TIL that 27" tubes can work on a 29" rim. (pawb.social)

submitted 1 month ago by OwOarchist@pawb.social to c/bikewrench@lemmy.world

10 comments fedilink hide all child comments

When my girlfriend suggested we take the tubes off an old 27" bike to fix the flats on my 29", I thought she was being crazy and overly cheap. No way it would work. Surely I'd have to go out and buy some 29" tubes.

But fuck me sideways, it did work, and I'm currently riding just fine with 27" tubes in my 29" tires. Wasn't even that hard to get them on.

So I guess that's just a PSA for everybody ... apparently, tube sizes aren't really rules, they're more like guidelines.

you are viewing a single comment's thread
view the rest of the comments

[-] hemko@lemmy.dbzer0.com 12 points 1 month ago

Yeah so it's perfectly fine to stretch up 1 wheel size, though the tube won't be quite as durable for example when you hit a curb and the tube is pinched between tire and rim, but it's pretty minimal

You could also use larger tube in a smaller wheel by folding the tube a little bit. I've heard fitting a 29" tube on 24" kid's mountain bike just to finish a day.

TPU tubes you probably don't want to stretch on bigger wheel, but folding down to a smaller is perfectly fine

Aaaaaaanyways whenever you use "wrong" size tube, only do so if you just need to fix quick to keep on going. Grab a right size from a shop when you can and replace it.

this post was submitted on 14 Apr 2026

26 points (96.4% liked)

bike wrench

1134 readers

3 users here now

A place to ask bicycle repair questions, and for bike shop monkeys to share advanced non commercial wrenching resources (no YouTube self promotion). This is only for repair related topics.

!bicycles@lemmy.ca

!micromobility@lemmy.world

founded 2 years ago

MODERATORS

j4k3@lemmy.world