My road bike has never seen a lock, except overnight during supported cycling tours. It's a very compact road bike with an aluminum frame, with oversize tubes.

Now I'd like to ride with this group but most of their rides include lunch somewhere in the middle and riders are requested to bring their own lock. I'm pretty sure that I could lock up with someone else but I'd rather be autonomous, especially for the first few rides I do with them. I don't need anything big, but at least I must be trying.

What do you suggest? I have looked at several locks but I don't know what I'd with a u-lock when on the bike, and even cable locks seem pretty big (I don't know where I'd wrap them on my frame without having it hit the rear wheel).

HELP!