Checking tyre pressures

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Checking tyre pressures

Postby Jerryjan » Tue Oct 23, 2012 11:32 pm

Hi I have recently bought another bike, it's a secondhand giant OCR zero. I have ridden about 1000 Kim's on the bike and I'm enjoying it. But I have a small problem with checking the tyre pressures, which I like to do every 3 or 4 days. I back off the small lockring, quickly push in the valve and then fit the brass adapter and the pump. I am finding that unless I drop the pressure down to about 80 psi I cannot get any air to go into the tube even thought the pump will pump upto 140/ 150 psi. I normal set the tyre pressure at about 100 psi. The valve is not clicking and allowing air to go in. Just to let you know it's not my first bike had similar pressures in the other bike no problems. Same pump, have tried both presta and schrader with relevant adapter. Help please.

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by BNA » Wed Oct 24, 2012 4:06 pm

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Re: Checking tyre pressures

Postby NhiTrac » Wed Oct 24, 2012 4:06 pm

Probably depends on how good quality a tube/pump you're using.

E.g. I switched over to cheap $4 tubes from cell. In order for me to get any air in, I need to quickly depress the valve to let a little air out before attaching the pump.

Using some continental tubes previously, I could just attach and pump away.
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Re: Checking tyre pressures

Postby Jerryjan » Wed Oct 24, 2012 9:25 pm

Thanks for your reply NhiTrac, I don't know what make the tubes are, as they came with the second bike. I will just have let some air out and then pump them up.

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Re: Checking tyre pressures

Postby AndrewBurns » Thu Oct 25, 2012 5:44 am

I have that problem sometimes too, I find that I need to 'crack' the valve a bit to break the seal before I start pumping. Basically unscrew the nut and tap it in so that some air shoots out before attaching the pump, that usually works for me.
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Re: Checking tyre pressures

Postby Bentnose » Thu Oct 25, 2012 7:10 am

I've always found using the valve adaptors as opposed to a pump head designed for presta ends up with poor results, some tubhttp://www.bicycles.net.au/forums/se ... gosearches musn't go well with these adaptors.
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Re: Checking tyre pressures

Postby il padrone » Fri Oct 26, 2012 9:59 pm

AndrewBurns wrote:I have that problem sometimes too, I find that I need to 'crack' the valve a bit to break the seal before I start pumping. Basically unscrew the nut and tap it in so that some air shoots out before attaching the pump, that usually works for me.

The way I read the OP he is already cracking the valve, but this is not enough and he needs to let the pressure down quite a lot. It seems very odd - I've never had a tube that did this to me. In the past I have had presta valves that would not release air when I needed to let them down, but they always inflated very well. Puzzled.
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Re: Checking tyre pressures

Postby bychosis » Sat Oct 27, 2012 10:01 am

I found that when using a valve adaptor I can't unwind the presta valve stop all the way, only just a little. Might be specific to my adaptor, but worth trying. It seems to block the adaptor somehow when the valve stop is unscrewed all the way, meaning I can't pump the tyre up.
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