Recumbent snow trike (behold!)
 

see photo? um... need to go back to the drawing board. It's dangerous. Goes great in a straight line. Need more room for snowcat rim and tire too. Hardly any snow in Idaho to test it either. $)(%*^&PQ#!

Wild!!....I would think you'd need some way to lean the skis for turning.....How about an upright bike frame with a single short ski or snow board upfront?..... :rolleyes:

snowmobile skis have a ridge down their length. On the bottom of the ski. That might address your steering problem, since I'm guessing the skis are flat on the bottom.

Uh................ a single bicycle wheel in front will work in the snow.

Congrats on the ingenuity. Keep havin fun and dont listen to the nay-sayers: man has been improving the wheel [and ways to ride it] for....a bunch of years now.

Yes yes... a single bike wheel works fine with big rims and tires. I've ridden the Iditabike before (and finished). But when things get soft you need more flotation. This year's Iditabike is a perfect example. It snowed and the bike riders got whipped by the skiiers. A lot of bikers just gave up. Two skiis have 7 times the flotation (if I did the math right). The nexgen snowrecumbent will have fixed front struts and the skiis will rotate on headset bearings, connected by a tie rod. Similar to the way snowmobiles work. We went to the snowmobile junkyard and had a look see. That way the geometry will not change when you turn. Maybe just slightly. We'd also like to put an ATV tire out back, but that would entail a jack drive. Still hasn't snowed much here, it's gonna be a long dry summer.

Until you get more flotation on the back drive device that will still be your limitation The atv tire sounds like an improvement. Can you find something even wider? The problem becomes rotating weight and pedaling. If you have ridden the Iditabike then you are familar with snowcat rims, did you try huge tires for them? Or maybe two tires on two snowcat rims side by side? The large diameter wheel helps with the flotation too.

I think the large marge rims are probably a step up from Snowcats 20mm wider. I think you are right the rear is the key. The skiis are easy. I think we'll build a bike from the frame up this summer. Stay tuned.

What you are faced with is flotation (big surface area) vs. friction to go forward (as little surface area as possible.) like shorter skis, or rolling. Then you need to consider the power required. And the total weight.

One perfect example is the trikes they use at resorts. They have huge flotation wheels that roll on the ground and float in the water. They do work ,but have to be geared down and are very slow and heavy.
I think you could put one in a snow drift and pedal right over it. If you had the time.

You can make something that will work for sure. If you want anything that has speed or efficiency and is not too heavy, the laws of physics are against you. If there was some way to pedal power something similar to a snowmobile track, that would give you flotation and traction and (sort of) low friction. The human cross country skier overcomes most of the friction on a ski by lifting one ski up when going forward. That uses less power, but lets the long ski be flotation. And of course it keeps the total weight down, just a person and the skis. Having two skis on the ground at the same time is a huge disadvantage. They need to be as short as possible without sinking. I would guess half length. That is equal to one ski, the one a cross country skier stands on for flotation when he takes a step.

One reason the snow bike turns so well is that it tips the skis to turn. Downhill skis turn by tipping them. That's why snowmobile skis tip as you turn them too.

THIS would be perfect:

http://www.limboland.net/Merchant2/m...&Store_Code=wv

He's right. It's called a skeg, snowmobiles all have them. Without that you won't be able to turn.

Otherwise, I don't think it will be the next fad. But it's cool and I'll bet you've have alot of fun with it.

Norton is partly correct in that 'leaning' the skiis could help your project. I don't think this mandates using an upright bike frame however.

One thing I noticed rather quickly when transferring from skiis to a snowboard is that the downhill edge is more of a killer on a snowboard. On skiis when you catch an edge, you can often lift the offending ski and recover. With a snowboard, that edge becomes a pivot point and slams the rider into the ground. With your snow trike, that 'downhill' edge has the potential to really mess with your stability. If you can fabricate a system that tilts the skiis just a little bit when they're turned I think you'll have a lot more success. Please note that snowmobile skiis do exactly this.

Good luck!

Also note the fatty tires that surly is prototyping for their large marge rims. They'll probably be a lot easier to adapt to your bike and take less energy to turn than an atv tire.

Our tour of the snowmobile graveyard gave us the key to how to make the skiis tilt. The skiis I'm using are very short. The little twin tip trick ones. The large marge rim would be easiest to adapt. We've been thinking up all sorts of weird chain arrangements for the ATV tire. Hannebrink does it, but I think it's problematic.

Something more like this will solve some of the problems.

Hmmm...cool, but looking at it....where is the breaks?

that thing is pretty hot, dual crown forks and everything.
I'd expect there is so much rolling/sliding resitance that you rarely need to worry about stopping quickly.
Looks like a deep powder machine!!! I need to know more about it...

After you go a block you realize that you're exhausted and if you stop pedaling it just stops. If you put brakes on a wheel in powder snow it ices over quickly anyway. If you go down hill too fast turn hard. Like ski's.
Regular knobbies on an MtB is much better up to about 5" of snow anyway. In deep snow the tires are exhausting and slow too. No brakes needed.