Since I have recently switched to a single speed from a mountain bike, I needed to buy a new pump to fit a presta valve. Is there some magical thing I should be doing to get the thing to fit right so as not to empty the tire before I get it filled? I know to open the nut on the valve, but I just couldn't seem to get the pump to grab onto the valve right. I finally got the thing to work, but what a workout! Then at one point I couldn't get it back off. I must be doing something wrong. I'm using a Serfas FP-50 on the stock tires on a Bianchi San Jose.

u have to hold the back of the tire and press the valve firmly on the presta valve. it takes practice. never pull on the valve, just twist it gently until it slide off.

DLBroox,

I don't mean to insult your intelligence, but I assume you are locking the pump head onto the tire valve by lifting the lever on the pump head?

I can pump up my road tires in a few strokes with my floor pump.

Yup, and the Serfas pumps are generally very simple and solid.. I haven't had any trouble with my FP200

If you really can't deal with it, you can of course get an adapter from presta to shrader

You're most likely pushing the pump head way in which in turn is 'holding' the presta valve in the 'open' position. The pump head just needs to grab just beyond the valve nut.

no trouble here but remember the tab flips up

Yes guys, I may be a newbie but I did lift the lever first!

I think I might have been pressing the pump head in too much as Roadfix suggested. Thanks.

presta valves, while they aren't complicated, are one of the most confusing things the first time you fill them up on the fly.

With some tubes, you don't want to open the nut all the way. Back it off from the top a little.

Did you make sure to unscrew the tip of the valve first? (after taking off the cap of course) Then, you need to push in the nipple with your finger to break the seal, THEN you put the pump head on.