I would like to know why you do not just add long forks to a stock frame and tilt it back, like a bike would.

This message has been edited. Last edited by: cutlasguy,

It's all about angles. You need to keep the engine relatively level for it to run properly. When you stick massive legs on a stock frame without adjusting the rake (angle from true vertical) of the neck, the angle of the engine in relation to horizontal (the ground) gets out of alingment (the longer the forks, the more the engine gets tilted back). Doing what you suggest also raises the center of gravity of the machine, which makes it eisier for a person to wipe out on a bike.

That's why people chop the frame to increase the rake of the neck when they want to add massive forks to a bike.