inrunners or outrunners

[Rapidrory]

the Lambert gearboxes on Gabriel that have the big Ampflow motors driving them, with the big and I mean BIG wheels 900mm diameter have first stage MOD1 and second stage MOD 1.5

I know people who have stripped MOD 1.5 on a Bosch 750 before... I just assumed MOD 2 was the standard for heavies. Impressed that the MOD 1 gears are working that well!

With brushless, it's worth bearing in mind that it's better to over spec the motor and run it below it's max power, as they have a lot less thermal mass to spread the heat due to being tiny and powerful. Most of these motors are designed to have a constant stream of air, EDF motors especially. Without it it is likely to get red hot if run at it's specified power rating. I'm looking at a minimum of 3kw motors for drive, and then limit them to ~1.5kw on the VESC, but if suitable cooling can be sorted then you may be able to use less. It's yet another one of those things that needs experimentation and combat testing to work out what size is right. (alternatively I could sit down and do some maths to work it out... but who does that? :L)

[supernova]

The torque a gear can handle greatly depends on the surface area of the contact patch, so a wider 1.5 Mod gear could handle the same torque as a narrower Mod 2 gear.

Also depends on the hardness of the gear material, the pinion gear usually is case hardened.

My first robot used Sinclair C5 motors that used a 5:1 Planetary gearbox with plastic gears. Was only 250W at 24V but I ran them at 36V and had no issues with the box.

I wouldn't use belts (personal preference), its the heavy, expensive, and doesn't allow for misalignment caused by being smashed by spinners! If space allows use chains, if tight on space, use gears.