Bicycle Mechanics - 25.8 bars in a 26.0 stem?

Hi guys, don't know if this is the right forum for this, but I just had a quick question and was wondering if I could get some input. I'm looking for a new stem for my bike, and the one that I really want has a clamp diameter of 26.0. Unfortunately, my bars have a clamp diameter of 25.8. It seems like such a minute difference, do you think it might be okay to just go ahead? Or am I way off base and this would be too unsafe.

Here are my handlebars: http://businesscycles.com/tbars-3ttt.htm

Here is the stem I've got my eye on: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=007&item=170030569797&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1

Any input you could give me would be great. Thanks! Oh ya, and I don't think there is a shim available this small, is there?

You'll probably be fine. You can make a partial shim from a piece of a soda can and put it along the bottom of the top, but a 25.8 bar in a 26.0 stem should be fine, especially a faceplate-clamp-style stem you're looking at. Only possible issue is the compressive force on the bar clamped between two plates where the curve isn't exactly matching is that the bar will end up slightly ovalized at the clamp section. But this shouldn't be a problem and it looks as if the bar has a sleeved construction, too.

For the record, the 3ttt Pista bars are available in 26.0mm clamp diameter too.

Great, thanks so much for your reply. I think I'll go ahead and go for it. Now that you mention that the 3ttt bars come in 26.0, I wonder if mine are. I actually got them off eBay a while back and was just assuming they were 25.8 because that's the only size I could find listed online.

Either way, I think it should be fine. If it seems like a problem, I might try your soda can shim idea. How much exactly whould I cover? Half of the area? Or just eyeball it and try to fill in the gap if it's noticeable?

Thanks again so much for your thoughts.

Just do it. Ritchey makes their road bars with a weird size: 25.8. Are your bars Ritchey's?

Anyway-- i've mounted my 25.8 Richey's in a cast alloy road stem with a 26 clamp. Been that way for a year now with NO problems. If you wanted to run a 25.4 (MTB clamp size) H-bar you might need to use a shim.

the 3TTT bars i've used in the past were advertised @ 26.0 but were actually 25.8. the pista's might be different.

ed rader

i'd get the proper size stem. the clamps diameters are sometimes slightly different than advertised -- e.g., 25.8, 25.9.

i used salsa stems back in the day and i went through a lotta grief with bars smaller than 26.0.

ed rader

I wouldn't worry about it, we're talking 0.003" on the radius. The pop-top stems are more forgiving as to sizing mismatch, they don't have the bending component involved like the quill type does.

I've had a set of 25.4mm bars in a road stem (pop-top) for quite a while, another in a quill (with shim).

I wouldn't worry about it, we're talking 0.003" on the radius. The pop-top stems are more forgiving as to sizing mismatch, they don't have the bending component involved like the quill type does.

I've had a set of 25.4mm bars in a road stem (pop-top) for quite a while, another in a quill (with shim).
+1 on the pop-top stems being more forgiving. Less bending, more squeezing = better... though I do love the look of a traditional stem. As Tim pointed out, this could very slightly ovalize your bars, although this is hardly a concern either.

As Tim suggests, you can make a soda-can shim. Although that may be too thick in this case. I've used those for 25.4 to 26.0 mm. We have some thick aluminum foil in our lab that would probably be just about perfect for this use...

the 3TTT bars i've used in the past were advertised @ 26.0 but were actually 25.8. the pista's might be different.
Okay, maybe the 3ttt Pista bars listed as 26.0mm clamp diameter are really 25.8mm, but are listed as 26.0mm at some places just as indicator that they're "standard road size" clamp diamter.

If I remember correctly, 25.8 is intended to work just fine with 26.0mm stem clamps.

Okay, maybe the 3ttt Pista bars listed as 26.0mm clamp diameter are really 25.8mm, but are listed as 26.0mm at some places just as indicator that they're "standard road size" clamp diamter.

If I remember correctly, 25.8 is intended to work just fine with 26.0mm stem clamps.

According to Sheldon, the Italians are just wishy-washy

http://www.sheldonbrown.com/cribsheet-handlebars.html

and playing both sides of the street.

We have some thick aluminum foil in our lab that would probably be just about perfect for this use...

Nicked a nice chunk of copper sheeting, 0.01" thick.

on the old style stems it was hit or miss. believe me i've tried many different combinations. there was an article on this some years back that listed the "real" sizes of handlebars (ITM was 25.9mm).

i bottomed out an adjustable 26.0 look stem trying to tighten it on a 25.8mm 3TTT handlebar and that cost me a couple of hundred bucks.

maybe it's different these days with the new stems. but i'm not into coke can shims, creaking or slipping handlebars and i will continue match my handlebars to the correct size stem.

ed rader

I have the 3T THE BAR on my track bike with a steel Salsa quill stem (26.0mm) and this is the only type of stem that can be trouble with a slightly smaller bar if you over tighten, as there is barely any space between the ends of my steel stem clamp where the bolt pinches the clamp around the bar.
Anyhow, most of the alloy 2 or 4 bolt 26.0mm clamp stems would be no problem on a 25.8mm diameter bar.Not sure, but I think 3t has their smaller diameter clamp handlebars in 26.0mm now.

I have the 3T THE BAR on my track bike with a steel Salsa quill stem (26.0mm) and this is the only type of stem that can be trouble with a slightly smaller bar if you over tighten, as there is barely any space between the ends of my steel stem clamp where the bolt pinches the clamp around the bar.
Anyhow, most of the alloy 2 or 4 bolt 26.0mm clamp stems would be no problem on a 25.8mm diameter bar.Not sure, but I think 3t has their smaller diameter clamp handlebars in 26.0mm now.

This would've been helpful about 3 years ago.