Tyre deflated Fancy caps?

[pesty]

Riding home "briskly" last night came off the motorway braked down to around 30ish for rounabout nothing coming so off brake.

tried to lean to go left bike went staight on big roundabout lots of room so was ok.
pulled up at side and found front tire flat

limped to a garage extremely stressful bike was not wanting to play at all ! and pumped up me tyre. just checked pressure and its stayed the same over night.

poped into my local bike dealer told him what happened and the first thing he asked me was have I fitted after market metal dust caps?

the asnswer was yes as I had just got 2 free ones with a magazine. he said he recons that may be the cause and he had had a guy in the day before with the same problem.

Ive put me plastic ones back on and tightened up the vavle with that tool thingy you can get. I'll let you know if me tyre stays up.

[gixxer1000]

Pesty, I had a similar problem with fancy dust caps having bought those ones that are SUPPOSED to change colour from green to red when your pressure drops. Well first off, they don't bloody work at all (always stay green), and secondly, given that they essentially hold the value open behind the cap (to sense when the pressure drops) they actually CAUSE air loss.

Go figure! Seems I was duped into buying them like plenty others I'm sure.

Back to bog standard plastic caps for me too.

[WoodE]

For anyone thinking about using, or already using the 'Tyre Flies'(?) (those stupid lights that connect to yer tyre valve), these also deflate your tyre... something about the centerfugal force created within the tyre pushes the (bulky & heavy) lights into the valve, effectively deflating yer tyre.

They look crap too ;D

[cazzo]

A few years ago I had a similar problem, I was told that metal caps with O rings are better and seal the valve so that if due to centrifugal force the valve presses it would not allow air to escape.

I fitted metal caps and about a week later I went to the bike to find rear tyre flat, I thought it was punctured so took it to tyre shop for repair or replacement and it turned out the O ring had twisted into the valve whilst tightening the cap and deflated the tyre I promptly re-fitted the original plastic ones and have never had a problem since, actually I never had a problem before either.

>> Edited by cazzo on Tuesday 10th June 23:51

[Gerrard]

gixxer1000 said: Pesty, I had a similar problem with fancy dust caps having bought those ones that are SUPPOSED to change colour from green to red when your pressure drops. Well first off, they don't bloody work at all (always stay green), and secondly, given that they essentially hold the value open behind the cap (to sense when the pressure drops) they actually CAUSE air loss.

Go figure! Seems I was duped into buying them like plenty others I'm sure.

Back to bog standard plastic caps for me too.

I've got these after some offer (buy 4 get 2 free! - ideal for your car and bike!) in reputable bike mag and like you have found they don't work - ALWAYS green even though the tyre's lost 3psi. The front one doesn't even work, can't get the centre to pop up (come to think of it, front pressure never seems to change either, hmmmm....) so back to standard plastic for me too.