Purpose built snowbike

fgauvin7

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Let me introduce you to a project that I have been working on for the past few years! From the time I saw the first snowbike I knew there was a lot to be done and the design really match the very tight terrain and dense forest that we have here in North Quebec Canada.

So a bit about me, I'm just 26 and I ride snowmobile since I can walk, over the years this sport became a passion. This project started when I was out of town for school, I first saw a picture of a PowerHouse custom propex chassis, this chassis just triggered something. I had a few years to think and draft many idea and concept on how I think something like this should be built and what it should look like. At the origin I wanted more of a lightweight machine more or less like the blast that we just saw last year. Over the years the project just merged to more of a snowbike since it matched more and more to all my expectation. So three years ago, I started working as a mechanical designer, got a house and then started gathering tools to build whatever project I wanted in the futur! As we are, I have around 1.5 years in building and drawing this thing. Sometime it is long to just get the tooling or get the skills to use them.

Finally I fixed some goals to make all of this quite challenging. Many told me that I was not realist and it would not work. But hey, I don't have much to lose here.... time, parts, material... Yes but at the end it would still works if I don't achieve all my goals.

Original goal was to be lighter than the donor bike, in this case a YZ 250 2013 2t that is rated at 227lbs from Yamaha I think. This one was the biggest one, other goals was to have a better weight distribution by being shorter over all, lower seat height since I'm not that tall and I want easy access to the bike and not have to climb that much on it when riding off trail.

Now here is the final product of all this time and effort. A machine that is built to do what I want to do with it, the way I want to! Yes it is probably not the best design for some utilisation, but this is not the point. I just wanted it optimal for what I do. All the main goal was achieved event the most challenging one being the overall weight!

As it sits right now, 99% done minus few panels to cover It up, I'm at 217lbs Dry weight! For me this is quite a achievement and I'm proud of it.

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There is still a lot of little Idea that I want to add or modify but for now It is mostly ready for some testing and I need those test to answer some of the questions. Design and idea also need to be tuned before going further. When this thing will be dialled in I plan on building some fairing to close it up a bit, a few pounds in bodywork will save a lot more in snow accumulation.

All in all, I think this little writeup do a good job telling the story of this project and I hope it won't be the last one! I became a member on this forum quite long time ago mainly because there was some nice writeup like this that was very inspiring, so here is my contribution!

I post this in the Snowbike section, Yes I know there is a modified one, but I think it will have a lot more interest here.

Thanks everyone for reading, and thanks for all the good info your are putting in this forum!
 

wwillf01

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Did you use a tunnel cooler with the one radiator?

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fgauvin7

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No tunnel cooler for the moment, but in the plan to add one this winter. For now this was the easy way to get to testing, plus I will be able to decide if I keep it or if I remove it with the tunnel cooler. A short two pass cooler would do the trick I think and would probably be around 3-4 pounds. So not a huge deal

I will try to add more pics soon

Thanks
 

wwillf01

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For spring we had a very hard time keeping the yz250 cool... we ran evans which worked but the tunnel cooler made everything way easier.

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fgauvin7

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Thanks, nice to know! Then maybe both air and tunnel cooler will be nice to have!
 
Dec 19, 2007
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I love it! Glad you will be test riding before building side panels and bling items. Geometry may need to change.

I wish the factories would change their stupid philosophy that kits are better because the bike can be used with tires in the summer. Nobody I ride with does that anymore we all ride dedicated snowbikes.
 

sledhed

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Nice work. Be prepared to have a big company steal your design work. Just what I would be wanting in a snowbike - light weight, AND a lower seat height. The seat height issue has been the biggest deterrent to crossing over to snow bikes for me. And yeah, I would prefer a dedicated snow bike and not run it in summer too. I could put tires on my Axys if I wanted that, right? :)
 

fgauvin7

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How did you make the shifter work? F'ing sweet build! WOW.
Thanks, shifter was actually pretty simple. I used a linkage from a Yamaha R6 that slip direct on the shift shaft of the 250 engine (same splines) and built a pivot lower in front of the foot peg. Bonus, the linkage let me fine tune the position of the shifter to my needs! Ruff adjustment can still be made by just offsetting one spline.
 

jim

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That is a really cool, clean build. A purpose-built snowbike. I assume you'll fight overheating with just one radiator and the wide open nature of riding. You'll likely either need a large fan or tunnel cooling to keep up. I know for dune riding, even with 2 radiators, and even in cooler temps, we get some overheating just because you are wide open a lot.
 
Jan 18, 2018
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That is awesome! I think you have been reading my mind. There are some really cool builds on here that push more towards the snowmobile/snowhawk type design (heavier, higher horsepower) but you have built what I would want!

I want to be able to pull my bike out of a tree hole by myself and still be able to ride after. I think the focus on weight is the right one as for differentiating what makes snowbiking so much of a different experience than snowmobiling.

I'd love to see the rear suspension you used, any pics?

Where you able to save weight with the A-arm front suspension instead of a traditional motorcycle headset or was that a decision based more on ease of fabrication?
 

fgauvin7

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So when are you going into production? ;-)

Production would be a ultimate goal in a few years but I will need many version to tune this thing and it would need a lot of simplification to be a reasonable product to produce in series! The actual design is way to complex and time consuming to build. There could be less parts and less home made parts too... All the 4130 swing arm, A-arm and chassis parts are a lot of work. We will see where it end up in a few years!

That is a really cool, clean build. A purpose-built snowbike. I assume you'll fight overheating with just one radiator and the wide open nature of riding. You'll likely either need a large fan or tunnel cooling to keep up. I know for dune riding, even with 2 radiators, and even in cooler temps, we get some overheating just because you are wide open a lot.

Thanks for the input, But for the first few test I think I will not have too much trouble since I don't think I will be riding it very hard the first ride.... But I definitely think that you are right, for tree riding, slow moving but high rpm's, this thing will get hot! But I have kept some space for a tunnel cooler, so the fix will be pretty straight forward.

That is awesome! I think you have been reading my mind. There are some really cool builds on here that push more towards the snowmobile/snowhawk type design (heavier, higher horsepower) but you have built what I would want!

I want to be able to pull my bike out of a tree hole by myself and still be able to ride after. I think the focus on weight is the right one as for differentiating what makes snowbiking so much of a different experience than snowmobiling.

I'd love to see the rear suspension you used, any pics?

Where you able to save weight with the A-arm front suspension instead of a traditional motorcycle headset or was that a decision based more on ease of fabrication?

When I was designing it I tought that we have a maximum weight that could be handled on a moto style product and still feel il comfy, stable and responsive. Weight is not always solved by more power, high power and high weight I think are two thing that can make you feel not in control and not confident... Sure not having enough power is an other thing... But actual snowbike do pretty well already and it is not 80-100lbs lighter that will make it worse, it can jut be better.

At the end I don't think I have saved a lot of weight (maybe 3-4lbs) with my front suspension because I need to compare the weight of my suspension including all the steering component to a fork setup... Because the fork setup is actually the steering too.... So at the end there is not much for all the work, but there is more to save in the frame work. I can not have a number but a headset require a lot of structure to hold all the font end in cantilever for just 6in at the top. Imagine all the forces that could apply here. With the A-arm setup the load is very well placed and all the parts that have to be strong can be kept closer to each other. The result I think is some pretty substantial weight saving in the chassis.

The back suspension is more of a guess to me, it will certainly need a lot of tuning but I'm confident I will make it work. It is a mono shock more or less like the Mototrax style suspension, I just don't use any linkage and pivot to make it a rising rate design. Instead I use a fox Float that by it's design give a rising rate air pressure, not as good as a true rising rate suspension because I will not benefit of more dampening by the same valve stack. It will just have a rising rate air preload and a more or less constant dampening.
 
Jan 18, 2018
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That really looks nice.

I have thought so much about a similar project. Yes, the headset becomes a significant stress point and you may be on the right track trying to go with A-arms. I really want a ride report, with the different front ski travel as you hit abrupt/steep snow surfaces, will the more straight up and down travel make the ski less likely to want to pop up and over stiff hits?

In my head if keeping a motorcycle style front, alot of changes could be made as there would never be a front tire. Spindle assembly could be much smaller as the entire suspension could be lowered. Headset could also be made significantly longer/taller to reduce the stress concentrations on it... but remember, I'm just thinking, I haven't built anything!

Hats off to you for putting this together. That's a ton of work and it really came out nice. Can't wait to see it on the snow and hear how it works.
 
Dec 19, 2007
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How long and wide is the track? I agree the snowhawk style sled builds aren't for me but probably what the manufactures will give us some day.

Since you don't have a strut rod or a fork, Do you have a way to adjust fork height, ski pressure or rail tip pressure? It should be way less critical since your center of gravity is on the track.

How much turning radius can you get with the front end? I'm building a raptor 700 quad frame bike and might try the a-arms vs adding a fork might make the quad frame super heavy.
 
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