This is a 20mm diameter bolt that will be the axle.
IT IS HUGE!!
That is a 1/4" diameter bolt below it.
I purchased it at my local Industrial Fastener store.
Big-Box and TSC don't carry something like this.
I'm thinking of getting the center turned down a little bit.
The Mickey Mouse ears just arrived today.
The top one has the 20mm axle bolt in it.
The ring on the rear drive wheel is for my GEBE engine.
I've got it leaning up against the tree so you can see the 20mm axle bolt in place. I'm sure the two of them will handle A LOT MORE than 300 lbs. (which is more than I weigh) ... just a little engineering overkill. Next time I'll use 15mm axle bolts and hubs.