I use a small rare earth magnet which fits over the crank key hole. Couple of dollars; no sticky, definitely no zip tie!
+1
me, too, since +1 isn't long enough.
My photoblog http://dragons-fly-peacefully.blogspot.com/
Bacchetta Giro (recumbent commuter)
Bacchetta Corsa (recumbent "fast" bike)
Greespeed X3 (recumbent "just for fun" trike)
Strada Velomobile
I will never buy another bike!