Campag front deraileur

outcastjack
outcastjack Posts: 237
edited May 2011 in Workshop
I am unable to engage bottom gear on the front set of gears.
when changing down just before it is far enough over to change into bottom the deraileur fouls the Frame and is unable to move any further.

Its a 9speed mirage deraileur.
Has anyone else had this problem, an if so how did you fix it?

Cheers

Comments

  • Wooliferkins
    Wooliferkins Posts: 2,060
    Has it ever worked or are you building something up? I would guess you have too short a BB fitted.
    Neil
    Help I'm Being Oppressed
  • keef66
    keef66 Posts: 13,123
    Double or triple chainset? I'm guessing double if it's Campag.

    As suggested by Wooliferkins, too short a BB, or you've fitted a JIS (eg Shimano) chainset on an ISO (eg Campag) square taper bottom bracket
  • outcastjack
    outcastjack Posts: 237
    Bottom braket being to shrt sounds about right, its a Campag chain set on a campag BB, but they are quite old and i think designed for a narrower frame

    Thankyou both!
  • keef66
    keef66 Posts: 13,123
    Unless it's very unusual, the bottom bracket shell on the bike will be 68mm wide.

    Is the front derailleur cage absolutely parallel to the chainrings, or has it become twisted slightly?

    Can you measure the chainline? Centre of the seat tube to a point mid way between the chainrings.
  • tatanab
    tatanab Posts: 1,283
    You need to move the right hand crank only a small distance further out, so I would fit a spacer behind the bottom bracket fixed cup. http://www.sjscycles.co.uk/wheels-manuf ... prod17701/
  • outcastjack
    outcastjack Posts: 237
    sorry i wasn't really explaining it too well.

    the shell is 68mm wide and the axle is 102mm long.

    the cage is fairly well parallel, but when i change down the arm hits the upright tube of the frame and is unable to get far enough inboard to change down on the smallest cog.
    i think the solution would be to push the crank set further out.

    If i change to a BB with a longer axle (say about 110mm) would that solve the problem, or is the spacer a better way to go about it?

    If the spacer would work then i think i will go for that as it will save a heap of money!
  • kozzo
    kozzo Posts: 182
    outcastjack wrote:
    Bottom braket being to shrt sounds about right, its a Campag chain set on a campag BB, but they are quite old and i think designed for a narrower frame

    Thankyou both!

    There were two types of Campagnolo 111 mm bottom brackets.
    One of them asymetric for triple chainrings.
    Your case seems to be 111 mm BB for double instead of 111 mm asymetric BB for triple.
    Details on Capmagnolo website.

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