Tyres

People say that Continental's TKC80 is pretty good and I agree.

Drivechain

A lack of attention to maintenance left my original chain a little knackered after Morocco and the word on the street was that the Renthal Sprockets (Hard Ano rear) and Tsubaki X Ring Gold from B&C Express were just the ticket.

Chain Breaker and Riveter

Actually doing anything with your chain requires that you be able to break the old one and fit the new one. Chains for motorbikes are a bit tougher than bicycles and there's no nice little link you can flip open. You really do need to break the chain (push a rivet through) and then rivet the new one on (push the new rivet through and then "mushroom" the end). Again from B&C Express.

In fact, you could buy a complete chain so long as you can either loop it over the front sprocket (can't see how) or take the front sprocket off (which requires three friends and a brick wall -- my newly purchased front sprocket remains in its packet).

So, £60-odd for a tool that takes 15 minutes to use and you might use once every few years...

Cigarette Adaptor Sockets

You're almost certain (if you're me) to have half a dozen things that can be powered off a cigarette adaptor. Funnily enough, bikes don't come with cigarette adaptors so you have to add them in yourself.

For some devices that are going to be permanently wired into the bike (arguably everything but as it's a bit fiddly the fewer you have to do the better) you, uh, wire them directly in. For everything else, you wire in a three-way cigarette adaptor thing that you find on ebay.

for example.

Make sure you wire it (and anything you're permanently attaching to the wiring) to the lighting circuit or some other circuit only enabled when you turn the ignition key. If you get your wires crossed you can trivially flatten the battery as you soundly sleep.