SJX426 

Did Cinelli offer the 1R for 26mm bars? XA and 1A 's can be found but I don't know if 1R's were available in anything other than 26.4.

I would like to use a 26 bar with a 1R but don't like the idea of using a shim(s). Any thoughts on skipping the shim for this configuration?

malcala622 

According to Velobase

repechage

measure it, but with the design it is, I would not bet on it.

SJX426 

@malcala622 - Dooh!

smontanaro 

The 1R relies on pressure from the wedge and the leading edge of the stem to keep the bar secure. I doubt the wedge is different for different diameters. The question would then be how much surface area at the front you'd lose by using a 26.0 bar in a 26.4 stem. It might not be much, but considering how iffy the 1R design was to begin with, you probably need every square nanometer you can get to keep the bar from rotating.

Charles Wahl

Just get a damn shim the right thickness (0.2 mm thick). You won't even see it. IMO the Worst Stem Design Ever, by the way (including the infamous and maligned "death stem") -- who the hell puts a huge hole in the front of the clamp, and fills it with plastic (that gets lost). And the clamp mechanism is easy to strip the threads on, or overtighten and break the clamp.

SJX426 

@smontanaro and @Charles Wahl - not going to argue your points about the design. I understand the concerns and opinions.

Finding a .2mm shim has been a challenge. I can imagine that the issues applies to any Cinelli stem that is 26.4 with a user wanting to use a 26 bar.

velomateo

Funny enough, I just did some work on an old Ciocc I picked up quite a while ago. I was changing out bar and stem to reduce the reach for Mrs Velomateo, and when I removed the Cinelli 1R stem I noticed that the bars are Specialized. I measured the bars and they were 26.0. I’ve never ridden the bike, it’s way too small for me, but there doesn’t seem to be any evidence of bar slipping at all. So it seems doable. This bike even had Scott clip-ons, so there was possibly a little extra pressure on the stem.

obuckler

I made my own out of a large 25 oz (I think) beer can. Mics out the perfect size and easy to do. Of course if you are an aggressive rider you may be counseled to never shim a bar/stem combo.

SJX426 

@velomateo - Good information. I did try it without a shim and it appeared to work just fine. I don't think 0.4 mm really makes a difference. The opening measures out to be....... not round. the closest to 26.4 is in the vertical. The horizontal dimension is about 27! It is likely ok to use and may do so . It is currently mounted on my 760 because it was easier to do on a bike with DT's. Lots of pressure needed with the shims. I am sure they act like Babbitt bearings! No serrations on the shim like on the bar and stem intended interface.
Even a 26.4 in a 1R 26.4 looks like it is too small.
P1030528 on Flickr
@obuckler - I don't drink much beer so am at a disadvantage! I am leery of the shim approach.

I confess that I like the looks of the 1R and that is the reason for having a few. I also really like the XA. Neither are low price options.
P1020201 on Flickr

jiangshi

Try going down a hill at 35+mph and hitting the brakes hard. Let us know how those 26.0 bars do on a 26.4 stem.

smoothness 

I would highly advise using 26.0 bars in a 26.4 stem without a shim. Even when used with matching bars and torqued correctly, compression-wedge "bolt-less" stems are known to squeak, if not slip outright under load.

The mating surfaces rely upon a tight slip-fit in order to provide maximum grip; with a .4mm gap, you're removing a majority of the necessary contact area.

If you're still insistent upon using this combination, I would suggest that you make a shim from an aluminum can, and liberally apply green loctite between shim and handlebar, and lightly grease between shim and stem.

RiddleOfSteel

25.4 and 26.0mm stem manufacturers, in my used vintage parts experience, have had their actual diameters vary considerably from their stated numbers, as have handlebar makers. That's been enlightening. Cinelli, however, has been on the money with their bar and stem diameters. Find an aluminum can--tea, soda, beer, whatever. Cut it nicely (though be careful for the sharp edges) to match the width of the stem clamp (you could even take a coarse file and rough up the main surfaces). You may have to have two wrappings/layers, and gently opening the clamp up just a touch will help slide things in there (and align the shim and center the bar). Once done, it will help the stem clamp the bar properly (concentrically) instead of elliptically.

I've gotten away with not shimming things before, years ago (and I am lucky/blessed/thankful), but when it came time to use a 1A stem with Soma Highway One bars, I made the 'beer can shim' and it worked well. I understand the inconvenience and frustration scarcity and dumb ebay prices, but there's always a 1A, brand new, in 26.0mm only, waiting. And it's going on a 760--only one of 1,300 of those that year!