Presta Valve inflation

gaffmaster

Hi all,

I just bought one of these for use with my new road bike. I'm having trouble inflating the tyres to the right pressure.

I opened the cap on the valve, unscrewed the valve nut. Then put the pump head all the way down over the presta valve and locked it.

I proceeded to pump.

On my first attempt, I could only inflate to 60psi before the pump felt like the handle would break if i pushed down any harder.

On my second attempt, I got each tyre up to 80psi before the pump handle felt like it could take no more.

Each time when i released the lock on the pump head i heard a loud whhoosh - an escape of air from the build up of pressure.

I can't really tell if any air is going into the tyres since they are already quite hard.

Am I doing anything wrong? Is my pump dodgy? Is the gauge on the pump just giving me a false reading.

Thanks.

DirkVoodoo

Its hard to tell just how much resistance you are experiencing. I havent used a Joe Blo but a lot of folk swear by them and it seems you are doing everything right. I normally pump up to about 110 PSI for dry weather riding and it doesn;t take too much effort.

The "whoosh" is normal, the air in that tyre should be about 7 atmospheres plus (well, about 5 for you so far) but in any case the pressure differential will lead to a forceful "whoosh" noise when you remove the pump nozzle.

It may be a case of you aren't used to pumping up tyres?

EDIT: If you are worried about gauge calibration, get your hands on a second pump, go to your local bikestore, etc. and try another one out.

Chips Lovell

This happens to me to. Bleed a bit of air from the tyres before you start to pump and it does the trick, at least for me. I don't know why this works, but it does.

blorg

+1 el tonto, sometimes I feel it's very difficult and bleeding a bit of air works. My theory is that it just makes sure the valve is openable before you start to pump.

gaffmaster

thanks for the replys

@blorg and el tonto: How much is a bit? Just a tiny bit or until the tyre physically feels softer?

72hundred

gaffmaster wrote: »

thanks for the replys

@blorg and el tonto: How much is a bit? Just a tiny bit or until the tyre physically feels softer?

What I just do is tap the nozzle (after loosening the inner screw)

gaffmaster

It worked!!!!

I gave the valve a good few taps. then sure enough it inflated that little bit easier.

i literally had to bounce up and down on the pump to get it up to 110psi, but they're there now.

For some reason I thought pumping them up would be easier! especially since the needle seemed to jump up 20psi at a time. until the real resistance around the 80psi mark.

Thanks for all of your helpful replies

Turbulent Bill

Slightly OT, but I find pumping 26" slicks (Schrader valve) using a Joe Blow Max II to be hard work at anything over 80psi. To get to the recommended 95psi I basically have to sit on the handle. The pump is rated to 120psi. Might try checking the valve the next time they're deflated.

gaffmaster

Hmmm,

Maybe it's a fault with the design of the pumps!? I practically had to jump on it to get it up to 110psi.

Raam

gaffmaster wrote: »

Hmmm,

Maybe it's a fault with the design of the pumps!? I practically had to jump on it to get it up to 110psi.

Sounds like your valves to me. I regularly have trouble with one tube that's on my roadbike. The other tube pumps fine.

ednwireland

i bought one of these for the road bike

http://www.chainreactioncycles.com/Models.aspx?ModelID=14133

160psi max for a frame pump works great

'68 Fastback

ednwireland wrote: »

i bought one of these for the road bike

http://www.chainreactioncycles.com/Models.aspx?ModelID=14133

160psi max for a frame pump works great

I've had a blackburn now for 12 years. Best little pump I've owned but it won't do the pressure now so I'm looking at this one too.
Have you tried fitting it "along the seatstay of the latest bikes" ?

Turbulent Bill

Raam wrote: »

Sounds like your valves to me. I regularly have trouble with one tube that's on my roadbike. The other tube pumps fine.

Now that I think about it, I've experienced the same effect with two different tubes, so it probably isn't an individual valve problem. The pressure gradually builds up as you pump like you'd expect, but it seems to top out at about 95psi, even putting body weight on the handle. Checked the pump head mounting, latch etc. and all seems in order.

Might be a good idea to overspecify the pump, e.g., use a 120psi pump for 80 psi tyres, 160psi pump for 110psi tyres etc.

Pj!

I have no problem using a JoeBlow up to 100-110psi.
Nothing anywhere close to jumping or sitting on it.