Self Healing Inner Tubes

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Self Healing Inner Tubes

Postby gaz1971 » 29 Jun 2020, 9:34pm

Hi all, does anyone else have problems with these when you have to pump up the tyres? Every time, when you attach the pump, some air comes out, along with sealant, the sealant gums up the valve and an hour later, the tyre is flat.

I have to replace the valve core in order to get it to hold air.

Its a Schrader valve type by the way.

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Re: Self Healing Inner Tubes

Postby mattsccm » 30 Jun 2020, 6:41am

I think you have proved the general efficiency of these things.
They can work but the idea is flawed I think. Too much flex in a tube to hold the plug of sealant maybe.
Sealant from the valve is going to happen a touch as you are letting a puff of air out. Keeping the valve at the top while pumping may help if it is there long enough to let the sealant flow to the bottom and you may have to practice getting the pump off without moving the pin in the valve. Possible but very hard to do.
Better idea would be to throw the things away.

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Re: Self Healing Inner Tubes

Postby NickJP » 30 Jun 2020, 10:06am

Before you inflate, rotate the wheel so the valve is at 5 o'clock or 7 o'clock, and let it sit for a few seconds so that any sealant there can drain out of the valve stem. Then you shouldn't have the problem.

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Re: Self Healing Inner Tubes

Postby roubaixtuesday » 30 Jun 2020, 10:41am

I've only ever used these for pram wheels but had similar issues.

On a bike, investing in tyres less likely to puncture is a much better option I think.

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Re: Self Healing Inner Tubes

Postby bikesandboats » 30 Jun 2020, 12:44pm

Going for a tubeless set up with sealant would probably be a better bet. I haven't had any punctures on my tubeless bikes in the years I've had them.

It is more expensive though unless you already have tubless compatible rims or tyres.

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Re: Self Healing Inner Tubes

Postby andrew_s » 30 Jun 2020, 1:14pm

The problem with sealant in tubes rather than tyres is that the tubes are almost always stretched, which makes any hole bigger and more difficult to seal. It's not helped by the tubes not coming in many sizes, and those that are made being undersized compared with the label.
Ideally, you'd want the tube to be the same size as the inside of the tyre when it's only got just enough air in to round out (when outside the tyre). I use 700x35-37 tyres, and I'd want a 29-er tube to stand much chance of the sealant working well.

Tubeless tyres don't stretch, which is why sealant works in them.