[tmronin]

ok, i assume that some pressure loss over time is normal - but i lose an average of 20+lb in 2 days!! i lost 30lb over 5 days. if this was a diet, it would be pretty cool, but when i walked out to move the bike and the back tire had less than 10lb of pressure in it...i got a bit nervous. the back tire is much worse than the front - the front only loses 5-10lb.

what could be the cause of this loss? what can i do to stop it? use that flat tire spray in stuff? that just looks nasty. it's annoying to have to got to a gas station before EVERY ride to fill up the tires.

thanks in advance!
steve

btw - whoever suggested using WD40 to perk up faded CF is a genius. wow - what a difference.

 

[Guest]

After the obvious visual check for punctures in the tire carcass, make sure your tire valves are closing properly/completely.

I had the same problem with a brand new rear tire and it turned out to be stuck/leaky internals of the tire-valve stem assembly....the service dept forgot to change-out my 7 year old valves (but left the charge on the invoice)......

being lazy and wanting to spare my rims any additional tire-removal butchery I shot it with WD40 and it cleaned up and started shutting properly....

now I am hoping the WD40 doesn't attack the rubber seal...

so far,(8 months) the pressure holds plus or minus 2 lbs (allowing for ambient temperature)...being a weekend rider mostly, one of my standard pre-ride checks is the tire pressure

 

[test-reg]

that ammount of air loss should be easy to find, particularly the rear. submerge in water and look for bubbles. the rear can probably just be sprayed.

 

[CRASH!]

If I were to lube a valve, I'd try Silicone or Graphite spray lube. I'd also be concerned about WD-40 because it's a solvent.

 

[ScottRNelson]

An alternative to submerging your tire in water is to just wash it with very soapy water. Any air leak will form a bubble that you can see. Pump up your tires first.

 

[krista_k]

i don't worry about valve and weak solvent like wd40.