Tyres losing pressure

[abo]

Schreaders will take 120psi and hold it for several days. My wife's Dahon Speed-Pro has narrow 120psi 406 tyres and they stay up well.

In my experience all tubes leak air, not via a hole or valve but through the rubber of the tube itself. At the moment one of my trikes loses 10lbs in one back tyre and 20lbs in the other over a fortnight, both from 70psi. This has been going on for months and is not due to a slow puncture or leaking valve. I know because I stripped the tube out and submerged it in a bowl of water. The tube that loses most was a cheap one I picked up from Halfords, the other is a Schwalbe.

Hmm, was wondering about migration through the rubber but I couldn't remember whether the various gas molecules in 'air' were small enough. I wonder whether a tyre fitters could do me a chav-racer nitrogen fill?

Anyway, sounds like I need to pick up a couple of quality tubes and see how I get on.

 

[byegad]

Not only does air permeate but CO2 goes out even quicker! I blew a tyre up using CO2 by the roadside and next day had lost nearly half the pressure.

 

[abo]

Went and bought a couple of new tubes today, nice excuse to go and covert the shoes in the LBS

 

[Rob500]

I set my tyres at 100psi and check them each time I go out.

However, I haven't been out on bike since last Saturday. I checked their pressures this morning (10am) and the front was down at only 80psi and the back 90psi. I pumped them back up to 100 each and have just rechecked them (11:30am) and they were back at 80 & 90. Am I right in thinking that a little pressure is lost during the initial fitting of the pump? But is -20 too much? Could I have a slow puncture at the front?

 

[Angelfishsolo]

I set my tyres at 100psi and check them each time I go out.

However, I haven't been out on bike since last Saturday. I checked their pressures this morning (10am) and the front was down at only 80psi and the back 90psi. I pumped them back up to 100 each and have just rechecked them (11:30am) and they were back at 80 & 90. Am I right in thinking that a little pressure is lost during the initial fitting of the pump? But is -20 too much? Could I have a slow puncture at the front?

If both are loosing +10psi in 1.5 hours I would swap out the tubes.

 

[User16625]

Why is it road bikes generally use presta valves and just about everything else from a wheel barrow to a juggernaut uses schrader? Whats the advantages and disadvantages between them?

 

[Rob500]

Hi Angelfishsolo.
Thanks for the advice. I'm going to get some practice in changing tubes.

 

[Rob500]

@ Sperminator - I guess it's because prestas are skinnier to fit the skinny tyres.

 

[Angelfishsolo]

Why is it road bikes generally use presta valves and just about everything else from a wheel barrow to a juggernaut uses schrader? Whats the advantages and disadvantages between them?

Road bike rims are smaller and thus need a smaller hole. Presta valves require a smaller hole Schrader valves

 

[Angelfishsolo]

Hi Angelfishsolo.
Thanks for the advice. I'm going to get some practice in changing tubes.

Better now than in the middle of nowhere in the pouring rain

 

[Rob500]

Better now than in the middle of nowhere in the pouring rain

Never a truer word spoken

Happy days. I've just taken out & replaced my first road bike inner tube. I checked the old one in a bowl of water for air leaks but found none. Took me ages but it wasn't as difficult as I feared. I've put new one at 100psi. I'll recheck it in a little while aftera cuppa

Must go to shop and buy another 1 or 2 spares.

ps. My old tubes have a little locking type nut that spins up the valve but the new tube valve does not. It isn't even threaded. Are both types just as good?

 

[Angelfishsolo]

Never a truer word spoken

Happy days. I've just taken out & replaced my first road bike inner tube. I checked the old one in a bowl of water for air leaks but found none. Took me ages but it wasn't as difficult as I feared. I've put new one at 100psi. I'll recheck it in a little while aftera cuppa

Must go to shop and buy another 1 or 2 spares.

ps. My old tubes have a little locking type nut that spins up the valve but the new tube valve does not. It isn't even threaded. Are both types just as good?

The only thing I have found with the unthreaded type is that the pump head can slip off a little more easily.