I have this 40 mile training route I like to take daily. At the end of 20 miles I like to get off and take a break, eat, etc. Problem is that my bike is often out of sight for 5 minutes or more as I pop into a store bathroom or something.

Does anyone here carry a small cable lock with them while on long training rides? Or even a small u-lock? I have a mini Kryptonite u-lock that happens to fit rather well into my frame bag. I am seriously considering carrying it and will try it out. Hopefully it doesn't rattle too much during sprints. Yeah, I know it's just dead weight but I ride solo and I don't mind extra resistance!

Am I the only one who does this? Also, has anyone actually had a bike stolen on a training ride or something where they were gone for only a few minutes?