counter

Try this web site http://www.veederroottimers.com/contents.htm

Have you tried the local cycle shop?

I have seen many applications using the humble bicycle counter;
which are quite cheap to buy.

They usually have a small lever attachment which counts the wheel
revolutions to give the mileage cycled.

A very simple, yet useable piece of equipment, for many applications.

Hope this helps.

jt

http://www.mfnb.at

A thumb type counter can be easily converted as well, but was also going to suggest the bike odom.