CrowSeph

I have a few tpu tubes aside for spares, today I had to change one since got rekt in a race and I noticed something.

Two in er tubes feel a bit too long for a 700c wheel, and I'm not able to insert the tyre since the tube is going to get compressed.
The other one just stay tight to the rim, and I'm able to put the tyre whiteout any problem.

Ofc I use a bit of pressure before installing, and yes the pressure is the same.

Here an image how the "longer tube" looks like.


Also I have to admit that the tubes are never used.
Can be fixed in any way?

Ps. If someone is interested to know how the race ended, I just lost my 10th rank. The inner tube failed after a pot hole at the last 1.5km and I had to run toward the finish with my bike on shoulder.
At least I was able to close at the position 17/29.

mpetry912 

suggest you use LESS pressure - just a few PSI - when installing.

these tubes are quite stretchy

/markp

ThermionicScott 

I think pretty much every tube I've inflated outside of a tire ends up with a bigger OD than the tire. When confined by the tire, it expands inward and... works.

CrowSeph

Trust me, the pressure Is very low.

CrowSeph

The TPU installation is kinda different, you must inflate a bit and then installing the tyre.
This particular tube is elongated somehow and I can't put inside the tyre.

Andrew R Stewart 

I had thought one of the differences between these and common butyl tubes was their inability to stretch much. As in the crossection/width had to match up pretty closely to that of the mounted tire. If the tube were allowed to stretch much it wouldn't return to the original "size". I hope this isn't what happened to the circumference already. Andy

ThermionicScott 

That's not different; I always put a little air in a tube before installing it.

tFUnK

You just want to put enough air for it to take shape. Like 3-4 strokes on a mini pump, or 1 stroke on a floor pump.

smd4

You inflate every inner tube before installing. You have a non- problem.

grumpus

First put the tube in the tyre, then put the tyre on the rim. It may take some manipulation to get the "extra" bit of tube to lie flat, and you have to be careful not to damage the valve stem.

Koyote

I usually just blow through the valve a bit. It doesn't take much air.

CrowSeph

I can understand that my question probably sounds very stupid. This is not the first tube I've installed 🤣But reading the instructions tubes must be inflated a bit before installed.Now take a look at those images 1- 2- Those are two different tubes inflated just a bit for the installation itself.One is completely flat against the rim and the tyre installation can be done easily.The other one is almost impossible since the tube folds on itself making it impossible to install correctly without pinching. Note that both tubes are newer, fresh from package.

Duragrouch

The tube may be too long. But first, understand that the rim outside seating surface, is significantly smaller that the inside tire seating surface just under the tread. So, with bare minimum pressure in the tube, try placing the tube inside the tire; If there is a large wrinkle or buckle in the tube, redistribute it carefully to spread that all in tinier parts all around, usually that is enough for installation. Then, put the tire on the rim, valve first of course, then the rest. Then inflate. If things go well, circumferential force trying to make the tube larger in diameter, will be constrained by the tire, and the tube will only expand in section diameter, completely filling the void between the tire and rim. Let us know how that goes.

hidetaka

We could spend hours overthinking the issue but what it looks like is a QC failure with the tube, gonna happen to someone, this time it was you. I've used quite a few RideNow tubes and none were oversized in such a way. Let's just toss it in the bin and move on?

smd4

There’s no problem with the second tube. You won’t need to fold it on itself. You’re way overthinking this.

Shadco 

There is a bit and there is too much, this is too much.

smd4

There's nothing wrong with that tube.

cyccommute 

If you have to inflate the tube prior to installation, put it in the tire first. That will constrain the tube to keep it from expanding too much. Every pressure vessel elongates as well as expands under pressure. Tubes just happen to be very weak pressure vessels that aren’t meant to be inflated outside of a stronger pressure vessel.

A rubber tube would expand and elongate much more than a TPU tube which isn’t very stretchy at all, contrary to what has been written above. The instructions on the TPU tubes say not to inflate them too much outside of the tire or the tube will be damaged.

Frankly, there is no need to inflate the TPU or any other kind of tube upon install. A tire that is tough to install will be harder to install with air in the tube. Just put the tube in the tire and mount the tire.

smd4

Wrong.

cyccommute 

Nope. Right. The tire bead needs to sit down in the channel of the rim and it the tire is tight, putting in a bladder that fills that channel will make it impossible to get the bead down in there. That increases the difficulty of installation. Additionally, the tube is more likely to be pinched during that installation.

smd4

Still wrong. You increase the chance of a pinch without inflating the tube to shape. There won't be any installation difficulty. If there is--you're doing it wrong. Or don't know what you're doing.

DiabloScott

The relevant property here, is that TPU tubes don't UN-stretch as much as butyl after you've over-inflated them. So they're always a little more difficult to install, doubly so when you've stretched them. Good news is they're pretty tough so even if you pinch or fold it going in, it'll still probably work at least as a spare... might be lumpy.

Andrew R Stewart 

This thread is beginning to drift into a "how to do it right" and a "what's right" pissing session.

I would ask if the OP has yet tried to mount the tire and see what the actual fit up results in. Does the OP feel that they can't just toss this tube, for whatever reason. At some point the value of moving on outweighs the cost of question or concern. Where that point is for each of us will be different. (just as how we mount tubes is different)

When our industry last tried non butyl tubes (about the early 1990s and poly urethane IIRC, my shop sold a few Panaracer versions briefly but we stopped after both poor sales and growing dislike of the after use stuff like "odd" patching methods). While we had little issues mounting them, we saw little benefits and greater cost besides the patching and needing to be far more specific in the sizing. Andy

Turnin_Wrenches

Holy moly, this thread cannot be serious... but I think it is

veganbikes

Install the tube as normal with the tire and then post the results. Showing more pictures of a tube around a rim doesn't solve your problem. Put one half of the tire on, then put a lightly inflated tube inside and then install the other bead and then slowly inflate while checking to make sure the bead is sitting properly. If there is an issue at that point then I would post pictures.