Valve Leak.. I think

[Sam Kennedy]

With my new road bike, I've already managed to rip off a presta valve pin, and bend the pin on the new tube I installed.

Since I bent the pin, I've had a really slow puncture, it takes like 3-4 days for the tyre to go flat.

I was wondering if I should try and bend the pin back straight?
If the leak is taking 3-4 days to let the air out, if I'm actually riding the bike, will my weight (63kg) make the air leak faster? Will I be able to do 50 miles if it's taking days for the tube to leak all it's air?

I just found out I was using my pump wrong, I'm supposed to knock the pump sharply from the valve, not wiggle it off!

I'm a bit hesitant to replace the tube, because these new ones I got were expensive, and would prefer not to use them.

 

[02GF74]

your weight will increase the pressure in the tube so make the air leak faster.

try to straighten the pin but you may end up breaking it.

I bent one recently and found tyre went down immediately the cap was fitted - due to pin being bent, I couldn't screw the round nut all the way down so the cap was pushing on it - solution was not to fit the cap.

although the tubes may be expensive, I wouldn't risk a bad tube - fit a new one and keep the leaky one as a spare for when you puncture.

 

[Ian H]

You should be able to straighten the pin with your thumb. Unscrew it a fair way first. In my experience tyres stay up even when I forget to tighten the locknut.

 

[swee'pea99]

Get some cheap tubes to practise with till you're 100% with your pump.

 

[accountantpete]

You should be able to check that it is the valve leaking with a bit of soapy water brushed around the area.

Try only to unscrew the valve as much as is necessary to inflate the tyre.

Ideally you should have a pump with a tightening mech so that when this is released the connector is easier to pull directly upwards and off the valve.

 

[Amanda P]

You can try straightening the pin, but it might break off, and it's my experience that once bent, they're never quite the same again. You will need another tube, I think.

If you're planning 50 mile days, you'll have at least one spare tube anyway - or if you haven't, you should have.

 

[swee'pea99]

You should be able to check that it is the valve leaking with a bit of soapy water brushed around the area.

Can't see this working on a leak so slow it takes 3-4 days to go flat. Worth a try but...

 

[Sam Kennedy]

I changed the tube
Alternatively I could have paid someone £6 an hour to stare at the tube and see if bubbles appear from the water..

 

[Amanda P]

I've had those. I eventually tracked one down to a leaky valve. Pumped up to four or five times its normal size and submerged in the bath, it would sluggishly emit a tiny bubble once a minute or so from the valve.

I must have been in a particularly mulish mood that day.

A really slow leak can be a pig to detect. If you can't see any leaks from the tube itself when it's ludicrously over-inflated like that, it's probably the valve. Since a leaky presta can rarely be fixed, time for a new tube.

 

[accountantpete]

You need really soapy water and a bit of patience - 5 mins should see a bubble forming.

 

[Domestique]

When I have had this problem, valve leak, I have deflated the tyre and spayed a small amount of WD40, using the plastic straw that comes with it, inside the tube from the valve.
I am not an expert, but would imagine its something to do with the rubber seal being dry
Anyway this method seems to work for me and has saved me the time and money replacing the tube

 

[andyhunter]

you should replace the tube when you bend the pin in any circumstance trust me as more hassell than its worth, i have bent a pin slightly before and well i got to the bottom of the street.
Before applying presta adapater for pump, make sure the pin screw is open to let air in. I have mine open full but others might open it slightly or a good bit just depends if your comfortable. Then when applying the presta adapter for the foot pump or any pump make sure it goes on vertically at the top of the wheel (above the fork dropout) which is best to add pressure in and make sure properly lined up correctly and firmly so no bending off the pin could occur. When removing presta adapater keep it vertical and jus pull down firmly depending on what type it is when removing could be slightly different and you be grand. When air in tube then turn the pin screw full way till it cant go any more in opposite direction to close it so no air escapes.