Rear Deraillieur Woe

Discussion in 'Bicycle Mechanics and Repairs' started by chugsy, 17 Apr 2010.

  1. chugsy

    chugsy Senior Member

    Location:
    Nottingham
    Hi,

    I've just finished turning my old commuter back into a knobbly mtb only to find that the rear deraillieur no longer shifts down into the smallest three cogs. Can't figure out how this has happened as I was only cleaning, regreasing the skewers and swapping slicks to knobblies...

    Only thing I can think of is when I was putting the back wheel back on I forgot to wrap the chain around the cassette on the first attempt:blush:

    Any ideas as I have never been very good at deraillieur adjustment and don't fancy paying my lbs to sort this out (again:o)

    Cheers,
     
  2. Gerry Attrick

    Gerry Attrick Lincolnshire Mountain Rescue Consultant

    Have a look at this.
     
  3. OP
    OP
    chugsy

    chugsy Senior Member

    Location:
    Nottingham
    Thanks - I watched many videos on this matter in past but have always struggled because I don't have a stand and doing these techniques with the bike upside down doesn't seem to work (for me). I plan on trying it again tomorrow but was wondering if anyone had any idea why this has happened - gear adjustment shouldn't be necessary from a simple wheel removal/refit.
     
  4. rh100

    rh100 Well-Known Member

    Halfords do a small bike stand for about £10, it's ideal for this kind of thing as it just lifts the back wheel of the ground a few inches. It's not very stable mind, but with care it does the job.
     
  5. longers

    longers Veteran

    If you've got two wheelie bins and a broom handle you might be able to cobble together a way of lifting the back end up. Sort of worked for me.
     
  6. OP
    OP
    chugsy

    chugsy Senior Member

    Location:
    Nottingham
    I'll be hanging an old car boot bike carrier from my clothesline post tomorrow:tongue:

    Or else fails I'll go to my folks and hang it from the garage roof.... last time I did that was 20 years ago to hammerite my first mtb (an Emmelle - what happened to them?)
     
  7. swee'pea99

    swee'pea99 Legendary Member

    Putting the bike stand to one side, it sounds odd. As you say, why should changing the tyres make any difference? The only thing I can think of to suggest is that if it's not chnaging to the smaller sprockets at the back, it suggests some kind of stickiness in the cable. It's the spring in the mech that changes up (to smaller) at the back. If it's not doing that, then presumably it's 'cos it can't...it's meeting too much resistance somewhere. Try detaching the cable, then turning the pedals - does it change now? It should. It's only the cable stops it from being in top gear all the time. Perhaps run some oil thru' the cable housing, and where the cable runs under the bottom bracket? Can't think of anything else. Good luck.
     
  8. OP
    OP
    chugsy

    chugsy Senior Member

    Location:
    Nottingham
    if by detaching the cable you mean loosening it from the derailleur end then I plan on doing so - it's just a last resort option for me given my past experiences! might try removing the cable outers from their housings to slacken off the tension 1st. I did lube my cables today - noticed as the light was fading that I could not push/pull the derailleur out to the highest position - maybe i did do some damage from forgetting to loop the chain around the cassette?

    thanks for the advice!
     
  9. OP
    OP
    chugsy

    chugsy Senior Member

    Location:
    Nottingham
    Finally got around to bodging a work stand together from an old car carrier - whilst working through the gears I noticed that the 1st three cllicks of the trigger yielded no response. Only after these three clicks did the derailleur start to shift hence the missing three gears at the top end.

    Does anyone know what could cause this? knackered shifter maybe? I'd like some more feedback before releasing the cable at the derailleur end.

    Cheers all,

    Chugs
     
  10. rh100

    rh100 Well-Known Member

    From Sheldon Brown: http://www.sheldonbrown.com/derailer-adjustment.html

    Have a look at the alignment of the chain pulleys from the back, does it look bent? I bent one back by hand but depends how brave you are/cost of damaging it. Also, with the index in top gear, is the cable a bit loose where it is bare cable on the frame?

    Have a good read of Sheldon's page - he explains it all well.
     
  11. OP
    OP
    chugsy

    chugsy Senior Member

    Location:
    Nottingham
    will do - cheers!
     
  12. OP
    OP
    chugsy

    chugsy Senior Member

    Location:
    Nottingham
    Sorted now - took the plunge and released the cable and started over again... quite a good experience this time around (sunny day and a'proper' stand and all...).

    Took the opportunity to lube the inners and outer properly - nothing was sticking or bent so I really have no idea how this happend in the first place but at least I have a better understanding of things now:tongue:

    Cheers for the help!
    [​IMG]

    http://www.cyclechat.net/forums/album.php?albumid=335
     
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