Originally Posted by treemuncher
I'm thinking that the easiest fix would be to put a front steering axle, mounted where the front wheel is, with 2 snowmobile skis
for steering/tracking. Keep the skis set wide to increase stability. Two more skis or, at the least, skegs at the rear of the sledge would add more directional stability. This should increase control of the bike-sledge combination during hard decelerations instead of the current instability due to the sledges lack of direction control.
The sledge actually has great directional control - so long as the direction you want to go is straight ahead.
The natives who live up there, and have accumulated a bit of experience in pulling sledges across the ice and tundra, will put a long - maybe 20' to 30' long - rope between their snowmachine and the sledge. They don't make sharp turns, but those are rarely needed if the rider is watching ahead. The rope's length allows the sledge to slide to a stop a safe distance behind the machine, and also has the added benefit of giving the sledge a sharp tug to get it moving after it has been sitting for a few minutes. Even in sub-zero temperatures the sledge's runners gain a bit of heat. Not enough to melt the ice, but when you add the pressure the sledge's weight puts on the ice, it will melt (try the string over the ice cube trick some time) and then refreeze, sometimes making it difficult to get the sledge moving again. With a long rope coiled behind the snowmachine, as soon as it becomes taut, the sledge comes loose. Of course, this also gives the rider a jolt, but they soon become accustomed to it, and are prepared for that. As long as Sjaak is moving in a straight line away from the sledge, the jerk would not tip his bike sideways, but might cause him to slide up onto the tank a bit