Smaller Diameter Wheels - What's the advantage?

[JamesCH95]

Originally Posted by Vikesrock

At the same gearing? Heck yes! 2/3 the radius means 2/3 the torque. That is a pretty substantial reduction.

I'm pretty sure you meant 2/3 the radius means3/2 the tractive force and 2/3 the speed, no worries, simple typo.

Smaller wheels mean less gear reduction for the same speed which does mean lower rotating mass (which is important) and it could mean fewer reduction stages which means a higher overall efficiency.

All the CG arguments are moot for two reasons:

1) A large wheel size does not mean you have to have a high CG

2) A "low" CG is not necessarily a good thing. If the robots CG is above or below the bumper zone there will be a moment on the robot if it contacts another robot. However, if the CG is in the height of the bumper zone then when the robot gets hit there is no moment and it can't be flipped, it's a simple bit of physics that is often overlooked that I didn't notice until I saw several "low cg" robots get flipped.

Edit:

@ Chris_is_me

The advantage of larger wheels is a larger contact patch, which generally means more grip. Remember that real coefficients of friction are generally inversely related to contact pressure.