After building a few 79cc predator bikes for friends of mine and having them turn out far better than the first one I built for myself, I want to have the best bike again, so I'm starting a new build on an old trek 820 with a 21" frame that I got off craigslist for $150. I figure I'll keep my first bike around as a backup bike so I can still get to work if my other one is being tinkered with. Here is the bike when I bought it... http://imgur.com/nuCdsYm And here it is now... http://imgur.com/5TirMqs I have replaced the junky front fork with a nice new one, stripped it down to the frame and painted the bike black and bright red, added a high end front disc brake with a 200mm rotor, replaced the seat, converted it to single speed, replaced the brake levers, added grip shifts (left grip shift will become a selector for my 2 speed transmission, right shift is being converted into a twist throttle), replaced the wheels with really sturdy ones (36 spokes, double walled rims, puncture resistant tires and inserts, etc), ground the teeth off the largest front sprocket and turned it into a chain guard (no more pants getting caught in the gears for me), cleaned and serviced everything, replaced the cables and cable housings, and a few other things I can't remember. The stuff I still need to do... Finish modifying my new predator engine. (mostly governor removal, and a few other little things) Mount the engine to the frame. (I have figured out an adjustable mounting system for these engines that eliminates the need for a chain tensioner) Add aftermarket exhaust and air filter. Mount the rear sprocket to the disc brake hub. Throttle linkage. Build a 2 speed dog clutch transmission from scratch. (I could probably buy one, but what fun is that?) Extend the pedals. Buy more stuff. Other stuff I can't remember right now. I'm going to try running gear ratios of about 20:1 for the low gear and 10:1 for the high gear. Hopefully I'll be able to hit 50mph and still have enough low end power to take off from a standing start without pedal assist. Should be fun. I will post more pics as I continue building. On another note, there will be an instructable on this bike!