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knocking from bottom bracket area

Discussion in 'Bicycle Mechanics and Repairs' started by DLB, 18 Sep 2007.

  1. DLB

    DLB Senior Member

    My hybrid has developed a clicking/knocking in the bottom bracket area. It occurs once on each rotation of the pedals/chainring, when my right foot is pushing down.

    It doesn't matter what chainring i am in of the triple and it stops if i freewheel or don't push down as much on the pedals.

    I took the bike to the LBS but when the guy there rode the bike the knocking didn't occur. He said it could be a pedal bearing or the bottom bracket (but there was no play in this) but as he couldn't hear it he couldn't help more.

    On my commute today it never stopped clicking which drove me mad for 13 miles. Any idea what i could try/do
     
  2. barq

    barq Senior Member

    Location:
    Birmingham, UK
    I sympathise because it is incredibly annoying. There are quite a few suspect parts and you are going to need to approach this systematically to track the noise down.

    Pedals: Do you have some spare pedals you can install? Failing that can you cycle one legged (clipless pedals or straps)? If you suspect the bearings in the right pedal then try injecting a decent load of grease - that won't be a permanent fix but it might help to identify the problem.

    Bottom bracket: There are several potential issues here. The bottom bracket may be worn and need replacing, although usually you can detect this because there will be some play if you give the cranks a good sideways tug. The bottom bracket may over time have worked slightly loose and simply need tightening up. Lastly it may be that your cranks are not as tight as they should be on the bottom bracket spindle.

    Chainring bolts: These are a common source of hard to pin down creaks. Check to seem if any are loose - if in doubt remove and then reinstall with a threadlock (e.g. Loctite 243).

    There is also a faint possibility that the noise actually comes from your saddle and is travelling down the frame. It's unlikely but try to eliminate that by standing when pedalling so see if the noise continues.

    See also Park Tools very comprehensive guide to creaks. It might take a while but creaks can always be nailed in the end. ;)
     
  3. skwerl

    skwerl New Member

    Location:
    London
    I'd go for pedals as first culprit, as the shop has said the BB is ok.

    Take pedals off, grease threads and re-install
     
  4. OP
    OP
    DLB

    DLB Senior Member

    how can i grease the bearings? how do i get to them?

    And do i need a pedal spanner to get the pedal off?
     
  5. domtyler

    domtyler Über Member

    Ear plugs/iPod?
     
  6. OP
    OP
    DLB

    DLB Senior Member

    i'd thought of those but would prefer to get rid of the problem. thanks anyway.
     
  7. OP
    OP
    DLB

    DLB Senior Member

    just found a pedal spanner on wiggle so will order that.
     
  8. barq

    barq Senior Member

    Location:
    Birmingham, UK
    Most pedals have a plastic dust cap on the outside edge. You can carefully remove this with a small screwdriver and squeeze a load of grease in there and replace the cap. The other method is to drill a small hole through the plastic and squeeze grease in until it starts coming out the other end of the axle. I honestly wouldn't bother disassembling a pedal entirely because it often makes them worse and is a real hassle.

    I don't think pedal threads are a likely culprit unless the pedal is loose in the crank. But if you do remove the pedals then a dab of grease is important to stop them seizing forever in your cranks.
     
  9. skwerl

    skwerl New Member

    Location:
    London
    remember, right is right, left is wrong.
    ie the left side pedal has a reverse thread so you need to turn spanner clockwise to remove. It's the opposite for b/brackets.
    apologies if you knew this but many people don't
     
  10. Tetedelacourse

    Tetedelacourse New Member

    Location:
    Rosyth
    I've had similar problems. Thought it was the BB too but turned out to be rear hub! Are you sure it's coming from that area? Incredibly hard to tell from the saddle.

    I put mine into LBS for a look and he spotted the actual problem in about 20 seconds flat.

    Mind you, I know more about the whereabouts of Michael Rasmussen's training routes than I do about bike mechanics.
     
  11. OP
    OP
    DLB

    DLB Senior Member

    i'm pretty sure it's coming from the bottom bracket area and so i'd be stunned if it was the rear hub. i'll give the grease a try first and then if it doesn't work i'll try swapping pedals. ifthose both fail i'll have a look at the BB.

    thanks for the advice