Tyre pressure

[Wobblers]

Could well be then. I have put my road tyres on and used the remaining spare tube. I used my old fashioned pump (you'll know the type). Pumped up until it felt right - can't squeeze very much and doesn't flex much when I put all my weight on the bike. Connected to my foot pump - 20psi. Sidewall of these tyres have 40-65psi.

It's a Polco foot pump only a few months old.

The pressure gauges on foot pumps are not always noted for their accuracy! It does sound like yours is reading low. AT 20 psi I would expect the tyre to be quite soft, even if it has thick side walls. Try measuring the tyre pressure with another gauge or pump if you can.

It might be worthwhile investing in a good track pump - I use a Topeak Joe Blow which works fine for me and the pressure gauge seems accurate enough.

 

[marinbearvalley]

Had the gauge tested and it was perfect. Verdict seems to be that 50psi on a mountain bike speeding downhill off-road was just way too much and it caused the tube to split with such an explosive force it damaged the tyre. When I then put in a new tube and pumped up to 35psi, the weakened tire gave way (it came apart at the rim) and the lack of support to the tube caused it to pop.

 

[swee'pea99]

Interesting. I'm still baffled by a tyre that 'doesn't flex much' with your weight on the bike at 20psi. I'd expect to be pretty much on the rims at that pressure.

 

[lukesdad]

Something defininetly wrong there. I can ride up to 45psi on the roughest of tracks with no probs. What size and tread pattern are your tyres ?

 

[Debian]

Had the gauge tested and it was perfect. Verdict seems to be that 50psi on a mountain bike speeding downhill off-road was just way too much and it caused the tube to split with such an explosive force it damaged the tyre. When I then put in a new tube and pumped up to 35psi, the weakened tire gave way (it came apart at the rim) and the lack of support to the tube caused it to pop.

Hmmm...

I regularly run offroad at 65psi and I've never had a problem.

 

[marinbearvalley]

Something defininetly wrong there. I can ride up to 45psi on the roughest of tracks with no probs. What size and tread pattern are your tyres ?

26 x 1.95 knobblies.

 

[Debian]

26 x 1.95 knobblies.

26 x 2.1 here and, as I stated, I run at 65 psi offroad most of the time. Never had a problem.

 

[Wobblers]

I run 26 x 2.0 Schwalbe big apple slicks on the Dahon at 70 psi without problems. It does still sound like your foot pump gauge is reading low - if it were me, I'd try another pump to see what happens. But, to be honest, if you aren't having any issues with inflating to 20 psi with your foot pump, I'd be tempted just to stick to that.