Turn Your Mountain Bike into a Snowmobile

tsellers

tsellers

100 W
Joined
Aug 23, 2007
Messages
190
Location
Rocky Mountains, Alberta, Canada
Not sure how many saw Daily Planet on Discovery Channel tonight, they had a feature on:
0107upgrade_rear.jpg

Ktrak's traction-boosting Rear-Drive Kit:, which consists of a composite wheel with a polyurethane track, is the first step in turning your mountain bike into a muscle-powered snowmobile. To complete the transformation, the Ski Kit swaps the front wheel with a single, steerable ski.

I can't find any reviews, but as an eBike aficionado, as well as an avid skier, I had two questions. The first, I wonder how hard it would be to throw a Crystalyte Hub into this. The second, from my skier background, probably a 2" track is too small to to do much other than ride on fairly hard packed snow. In my neck of the woods (Banff) there are a fair number of track-set trails that may suffice, however I'm not sure if the skiers would beat the S*&T out of me if they caught me wrecking their track with it.

Anyway, it looks pretty interesting, funny it took so long for someone to think of it.
Video Here
My take: Nice idea, however, keep in mind all the video is *downhill* on a groomed (read: packed) surface. Results on the flat, expecially where the snow surface has not been packed by some mechanism will not be as rewarding. The problem is a 2" track which is only 25% of the width of my fat AT skis together, which are supporting less weight overall than the combined weight of the bike plus rider.
 
Tempting!!

Still though, even with a guaranteed hub motor install, I have reservations:

Fun Factor
- the video makes it look fun but what about falling at speed on this (and into it as well)
- I can jump a lot higher on my full suspension bike, watching the one guy bail on a few feet of air is telling and I think in general, I'd be less confident to launch...
- falling on groomers and hard pack at speed is just plain not fun
- even their website claims it doesn't really work in deep powder, so forget about it for backcountry or big powder day use unless you have a nice groomed trail to get up the hill with.
- anyway, in deep snow, I'd rather be on a pair of skis going a lot faster.

Commuting
- my ebike with good studded tires does just 45km/hr in a few cm's of fresh snow, does fine on ice and hard packed too and pavement too of course
- if I lived where it was snow packed roads all winter long, it might be more compelling...
- pavement or dirt wouldn't work

Off Road
- off road on flat ground would only work if the snow was packed down by something else.
- off road on summer-rideable terrain on a full suspension e-bike would be fine with the amount of snow coverage I get where I live, few inches at most times of the winter season.

Ski or Toboggan Hills
- seem to be the best place for this thing
- most ski hills wouldn't let you on it

The best e-bike application for this thing I can think of would be to shuttle people with a rope or attached toboggan up to good powder stashes or perhaps as a a way to get to back country locations where you could skin from. I wonder how many amps/volts it would take with one of these to tow some one up a ski hill cat track or a logging road that has some skidoo traffic on it.

Most people I know that buy skidoos, get them for the backcountry access to good ski/snowboarding. Usually two people with sleds and ski gear will go out for a day and park a sled and then one person shuttles while another skis. Or if they just share a sled for the day. Not do-able with this setup unless it could really toe some one.

On a bit of a tangent, I'm considering getting something like this to supplement my summer windsurfing addiction:
http://www.snowfer.com/
 
thats mad... but what i REALLY want to see is that bike wheel wiht a hub motor built in...


damm spoke breakage!!! GRRRR
 
Considering snow mobiles can travel on water if they're going fast enough, maybe this could too with an appropriate motor (waterproofed of course). Then again, the track is a lot narrower than on a snow mobile.

Ahhh, good old Australia, where you don't have to worry about snow.
 
I hate to say it, but this is a case where gasoline is probably the right choice. Recreation is not like commuting. If you've driven for 2 hours to get to the right spot to ride this, you aren't going to be happy with 10 minutes of operation, and you aren't going to be easing it up a snowy hill. And cold temperatures don't bring out the best in batteries.

Maybe you could have a generator at your car recharging DeWalts so you can ride in blissfull silence.

But its probably begging for a small (uhg) two-stroke on the way up, and legs on the way down.
 
if you look at the wheel, it seems to be a one piece rim-spoke-hub combination made mostly of plastic so you wouldn't be able to just lace in a hubmotor to the rim.

I've always thought that the best way to make a snow-bike would be to use 12" to 18" tires... you might even be able to use truck tire tubes as your tires. :) At that point you'd be able to float over some pretty darn soft snow and it wouldn't take too much more to be able to ride on water (using buoyancy rather than hydroplaning).
 
I'm thinking that design might possibly work on a mtn bike in the sand. We got lots of that around here in Florida, but no snow. :cry: And it's all flat, so the whole up hill thing could be negated.
 
I'd have to agree with ebinary, you probably can't beat the gas still. A friend of mine was explaining a good way to look at things in this regard interms of the yield of watts you get per wieght where the weight of lead in an SLA bettery versus the weight of gasoline, you get something like ten times more watts per unit of weight from the gas than the lead. Of course that has always been obvious, but a good reminder nonetheless. Also he said someone is just coming out with a tiny gas powered hub motor, has anyone seen it?
 
Well, it arrived today.

It took a few hours to get it figured out, as mentioned in another post the instructions are a bit sparse and hard to decipher but in the end anyone who is used to working on bikes should have no problem, I brought the bike into the living room and didn't bother with the bike stand. I mounted it on a Rocky Mountain Frantic 19" frame, it took about 2-3 hours but you could probably get it done in an hour. If you use disc brakes you'll need a new rotor or you'll have to take it off your wheel.

THe weight is fairly hefty, I would have guessed it felt more like 12 lbs but I thought I read 7 lbs somewhere. Anyway, instead of putting the roof rack on my car due to my suspicions that it may not even work, I just threw it into the back of my truck.

As soon as I pulled into the trail head and get out of my truck, this lady, who can just see the handlebars sticking up, starts to yell at me, "you're not going to take that damn thing down the trail and wreck the track are you?" I was able to calm her down when I pulled it out and showed her the ski, and for good measure, I made up a lie that I knew the trail was being track set again in the morning and as it was almost dark already, it would be improbable I would be wrecking it for the skate skiers.

I also assured her I had no plans to drive it in the double ski track set for classic skis which is what she was on.

So she insisted on seeing it work, so off we go together. I hop on my bike and off we go. I'm riding down the center of the packed trail that had been set by a skidoo pulling the drum to create a good skate ski surface. Off the bat it is a bit squirrely, the ski tends to slip from side to side on the packed snow and you have to get pedaling fast and decisively. After about 50 meters the lady has seen enough and she poles off ahead of me, explaining that she needs to get going if she's going to complete the loop before dark. Although I try, I cannot get enough speed to keep up with her and within a minute she's out of sight. A few more minutes and I have to stop for air, my quads are burning, time to try a more realistic pace.

I continue on for about 500 meters then stop and check the trail to see if I am wrecking it. A very attractive female in very tight spandex skate skis past me, and doesn't stop when I ask her to let me know if my track is interfering with her glide, obviously any old fart on the trail in the dusk on such a stupid contraption drooling at her retreating rear must be a weirdo to be avoided at all costs. The the rear track is making about a 2-3 cm groove in the snow, nothing to worry about. I carry on again, but on the hills I cannot get enough speed to keep my balance and I have to walk up them. I try shifting gears, but even on the downhill sections it seems pointless to use anything other than the lowest 3 gears. Eventually I turn around and come back. I try to get going on some uphill sections and sometimes I can get enough momentum to keep pedalling, others I have to walk it uphill. I should mention, I'm not generally the guy you see pushing his bike up hills (especially if there are members of the opposite sex around in tight spandex), but I swallowed my pride on this one, one of the reasons I waited until it was almost dark so I wouldn't see anyone I know.

Overall it probably won't get me 12km's down the trail faster than skiing as I had hoped. I find the rolling resistance is such that even on the moderate downhill grades where on wheels you could physically could coast down it without pedalling, you still need to pedal the Trak in a relatively low gear. I'll have to try it some more, but so far I'm finding I can't get too excited about the cross country possibilities, these are
probably a lot more fun when you can ride a lift up and go like hell on the way down. At least then maybe the girls will talk to you!
 
tsellers said:
Well, it arrived today.
Click to expand...

Thanks for trying it out and letting us know. I guess thats the reason all the videos showed people going downhill.
 
tsellers said:
I'd have to agree with ebinary, you probably can't beat the gas still. A friend of mine was explaining a good way to look at things in this regard interms of the yield of watts you get per wieght where the weight of lead in an SLA bettery versus the weight of gasoline, you get something like ten times more watts per unit of weight from the gas than the lead. Of course that has always been obvious, but a good reminder nonetheless. Also he said someone is just coming out with a tiny gas powered hub motor, has anyone seen it?
Click to expand...

The Gas powered hub you speak of. Is it the "Revo-Power" wheel?
 

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That sounds like the one that was described to me, thanks for the post. It looks like a nice design. I see on their website you'll need to go back to V Brakes, and that it should be available sometime 2008 for about $600.00. For anyone interested in more info BTW, here is the link to their FAQ:

http://www.revopower.com/faq.php

Back to the snowmobile, you could always try this (Not a working model pictured), if I put power to the hub it would torque the dropouts into oblivion, mayby once I can get some torque arms made I can give it a try):

ebike.jpg
 
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