True, but there are ways to get it done safely(to a degree). I found that while we were running the Novak 13.5 here with the bonded rotor(they forced us to do that, so they'd be closer in performance to a brushed stock motor), if you geared it right for the track layout, it would DEFINITELY overheat, no one could find a gearing that'd allow it to stay cool enough to avoid a thermal shutdown. So after some experimenting, I ended up first adding Novak's own heatsink to the motor, & then using a freezing spray on the heatsink(& ONLY the heatsink) right before a run, & THAT finally allowed it to stay cool all the way through a race. You don't have to freeze the whole thing, just enough to prevent a thermal shutdown will work....
