Reasons for different valve standards / advantages??

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mjr
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Re: Reasons for different valve standards / advantages??

Postby mjr » 1 Aug 2020, 11:43am

Marc wrote:Not to mention, that Dunlop/Woods valves don't allow to check tire pressure...

Huh? Attach pump and increase pressure slowly until the valve opens and gauge indication stops rising so quickly, same as you can with any valve.

The only difference is you must pump to increase pressure in the gauge, rather than deflate the tyre a little into the gauge - but if you deflate a low-volume tyre a bit to get a reading, that's not exactly checking what the pressure was!
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mercalia
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Re: Reasons for different valve standards / advantages??

Postby mercalia » 1 Aug 2020, 11:49am

are woods valves the ones that you that small piece of rubber tubing you some times get with puncture repair kits?

I didnt realise that the inserts are different for bikes cars etc. Ebay seems to sell them as the same. Is there any benefit from using a car insert in a cycle tube? is there any kind of colour coding - I see that some have a black plastic surround some a red.

Brucey
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Re: Reasons for different valve standards / advantages??

Postby Brucey » 1 Aug 2020, 12:50pm

mercalia wrote:are woods valves the ones that you that small piece of rubber tubing you some times get with puncture repair kits?


that is one pattern of woods insert, the oldest in fact; not as good (IMHO) as the 'Aligaro' type insert, because the aligaro insert is easier to pump.

Image
'aligaro' Woods type insert

Image
traditional woods inserts combine the valve seal with the insert seal using one length of rubber tubing; the same insert can be used over and over again

The traditional insert will last forever, given supplies of the rubber tubing, but is less easy to pump through. I have quite often burst the rubber sleeve (even when new) simply by pumping vigorously.

The ribs on the traditional insert also mean that many pump connectors leak more than they should when they are connected to this style of valve.

I didnt realise that the [Schrader] inserts are different for bikes cars etc.


they often are; what you shouldn't do is assume a lower spec insert is suitable for a more demanding application.

Ebay seems to sell them as the same.


which tells you everything you need to know about ebay

Is there any benefit from using a car insert in a cycle tube? is there any kind of colour coding - I see that some have a black plastic surround some a red.


No benefit from using car inserts in bicycle valves. I don't know of any colour coding convention. Some inserts don't even fit some valve stems, and some don't use (seal etc) materials which are compatible with the substances in use.

BTW I agree with the post above about 'checking pressures'. Very few Schrader valved bicycle tyres are large enough in volume that the pressure isn't in danger of being changed when being 'checked' using a gauge. You also tend to lose air from the tyre when disconnecting Schrader. Strictly speaking you only get a true reading of tyre pressure with woods or presta, during pumping.

cheers
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