I'm posting this here in case someone is considering buying one of these things and wants a first-hand account.
This gadget could have been the best thing since beer. It's lightweight, an adult can sit on it comfortably, the 49cc 2-stroke motor is big enough, it's not too noisy, it has great ground clearance, and the fat tires can take you over rough ground. And it's cheap too!
Unfortunately, it has a fatal flaw. It won't climb hills. It's geared too high and the motor lugs down on even moderate inclines. Just before the engine stalls the centrifugal clutch disengages and the bike stops. If it had a manual clutch it would just stall.
I don't see any way to lower the gearing. The manufacturer could have made a gear box with sufficient geardown but didn't.
The dealer who sold it doesn't ride them or fix them, so all he could do is give me the phone number for the company rep. The rep doesn't answer his phone or return messages.