[chrisguyw]

I have several  MRSlotcar sidewinder motor pods that utilize an 050 motor, and use a MrSlotcar 15.5mm spur and a MRslotcar 4.5mm pinion, and still have ample clearance between the backside of the can and rear axle. The motors in these cars are fairly hi revving 30K, so need ratios in the 4:1 + range, and mine are geared with a 7T pinion (MrSlotcar) makes these with a 1.5mm bore, and, a 31T 15.5 mm spur.

If you are looking at gear ratios in the mid 2:1 range (I personally think that something in the 3:1 range will be much more suitable) you could use a 10 or 11T pinion (6.5mm) and a 28/29/30/31 T 15.5 mm spur and have a ton of clearance between the can and the rear axle.

You should not have really much of an issue with the sidewinder configuration, as the 050 motors are no longer than a typical "S" can, and if you use appropriately "skinny" wheels and tires you should be OK....it will be snug but more than likely manageable....if not, try the 030's as John mentioned, and, they will also be much happier geared in the 3:1 range

Cheers
Chris Walker