"Chain Rub" but not...

Discussion in 'Bicycle Mechanics and Repairs' started by Jdratcliffe, 7 Aug 2012.

  1. Jdratcliffe

    Jdratcliffe Well-Known Member

    Location:
    Redhill, Surrey
    umm have an issue bike is only 6 week old but has been used daily for commute has had its "check up" for cable stretch etc but in the top chain ring and 4-5-6 on the cassette ( 10sp) i get a consistent chain rub like noise when i pedal forwards on the right pedal down stroke. the noise is greater on the 5th cassette ring.

    ideas where to look i have had a short poke around over the weekend but it was there again this morings commute.
     
  2. Dave7

    Dave7 Guru

    Location:
    Cheshire
    What gears are they ?
    I have very limited knowledge (as a beginner) but I know that 105's have what they call "micro adjust" so if the chain is rubbing then you slightly 'tweek' both levers on the left (i.e. for the front 'cogs'). It may well be the same on all modern gears.
    BTW I know this as I took mine back to find out why it was rubbing and the guy showed me:rolleyes:
     
  3. OP
    OP
    Jdratcliffe

    Jdratcliffe Well-Known Member

    Location:
    Redhill, Surrey
    Yea it 105 but i only have 3 "clicks" on my shifters up, up and down is this what you mean? but surly this is only for the xtremes of the cassette which is silent is the middle that makes the noise? unless it up once to get to 1-4 and then 2nd click up for 5-10?
     
  4. OP
    OP
    Jdratcliffe

    Jdratcliffe Well-Known Member

    Location:
    Redhill, Surrey
    Tried on the way home and in today if im in the botttom ring no noise click "up" once the chain doesnt move just rubs ALOT and then 2nd click up shifts to big ring and i get the noise on my 4th 5th 6th cassette cog.. ideas?
     
  5. lukesdad

    lukesdad Guest

    Has this happened since the service ? The only thing I can think of is the crank bolts havn't been done up tight enough and you may be getting some deflection on the down stroke. ( trimming is the term you are looking for when adjusting the front cage by clicking your shifters on the same chain ring )

    Take it back to the shop and let them have a look.
     
  6. OP
    OP
    Jdratcliffe

    Jdratcliffe Well-Known Member

    Location:
    Redhill, Surrey
    happened since i had the bike "disappear" after the service when i mentioned it and has since come back... umm in regards "trimming" i dont think it does anything as i the middle "click" seems not the do anything.
     
  7. ohnovino

    ohnovino Large Member

    Location:
    Liverpool
    If the rub isn't consistent (i.e. only at one position when the cranks rotate), then the chainring isn't staying perfectly vertical as you pedal. First things I'd check for are a loose bottom bracket, loose crank bolts or loose chainring bolts.

    Last time I had those symptoms the bb was very slightly loose, so the chainset would rock slightly as I shifted weight on the pedals.
     
  8. lukesdad

    lukesdad Guest

    Can you determine where the rub noise is comming from ? Is it the cage of the front mech ? Can you put the bike on a work stand and rotate the pedals does it still rub ?
     
  9. PpPete

    PpPete Guru

    Location:
    Chandler's Ford
    I had an odd one the other day. The front mech wasn't aligned quite right which was causing a few problems, but when I corrected that I got a new noise. Took me ages to identify the cause. Turned out the teeth of the big ring were just clipping the back of the FD cage (the little screw piece that holds the two halves of the cage together. Evidently whatever had knocked it to put it out of alignment has also allowed the FD to slip down a fraction.

    As LD suggests - putting it on a workstand and going through the gears whilst turnig the pedals can make tracking down the problem a bit easier.
     
  10. OP
    OP
    Jdratcliffe

    Jdratcliffe Well-Known Member

    Location:
    Redhill, Surrey
    ok had it up last night i a work stand tracked the problem more to the rear mech on the ride in today noise was worse and spread over the top 4 gears 5th 6th 7th 8th and 9th 10th gear was quiet ( apart from my painting) seems that i can temporally stop the noise when i shift up and then down the the gear i want eg 9th - 7th and then to 8th is quietens down for a bit... tis elusive and annoying as the bike is only 7 weeks old!
     
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