Tyre pressures - floor pump

[yello]

You were only supposed to blow the bloody doors off! or words to that effect anyway!

Okay, so perhaps the gauge is faulty! Perhaps I should have first asked you how hard the tyres felt as there's a noticeable difference between 40 and 100psi.

Have your tyres got presta valves? Those are the longer, skinny ones rather than the shorter, fat ones that mtbs (and cars) tend to have. Presta valves have a small nut on them that requires loosening first. Without doing that, you'll not get any air in the tyre.

The reason I said 'let some air out first' was that sometimes, even after loosening the nut on the presta valve, an air seal remains in the valve and prevents air getting into the tyre. The first couple of pumps normally break that seal... but not always. By letting some air out first, you ensure the seal (if there is one) is broken. I do it as a matter of course now. It's routine for me; unscrew the cap, stick it in my mouth, loosen the nut on the valve, tap the valve top to release some air, attach pump.

I have a Joe Blow pump too and it doesn't start requiring effort until around perhaps 90 or 100psi.

 

[gavintc]

Personally, I think the slime is the problem. Fit some new inner tubes without the slime, pump up to a decent pressure and I think you will find a lot less of an issue with punctures. I strongly believe that most folk's punctures are directly related to under inflation.

 

[aJohnson]

I have the same pump, I also find it hard to get it up to a higher pressure. Trying to get it up to about 110psi requires a good amount of effort from me. Quick question, should you be able to squeeze the tyres inwards a bit or should they be very hard? Normally I don't pump it up so high so I'm wondering.

 

[accountantpete]

I have the same pump, I also find it hard to get it up to a higher pressure. Trying to get it up to about 110psi requires a good amount of effort from me. Quick question, should you be able to squeeze the tyres inwards a bit or should they be very hard? Normally I don't pump it up so high so I'm wondering.

You will find that rock hard tyres roll far better on flat tarmac but are pretty useless on course surfaces as they keep bouncing up and down - so it's a matter of getting the right pressure for the terrain.

 

[ColinJ]

aJ - you've ridden with me so you know what a big fat bugger sturdy chap I am compared to you. Well I only put 95-100 PSI in my rear tyre and 85-90 PSI in the front (you need more in the back because more of your weight is on the back wheel). At just over half my weight, you really don't need to be going to that sort of pressure, especially for the crap road surfaces we have round here. Some of those aches and pains you're getting out on the road are probably caused by getting battered through rock hard tyres!

As for tyres being hard at 40 PSI - even big MTB tyres wouldn't be. Road tyres would be very soft at that pressure. Even at 70 PSI, I could easily squeeze tyres between thumb and forefinger and I don't have strong hands. At 90 PSI tyres are getting very firm but still have a bit of give which is why they are more comfortable than at 100 PSI plus. High pressures are great for velodromes and smooth roads but for the rubbish roads in vast swathes of Yorkshire and Lancashire - no thanks!

 

[ChrisKH]

Have you tried undoing the presta valve fully before pumping up the tyre? Serious suggestion, some people may not realise..........plus I have difficulty occasionally in getting the tyre to inflate if the valve is not fully undone and the head of the pump placed sufficiently far enough down on the Presta valve. It then only goes to 40 psi as the air isn't going into the tyre.

 

[ColinJ]

Have you tried undoing the presta valve fully before pumping up the tyre? Serious suggestion, some people may not realise..........plus I have difficulty occasionally in getting the tyre to inflate if the valve is not fully undone and the head of the pump placed sufficiently far enough down on the Presta valve. It then only goes to 40 psi as the air isn't going into the tyre.

I often point that out to people, and also that sometimes the valve sticks and needs to to be pressed to let some air out before you can get more air in.

On my track pump the gauge shows an increasingly high pressure if the valve is stuck until the valve suddenly 'gives' and air rushes in to the tube.

 

[Ball]

Reading what you've all said, it's pretty clear, the gauge is foooked. That means all of you who told me to pump hard owe me a slime tyre, donations made payable to Acc: ...

Seriously though, the first 4 or 5 pumps of air don't move the pressure gauge up at all, the needle moves up and then goes back down to 0. Only after that does it start to stay up, and at about 40psi takes a lot of effort while the tyre feels very hard.

From now on, I think I may just use the pump and read 40 as 120. I bought it from Wiggle and don't have the original packaging, so I don't know if they'd accept a return.

 

[Theseus]

On my track pump the gauge shows an increasingly high pressure if the valve is stuck until the valve suddenly 'gives' and air rushes in to the tube.

Same here. With some inner tubes I find I have to let them completely down in order to be able to pump them up again.

 

[ASC1951]

From now on, I think I may just use the pump and read 40 as 120.

Lots of gauges aren't that accurate and TBH they aren't essential anyway. I have calibrated my thumb against a proper readout and I reckon I can get the psi pretty close just by feel - for me, that means a slight deflection on the top of the tyre, pressing with full force.

IME it's vital to tweak the valve in a touch before attaching the pump, because they can have a release pressure over 120 psi and you can wear yourself out just inflating the hose.

 

[Cubist]

Reading what you've all said, it's pretty clear, the gauge is foooked. That means all of you who told me to pump hard owe me a slime tyre, donations made payable to Acc: ...

Seriously though, the first 4 or 5 pumps of air don't move the pressure gauge up at all, the needle moves up and then goes back down to 0. Only after that does it start to stay up, and at about 40psi takes a lot of effort while the tyre feels very hard.

From now on, I think I may just use the pump and read 40 as 120. I bought it from Wiggle and don't have the original packaging, so I don't know if they'd accept a return.

The bold bit is the giveaway. The gauge is measuring the pressure in the hose, not the tyre for the first few pumps. As the pressure in the hose reaches 40psi it looks like that is now enough pressure to open the presta valve, and air flows from tyre to hose , where the gauge is reading it (and then stays steady). 40psi will seem firm, but nowhere near the limit. Yes, it will take some effort to pump the tyres up. You need somehow to take a reading with a borrowed pump to compare.

 

[Ball]

But Cubist how do you explain the tube that I burst at 60 psi then?

I think basically yes I need to get a reading from a proven accurate gauge/