Our team currently uses 4" wheel with 200rpm. Compared to other teams’ robots, it is slow and non-smooth on the field. I notice almost all other teams use smaller wheel size. I thought smaller wheels tend to have lower speed given the same rpm. What are the advantages for using smaller wheel? Thanks.
You are correct. Most teams use smaller wheels, but with gear ratios. Using 200Rpm motors, the most viable gear ratios can be found here:
It is worth noting that gear ratios are highly versatile in i reccommend one over running direct drive from the motors.
1 Like
The biggest advantage our team has with a smaller wheel size is the height difference; the smaller wheel size allows us to fit under the Ladder easier. I would recommend gearing down a 600 rpm motor (blue cartridge) to 450 rpm using a 36:48 gear ratio on 3.25 inch wheels. This is what our team uses, and it works well for us.
Check out Catalogue of Drive Gearings, it’s really useful in choosing a gear ratio for your drivetrain.
You are right that smaller wheels give less linear velocity (speed) for the same angular velocity. But a big advantage of small wheels is that they give more linear acceleration for the same angular velocity compared to larger wheels, allowing teams to get to those higher speeds faster.
1 Like
Steeltron0419, jfepojgpej, thank you very much for good points and resources!
1 Like
Good point! This is a subtle difference. Then, the controlling program has to be somehow modified accordingly.
Smaller wheels allow for a better center of gravity, and better weight distribution, which leads to faster acceleration. The big thing however is an increase in feet per second traveled.
For this game, I recommend 2.75in wheels with a 450rpm drivetrain.
Choosing the right drivetrain can be tricky but personalized to what you like/need. Remember that the smaller the wheel, the less your will travel per rotation of that wheel. However, using smaller wheels allows you to have more of them attached to your drivetrain, and both of these factors can account for better weight distribution. Also the smaller the wheel, the less the weight, though it’s not much a difference. Typically, teams use 3.25” wheels running at 450 RPM, and it is a great balance.