Can't pump up a presta valve..help!

[Danny251]

I have the Bontrager Charger and it is both a presta and shrader track pump. My rear tyre is a presta 700x23 and it is flat at the moment. When I unscrew the small brass cap so the air can flow and lock the head on it the pump doesn't bite properly and when I try to pump it up it doesn't accept any air!

Can anyone help?

Thanks!

EDIT: Eventually I had to use my presta hand pump to pump a lot of air in before it would bite properly so disregard this

 

[ASC1951]

Sorry if this is teaching your granny, but it isn't enough to just unscrew the knurled brass nut on the valve stem - you should also tap it with a finger and release some pressure (or just tap it in, if the tube absolutely flat).

If a Presta valve hasn't been opened for a while, it can take more pressure to open it than even a track pump can deliver.

 

[Cubist]

I have a Bontrager Charger. In order to inflate prestas you need to push the head onto the valve as far as you can, then lock it. Your description simply sounds like you aren't putting it on far enough. You'll know when it's on solid enough, as it won't wobble when it's locked. .

Unscrew the knurled valve top, press it in to break the seal, push the pump head on at least a full inch, lock the lever, pump.

 

[biggs682]

+ 1 make sure its really home then try and inflate as required .

 

[Danny251]

Yeah I always let some air out to release pressure beforehand. I haven't had my road bike for long so still learning. I actually configured the rear brake tonight instead of needing to run to the LBS lol