[Ether]

Originally Posted by Chris is me

Something interesting we noted with 6 CIMs this year. We noticed a significant advantage in acceleration, but more notably we noticed that our actual top speed was higher than we expected. Everyone is aware of the 81% speed loss constant for a 4 CIM drive, but our 6 CIM drive's actual speed loss coefficient was around 90-91%. We measured an actual robot speed of 13.7 FPS with 4" wheels and a 6.1:1 gear ratio... It's possible that more motors actually results in less top speed loss.

There is no reason to expect the "speed loss constant" to be the same for all drivetrains and floor surfaces, as it is substantially affected by the floor surface and the type of drivetrain design (chain and sprocket, belt and pulley, direct drive, type of gearbox, type of wheels, etc) and workmanship (chain or belt tension, proper assembly and lubrication of gearbox, wheel alignment including toe-in and camber¹, wheel axial offset², etc).

¹Toe-in and/or camber of a wheel causes the wheel sprocket (or pulley) to be non-coplanar with the driving sprocket (or pulley), and thus contributes to friction between the chain (or belt) and the sprocket (or pulley). Toe-in also causes scrubbing friction with the floor surface.

²"wheel axial offset" in this context means that the wheel sprocket (or pulley) is axially offset from the plane of the driving sprocket (or pulley), causing the chain (or belt) to be non-planar, thus creating additional friction between the chain (or belt) and the sprockets (or pulleys).