Presta valve or mini pump issues?

Good morning guys and HNY to all :slight_smile: .

I’ve got a burning question that I’m sure you can all answer very well.

Recently, I’ve suffered far to many punctures and I’ve had a lot of issues with my roadside pump (I think). Pump is a Topeak Race Rocket.

The problem is when I’ve changed the tube and inflated the tyre. I unscrew the pump from the presta valve, the pump seems to still be gripping the valve core and strips it out of the valve meaning all the air I’ve inflated immediately comes out of the valve.

Now, what I’m unsure about, is this likely to be ‘operator error’ :wink: or a dodgy pump? I’ve tried not screwing the pump onto the valve so tightly but that just stops the air going into the tyre.

My options for changing are either, learn how to inflate a tyre properly :frowning: , go CO2 (which I’ve never really used) or get a new pump that ‘snaps’ onto the valve instead of screwing it on. Any recommendations would be gratefully received.

Note - It’s not a dodgy tube/valve as it’s happened on a couple of occasions with different tubes.

Thank you all, have a great day :slight_smile:

The screw-on type pumps don’t work too well with removable valve cores. Lezyne pumps are really bad for this, in fact they are so bad my initial thoughts were that’s what you had.


  1. Use a pair of pliers to tighten down the valve core that it doesn’t come undone when you remove the pump.
  2. Get a pump with a lever action fitting.

The problem with the first is that if you need to lend your pump to someone who has a removable valve core and they haven’t tightened things down then you’ll remove their core!


What he said. I would just buy a valve core tool and carry it with you. Handy to have anyway - and very small. I use the Park Tool VC-1 Valve Core Tool

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Agree with this 100% - love their quality but annoying habit of removing the core.
I tend to remove the core from new tubes and loctite them back in to prevent the problem

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Thank you guys and even better news is there appears to be a cheaper solution than a new minipump. I didn’t even know there was such a thing as a valve core tool but then again if you knew my technical/mechanical skills you wouldn’t be surprised. Thanks again.

A valve core tool might not have enough torque to be able to tighten it enough which is why I suggested a pair of pliers.

This is what’s being discussed - one end fits Presta, the other Schraeder


There’s also this style:


I’ve found there’s a bit of a trick to thread-on pump chucks.

Trick #1 is to not thread it on all the way. Just the bare minimum to get a seal. You don’t need to tighten it down like you would a bolt. You’ll get a feel for this.

Trick #2 is to put a bit of angular pressure on the valve core and the valve when unthreading. Hard to explain. It imagine you’re trying to wedge the core into the valve while unthreading the chuck.

Trick #3 is, as others have mentioned, make sure the cores are tight. I wouldn’t lock-tight them but just make sure the cores are threaded in tighter than the chuck is threaded on.

I’ve been using my thread-on Lezyne pump for 15 years now with very little issue.


Whoops. I have no idea how I ended up on a year-old thread. Lol. I hope by now OP has put air in their tires and it has stayed there.

I have a valve cover on each bike that’s metal and has a hole that’s a core tool. Always check the valve before threading a pump on, and you’ve never forgotten to bring it as if it’s not attached to the wheel you’re pumping, it’s on the other one :wink:


Oh that’s f-cking genius on several levels. Getting me some of those.

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