car5car

I needed 26" tube and found 24" tube at home and installed it. Now what? I already bought right tube, should I replace it or it is OK to ride? thanks.

UniChris

I'd probably install the correct tube since you have it and it's not a big job at home, but might not be beyond carrying the undersized one as a spare. For that matter you might patch the original and put that back in.

Opinions are going to vary, but will throw out as a data point that the limited availability of tubes for giant 36 inch rims (and the fact that the early butyl tubes that were available weighted a ton) means that a fair number of people in both the giant bike and unicycle communities just started running 29er tubes in them, which is quite a bit more stretch than 24 to 26. I installed one once to see if I could, but haven't ridden it since some lighter weight tubes made for that size were economically available for a bit a couple of years ago.

Cyclist0108

It is 8% stretched. You will be fine.

Iride01

I'd only expect that the 24" tube will wear out faster and flat quicker if punctured.

If that is unsafe to you then change it. Otherwise just wait till it gives you troubles.

car5car

Thanks.

cyccommute 

Say What?! Tubes don’t “wear out”. Tubes don’t move inside the tire so there is no mechanism for wearing one out. And air will leak from the tube at the same rate as any other tube if punctured.

I don’t necessarily see a downside to use a smaller tube other than having to stretch the tube on installation.

Iride01

Of course it's moving in the tire. Though it's not going anywhere. There is stretching and contracting of every portion that encounters the area of the contact patch and the tire rolls along the ground.

And since many people don't do so well with keeping their tires inflated, then a stretched tube is going to be worse in that situation than a proper size tube.

You know how many people riding Schrader valves have the stems at an angle from riding under inflated tires. I'm certain every one of those valves where straight when the tube and tire installed. So what moved? The tube or the tire and rim?

cyccommute 

Tubes don’t wear out. Period. I’ve taken 30 year old tubes out of tires and reused them. I’ve got tubes with 30+ patches on them that have no signs of wear. The tube moves with the tire but a properly inflated tube doesn’t move independently of the tire. Tubes “wearing out” just isn’t a problem that anyone has ever experienced.

The tire and tube moved…together. Every straighten out a valve that is at an angle? To do so you deflate the tire (tube actually) and grab the tire and rotate it to move the stem back to vertical. If you just grab the valve and try to move it back to vertical, it won’t move or it won’t stay. You have to move both the tire and tube but mostly you have to move the tire.

On the other hand, if a tube is the wrong inner diameter, I could see it as more likely to keep the tire from moving because the tube sits further down in the channel of the rim. This would press on the bead tighter than a larger inner diameter tube and keep the tire in place.

2old

I built my first 29er from a frame and there weren't tubes at my LBS yet, so used 26er's for at least a year until they got flats or whatever (might have been much longer). No problem.

HTupolev

Assuming that the setup wasn't out of alignment to begin with, I would guess that it's typically the tube and tire moving together. It hard to visualize why a tube would experience axial slippage by itself relative to the surrounding rim and tire, but an underinflated tire slipping against a rim would be understandable, and would tug on the tube.

Iride01

I guess your issue is my choice of using "wear out". Yes, in your definition of wear out, they don't wear out per se. I guess maybe fail would have been a better choice.

So do you have an issue with this re-write?

Maybe I'm completely wrong, it just seems that the more you stretch a tube the thinner it is and the more stress it is under. So it will have a shorter life. And to me a shorter life is wear, whether any material is worn from it or the material changes properties or not.

Iride01

Yes, it was a hasty late addition to my reply. Since I posted it before I fully thought about it I'll have to take the hit for that.

dabac

The years I rode a 29er I never bothered stocking up on new tubes. When the ones that came with the bike got scrapped, I dipped into my 26” stash. Install required a tiny bit more finesse, but the tires I ran were quite user friendly and didn’t cause any drama. Maybe a 15-30 seconds penalty on a swap.
Once in place, entirely uneventful.
OTOH I’ve had other tires that have been more temperamental, and where ALSO fighting an escape-prone tube quickly turns into a real PITA.
So that’s really what I use as a judgement base. Can I fit the smaller tube w/o cursing, then I’m quite happy to do so, and to leave it in for its operational life.
If it’s a wrestling match making me wish for a 3rd hand, then it goes back out at the next appropriate opportunity.

cyccommute 

When you said that the tube “wears out”, I was thinking more about frictional rubbing. I think we can agree that’s just not something that happens.

I’ve addressed something like this here. If what I was saying in that post is correct, I think that a smaller diameter tube would actually solve the issue of the tube stretching thin in the spoke channel of the wheel quite handily. It would be slightly thinner on the outer edge but that’s not going to result in more frictional wear. The thickness of the tube…with the exception of very thick “thornproof” tubes…doesn’t do much to prevent flats from occurring.

On my trip, I actually attempted to address this with a 27.5” tire. I didn’t use them because they were too wide to fit in my road tires.

morecommas

Shouldn't be a problem.

Steamer

In a pinch I used a 559 tube in a 622 wheel and intended to swap it out later but forgot. I rode about 6 months with it like that and there were no problems. I only realized I had forgotten about it when I went to put on a different tire.