Claris front mech too short

mrfpb
mrfpb Posts: 4,569
edited May 2014 in The workshop
Hello all

I recently needed to replace the front chainset on my Ridgeback Speed. As my rear cassette was getting worn, I thoght I'd do a major upgrade.

Replaced the wheels a few years ago, and I was using a 7 speed cassette and spacer on an eight speed hub. So I thought I'd upgrade to Claris 3x8. The rear mech and cassette work beautifully but the front mech won't reach the big ring!

Do I need a narrower axle (there's about 1 cm between crank and BB), or is there some other solution.

I've just ordered a CX as an N+1 for my main riding, so the Speed can be relegated now to shopping in town and being left at places I wouldn't leave my nice bike. So even if I only have 39/30 at the front, I could live with it, but it would be good to have the 50 ring back in action.

Comments

  • mattv
    mattv Posts: 992
    Sounds like the bottom bracket axle is too long. Replace with shorter axle if it's a loose one, or a smaller cartridge if it's sealed.
  • PBo
    PBo Posts: 2,493
    is it missing by miles, or is it jumping up but not quite catching?

    Have you tried the obvious? cable tensioned enough? High screw not stopping the mech too soon? did you put a new cable in?
  • mrfpb
    mrfpb Posts: 4,569
    I was enjoying my new bike too much to look at the Speed. But this week I got the bottom bracket tool and had a go. The bottom bracket is seized up.and I can't get the lockring to budge. The tool doesn't want to grip when I put full pressure on or if I use a hammer on the spanner. Possibly I could get a long bolt to hold the tool on but otherwise I'm stuck.
    PBo wrote:
    is it missing by miles, or is it jumping up but not quite catching?

    Have you tried the obvious? cable tensioned enough? High screw not stopping the mech too soon? did you put a new cable in?

    Did all the above. New shifters and cables. The mech doesn't get near, lots of room at the low end, hence I'm looking at the shorter axle option.

    Other tips I've followed. Spray lots of WD40 on the BB and leave for 20 mins. Pour boiling water on the BB before trying to remove. All to no avail!

    Still, I do have a new bike so I'm still smiling.
  • The Rookie
    The Rookie Posts: 27,812
    Start by measuring the chainline, from middle of frame to the middle ring, should be about 45-50mm, more and you definitely need a narrower axle.
    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.
  • slowbike
    slowbike Posts: 8,498
    mrfpb wrote:
    I was enjoying my new bike too much to look at the Speed. But this week I got the bottom bracket tool and had a go. The bottom bracket is seized up.and I can't get the lockring to budge. The tool doesn't want to grip when I put full pressure on or if I use a hammer on the spanner. Possibly I could get a long bolt to hold the tool on but otherwise I'm stuck.

    Other tips I've followed. Spray lots of WD40 on the BB and leave for 20 mins. Pour boiling water on the BB before trying to remove. All to no avail!

    Still, I do have a new bike so I'm still smiling.

    you are undoing the BB aren't you?