26.0mm peg in a 25.4mm hole?

[Steve]

 Would I be ill advised, foolish or just plain stupid to mount a 26.0  heat treated aluminum handlebar on a 25.4 Nitto Tallux (forged aluminum) stem???

  I did this several decades ago without suffering consequences by spreading the stem open a bit with a wide flat screwdriver.  However,  I hesitate to try it again without seeking the opinion of those who know more about metallurgy and/or physical engineering than I do.

Thanks, Steve in AVL

[David Ross]

Ron from Ron’s bikes does this all the time and apparently designed his Crust Ron’s ortho bar specifically with a 26mm clamp diameter for use in 25.4 stems. It always sounded crazy to me, but he’s a pretty hardcore rider so it seems he’s field tested it. I feel like it would work ok in a tallix type clamp but would be less likely to work in a four bolt faceplate type stem. 

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[Steve]

I think I have an answer to my question, provided by a Google search which linked to a thread on this group from 2023 (surprisingly, a search within this site, despite multiple combos of search terms failed to lead me to it)

Anyway...in short, the answer is don't do it!       https://groups.google.com/g/rbw-owners-bunch/c/ZJ8EbT6aN88

David, I appreciate your referencing Mr. Romance and though I find his style entertaining and admire his various builds, he also into bending bars, which is something I'd definitely be hesitant to do.

[Nick Payne]

I've fitted 26.0 bars in 25.4 stems by using an expanding reamer to remove the 0.3mm of material from the inside of the stem.

Nick Payne

[David Ross]

Me too. Aluminum is a tricky metal. I’m running steel or ti bars with BMX stems. I like my bars to stay where they are and preferably in one piece. 

To view this discussion visit https://groups.google.com/d/msgid/rbw-owners-bunch/18c7bbe6-424b-43cd-97d5-478d53337756n%40googlegroups.com.

[Jeff Bogdanovich]

PM sent - I have a 26.0 stem if you want to trade.

Jeff

[Steve]

Jeff, your PM hasn't appeared yet in my email - perhaps it wound up with someone else who posted on the thread.  I had run across the Rune Hilt bar sold by Woods Cyclery in the UK which is only available in a 26.  I've decided though to give the Noodle I just recently purchased (along with a 5mm 25.4 Nitto stem) a fair try. I'm liking it a bit more with each ride.  Thank you though for the offer.

Steve

[Patrick Moore]

IMO, stuffing a 26.0 mm bar into a 25.4 clamp is less fraught (shims are a pain) than trying to squeeze a 25.4 mm clamp around a 25.4 mm bar; after all, the 0.4 mm diametrical difference is so small. 

I’ve been doing both for years without much forethought, and so far have lived to tell the tale. If anyone has engineering reasons why either is a bad idea, I’d like to hear them.

Also, I’d be even more inclined to use an open faceplate 25.4 to hold a 26.0 bar than an old-fashioned 1-bolt aluminum stem; tho’ I’ve often stuffed a old Cinelli 26.4 Giro d'Italia into a steel 25.4 mm stem. 

To view this discussion visit https://groups.google.com/d/msgid/rbw-owners-bunch/38673bcd-d426-401c-ba5e-a49f1acc9e50n%40googlegroups.com.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

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[Patrick Moore]

Damn!

I meant of course, trying to squeeze a 26.0 clamp around a 25.4 mm bar.

On Sun, May 17, 2026 at 2:56 PM Patrick Moore <bert...@gmail.com> wrote:

… than trying to squeeze a 25.4 mm clamp around a 25.4 mm bar;