Confused over what size to buy...
I've always just got tubes from my bike shop before so never had to think about which size to buy and there's a bunch of options. I'm on a standard road bike and on my current tube box (different brand) says 700 x 18 - 23C Presta 48mm.
I've just had new tyres put on - Continental 4000S.
Any advice on which of the tube sizes I should buy is much appreciated.