Bicycle Mechanics - How to fit handlebar to wrong size stem?

Looking for a Thompson stem for my road bike with about 15-17 degree rise but they do not make that size for a 26.0 handlebar. They do make a 5 degree rise and you can flip their -10 degree to get +10 but that is the limit on what they make for a road bike bar. They do have what I want for a 25.4 and the 31.8 handlebar. Is there any kind of standard shim that can be used to adapt a 25.4 or 31.8 stem to a 26.0 size? Even if there is, am I asking for trouble using them?

(Yes...I want that much rise. You will too when you get older)

Perhaps the easiest solution would be to get a 25.4 handlebar. Nitto, for example makes one.

If you decide to force fit an oversized handlebar into your stem it might be a good idea to chamfer a little relief into the edges of the stem body and front plate. I wouldn't use the lightest handlebar that i could find either.

I agree with RG that forcing a 26.0- bar into a 25.4 stem is not the best idea and I don't know of anyone who makes a shim to reduce a 31.8 stem to accept 26.0 bars. Unless you are wedded to your current bars for some reason, either get the Nitto 25.4 bars or you have a wide choice of 31.8 mm bars these days.

What do you think google is for, people? (http://www.bti-usa.com/item.asp?item=TC9102&searchtype=&itemsearch=&showSec=)
Tighten it down like a gorilla and it should be fine. Or buy a 31.8 handlebar. IIRC some people have had good luck putting 26 bars into 25.4 open face stems but I wouldn't try.

I've fitted a 26.0 mm bar into a 25.4 mm open face stem with CARE so as long as your not ham fisted its OK. Make sure there are no sharp edges where the half circle of the clamp meets the open clamp face. A sharp edge here may dig into the handlebar when tightened so remove it with a file or find another stem. Loosen the clamp right off when you wan't to adjust the handlebars so as to avoid deep scratches in the handlebar which can act as a stress riser and carefuly and evenly torque down the handlebars.

OK, one more thing. I measured my 26.0 mm bars as an actual 25.9 mm. If your bars are actualy 25.8 mm then they will fit without any issues anyway. If they are actualy a tiny bit bigger than 26 mm then things may be different.

Regards, Anthony

Sticking 26.0 bars into a 25.4mm stem is just plain dumb. Get the proper sized parts and don't monkey around with a part that could land you on your head if it breaks.