tmh657

I bought a 31.8 FD on ebay by mistake. I would rather make it work than re-sell it. I know you can buy a shim to make the reduction but it cost almost as much as the derailleur.
Is there another,(cheaper) solution?

operator

Which 31.8 F.D did you buy? The tourneys come with a range of shims that can take the 34.9 derailleur all the way down to 28.6. The only thing i'm not sure of if the plastic brackets that hold the shim in place are compatible with your derailleur.

tmh657

It's a Shimano 105, FD 5501.

PlatyPius

I've used the Tourney/Acera/Alivio shims on a Dura Ace (mine), so I would guess it would work on a 105.

You can also MacGyver a shim with a Coke can and a pair of tin snips.

If your local shop won't give/sell you one, let me know... I'll see if I can dig one up.

tmh657

I could possibly MacGyver a shim. Perhaps with a strip of inner tube and then it wouldn't slip. I guess the rubber would decay after awhile and lose it's position but by then I could get the real mccoy.

Thanks for the idea PlatyPius.

operator

I've used a heneiken can to shim a 31.8 down. It worked fine. It was just annoying as hell if you ever had to adjust the derailleur position/rotation.

Jeff Wills

Don't use rubber- the front derailleur mount needs to be rigid. I made one out of a short piece of PVC pipe. The different "schedule" pipes are different thicknesses- I think Schedule 40 is 1/16" thick, perfect for fitting a 1 1/4" clamp on a 1 1/8" tube.

I pulled the same fummducker as TMH a while back and I wasn't willing to try to find the same model with the correct clamp. A PVC shim worked perfectly the first time, and it's kept working for 6 or 7 years. I painted it black to match the frame, but you can make it out here:
https://home.comcast.net/~jeff_wills/...es/bike025.htm

BFW

If you have a local shop, check with them. I know I have 3 or 4 of those shims in a drawer on my bench. Leftovers from replacing broken/worn out derailleurs. I also remember that the 105 triple I put on my touring bike had one of those shims in the box as well. You shouldn't run into any compatibility issues.

BCRider

From a touch of math I make this out to be a .063 inch shim that you need. That's pretty much spitting distance to a 1/16 shim. If you can get some 1/16 or .060 to .065 sheet metal or HARD plastic it would make an acceptable shim. But I totally agree that you don't want to use rubber or electrical tape or anything else that is soft or will creep over time.

meb

Bikestop sales usually has great prices on front der shims.

griftereck

Ive got some of the shimano shim sets in my box of bits. the plastic frames are quite wide. so presumably would fit mechs that are thinner section.

tmh657

I went to 2 local shops today and the reply was, we can order it for you. I can do that. I think I have something that will work though.
The plastic part that Velox rim tape is wound on. I cut the rib out of the middle on 2 of them. They are thin enough to be flexy so it was easy to go on the tube. It seems they will do the job.
Good thing is the seat tube is white so I might not even have to cut it down to hide it.

cs1

That's slick.

Butcher

https://branfordbike.com/product/le-t...p-shim-878.htm

mas-az

I just took a seat post shim I had and split it into two and then spred it a bit to shim a 31.8 105 FD to 28.6.

Works great.

noglider 

I recommend metal as a shim, not rubber or plastic.

You don't need tin snips for a coke can. It's extremely thin. You can use regular scissors, and it's still extremely easy to cut.

It takes me a lot of trial and error to size my shims, but it definitely isn't rocket surgery.