I took my 56" big wheel with solid 7/8" grey wheelchair tire out for a
few rides (each about an hour long) this past Labor Day [1 Sept.]
weekend.

Gearing: Based on Mikefule's wheel radius / crank length ratio, the
ratio of a 56" diameter wheel to 4.5" cranks is 28/4.5 = 6.22222...

This thing goes fast on the level and even faster down hills, but it
accelerates slowly and is a bit of a problem going uphill. Need a good
handle for the Schwinn seat on this beast; that may solve the minor
acceleration and uphill riding issues. A major problem is the down
hills can get this cycle going in excess of 30 mph; not fun when neither
maintaining speed nor slowing down is an option. Clearly the handle
would help with this problem, but the cycle clearly needs brakes as
well!

The cycle isn't that easy to mount either. You have to roll it forward
about 5 mph, jump up on the pedals, and overcome the angular momentum
of the wheel to correct the balance once up, but not quite in control.
I broke one of the spokes coming down from a failed mount attempt and
built a new spoke and replaced the broken one the following day.

Should I put even shorter cranks on this cycle? I'd guess that 3 to 3.5
inch cranks would require nearly the full weight of the rider to
approach 20 mph on a level course. Since the cycle was built to be a
speedster, I'd say that the 4.5 inch cranks are the perfect length.
Any longer crank would be a waste of wheel diameter, in my opinion.

I laced the wheel of this cycle in October 1980 while watching, on TV,
Steve McPeak's attempt at setting a new altitude record (101 feet 9
inches = 31.01 m) on one wheel for 114.6m in a circle.

Sincerely,

Ken Fuchs