraying the bottom bracket area with degreaser, muc off, detergents and lubes (wd40 etc). Also try not to spray hose pipe directly at bearings as they aren't particularly well sealed.

    Funny you should say this a it just reminded me that both times they've gone, a few weeks before there's been a brown liquid discharge from between the BB and pedal arm, which ends up all over the left pedal arm. I thought it looked like rusty water, but as it's all alu i couldn't work it out or where it had come from.

    My original thought was a seal inside the BB had failed, maybe water getting in and rust is from the bearings? I do ride in all weathers and wash it a lot, but didn't realise it would be that easy for water to get in?
  • 2Smart
    2Smart Posts: 105
    Sounds like you don't have a little drain hole under the bottom bracket shell to let water out. Take your seatpost out, hold your bike upside down and see how much water comes out. This maybe your problem. Small drain holes can be drilled in bottom bracket shells if you are careful. Alternatively ask a LBS to do it.
  • desweller
    desweller Posts: 5,175
    The sealing arrangement on these systems is crap, to put it mildly. The water usually makes its way in around the rotating dust seal (clue's in the name) and the crankshaft.

    It's not usually a problem to have water inside the BB shell as there's a plastic tube that incorporates o-rings that seal against the cups. As this seal doesn't have to cope with a sliding surface it's usually pretty good.
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  • Erudin
    Erudin Posts: 136
    edited May 2012
    My Tiagra bb got wrecked after riding flooded roads, but managed to replace the bearings.

    I bought a Hope bb tool (£19). The job can also be done without specialist tools (eg. vice, hammer and drift, see vid here). I filed the centre hole of the shimano cups so diameter was big enough so the tool would fit in making it easy to tap the bearings out in future. Pressed in the cheap (£3.40) ebay bearings (branded Zen) using a vice. I filed the lips off of the nylon bearing "Top Hat" caps (needed as replacement bearings are 7mm wide rather then the 6mm ones they replaced), otherwise caps that fit can be bought, eg. RaceFace X-Type Bottom Bracket Bearing Cap. Fitted refurbished bottom bracket to bike and it's running as good as new. Don't know how long they will last, will try higher spec bearings if they're worse than the originals.

    img0603o.th.jpgtophatsealimg0604.th.jpgimg0735wc.th.jpgimg0615vi.th.jpg

    See also: http://www.mountainbikerides.co.uk/fett ... ement.html
    http://www.smbbearings.com/BB_BRGS.htm
    http://faqload.com/faqs/bicycle-compone ... ng-service
    http://www.peterverdone.com/archive/bik ... ackets.htm
    Katec outdoors specific bearings
  • TheStone
    TheStone Posts: 2,291
    I don't think the Shimano HT2 BBs are very good.

    Eventually switch to a Chris King which I think might outlast me.
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  • Erudin
    Erudin Posts: 136
    TheStone wrote:
    I don't think the Shimano HT2 BBs are very good.

    Eventually switch to a Chris King which I think might outlast me.

    I like the way the Chris King can be regreased:
    http://www.competitivecyclist.com/review-tools-bottom-brackets/Chris-King-Bottom-Bracket-and-Injector-Tool.1197.html

    48779.jpg

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