Hi! I live in Finland and the summer has just started around here. I love to just cruise around on sunny days on the dirt roads in my hometown. I was reading one blog and I saw one post about automatic gears in bicycle. The price was near 2000€. It would be just awesome to have something like that in my bike. I thought, that I could make the same system myself. I'm planning to use speedometer in the rear wheel connected to arduino board wich tells the gear changing system to change the gear. When the speed increases, system changes to upper gear. When the speed decreases, system changes to lower gear. I planned to use magnet and reed-switch for the speedometer. I found one old cordless drill and removed the motor from it. Maybe I could use it for changing the derrailleur position? For first I'm planning to make the rear gears only automatic. Any opinions?