bottom bracket broken?

jakjtb
jakjtb Posts: 111
edited July 2012 in MTB workshop & tech
Hey guys, I've come back to biking after a long hiatus and bought a careers vengence. I love the bike but when im putting pressure on it getting up hills and even just on flat road trying to get some speed the cranks slip like mad. I can only assume it is the bottom bracket that is knackered but thought I would seek more experienced help.
Any ideas guys?
Cheers
Jak
i find that if you just talk, your mouth comes out with stuff - Karl Pilkington

Comments

  • nicklouse
    nicklouse Posts: 50,675
    will not be the BB.

    what it is depends on what you mean.

    is the chain slipping on the cranks?
    is the chain slipping on the cassette?

    or os the cassette slipping on the hub?

    or is it just poor gear set up and the chain is jumping arround?

    might be good to have a read of the info on Parktools about general gear set up etc if you plan on sorting this yourself.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • jakjtb
    jakjtb Posts: 111
    Sorry, its a carrera vengence. Stupid auto correct
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • jakjtb
    jakjtb Posts: 111
    thanks for the info,
    its not the chain slipping as such. when it does it it makes a sort of crack sound and then the pedal thats taking the strain, usually at the top, will slip from the top to the bottom.... its unbelievably annoying
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • 1mancity2
    1mancity2 Posts: 2,355
    have you checked your chain is not too long? also was the bike new when you bought it?
    Finished, Check out my custom Giant Reign 2010
    Dirt Jumper Dmr Sidekick2
  • jakjtb
    jakjtb Posts: 111
    yeh it was from halfords, the chain is okay not too baggy.
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • 1mancity2
    1mancity2 Posts: 2,355
    It sounds like the chain is slipping so either the chain, chainrings or cassette are badly worn or its setup incorrectly, got any pics?
    Finished, Check out my custom Giant Reign 2010
    Dirt Jumper Dmr Sidekick2
  • bails87
    bails87 Posts: 12,998
    I bet the rear mech isn't quite set up right. When you're applying pressure the chain is jumping from one gear to another and slipping as it does so.

    Read Park Tools to look at how to set up gears.
    MTB/CX

    "As I said last time, it won't happen again."
  • ilovedirt
    ilovedirt Posts: 5,798
    1mancity2 wrote:
    It sounds like the chain is slipping so either the chain, chainrings or cassette are badly worn or its setup incorrectly, got any pics?
    It sounds like this to me.
    Production Privee Shan

    B'Twin Triban 5
  • YeehaaMcgee
    YeehaaMcgee Posts: 5,740
    jakjtb wrote:
    thanks for the info,
    its not the chain slipping as such. when it does it it makes a sort of crack sound and then the pedal thats taking the strain, usually at the top, will slip from the top to the bottom.... its unbelievably annoying
    Let's think about this logically.
    The chainrings are attached to the cranks. The cranks are attached to the BB. The BB does not have an effect on the chain.

    Now, if the pedals are seemingly slipping down when under pressure, then one thing must be happening - the chain is slipping or jumping on the chainrings. There is no other explanation that concerns this section of the bike.

    If we take a broader look, then the problem may also be at the rear cassette. Either chain slippage / jumping, or freehub slippage.

    There is simply no possible way for the BB to cause this.
    My photos
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    You wrote what I was think about this. Thanks yee. What he said
  • nicklouse
    nicklouse Posts: 50,675
    Which is what I said at the start ;)
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • cooldad
    cooldad Posts: 32,599
    No one can understand your Yorkshire type accent.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • YeehaaMcgee
    YeehaaMcgee Posts: 5,740
    nicklouse wrote:
    Which is what I said at the start ;)
    Yeah, I know. I was trying to explain why it couldn't possibly be the BB.

    But then, you've got the Yorkshire accent thing going on, I've got the Welsh accent thing, between us we're screwed.
    My photos
  • cooldad
    cooldad Posts: 32,599
    Nope, no one understands Nick, everyone knows better than to listen to you. Can only lead to chaos and mayhem.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • jakjtb
    jakjtb Posts: 111
    thanks for all the help guys. what is the remedy for this problem with the chain? happened about 10-15 times on the way home from work, a 6 miles journey. also the cranks have started making a groaning noise under pressure, only the left crank does it. any ideas?
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • jakjtb
    jakjtb Posts: 111
    as well the bike is brand new so everything is brand new and is lubricated well using gt85
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • cooldad
    cooldad Posts: 32,599
    Could be anything, but check all bolts etc are done up tight. Loose crank bolts can trash your cranks in seconds.
    And use a better lubricant than GT85.
    Proper chain lube for the chain. Fork oil or Float Fluid on the stanchions. Grease for bearings, and light oil for mech pivits etc.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • The Rookie
    The Rookie Posts: 27,812
    GT85 isn't a lubricant as far as a chain is concerned!

    The most likley casue is the rear mech isn't adjusted corectly, so have you checked it?

    Groaning, check bolt holding cank to BB is tight!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • jakjtb
    jakjtb Posts: 111
    tightened up the cranks, the left one was a tiny bit loose. I have adjusted the rear mech, it was doing this thing where the chain wouldnt go into top gear. but stull getting major chain slip and its seriously annoying.
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • jakjtb
    jakjtb Posts: 111
    also. any recomendations on chain lube?
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • cooldad
    cooldad Posts: 32,599
    Squirt.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • jakjtb
    jakjtb Posts: 111
    cooldad wrote:
    Squirt.
    i thought this was a sarcastic dirty reply but just googled it. ha. gonna ebay some tomorrow
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • cooldad
    cooldad Posts: 32,599
    Get it directly from http://www.in2dust.co.uk/Squirt.html
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • cooldad
    cooldad Posts: 32,599
    Just follow the directions properly.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    Don't you just click on the link?
  • cooldad
    cooldad Posts: 32,599
    Yeah but you need a wifi connection on your bike.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • jakjtb
    jakjtb Posts: 111
    Got some. Got a degreaser as well just to make sure its clean before putting it on. Noticed after tuning my gears that my chain isn't slipping half as bad. Lets hope this stuff sorts out the remaining problem
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • jakjtb
    jakjtb Posts: 111
    Problem sorted. Had a massive ride on Saturday, 35 miles or so, without one slip. The only time it started slipping was when the cogs got clogged with mud and dirt. Just cleaned the chain, degreased and reapplied squirt. Just a 5 mile ride tomorrow to see if its right. Thanks for the help guys!
    i find that if you just talk, your mouth comes out with stuff - Karl Pilkington
  • cooldad
    cooldad Posts: 32,599
    Don't degrease, just wipe and reapply.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • adamgraves2009
    adamgraves2009 Posts: 31
    If the bike is brand new take it back to halfords. It should be covered under the guarantee. Or in respect of the groaning crank take it off and grease the B2B axle and make sure the crank bolts are tight.
    Specialized big hit pro
    Orange 5

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