How do they come out?
AFAIK, they are inserted from the tube side and then the valve unit is vulcanised into the tube.
Any more details Dougie?
Any road up, if the valve fails and you can repair it like a removable Shcwalbe valve, you would need a spare valve and a spanner. Personally, I always carry two spare tubes and not bother repairing anything until I get home.
Puncture or no puncture?
Re: Puncture or no puncture?
Mick F. Cornwall
Re: Puncture or no puncture?
I'm no expert... but if they are like car valves you can unscrew them to let the air out faster. and, there's a special tool for car valves.
I woke up in the morning to a flat. Swapped the tube out, as a couple of guys were with me and we wanted an early start. new tube in, tyre back on, inflate the tube, remove the pump (Zefal full length pump) and the valve core shot off somewhere and the tyre deflate fast. It was a tube I hadn't use before (new). I can only think that the incoming air was somehow unscrewing the valve core, but while the pump was on it was all sealed.
I woke up in the morning to a flat. Swapped the tube out, as a couple of guys were with me and we wanted an early start. new tube in, tyre back on, inflate the tube, remove the pump (Zefal full length pump) and the valve core shot off somewhere and the tyre deflate fast. It was a tube I hadn't use before (new). I can only think that the incoming air was somehow unscrewing the valve core, but while the pump was on it was all sealed.
Re: Puncture or no puncture?
in the interests of experimentation I've just wrecked a tube I had. the knurled nut completely unscrews. using pliers I twisted off the shaft of the valve core (half way up). I've just pushed the remainder down inside the tube, with hardly any effort.
therefore I think what must have happened before is that maybe I unscrewed the knurled nut to it's limit (locking it against the threaded shaft), and the friction of the incoming air must have heated it to the point of brittleness, snapping it off. the remainder just popped down inside the tube, giving the impression of the whole thing flying away.
therefore I think what must have happened before is that maybe I unscrewed the knurled nut to it's limit (locking it against the threaded shaft), and the friction of the incoming air must have heated it to the point of brittleness, snapping it off. the remainder just popped down inside the tube, giving the impression of the whole thing flying away.
Re: Puncture or no puncture?
That makes sense Dougie. I've broken off the pin with the screw in the past and therefore wrecked the tube.
I suppose Schwalbe have the right idea with replaceable Presta valves, but I wonder if the cost is more/similar to a new tube anyway.
I suppose Schwalbe have the right idea with replaceable Presta valves, but I wonder if the cost is more/similar to a new tube anyway.
Mick F. Cornwall
-
Jonty
Re: Puncture or no puncture?
These things happen. Noone knows why. It's like black holes, blace energy and anti-matter. Put in a new tube and leave it to the scientists. 
jonty
jonty
Re: Puncture or no puncture?
a mate of mine brought me his nephews bike on which the tyres kept going flat he had pumped them up but stil wanted me to check the bike out
rear wheel off tyre off tube out inflated tube tried it in water no bubbles so i removed the valve core to find that there was white gunge on the valve core and when i folded up the tube to expell all the air white runny water came out which as it turned out was tyre sealant the kind you put in car tyres
i replaced the valve core and refitted the tube and inflated the tyre but left it off the bike for an hour(a habit of mine as nothing worse repair a puncture put the wheel back on then find an hour later the tyre has gone flat) and it was still inflated
only conclusion i can come to is the sealant possibly sealed a puncture but the sealant also caused the valve to leak hence the flat tyre which shows that car tyre sealant isnt suitable for bikes
the front wheel inner tube incidentally didnt have a puncture and can only conclude that the tyre was soft and riding on a rough suface caused the tyre to go flat or nearly flat
rear wheel off tyre off tube out inflated tube tried it in water no bubbles so i removed the valve core to find that there was white gunge on the valve core and when i folded up the tube to expell all the air white runny water came out which as it turned out was tyre sealant the kind you put in car tyres
i replaced the valve core and refitted the tube and inflated the tyre but left it off the bike for an hour(a habit of mine as nothing worse repair a puncture put the wheel back on then find an hour later the tyre has gone flat) and it was still inflated
only conclusion i can come to is the sealant possibly sealed a puncture but the sealant also caused the valve to leak hence the flat tyre which shows that car tyre sealant isnt suitable for bikes
the front wheel inner tube incidentally didnt have a puncture and can only conclude that the tyre was soft and riding on a rough suface caused the tyre to go flat or nearly flat