There are four main components that make up a tyre valve - seat, stem, cap and core.
For road use it matters not what seat, stem cap or core is used, they are rated at something like 70psi/140mph.
For track, competition or high speed use a higher rated valve assembly is used. These typically have a screw fitment as opposed to push fit and metal caps.
I’m no expert but I’ve heard the 90° stems are preferred over straight stems for track use because they are less likely to fail due to centrifugal forces.
Regardless of type most of the manufacturers appear to recommend replacement valves alongside replacement tyres although I can’t see why valves would not be be good to go for 4 or 5 years.
Thanks for all the advice but looks like I’ll be getting the tyres swapped out during repair since my accident has taken a chunk out of the front one :crying:
I used to live in Hammersmith, and longed for something closer - though Essential Rubber were always pretty-much impossible to beat and worth the trip over to East London. They can be a little gruff at first, but great once you “know” them better. Also, the LB discount isn’t exactly “offered”, just ask for it. However, I and many people think the prices are good enough without the LB discount and just let it ride as a “tip”.
I am a bit amazed there isn’t something better for bike servicing in West London, even near the Ace Cafe perhaps.
I did find a little motorbike/scooter place on King St surprisingly useful for my unusually sized Tiger 800XC battery, and looks like they might do servicing and tyres. They seemed reasoanable, if not the Essential Rubber bargain. http://goo.gl/maps/2oC8o