Flywheel Discussion

What are some tips for designing a consistent and fast flywheel? I know it will eventually come down to copious amounts of iterative testing, but I want to just get a general idea of where to start.

Some questions, some of them probably need testing with physical foam disks to be answered:

Flywheel rpm?
Flywheel diameter?
Flywheel material? More ridged traction wheels or more compliant flex wheels?
Does more disc contact with the flywheel matter or mostly just compression with the flywheel?
How much weight would be a good balance between spin up time and inertia for 1 motor? 2 motors?


RPM: During ball games we usually see flywheels in the 3000-3600 rpm range (with change up being a major exception), but with discs the flywheels, at least in FRC, have generally been slower, though time will tell how it works in Vex. I believe BLRS used 3000 rpm in their Ri2D.

Diameter: 4 inch is basically your only option, though you could use the 3 inch flex wheels.

Material: As flex wheels are pretty new to vex, it will take some testing to determine, but flex wheels will likely see a lot of use.

Contact: This does matter, but it looks like teams are able to shoot cross field with a one-wheel linear flywheel, so really it more about RPM and compression.

Weight and spin up time: This is something you’ll have to figure out yourself through trial and error. Every robot is different.


Put rubber bands on your flywheel (they will give it more grip on the discs.)

im pretty sure the rpm is 4200…

It’s 3000.
(20 char)

whatever works best ¯_(ツ)_/¯
4200 makes a nice death hum :slight_smile:


4" Flex Wheel will almost certainly be the correct move, it’s just a matter of finding the correct durometer and speed for it. I think that either 3000 RPM or 4200RPM will be the dominant choices this season.


our organization currently doesn’t have flex wheels so what hardness of flex wheels should we get?

Why 4" as opposed to 3"?

I guess “durometer” means hardness; aren’t flex wheels all supposed to be the same?

I guess 3" might work but you would need to spin it up faster to get it to work.

Flex wheels come in 30A, 40A, and 60A hardness.

4" has more inertia meaning it won’t slow down as much every time you launch a disc :muscle:

Why would you need it to Spin Up faster to work?

@apandey, since 3" would presumable be better for size constraints, couldn’t you screw screws into them? Or do people not do that since it might make them unbalanced?

The edge of a 4" flex wheel spinning at 3000 rpm should be moving at approx. 52.3 feet per second, whereas a 3" flex wheel will only be going at 39.2 feet per second.

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So, I guess you are saying you just worded it wrong?

Got it.

Ah, my bad. I meant to say that a 3" wheel might work.

You always could but there’s also the point taran made. You should be able to fit a 4" wheel but there’s a lot of time to see what other teams are doing as well