Next build GEN 3 snowbike, home build project

Test fitting our new frame design. Everything looks to fit nicely. No welding, just bolt it together!
The shafts on this frame are made out of 7075 aluminum. We hope this will be strong enough without bracing.




The rim of the chain case is water-cut of a 30 mm aluminum plate. We have kept extra material around the mounting screws to provide extra strength.
We think this rim is the key to get rigidity of the tunnel panels, especially axial forces on the drive shaft.
Milled a 2 mm recess corresponding to the thickness of the cover.

We ordered the 120 mm brake disc online from a swedish website. Probably for some cheap chinese **** but it will work just fine for this aplication. The wave shape will hopefully clean off some snow and ice.



Start getting together something resembling a bogie. Only remaining front straps and the shaft to the rear suspension mount . For the joints we have chosen to use bronze bushings with grease.

Carbon fiber may be the next step.
Leaves room for more improvements. This prototype needs some more testing
Thanks for the link M5


Completed the linkage assembly and mounted the shock.





We assemble the tunnel top to the side panels.


L-shaped aluminum angle profile is drilled and bolted. Bolts enables removal of the side panel in the event of, for example, rock impact.

A cut template ensures that the tunnel roof is in the proper location.

The tunnel ceiling is glued in angles with a special double-sided tape. This should withstand the heat of a powder coating oven.

No screws or pop rivets. Just the tape keeps the tunnel roof in place to the L-profiles



Test mount the suspension.

We choose bronze bushings, grease lubricated with grease nipple as swing bearings.

Swingarm bearings was originally planned to use OEM KTM swing arm needle bearings. However, we chose to machine our own greasable bearings with bronze bushings.

For a more compact chain case design, we have chosen to tension the chain from outside. Of course it is better to put a idler sprocket from the inside but then the chain case would become too bulky that the heel didn't got room enough
Have made a first prototype of tensioner out of a slippery plastic. It has a ridge that slides on the rollers of the chain. We will probably at the end go for a Little different design on this slider but we are so eager to get our first test ride



2 mm carbon fiber cover is lightweight but not the least, looks really nice and high tech;-).

Almost done. Just the ski left to assemble. Tomorrow will be our first test ride of our GEN3!

Finally maiden voyage in the Swedish mountains with Gen3, really fun!



Gen3, has as you may have seen an enclosed load carrying tunnel design which we believe is very positive because we both avoid snow spray and gets a significantly more rigid structure. The pictures show what we experienced in the short time we've test ridden. The bike gets almost no snow on itself which is really good.


The question will surely come regarding weight. Current kit weighs now 44.5 kg (98,1 lbs) with a potential to reduce weight by 1-2 kg (2-4 lbs) by for examle making tunnel roof thinner i.e. 1mm aluminum instead of current 2 mm. Some parts/covers can easily be made out of carbon fiber sheets.


The brake hose on the right side will get a protected and more apropriative fitting. Currently just a simple attachment with temporary plastic straps.




The lever on the handlebars controls the locking of the third shock. It is originally used on mountain bikes in conjunction with the type of damper we use. The locking can be controlled in three steps. You might also recognize these from Skinz Arc. They use the same system to choose between a coupled or uncoupled bogie.


After our first test ride, we've concluded that mountainbike shock will be strong enough for this aplication. It is rated at max 300 psi but we reached sufficiant firmnes at a modest 220 psi. With the correct geometry will likley end up in 150-170 psi for a good suspension performance.
After our first test ride, we had used 40 mm stroke at the normal running of the total stroke of 55 mm.
It may seem good but we had a lot of sag and it got quite firm at a modest stroke. In other words, the suspension wasn't is not quite optimal.
We would have preferred less sag and less progressive travel.
The solution is to move the rear attachment point downward. By this way, we will have more shock compression in the beginning of travel (start pressure) and as compression travel gets reduced, the shocks built in progressivity kicks in.
We feel confident that this will end up to a better use of the shocks entire spring travel.
We will watercut some new damper brackets with several holes so we easily test out the optimal point of attachment.


The brake disk on the drive shaft seems to work out quite good. A compact, simple and light weight design.
One problem with this solution could probably be more exposure and risk to icing on the disc, leading to some degree to delayed breaking action.

Our previous build Gen2 is a LT.
Its definatley nice to have a longer track in deep snow conditions but at the same time you loose some of the nimbleness that we all like in snowbiking.
I'm not sayin that LT is bad but I think that a ST is overall the best crossover for most conditions, at least where I ride.
Turbo bikes can benefit of a longer track. More power needs more track to put the power in use. Had the turbo on the first short track build with small lugs. It more or less hit the rev limiter every climb. The LT seemed to work better with the turbo. Maybe a ST with longer lugs will work better....

Here in Sweden we don't have those extreme snow conditions that we've viewed on youtube from BC or similar.
The total snowcover gets regurally around 3-4 feet. Some winters we get one or two overnight snowfalls of 1-1,5 feet and thats nice but mostly the snow sets quickly. Recent winters has been miserable with less snow and thaws that ruins that nice deep pow.

I was very happy with the LT but I think ST will work fine for me. In fact, I will keep my other bike so I have both of them to choose from depending on conditions ;-)

For now, we will test this design and try to find its flaws or possible improvements. Putting a longer track on this is probably not the right way to go. From what we have learned, the suspension arm and the attachment points has to be changed in order to get it to work correctly.

Last ride of the 2016 season 12th of may in Pjeskehaure in the swedish mountains, close to the norwegian border.
Our new GEN 3 snowbike works really well! We havent had any mayor issues despite that this is a completely new and untested design.
We need a few more rides for testing out optimal suspension settings.
The third shock seems to work as planned. Currently running 250 psi and its rated at max 300 psi.



Have redisigned the shock mount. The idea was to get more shock movement in the beginning of travel getting less sag and less progressive springrate.
The plan was initially to have multiple attachment points for testing but the shock had the wire operated locking lever and chamber so badly placed, that we ended up using only one.
An adjustable mount is probably a better solution than a fixed, at least for finding out the optimal attachment point.



The chaincase slider tensioner looks to work very well. With this solution of tensioning, pushing from outside instead of an idler sprocket tensioning form inside, we will have a extremely compact chain case. Shorter chains, less weight, less parts to break down are some the benefits with this design.
Made a new improved slider prototype made of a combination of aluminum and plastic. We havent seen much wear but we will probably go for a higher quality teflon based material.
We chose to go for 1:1 gear ratio in the side transmission and adjust gearing with sprockets on the engine and jack shaft. By going for only one ratio in the case, we don't require a large tensioning range.

The 2015 Argentina bike sold. New bike on the way!

The new bike has arrived, a 2017 KTM 500 EXC SixDays. Looking good!


Have ordered some turbo parts from MCX that will be delivered soon.
The brand new 2017 500 EXC is in many aspects redesigned so my previous turbo build templates can't probably be used as planned.
The next turbo build will be a lowpressure system with only 0,5 bar or 7,25 psi of boost. This means that it doen't need any engine modifications such as a custom made lowcomp piston, stronger studs, high flow water pump and so on....
The engine will be left more or less untouched which is neat if you look for a easier turbo build.
With a lowpressure system, the engine will deliver aprox 90-92 whp which I believe is sufficiant in most snowbike conditions.
100+ hp is nice but at the same time more picy to obtain and likely less reliable for the average day to day snowbiker.
Because I will run the standard 11,8:1 compression, 102 octane race fuel is likely required.
I'm not sure if I need an intercooler under such low boost. It will be a simpler build if I could delete that but at the same time, a cooler would probably be more reliable and eliminate any risk of detonation....
If I go for intercooler as previous build, it has to be mounted on the bike as this is a pivoting snowbike kit. Previous kit was a rigid kit that had the intercooler mounted on the tubular frame.
A bike mounted intercooler would look similar as my buddys turbo build as this photo below.
(The wheel is only for runnin on the dyno. It does'nt have any suspension travel for on road use)

Thanks Sno101.
The drawings in my thread of the Gen2 bike is not up to date.
We have made some changes to the rails, fixings, shocks, bearings and tunnel panels.
I hope I will have time later to compile everything so the drawings are accurate and up to date.


Our Gen3 is still under testing. We still have some adjustments, including the linkage of the third shock.
We will also examine whether it is possible to increase the torsional stiffness of the frame. Has not proved to be a problem so far but may possibly be an area for improvement.


Will be some time before we'll post the drawings on the Gen3. We do not know if this is something that in the future may be something that is going into series production. For now, this is only a one off prototype.

No major issues, the brake works fine. In certain conditions we are experiencing some delayed braking action when the disc gets a thin cover of ice that takes some break time to melt off. Most snow bikers probably experience the same issue. I think the only way to make it work flawlessly is to encapsulate the brake. That is probably difficult to achieve on our design as the disc is mounted on the drive shaft with limited space. Overall, we feel that present solution works good enough that we will not look for a design change, at least for now...