it's definatly not too much load on the lipo's.
zippy-H 5000mah 20-30C 6s and geared for 40mph.
motor temps are like 120*f MAX and lowering the teeth count didnt help the issue.
i THINK i was running 17/68 on a 3905 tranny, so that does come out a bit higher than 48 mph so i guess not too wimpy gearing. but temps for that day on the motor never say 110*F and the ESC never hit 150.
that was a MMM combo (2200 of coarse)
my mate has the same thing, he's running 15/68 (42mph) on the same 6s batt and his temps were about 100, needless to say his fan never came on either. but he was also running a mudusa 70mm 2000kv (which i think is a supirior motor to the castle new
)
i dunno, i figured it might have come down to firmware, we are both running the new stuff (not 1.20, next one up what ever that was hehe)
not that it's a problem just thought it might be worth looking into.
shaun