Here is an alternative bearing arrangement that I'd like some feedback on:



It uses a pair of 30205 tapered roller bearings, which are very common & cheap. They are enclosed in a stepped roller that distributes force from the ring and keeps them aligned. here are the pros & cons compared to having separate vertical & horizontal bearings

PRO:
* Half as many bearings to mount & maintain.
* The bot can have a lower over-all hight, which offsets the weight of the rollers.
* The armour above the ring can be lower, which offsets the weight of the rollers.
* The ring is much lower, which is more effective against most bots and harder for vertical spinners to damage.
* Less (or no) armour needed under the ring.

CON:
* Increased friction between the ring and the lower shoulder of the roller.
* Might be more complex to assemble.
* The rollers might increase the over-all weight unless the smaller side armour and fewer bearings & their supports offset the roller weight.