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It's correct except possibly for the clamp size. The good news is that it has the largest clamp so you can shim it down for your bike which is probably 1-1/4" (32mm). Measure your seat tube diameter, and ask them about a shim if/when you buy it.
 

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The one at Wheelworld doesn't come with shims because it's not in retail packaging. Unless you have 1 3/8" seat post, you may want to look for one in retail packaging that includes the shims. Shims, by themselves, may cost more than the der.
 

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Your current derailleur should have the clamp size written on it somewhere (inside the clamp? Take note of it and just order online or go visit your local bike shop.
 

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I'd get a nicer one. The front derailleur is a woefully undersung part of a bike - a better one really is better.

The XT derailleur comes with shims and is the same swing and pull (I assume you want top swing, where the cage is above the mount?)

http://wheelworld.com/product/shimano-deore-xt-front-derailleurtop-swing-43032-1.htm

The plain Deore one is a lot cheaper but will still be a big improvement. Whether or not it comes with shims was unclear, though.

http://wheelworld.com/product/shimano-deore-fd-m530-9-speed-triple-front-derailleur-6831.htm

Doing a Google search by name will probably get you a bunch of other options. And remember... "Shim" is just a fancy name for "piece of metal I used to make something thicker."
 

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If the original is a 31.8 but has shims, than you probably have a 28.6mm (1-1/8") seat tube.

If it's steel (check with a magnet) upgrade "probably" to near certainty.

You can still buy the bargain FD but have to get the right shims, or another 31.8 mm FD and reuse your shims, or a 28.6 which would mount without shims.
 

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Discussion Starter · #10 ·
The shim is where the 31.8 is imprinted on, not on the actual derailleur. I need to order a part soon here, want to get the right one, might post up some pics...
 

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We can't tell for sure from pics, but you can measure what you have. FDs come in 3 clamp diameters to match seat tubes, 1-1/8", 1-1/4", 1/3/8" or 28.6mm, 31.8mm (often rounded to 32mm), 34.9mm (35mm).

You can measure with a strip of paper and a pencil. Wind the strip around the seattube making a bit of spiral so you can draw a line across 2 overlapping layers. Lay it flat and measure the distance between your lines. That's the circumference, and if you divide by 3.14 you'll get the diameter.

You don't have to be super precise since it has to be one of the three sizes. The shim will have a thickness equal to half the difference in the seat tube diameter, and FD clamp diameter, or either 1/16" or 1/8", so it's easy to eyeball the difference, either about the thickness of a nickel or twice that.

Once you know what you have, you can know what to buy.
 
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