ph0ust

hi. i've searched the forums and generally found only questions doing the inverse.

my '81 colnago superissimo has the original cinelli stem, which i understand should be 26.4mm. i want to replace the bars with something new, all of which would be 26mm in diameter.

my question is whether there would be an issue. i assume that the marginal difference would not pose any issue to the clamp on the stem.

any thoughts/experiences with this? thanks.

tatfiend 

Nitto makes a shim pair to use 25.4mm bars in 26.0mm stems and it is widely used for that purpose. The Nitto shim material is .012" thick. A similar shim pair made of .008" material should work with the Cinelli stem. I would not use the stem w/o the shim on a 26.0mm bar as tightening it down could overstress it and the difference in radius between the bar and stem will likely put uneven pressure on the bar's clamp area while still not clamping it as firmly as normally wanted.

ColonelJLloyd 

I would try fabricating a shim from an aluminum can, which I think is only slightly thinner than the Nitto shim. Just test it out in a relatively controlled environment. Don't wait until you're at the bottom of a steep descent to learn that your bars are going to slip forward.

red sox junkie

This is what I did and it worked fine. In fact, I forgot I did it unitl I took the bike apart recently and the aluminum pieces came out.

unworthy1

I have used the old beer can shim many times with success, except for this very same combo: an old 26.4 stem and a new 26.0 bar, both Cinelli...it slipped and was unreliable until I bought some real brass shim stock and used that. No idea why brass would be less slippery than aluminum, but it is. Maybe the paint or the coating/lining inside the can...anyhow, I'm sold on brass and have enough to do all the h-bars I'll ever own.

ph0ust

thanks everyone. i've since realized that my stem is just too long and has too much of a negative angle to it. i think i need to replace it. after playing with it, i thought new bars would help, but i'm pretty positive that the whole stem needs to get yanked.

any input on getting my bars pulled back and pushed up? are the old cinelli stems 1" or 1.125"? i'm thinking i may have to go with a stem adapter and a separate stem, that way i can get one very short with a positive angle to it.

any advice is appreciated!

unworthy1

old Cinelli stems are all 1" quill, if you can't find something like a Nitto DirtDrop that's short enough, you'll have to go with a 1" Mtn bike stem or that quill adapter and a modern stem.

ColonelJLloyd 

I have a Nitto Technomic with a 60mm reach. I think they're available in a 50mm reach. The DirtDrop is a nice stem, but I don't like the aesthetics of stems that don't have a 73/17 angle on vintage bikes with horizontal top tubes.

SJX426 

I too have a Superissimo. Tried various combinations due to the stem being too short for me. Ended up finding a 1A in 115 to meet my needs and settled on it. I did try the updated version but didn't stick to it. Bunch of pictures here: https://s985.photobucket.com/albums/a...20Superissimo/