In case anyone out there is as daft as me, cheapo cat eye LED lights (just the single high intensity ones) should be detached before leaving your locked bike. Yesterday my partners lights were stolen - just lights, no brackets - I had incorrectly advised her that they were only cheap and would be ok to leave for a few minutes...... GRRR what is it with people??? ....Its so unpleasant.
We we in a cafe the other day, and I left my computer on my bike, I don't normally do that, they're so easy to nick. All was ok when we came out, thank goodness!
Also, a couple of weeks ago, I was in town and called into Specsavers, locking Bike to a big fat drain-pipe. When I came out, I'd realised I'd left the key in my little saddle-bag still velcro-ed to the seat!
Far better to be safe than sorry. I wasn't safe - but I could have been very sorry!
I too have been victim to the little light-fingered opportunists. Remove it if you can, bolt it down tightly if you can't. Where can I get five-sided allen-key left-hand-thread bolts?
"Little Green Men Are Everywhere... ...But Mostly On Traffic Lights."
If you use a permanently installed system such as a dynamo set up it won't go walkies. The scum can't be bothered undoing all the nuts & bolts! The only light I had nicked was one of the original 3 diode Vistas with the knurled nut fastening. Later models use a countersunk screw & they always stay put.
Have used a variety of systems over the years. These days use cheapish clip on LEDs and a mixture of bands with several small LEDs in them, also wear arm bands with hook on LEDs, this widens your perspective to drivers and they seem to give you a wider berth. By using more than one light at least one is likely to survive any attempts to be stolen esp those attached to the body. Having more than one light also means you are less likely to end up without if batteries fails.
i've given up on clip on lights since a mate had a cateye LD1100 nicked.
i'm using busch and muller 4d toplight permenants bolted to the pannier rack. hopefully the sticky fingered ones dont carry spanners.
front light is a dynohub light allan key bolted to the bars.
if you do use clip ons tabbed to a bag and don't want to remove them try a couple of cable ties to fasten them on through the tab and make them that bit harder to nick, you may have to drill a small hole though the "clip" part of the light to get the cable tie though.