dmr bikes 4 eva

the only way you will get a 21 in a rush is to make a new chassis then put tranny from a 1/8 buggy or a jato or somthing i no they may not fit but even if you can try and fit a 21 in you will rip the tranny more specifically the idle in 1 tug of the radio the only 21s that may not do this a low quality rtr moters with 2 or less hp and higher end power with low toque
my 2pence