Today’s dirt bikes are pretty capable machines, light weight with long travel suspension and able to traverse rugged terrain with ease, but there are times additional drive from the front wheel would be an advantage. Marty Lawson and his dad decided to design a front drive system for a KTM 300 EXC and what you see here is their third prototype and it looks like they’ve got it working pretty well.
The new Hossack style double A-arm front suspension brings anti dive and anti rise capabilities by itself, but with the addition of a front sprocket, a single universal joint and two chains, they’re now powering the front wheel with a surprisingly simple system. It adds just 28 pounds, however, their aim is a production unit with a target weight of just 13 pounds. That’s a minor weight penalty for a potentially major traction advantage.
It is easier for an average rider to control on steep bumpy slopes, to surmount rocks and logs, and to maneuver in sand, mud, and snow. As both wheels are pulling to surmount obstacles, the Lawson design motorcycle does not require speed and aggressive spinning of the rear wheel. As a result it is much greener, doing less damage to the terrain, and it can be much more easily walked through narrow backcountry trails such as those used by firefighters or rescue personnel.
An overrun ratchet in the front wheel allows it to spin faster than the rear wheel in turns and adjustable gearing allows as little as 1 percent rear wheel slip before the front wheel engages, which means essentially full time AWD.
This looks like a very well engineered system, though actual comparison tests will help anyone decide how well it works. The video below shows the bike in action compared to a standard 1WD.
Nice job, Marty!
Link: New Tech Development