gauvins

I'll be trying these TPU tubes once more - they could have improved.

One thing. The valve isn't threaded and there's no retaining nut to secure it to the rim, which is what I do with butyl.

Thing is that when I inflate the TPU, with a hand pump, the valve is pushed inside, and eventually gets caught by the tube pressure, more often than not at some angle out of the vertical, and halfway inside the tire. Not good.

What is "the way"?

jadmt

not sure why you are having that issue. I have not had an issue with maybe trying pushing down on the tire above the stem until there is sufficient pressure to hold it in place. looking at mine I can't see how the valve could even shift but probably more to do with the wheel then the tube in my case. I have them in two different wheelsets but both wheelsets are really similar.

RB1-luvr

like jadmt wrote, press down on the tire where the valve is while putting the pump chuck on and keep the valve seated until there's enough pressure to hold it in place.

gauvins

One reason could be that I've used a rather small MTB hand pump where the seal requires you to push against the valve (i.e. no chuck). I've switched to a MTB Morph (lightweight floor pump with chuck) -- there's no pressure on the valve, which has solved the problem. Conclusion seems to be to carry the Morph (or equivalent). Too bad -- I liked the hand pump

Crankycrank

I worry about those plastic valves and using a mini pump with no hose or no proper chuck as it will wiggle the valve and possibly break it. Having a plastic valve is part of the reason those tubes are so lightweight but seem a little fragile to me. Any experienced TPU'ers have problems with this? I wouldn't mind trying them on my bike if the price wasn't so high but they sound interesting.

mpetry912 

here's a trick I do - get some neoprene foam, fairly thin, and make a little "pillow" for the valve where it sits inside the rim bed

this will reduce or eliminate the little "pinches" that occur right next to the valve.

/markp

t2p

I’ve had the core pull out of the stem on an Aerothan tpu tube - ham fisted user error mostly - but the plastic threads can be defeated

just gotta make sure the removable core is properly tightened / snug - and don’t pull up on it with a threaded chuck without loosening completely or pull up with chuck with a lip that can grab the threads of the core

RideNow tubes have a metal valve stem (the RideNow tubes I have at least ?)

jadmt

so I called Schwalbe and they told me to really tighten the cores down much more than you think was necessary. I said I was worried I would crack the stem and they said I would be ok. I tightened them down pretty good and have not had one pull out since. he said just using bare fingers would not get them tight enough and too use a valve core tool. this is how far I have them tightened down.

FBinNY 

You shouldn't be relying on the nut to keep the valve straight. It might end up masking a problem.

The key lies in the initial installation, making sure the tube is spread evenly around the rim so the valve is naturally straight. If so, it'll normally come back the same way.

That said, sometimes braking and accelerating forces the tire to walk on the rim, taking the tube with it.
Without a nut, the valve will alert you by leaning. A nut prevents that, and you won't know until the tube rips from the valve.

gauvins

Not really to keep it straight, but to keep it stable during inflation. My hand pump works without chuck/screwed connector. The seal relies on applying pressure on the valve. I was hoping that as the tube inflates, the valve would progressively move into position (i.e. straight and out). Unfortunately, it tends to be pushed obliquely by the reinforcing layer close to the base of the valve.

I'll get a mini floor pump with threaded connector, which will hopefully solve the problem.

rekmeyata

You have every right to be concerned because they have been breaking just as you are worried about them doing.

Andrew R Stewart 

Why don't you want to use the common flip lever compressing a "rubber" seal around the valve type of air chuck on your pumps? One of the reasons why they are the common air connector for so many pumps for so many years is that they work better than screw on or push on chucks do.

When I did use push on only chucks (back in the 1970s with the Zefal Competition frame pump)let the tire become nearly flat (s long as the tire had some pressure already in it the valve wanting to be pushed in by my handling wasn't a big deal. When the tube had near zero pressure in it I would push onto the tire so it would crush down and press against the valve deep in the rim, this keeps the valve from being pushed in too much.

But the real solution for the (we hope) vast number of times when you use a pump (as you start out for a ride) is to have an easily worked with floor pump. When I was selling bikes that suggestion came before on the ride flat fixing stuff. Being able to start your ride with topped off tire pressure (whatever that is for your bike) is the #1 way to avoid flats on your ride. When you shop for that floor pump you mention I strongly suggest you test/trial inflate your tire with it BEFORE buying. Bring your front wheel to a shop and ask them if you can buy THE pump that you find you can work with. If you have a difficult time working their pumps ask for instructions/help. Andy

gauvins

[Thanks for your detailed answer]

It is not what I want, but what I had. An otherwise excellent high volume pump. Didn't notice any issue because I was riding on butyl (threaded valve secured with a nut).

This is in the context of touring, where a full size floor pump is impractical. I already have a chuck+lever hand pump (1) not that easy to raise the lever with a 36-spoke wheel and fat fingers; (2) hand pumps are quite likely to exert pressure on the valve. So I got the Lezyne Micro Floor pump. The connector is not the easiest to set on the valve (or on the pump receptacle for that matter), but it is certainly much gentler on the valve than what I had.

Being somewhat lazy, and touring on 2.1" tires at low pressure (30psi) I add air... once a month or so