I needed to replace the Flywheels on my quantum and there is no source for such a ting on the market.
I saw a couple of projects for fully custom cage and wheel setups and i decided to try some of them for what i needed.
This is a remix of one of them, check out the original for more info on that project.
I had to add a section above the cap of the flywheel for it to fit correctly on the cage and around the motors, and i had to try a few different size motor stem holes for them to fit correctly since i did not have a precise drill size. This should fit on the regular rival size motors stem.
I have not tested this in a rival cage, but it might work for that.