[Solace]

we've never used heatsinks per se (although i guess you could argue that our mounting brackets have doubled as heat inks in the past). what we usually do is mount small muffin fans directly under the motors. if you drill holes in the floor of your bot directly under the muffin fan, it will suck the colder air up from outside the bot and directly into the motor. works pretty well, we never tripped our breakers last year even though we had a high speed bot (12 ft/sec) with a grossly inefficient turning process.

oh, and by the way, although gearing your bot to lower speeds like 3 ft/sec will definitely solve your overheating problems, you will be far too slow to actually compete in the game.