Claris front mech too short

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mrfpb
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Joined: Tue Apr 16, 2013 10:44 am

Claris front mech too short

Postby mrfpb » Fri Apr 04, 2014 10:13 am

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.

mattv
Posts: 979
Joined: Mon Apr 03, 2006 20:04 pm

Re: Claris front mech too short

Postby mattv » Fri Apr 04, 2014 11:35 am

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.

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PBo
Posts: 2353
Joined: Wed Mar 04, 2009 22:53 pm

Re: Claris front mech too short

Postby PBo » Sat Apr 05, 2014 19:43 pm

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
Posts: 637
Joined: Tue Apr 16, 2013 10:44 am

Re: Claris front mech too short

Postby mrfpb » Sat May 10, 2014 15:42 pm

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.

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The Rookie
Posts: 23079
Joined: Thu Apr 30, 2009 09:29 am

Re: Claris front mech too short

Postby The Rookie » Mon May 12, 2014 10:40 am

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.

Slowbike
Posts: 5049
Joined: Wed May 02, 2012 09:26 am

Re: Claris front mech too short

Postby Slowbike » Mon May 12, 2014 11:06 am

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?


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