Some tips and techniques, will update more as I come across them
Covering scratches: Use nail polish, its available in almost every colour imaginable and provides good protection against rust. Personally, I use Sally Hansen cus its easier to apply and dries fast, costs about $4-6/bottle.
Theft deterrance: If you've no lock and have to leave your bike alone for a few minutes, you can do one or all of these:
1) With your chain on the largest chainring (the front gear part thingy), shift so that the front derailluer (the front shifting thingy) would move to the smallest chainring. But do this WITHOUT pedalling.
Anyone who tries to cycle off would have to kick the pedals into position first, and this would render the chain jumping off the gears and getting stuck between the bike frame and smallest chainring. This effectively makes your bike unridable.
2) If you are using V brakes, disengage the front and rear brakes. This can be done by pressing both sides of the brake arms together and unhooking the brake cable from its holder. Anyone trying to cycle off with your bike will be in for a nasty shock when he finds out that he can't brake!
3) Unscrew the knob on your brake levers just enough so that it backs out without being disengaged from the rest of the brake lever body. This tightens your brakes. Meaning, it'll only require very little finger movement to give a heckuva powerful stopping power! This should give the person a rude shock as well! :happy:
4) If you are using quick release skewers on your wheels, unscrew the front skewers out and rest the front fork ends on the skewer rod. This should give the illusion that the front wheel is still attached to the fork, but the moment the would-be thief tries to cycle off, the fork would slip off the skewers and give da fella another shock. Hurhurhur...
*Added* 04/12/05
How to lighten your bike without lightening your wallet much:
1) Change your inner tubes (the stuff that inflates your tyres) to lightweight ones. Standard tubes cost about $5 and weigh about 200g each. Lightweight ones can cost around $12 and weigh 150g each or less.
Cost: $24
Total weight savings: +/-100g
2) Change your knobbly tyres to either semi-slick/slick (botak) tyres or lighter knobbly tyres. Most knobbly tyres can weigh 600g each. Lighter weight ones weigh around 300++ g, e.g. Maxxis Flyweight. But beware, the softer and lighter rubber means that it can be prone to debris getting stuck and wearing a hole through the tyre and to the tube, resulting in a puncture.
Cost: $70 and up for a pair of tyres
Total weight savings: up to 600g or more depending on the tyres.
Lighter weight at the wheels, especially the outer edge, equals to lesser rotating mass and faster acceleration.