Quote Originally Posted by RestoRod View Post
If I correctly understand, you are saying that gearing is a trial and error attempt to get the highest speed at the lowest current draw? Do you change gears during a race or do you fix the gearing for each race track and essentially run a single speed vehicle? I didn't notice a gear change lever in the car being built even though I think Jim used a derailier unit.
That is essentially correct. With the limited battery power we are allowed in a race, we need to make the batteries last for the entire hour while still running fast enough to outdistance everyone else. After a few races we begin to get a "feel" for what gearing is necessary for a certain type and length of course. It's a trade-off between speed and longevity; we have to find that happy medium.

My orange car had a 6-speed derailleur in it, but I never found the right primary gear reduction to make it work effectively. Dana ("The Bat") put a 6-speed derailleur in his car and it seems to work very nicely. My team's cars now all have single-speed drive including the one I just built in this thread. I try to make an educated guess on gear ratio before a race and select the sprockets accordingly. It ain't high tech, but it's reliable.