Yes, we know it's an old chestnut, we've all seen two wheel drive bike prototypes come and go. But how about a hard tail with a SID 100 fork, disc brakes and two wheel drive weighing 26lbs?
Christini, check out the excellent website at www.christini.com have developed a perfectly, on the face of it at least, usable two wheel drive system. Bevel gears at front and rear hubs are connected via tubular aluminium shafts, which are mostly hidden within the frame tubing. All the gears and bearings are made from stainless steel, and the system adds only 2lbs to the weight of the bike.
A thumbshifter on the bars engages, or disengages, a clutch at the rear hub to operate the drive, but even when engaged the gearing is set so that the front drive is slightly slower than the rear. Combined with a front freeehub this means that drive is only transfered to the front wheel when the rear loses traction, the front strikes an obstacle, or the front wheel washes out in a corner.
Rumour are that Raleigh are to buy the system and sell it on some Diamond Back models... we'll wait and see.