Just got a tubeless inflator chamber thing and it has a stupid two hole head, one for Schrader and another for Presta, and one lever to lock it on (like in the photo below). How in gods name is it meant to work out which one to use as with it locked on my presta valve with the core removed the air is just blowing out of the schrader hole. Bloody useless. My heart sinks whenever I see these stupid pump heads 😡

There’s a little engraving of the valve type on that image…

Yes, I know which valve goes in which hole 🙄 It’s just that with a valve in and locked on the right hole the air just comes out the hole without a valve in it!

they rely on the valve core sticking up to close off the schraeder hole.

I use one of these in a schaeder adapter for tubeless setup – it allows more airflow and may well solve your problem…

http://www.chainreactioncycles.com/stans-no-tubes-presta-schrader-valve-adapter

Can only assume this one is broken. Presta valve core back in and it’s still blowing out the Schrader hole. Adapter into the Schrader hole and pop that on the valve and now it’s blowing out the Presta hole. Just not shutting off the hole that’s not in use. Rubbish.

I have one like that on a blackburn pump. without a little back pressure from the tube it won’t flip from one state to the other.

which is really handy when you have a totally flat tyre….

I think that might be it jambo, maybe blows out of both holes enough for a little back pressure to build up and trigger it to switch maybe. I’ll experiment. Or lop it off and replace it with something that it’s a piece of junk.

I have one that does that as well – solution with a flat tyre is to squash the tyre at the valve – allows enough pressure to build up to flip it.

Argh I’ve had the same issue with my PT pump for 10 years. REALLY winds me up when it happens – what tjagain says is right but that seems to be effective 50/50.

If that is indeed the case then it’s about the most stupid adapter you could possibly stick on the end of a tubeless inflator 😡

I don’t have any issue with it. all you need to do on the rare occasions it happens is to put the wheel on the floor valve side down and lean on it. Works for me having a dual head as I use both sizes of valves

Had another quick play with it. Seems that is the case. If i put my finger over the presta one and get a little pressure going then it blocks off the schrader hole. Useless if you are trying to seat a tubeless tyre.

I have 2 track pumps with this type of head.

The cheap Blackburn one has never been a problem, works well and the gauge is spot on (according to my digital gauge).

Whereas with the more expensive Park tools pump the head only works 50% of the time and the gauge under reads by about 15psi. It’s crap!

I have a park tools pump with a head like that – as per ajantom’s, it’s SHIT

Bad choice on the part of the manufacturer. Put it on an inflated tyre with a Presta valve, so the back pressure makes it switch. Then put it on your target wheel.
Or cut it off and buy a presta-only head.

I’ve inflated tubeless with mine no problem

Just be thankful it’s not one of these abominations… 👿

I stuck an Sks head on my airshot pump. Does either valve with one hole. It’s lush.

Stupid head pulled off and in the bin. Much better solution…

Still won’t seat the bloody tyre though 😡