Heavy Ski Pressure on 2021 Aro

[gpr]

Bought a 2021 ARO 129 to put on a 2015 YZ450f. I have ridden other older ARO kits and the ski pressure was light and the bars easy to turn. However on this bike the ski pressure is very heavy and hard to turn the bars. How do i change this?

Did they change something on these newer ARO kits causing this? I know they drop and rolled the chain case to get a 3" track to fit, which changed the track approach angle (i am running 2.5" track version)

I have lowered the solid strut and that helped, but it is low enough while sitting on concrete the back of the track is higher then the front, and it still has high ski pressure. (plus it doesn't seem to climb as well like this, even though it does now turn easier) I increased the spring preload on the front track shock and lessened the rear. Next thing i was going to try is drop the forks in the triple clamps.

Any ideas or suggestions?

 

[CB-BLR]

You are headed in the correct direction.

 

[jethro450]

done anything to your forks? springs? airpro? revalve?
My experience is that first the forks need setup, then mess with strut length and preloads on the springs. If the forks are soft, it doesn't matter what you do on the rear, it'll feel heavy. Also, the deuce boy skag helps it feels easier steering.
I think you went too far with the strut length. It should be about 11-7/8" from center of hole to center of hole.

 

[aka Mr Floyd]

I'd second the air pro for the front forks. Just a few psi in the front can make a huge difference in whether or not the front wants to dive while turning.

 

[glenn booher]

Bought a 2021 ARO 129 to put on a 2015 YZ450f. I have ridden other older ARO kits and the ski pressure was light and the bars easy to turn. However on this bike the ski pressure is very heavy and hard to turn the bars. How do i change this?

Did they change something on these newer ARO kits causing this? I know they drop and rolled the chain case to get a 3" track to fit, which changed the track approach angle (i am running 2.5" track version)

I have lowered the solid strut and that helped, but it is low enough while sitting on concrete the back of the track is higher then the front, and it still has high ski pressure. (plus it doesn't seem to climb as well like this, even though it does now turn easier) I increased the spring preload on the front track shock and lessened the rear. Next thing i was going to try is drop the forks in the triple clamps.

Any ideas or suggestions?

When you say drop the forks in the triple clamps do you mean more sticking out the top or less? I am thinking about the same thing.

 

[dwigmore]

When you say drop the forks in the triple clamps do you mean more sticking out the top or less? I am thinking about the same thing.

Typically, dropping means less sticking out the top. Should shift weight towards the back of the bike - at least in the dirt! Not sure what the effect would be with a track...

 

[eric82930]

yes doing that on a bike with tires rolls the cg slightly back and may be take a pound or 2 off the front. but that's not what happens on a track kit. the track has a center shock that is carrying some of the weight so if you raise the front it will take weight off the center and split it between the rear paddles and the ski which makes MORE ski pressure and hard steering. if your fork is diving a lot on landings or down hills that is a totally separate issue that usually needs more fork spring but that change alone will make a ton more ski pressure so if you do an air pro or stiff fork springs then you need to readjust strut or track shocks to get the center shock to carry some of the weight off the front. snow bike kits are a huge compromise of weight distribution because most of the static weight is hanging over the front of the track and is naturally carried by the ski. think of it like a see-saw with the fat kid on the front and the pivot is the center shock. if you don't have the center shock lifting a good portion of the center of the see-saw then the fat kid stays on the ground and sinks in the deep snow. it truly is a balancing act but understanding is important.

 

[dwigmore]

yes doing that on a bike with tires rolls the cg slightly back and may be take a pound or 2 off the front. but that's not what happens on a track kit. the track has a center shock that is carrying some of the weight so if you raise the front it will take weight off the center and split it between the rear paddles and the ski which makes MORE ski pressure and hard steering. if your fork is diving a lot on landings or down hills that is a totally separate issue that usually needs more fork spring but that change alone will make a ton more ski pressure so if you do an air pro or stiff fork springs then you need to readjust strut or track shocks to get the center shock to carry some of the weight off the front. snow bike kits are a huge compromise of weight distribution because most of the static weight is hanging over the front of the track and is naturally carried by the ski. think of it like a see-saw with the fat kid on the front and the pivot is the center shock. if you don't have the center shock lifting a good portion of the center of the see-saw then the fat kid stays on the ground and sinks in the deep snow. it truly is a balancing act but understanding is important.

Thanks! Great explanation of figuring out the balance on a snowbike!

 

[ski force]

I struggled with the same thing on my aro 120. I put a 300 pound spring on the front of the skid and a 150 on the rear. I weigh 140 lbs and if you are closer to 200 lbs use a 350 on the front. The front lifts a little more on climbing but is controllable. The climbing ability didn't seem to suffer appreciably. Also the center skegg on my ski was pretty abrupt on mine and I blended it back to be more gradual. Also I took off about an inch of the front edge of the outer runners and blended them since they were pretty aggressive. Side hilling still was sufficient Start with the springs first.

 

[GKR]

Eric is correct and I would suggest the Air pro or fork spring for sure to start, then adjust your forks in the triple clamps. Easy to do when you are out riding. Move forks up (more stick out at the top) and you will reduce ski pressure. Try 1/8” at a time. The difference is significant, even with small changes and don’t be afraid to go up 3/4” if that achieves the ski pressures you want.

To build on Eric’s post, consider that with the length and width of the track under a snowbike, in most instances the track will try and remain flat on the snow as you ride. Picturing this on a packed road, when you roll on the throttle, the track grabs traction and propels the bike forward on the track. It’s going to try and plant the track flat against the snow for maximum grip. What this means in your static setup is that if your track is raised slightly in the back, the weight will transfer back during forward acceleration to a “flat track” position and your ski will tend to lessen its ground pressure because the bike has rocked back onto the raised rails.
If the track is flat to start with it will remain flat, and ski pressure will be greater.
If you actually lowered the rear of your skid below flat at the back (longer strut rod) you will have even higher ski pressure as your track tries to “get flat” to get traction and drives the ski down in the process.

Raising your front skid shock pressure or spring preload lifts the center of the bike and does reduce ski pressure but does less to influence weight transfer. Softening rear shock preload will assist weight transfer and lessen ski pressure under acceleration only.

Does this make sense? It’s all about allowing or enabling weight transfer to the rear. I find that strut rod adjustments will affect ski pressure most during acceleration, climbing, etc.

Now, having said all this about the skid, strut and rear shocks, what else?

Well that’s where the fork position comes in.
Let’s assume you have a flat or slightly raised in the rear orientation for the track. The ski pressure that is felt as you ride with this setup is set. Keeping the thought in mind that the track stays flat to the ground as you ride, imagine if you raise the forks in the clamps. It will, in essence, “ lift” the ski up towards the bars which will reduce the riding ski pressure. This is most prevalent during cruising because remember, if you accelerate hard you transfer weight back by default and your ski pressure goes away. But if you are not accelerating hard and are just cruising, raising or lowering your forks will change the “set” ski pressure.
You will find as I said these fork adjustments are significant and you really feel them in the steering.
I generally ride with my rails slightly raised in the back, about 1/2” over the length of the rails. Then I set fork position to get the ideal ski pressure.

I hope this makes sense and helps. I have ridden bikes that are off and ones that are dialed and the difference in the riding experience is so drastic that I’m afraid that there has been more than one rider that got completely turned off of snowbiking because he rode a poorly setup bike.

All these effects lessen greatly when you get in the powder but if you have to ride any trails or hardpacked snow to get to your riding, that’s where this setup pays off big.

There may be plenty of other opinions about this but this is my experience.