US-based bike brand Christini, which has almost two decades of experience in producing two-wheel drive mountain bikes as well as dirt bikes, is pushing boundaries once again. The brand has released a production version of its innovative two-wheel drive system.
Two wheel drive? In motorcycles?
Of course, it’s not the first time we’ve seen two-wheel-drive tech for motorcycles. Both Yamaha and BMW (and Wunderlich) had registered patents back in 2017. At that time, BMW had even released a trick concept GS for 2017. However, both of these concepts were based on electric tech, with the front wheel powered by a motor in the hub. That tech is still on BMW’s design desk, with the brand still in the process of filing patents for an electric front wheel drive system.
So what is Christini doing differently?
Christini had first developed their technology for mountain bikes. Subsequently, the brand moved on to dirt bikes, with a few of their creations even being considered by the US military. And now, it’s getting back to its roots, creating kits for KTM adventure bikes.
The front wheel on a Christini motorcycle freewheels, as it would on an ordinary rear-drive bike. This is until the rear wheel start losing traction (as is the case during off-road sojourns). Thus, it acts like a rear-wheel-drive motorcycle until the rear wheel slips—that’s why it’s AWD rather than 2WD.
How does the system work?
Christini’s system uses simple machines to get power from the engine to the front wheel. A chain takes power from the bike’s gearbox and routes it through a slipper clutch, then through a driveshaft under the gas tank. The driveshaft pierces the head tube and turns a bevel gearset, which in turn spins shafts that drive stepover chains in the fork crown. A sprocket at each side of the crown turns a telescoping driveshaft in front of each fork leg. Finally, a ring and pinion gearset rotates power ninety degrees to turn the front wheel.
The front wheel is under-driven compared with the rear wheel, at a ratio of 0.62:1. That means the rear wheel has to be turning significantly faster than the bike’s forward speed for the front hub’s sprag clutch (a slipper clutch designed for one-way drive, kind of like on a bicycle) to engage and begin driving the front wheel. Arguably the kit makes even more sense for a big adventure bike, as it allows easy cornering, since the wheels can turn at different speeds during a corner.
The kit will be available at the start of the summer. If you’re interested in getting your hands on a KTM Adventure kit from Christini, visit: www.christini.com
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