this little item hardly ever gets a mention. They are not all the same, some rock solid while other over sensitive so that when you try to put a pressure gauge on them you invariably loos a couple of psi's so have to pump the tyre up! Are there any brands out there worth spending money on compared to the ones supplied by the tyre fitters?
Why use straight ones? Angles valves are far easier to get into to check pressures and also don't need relaced when changing tyres.
There's not much to go wrong on a valve. If it's seated on the rim and not leaking ( check with soapy water ) then there's only the core that's left. If the valve cores leaking ( check with spit each time you do your pressures ) then change it. Simple job. When you inflate a tyre ( even when topping up ) slightly over inflate and reduce the pressure with your gauge to the desired pressure. On bike's I'd still recommend bridport right angle valves. Always run with good valve caps as dust or centrifugal force can press on the valve core.
Got to agree with @ColinBR Bridgeport 90 degree valves are far better than straight type for either pumping up the tyre and for checking pressures and for only £10 roughly a pair! Some manufacturers like triumph actually put them in as standard others only use rubber straight ones as cost cutting
