who makes decent ones, or are they all much the same
what makes a good one good anyway ?
(not expecting to use all that often so cost of cannisters isn’t a massive deal – or maybe they’re all the same design/fitting and I can use any?)

Depends. A lot of the head valve only units are exactly the same but with different branding.

For example, I have a Sram one that looks the same as Genuine Innovations one. They all seem to do essentially do the same thing.

[img]http://i.imgur.com/EgU2eBp.jpg[/img]

Depending on usage, you’ll be looking at 16g threaded carts, which get cheaper the more you buy. Don’t get branded ones, as they are a rip off. Although the Lifeline ones on Wiggle aren’t too bad at a tenner for 6, but you usually get 10 for £12 on eBay.

Ta Jamie

no “trigger” on the head part ? they just jizz the whole lot at once ?

cheap CO2 here

no “trigger” on the head part ? they just jizz the whole lot at once ?

You screw it in one way to pierce the top, then backing it off works as your release valve.

Some more info:

[video]https://www.youtube.com/watch?v=EwVctgQJ6Q8[/video]

Really rate my Topeak CO2bra. Never let me down and neatly packaged with Levers.

Bought an Unich the other day, really like it. Bonus is it has a botton on the top to control airflow.

http://www.ebay.co.uk/itm/290977010800?_trksid=p2060778.m2749.l2649&var=590159193571&ssPageName=STRK%3AMEBIDX%3AIT