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Old 04-15-12, 12:26 PM   #1
dellwilson
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Front derailleur problem

Hi y'all

I'm not much of a mechanic, but I've been trying to do all my own wrenching for about two years now. I still drop by the LBS every now and then on things I've not yet learned. I started a new build partly as continuing education and partly to get exactly what I wanted.

The build of a Surly Crosscheck frame with SRAM Rival groupo is complete, but I have a bit of a problem. The frame has no braze-on for the front der and the 31.8 Rival clamp is a bit big for the frame. So, I had to use a rubber shim. However, the tension from the cable pulls the der down off of the shim.

Is there a trick to getting this to stay or is it simply a matter of tightening it down enough?

Thanks
Dell
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Old 04-15-12, 01:08 PM   #2
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It looks like you'll need a different front dérailleur. Surly's website indicates your seat tube is 30.0 mm. In any case, a soft shim will not do the trick. Possibly a 0.9 mm (.035") metal shim would work.

Any other thoughts?
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Old 04-15-12, 04:27 PM   #3
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The frame takes a 28.6 clamp. You'll want to get either a FD with the correct clamp or a 31.8>28.6 shim.
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Old 04-15-12, 04:33 PM   #4
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http://www.ebay.com/itm/Shimano-Fron...#ht_500wt_1054

I'm sure there are cheaper options, and measure your tubing size of course.

Last edited by aramis; 04-15-12 at 04:37 PM.
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Old 04-15-12, 06:56 PM   #5
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Quote:
Originally Posted by MrPhil View Post
It looks like you'll need a different front dérailleur. Surly's website indicates your seat tube is 30.0 mm. In any case, a soft shim will not do the trick. Possibly a 0.9 mm (.035") metal shim would work.

Any other thoughts?
It is absolutely ubsurd that Surly does not publish it's front derailleur clamp size. It's 28.6. The fact that the seat tube clamp is 30.0mm does not necessary tell you the indicate the size of the derailleur clamp. There is no reputable bike manufacture that would spec a seat tube that is not one of the standard sizes for derailleur clamps. Crazy or not front derailleur clamps still come inch sizes; 31.8= 1 1/4 28.6= 1 1/8. A 1 1/4 to 1 1/8 shims are very plentiful and relatively cheap. http://www.amazon.com/Wheels-Manufac...2&sr=1-2-fkmr1

Last edited by onespeedbiker; 04-15-12 at 07:13 PM.
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Old 04-15-12, 08:12 PM   #6
dellwilson
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Thanks for the responses, y'all. The Wheels Mfg. shim is the one I have. It is more narrow than the clamp so there is nothing to keep the clamp on it except tension and a bit of double-sided tape I put on. But the tape wont really stick to the rubber. The Shimano shim looks wider and looks like it has raised edges to contain the clamp. I'll stop by the LBS tomorrow to see if they have one of those in stock. If not, I'll order that. I guess I'll just ride in the small ring to work tomorrrow and try not to put too much stress on it.
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Old 04-15-12, 09:34 PM   #7
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A good inexpensive option for a Ft. Derailleur clamp shim is to use the plastic core from a roll of cloth handlebar tape.
The plastic is wide enough to cover the width of the derailleur clamp, and can be shortened to make the derailleur fit tight.

There's a little bump that needs to be removed from the core, but by using a pair of diagonal cutters you can cut the bump out
and open the core to slip over your seat tube.

Alan
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