>>1607545simple options:
* plastic bag over saddle
* stickers
* unique after-market parts to make identification easier when stolen
* never clean the non-moving parts
* white cork tape smeared with dirt, sweat will do the rest and it will look like a rotten mess
harder
* spray paint it on shitty ways
* fake rust spray paint
* scratch up the paint over aluminum frame (won't rust)
there are a few types of thieves. the dumb ones who know nothing about bikes will target the cleanest, newest bike. the professional thieves will know the exact value of nice components, but will also know if the bike is "somebody who knows bikes" and who might know how to track down the bike. the third category is punk kids who will steal anything that looks like a yuppie or college kid owns it.
best bike is dirty, self-assembled from nice but worn out parts, and covered in stickers. locked with mini U lock in the Sheldon brown style with locking skewers