carrying spanners

[Biggsy]

Mine has been ok for a Brompron rear wheel so far - but perhaps I won't rely on it!

[pumpkin]

Might have been mentioned already but a ratchet spanner with one open end is the one I go for. You can do up the nuts quickly and a quality one will last forever. Think I paid  £10 in B&Q for one but it's not going to fail (given normal temperatures/use etc)

[1gear]

If you attach an adjustable to your frame then keep it oiled. I had one seize up on me after a winter on the bike and couldn't get it to adjust. I used to have a small-ish spanner that I kept in my jersey pocket, until I forgot to put it in one time and was paranoid I'd get a puncture in the middle of know-where.
So I just got a small saddle bag and put the spanner in there. Sorted.