Mountain Sled Geometry
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Interesting but I have no idea what it's telling me?
M A X W E L L.
M A X W E L L.
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Iron Horse Racing
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The illustration is hinting at how close the geometry appears in a 2 dimension view
koby
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helloooo.......it clearly indicates the cat is the superior machine
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I'm thinking it will be all that and more.
moto5151
Active VIP Member
I find it interesting that the Polaris and cat are very similar in design when you line it up like that. I didn't realize the skidoo was so much different then the rest. A complete different approach, yet most of the rider positions are close. I guess this is a true black AMD whit reason why some people prefer different machines when it comes to comfort. Would like to see some drawing that would show balance points and center of gravity for these as well. On a similar note, I saw a video on speed works site, that showed the different machines weights wet, and with snow pack. Amazing what they found.
sledslut
Active VIP Member
i see by this pic that the SKI-DOO has more of an area you can stand on with keeping the sled balanced. meaning ease of ride.
takethebounce
Active VIP Member
Doo actually changed their spindle location in the XM to me more inline with the Poo and Cat.
I don't see any more area you can stand on the DOO like sledslut says.
If you actually look at the steering post pivot point location and the rear mount for the skid, the distance on the DOO is the greatest. What I have found with this distance is the Doo will wash out quicker if you do not have weight further forward. The XP suffered because people couldn't get their weight far enough ahead. The XM with its more forward post design and open footwells helps people ride the chassis easier.
On a Poo the distance is smaller between (as is the cat) and the sleds don't tend to wash out and the rider position is more forgiving. What you would think is the opposite but it is not true.
Just my experience.
I don't see any more area you can stand on the DOO like sledslut says.
If you actually look at the steering post pivot point location and the rear mount for the skid, the distance on the DOO is the greatest. What I have found with this distance is the Doo will wash out quicker if you do not have weight further forward. The XP suffered because people couldn't get their weight far enough ahead. The XM with its more forward post design and open footwells helps people ride the chassis easier.
On a Poo the distance is smaller between (as is the cat) and the sleds don't tend to wash out and the rider position is more forgiving. What you would think is the opposite but it is not true.
Just my experience.
Mike270412
Golden Boy
lhf should be here any minute to explain "attack angle "
scrfce
Active VIP Member
Completely agree. Thats about the only thing the xm is lacking in, steep sidehill lines. They tend to wash out. I always attributed it to the wide running board stance at the riders feet then how they drastically taper towards the rear??
gibsons
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Someone should put LHF's wedge in the line up to see how it lines up.lol
sledneck_03
Active VIP Member
The doo and polaris rails look similar but polaris looks to have the best approach angle. Probably why it gets on the snow so well. The doo is close the cat looks like a terrible approach angle with the hockey stick rails.
I think they made a mistake in choosing to draw lines at that particular point in the steering linkage. There's nothing important about that point in particular. The only important things are the angle of the post and position of the bars. The angle of the post determines how the bars will move through their arc, and the position of the bars determines where the rider can stand.
maxwell
Active VIP Member
how does that make any sense whatsoever? the steering post postion on the polaris and cat machines are so far back that the rider weight is closer to the rear of the sled therefor causing the sled to wash out easier. mountain riding basics if you want to recover a washout on any machine you move forward. so how on earth does having the rider in a starting position further back create less washout? its pretty clear by comments like this and the photo that its not a matter of any sled "washing out" more than the other but its the rider that needs to adjust there position to controll the level of sidehill washout they desire. i can control my washout on a steep sidehill very acurately. but jump on another sled and you need to adjust your rider position to control this differently. before we get carried away how are these photos taken? are they lined up on a mark on the floor to the spindle location? camera in the same spot? distance kept constant from the machine center point? have reference points been chosen on the sleds and scaled to real life distance measurements? in order for this to be true and correct it would have to me input into autocad and scaled correctly. and by that i mean you could click a distance between any 2 points on either machine and compare it to actual.
skegpro
Active VIP Member
[h=3]The Ins and Outs of Sled Steering Control[/h][h=4]Steering wheel vs. motorcycle handlebars vs. cost[/h][h=5]Story by Matt Allred, Created Jun 25, 2009[/h]
When steering a car to turn right or left, you, like a billion other people, rotate the steering wheel clockwise to navigate a right-handed turn or counterclockwise for a left-handed turn. Snowmobile handlebar posts that run over a motor (known as either laydown or horizontal), swing much like a steering wheel. Why? Because, the flatter the angle the more clocklike the rotation.
Ski-Doo and Yamaha have rallied around a business and production concept that allows commonality – parts shared across most, if not all, models. The Ski-Doo Summit and Yamaha Nytro MTX have over-the-motor steering posts; these posts are also shared with the mountain sled’s flat land buggies.
By sharing common parts across several platforms, production costs are reduced. This is good business sense. So, the TNT and Renegade share the same over-the-motor steering post as the Summit. Likewise, all Nytro platforms have the same. Furthermore, over-the-motor steering posts have far fewer parts than under-the-motor (vertical) steering posts; fewer parts equal less weight. Ski-Doo and Yamaha, filled with business-minded bean counters, look for every advantage to cut costs, which also plays into an engineer’s hand when looking to reduce weight.
We must be clear here, steering wheel-like swing (turning) benefits the snocross racer and fast trail burner. Sno Pros, MXZs, Nytros, Rush, IQs and SPs use this style of steering post. It works, it’s comfortable and it gives riders speed control for aggressive sit down riding.
So you drive a KTM or Honda CRF during the summer months. On these dirt toys, the handlebars swing, yes, clockwise and counterclockwise, but flat as compared to a car. The close ratio, nearly vertical steering mechanism is similar in function to Polaris’ RMK Dragon, Cat’s Ms and Yamaha’s Apex MTX. This behind-and-under-the-motor steering post is key to superb and easy sidehilling of those sleds. This steering post design gives drivers easy leverage to the chassis, while at the same the handlebars are properly positioned for sidehilling – when the driver is standing.
Bret Rasmussen, who works as an independent researcher/developer and performance consultant to the snowmobile aftermarket industry (his company – Snowmobile Research Services – SRS), has this to say, “Lay down, or horizontal steering posts are preferred for sit down style riding. I know because I rode an F6 for 2,000 miles in Alaska’s Iron Dog race last season. In a turn, the inside handlebar grip rotates down, thus allowing your body to be able to move forward and over the bar for more cornering control.
“With a vertical steering post (behind and under the motor) the inside grip will move into your body and prevent optimal body position [for sit down riding].
“Now let’s relate this to aggressive stand up mountain riding, Bret Rasmussen style. If I am on one running board and negotiating a technical side hill, or even a moderate side hill, when I pull on the outside handle bar grip to tip the sled up, it will easily go into a controlled counter steer. This is characteristic of a vertical post. If I do the same maneuver on a sled with a horizontal steering post, pulling on the outside grip will naturally turn the skis into the hill and prevent the sled from tipping up on one ski. Horizontal (laydown) posts keep both skis on the snow, thus greatly limiting the terrain that can be safely negotiated.”
The downfalls to the behind-and-under-the-motor steering post (vertical) is that its numerous components (up to 12 and more) are heavier than over-the-motor, resulting in higher production costs. These steering posts are specific to the RMK and M-series, and are not shared — mostly — with other platforms (except for the Ms and Crossfires; and the RMKs and Switchbacks).
Some may argue, and I am one, mountain sleds are unique and mountain riders want a steering post that allows for easy sidehilling. However, engineers, product managers and accountants may argue that the higher costs won’t please shareholders.
I see both sides.
When, and I believe the time will come, Cat and Polaris move to over-the-motor steering posts to reduce production costs and weight, then the Snowmobile.com Mountain Team implores: Do not sacrifice boondocking and sidehilling agility for a few pennies and ounces; unique works and unique is what a mountain sled is all about.
Sometimes, a penny saved is a dollar lost in sales.
When steering a car to turn right or left, you, like a billion other people, rotate the steering wheel clockwise to navigate a right-handed turn or counterclockwise for a left-handed turn. Snowmobile handlebar posts that run over a motor (known as either laydown or horizontal), swing much like a steering wheel. Why? Because, the flatter the angle the more clocklike the rotation.
Ski-Doo and Yamaha have rallied around a business and production concept that allows commonality – parts shared across most, if not all, models. The Ski-Doo Summit and Yamaha Nytro MTX have over-the-motor steering posts; these posts are also shared with the mountain sled’s flat land buggies.
By sharing common parts across several platforms, production costs are reduced. This is good business sense. So, the TNT and Renegade share the same over-the-motor steering post as the Summit. Likewise, all Nytro platforms have the same. Furthermore, over-the-motor steering posts have far fewer parts than under-the-motor (vertical) steering posts; fewer parts equal less weight. Ski-Doo and Yamaha, filled with business-minded bean counters, look for every advantage to cut costs, which also plays into an engineer’s hand when looking to reduce weight.
We must be clear here, steering wheel-like swing (turning) benefits the snocross racer and fast trail burner. Sno Pros, MXZs, Nytros, Rush, IQs and SPs use this style of steering post. It works, it’s comfortable and it gives riders speed control for aggressive sit down riding.
So you drive a KTM or Honda CRF during the summer months. On these dirt toys, the handlebars swing, yes, clockwise and counterclockwise, but flat as compared to a car. The close ratio, nearly vertical steering mechanism is similar in function to Polaris’ RMK Dragon, Cat’s Ms and Yamaha’s Apex MTX. This behind-and-under-the-motor steering post is key to superb and easy sidehilling of those sleds. This steering post design gives drivers easy leverage to the chassis, while at the same the handlebars are properly positioned for sidehilling – when the driver is standing.
Bret Rasmussen, who works as an independent researcher/developer and performance consultant to the snowmobile aftermarket industry (his company – Snowmobile Research Services – SRS), has this to say, “Lay down, or horizontal steering posts are preferred for sit down style riding. I know because I rode an F6 for 2,000 miles in Alaska’s Iron Dog race last season. In a turn, the inside handlebar grip rotates down, thus allowing your body to be able to move forward and over the bar for more cornering control.
“With a vertical steering post (behind and under the motor) the inside grip will move into your body and prevent optimal body position [for sit down riding].
“Now let’s relate this to aggressive stand up mountain riding, Bret Rasmussen style. If I am on one running board and negotiating a technical side hill, or even a moderate side hill, when I pull on the outside handle bar grip to tip the sled up, it will easily go into a controlled counter steer. This is characteristic of a vertical post. If I do the same maneuver on a sled with a horizontal steering post, pulling on the outside grip will naturally turn the skis into the hill and prevent the sled from tipping up on one ski. Horizontal (laydown) posts keep both skis on the snow, thus greatly limiting the terrain that can be safely negotiated.”
The downfalls to the behind-and-under-the-motor steering post (vertical) is that its numerous components (up to 12 and more) are heavier than over-the-motor, resulting in higher production costs. These steering posts are specific to the RMK and M-series, and are not shared — mostly — with other platforms (except for the Ms and Crossfires; and the RMKs and Switchbacks).
Some may argue, and I am one, mountain sleds are unique and mountain riders want a steering post that allows for easy sidehilling. However, engineers, product managers and accountants may argue that the higher costs won’t please shareholders.
I see both sides.
When, and I believe the time will come, Cat and Polaris move to over-the-motor steering posts to reduce production costs and weight, then the Snowmobile.com Mountain Team implores: Do not sacrifice boondocking and sidehilling agility for a few pennies and ounces; unique works and unique is what a mountain sled is all about.
Sometimes, a penny saved is a dollar lost in sales.
Longhairfreak
Active VIP Member
I was thinkin the same thing.
maxwell
Active VIP Member
That's the biggest load of horse chit I have ever read
skegpro
Active VIP Member
Now don't get to excited Maxy, Like I said in another post, I am very close to snowchecking an XM but the steering post angle throws me off a little.
I always think there are things that could be improved upon, and on the summit I think this is one of them.
Polaris could use an etec of their own and the cat could use a trip to Jenny Craig.
Now correct me if I am wrong, but based on the angle created by your foot stance on the running boards and the angle of the steering post, wouldn't you have less mechanical advantage on the summit than the other two sleds?
I find it ironic that this is something that Ras' himself has always preached, but has recently taken the big back of doo cash and has silently changed the angle of the steering post on his xm. Whats even more ironic is that he hasn't been caught in public riding his xm.
I always think there are things that could be improved upon, and on the summit I think this is one of them.
Polaris could use an etec of their own and the cat could use a trip to Jenny Craig.
Now correct me if I am wrong, but based on the angle created by your foot stance on the running boards and the angle of the steering post, wouldn't you have less mechanical advantage on the summit than the other two sleds?
I find it ironic that this is something that Ras' himself has always preached, but has recently taken the big back of doo cash and has silently changed the angle of the steering post on his xm. Whats even more ironic is that he hasn't been caught in public riding his xm.
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