[Stefan]

John, I was thinking of a 400 W bl outrunner or a low rpm brushed motor and a three or four gear transmission. A problem is that the gear spread between the lowest and highest gear on the real 11 gear transmission is 15 times, i.e at 2100 rpm the ground speed is 2.1 mph in gear F1 and 30.8 mph in gear F11, so I have to find out how much of that spread can be taken up by the better low rpm torque capability of an electric motor.

Steve, the "large" part, which is 14.3 mm high, cost 12.50 euros (they actually quote the price in euros when you give a "Euroland" address). There are also different grades of plastic starting at one fifth that price. The small part is 10 mm across, 3 mm thick and went for € 6.27. For each item there is a 6 $ (yes, dollar) handling fee included, so in some cases it would pay of to upload drawings of suitably connected parts. Maybe increased competition will lower the price in the future.

Dan, a German forum colleague found out that you should enlarge your drawing by 1.8 percent to get it right at the end. I did that and 14.3 mm turned out to be 14.34 mm, not bad, and the 0.34 mm will be machined away, anyway.