Gearing

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Gearing - Mountain Specific

Gearing - Trail / Backcountry

Gearing - Summit, change from 21 to 20 or 19 (Track speed Staying power)
Gearing - Summit gearing from 10th 2.52 to 8th 2.86
Gearing - Trail, change from 27 to 26 or 25
Gearing - Rpms during long touring
Gearing - XP 800 - My gear is 27 top, how low can I go without a new chain?
Gearing - XP 800 - My gear is 25 top, how low can I go without a new chain?

Gearing - REV / MXZ SPROCKET and CHAIN chart
Gearing - XP SPROCKET and CHAIN chart.

Gearing - Lowering ratio and effect on flyweight.

Gearing - Commentary 2

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Gearing - Mountain Specific

If you ever want to regear, it’s not a problem with this kit to go any of these ratios, in fact my helix’s work so well with lower gearing for whatever track speed you achieve, it will maintain it with great strength.  Lower gear; even stronger track speed holding power.
21:49 = 2.33 = 104P
19:45 = 2.36 = 102P
21:51 = 2.42 = 106P – Customer faves 
20:49 = 2.45 = 104P – Customer faves
20:51 = 2.55 = 106P  
19:49 = 2.57 = 104P
19:51 = 2.68 = 106P

Rev chassis w/10tooth driver
19:45 = 2.36
19:46 = 2.42
19:47 = 2.47 – This is a common customer favourite.
19:50 = 2.63
19:51 = 2.68

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Gearing - Trail / Backcountry

Every 1 tooth off the top gear will reduce your maximum theoretical mph by 3~4 on gps.  So then a question arises; what is the highest most reasonable peak mph do you expect to get in the normal every riding day conditions?  You can gear the sled to do that maximum mph.    Use my online gearing calculator to find out what a gear change will do for you.
Say you gear lower by 2 top teeth – that will reduce your peak mph by 6~8mph however for the upside of accelerating harder by 6%~7% to get to that peak mph.

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  Gearing - Summit, change from 21 to 20 or 19
The gear teeth mentioned are only for a reference, to indicate a point of one operative cause, of what a gear change(s) does.  The demonstration here is to support the assertion of what a gear change can do for "staying power"

Question) Joe, I have an 07R summit 159 at 5000 to 8000 feet. What do you think about going from a 21 to a 20 or 19?

Answer) A gearing decision is influenced by “elevation and snow type” so then what elevation do you run at and what kind of snow types do you normally see?

Facts; Any lower gear will help enhance acceleration.
Observation - You can hit the bottom of a hill with a few more speed units and help maintain that holding power needed without track speed diminishing too quickly.

Facts; Track speed will diminish at a slower rate with any lower gear.
Observation - "Elevation" Feedback I get from tuners is many who run higher than 7500’, they seem to like the lower gearing as they see power loss as elevation increases. The engine power decreases however the driver can still maintain a good track speed.
Observation - "Snow load" Where tuners get into deeper snow, or wet/heavy snow and observe an example of 29mph~35mph track speeds, then the lower gearing will be beneficial to hold track speed for a longer time especially when it’s hard running. Improves "holding power" regarding track speed.

There are guys I talk to who run from 3500 to 7500 feet that particularly boondock, not running on big climbs at all. Guys report back to me they like the lower 20 and 19 gears for technical riding in the trees when they need that extra quick burst of acceleration to climb little hills and get into side hilling, winding up through the salad.

Example; Run #1  23:49 gears.  If you were to run up a hill for say 600 feet at 40mph track speed and watch the track speed diminish and turn out, return to the start.

Run #2  22:49 gears.  Change out to 1 tooth lower and go again. Full throttle up beside that previous track, you will probably see 40mph track speed again, however travel up the hill 660 feet before the track speed starts to diminish, return to the start.

Run #3  21:49 gears.  Change out to 2 teeth lower and go again. Full throttle up beside that previous track, you will probably see 40mph track speed again, however travel up the hill 700 feet before the track speed starts to diminish.

Consider the sum of #1,2,3 reveals "track speed staying power".  Trace the staying power back to its source, to it's original principle one observes gearing lower.   How much is too low is a matter for the tuner to chase out themselves for their personal situation/requirements.

One of the elements that the sled achieved the farther distance is that with the lower gearing, the drive system has the ability for increased torque from the start, allowing the sled to accelerate harder from the start point to the "up" of the hill;  in that first "X" amount of feet, the sled achieves a higher velocity.  By the time the sled hits the curve of the hill, more than likely it was at 1~2 mph more "velocity"

There can be a point to where your sled may have a velocity of only 3~4 mph however the track speed augering there at 40mph track speed, full throttle, engine at rated rpms, smile on your face you couldn't wipe off with a shovel.
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  Gearing - Summit gearing from 10th 2.52 to 8th 2.86
Question)Hey Joe, I have an 05 summit X 800. I'm going to run the 06 440 Racer 2.86 8 tooth drivers with the new 155 camo extreme. I ride at 5-8,000' and weight about 230lbs w/o gear. I was running 19/46 with the stock 10 tooth & have your SX8 clutch kit, I was wondering what you'd recommend for gearing.
Stock gearing is 19/45. Thanks Brent

 

Answer)That 440 2.86 driver set is nearly the same diameter as a 9th 2.52 driver, however the 2.86 is slight more efficient. So then you can think of the 8th is like a 9th then can calculate the ratio difference. 10th / 9th = 1.11 or 11%

 

19:46 is 2.42:1 ratio. You changing nothing in the system except the drive sprocket, you are lowering your gearing by another 11% which would be (2.42 x 11%) = 2.69
To find out the new "overall gear ratio" you take 46gear and divide by 2.69ratio = 17gear.
Going from a 19:46-10th{2.52} driver to a 8th-{2.86} driver would be the equivalent of gearing to a 17:46

You did not mention the reason why you wanted lower gearing so I cannot recommend a gear ratio. If you wanted to go to the 440-8th{2.86} and maintain the same "overall" gear ratio as your 19:46-10th{2.52}, then you would have to go to a 21:46 and that would be "mathematically" the same gear ratio as you presently have however 1 size smaller drive sprocket. 19gear x 1.11% = 21 gear
Result; 19:46-10th{2.52} = 21:46-8th{2.86}

Don't forget to try the Gearing Calculator .
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  Gearing - Trail, change from 27 to 26 or 25
Question) Joe, I have an 08 XP trail sled and wonder if there is a benefit to gear down? Will I get more performance from lower gearing than factory?

Answer) A gearing decision is influenced by “Application” so then what kind of gearing applies to you?

Facts; Any lower gear will help enhance acceleration.
Observation - Using traction products and having good capacity for your suspension to hook up, you can gain acceleration over a similar sled. The gear reduction increases the available torque to the track to move the sled quicker in a shorter amount of time.

Facts; Track speed will diminish at a slower rate with any lower gear.
Observation - Snow depth, where rider gets into deeper snow, or wet/heavy snow and observe an example of 59mph~65mph track speeds, then the lower gearing will be beneficial to hold track speed for a longer time especially when it’s hard running. Improves "holding power" regarding track speed.

Facts; Any lower gearing will raise rpms when using sustained throttle positions cruising at sustained sled speeds.
Observation - A clutched 800R with 27:45 can cruise at a sustained speed of 65mph(105 km/h) with 6200 rpms. Using a 26:45 on the same pass, will be about 6350 rpms. Using a 25:45 on the same pass, will be about 6500 rpms.

Taller gearing delivers very smooth power delivery when cycling the throttle. Gearing lower will make the sled react with a more sudden power feel.
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  Gearing - Rpms during long touring
Question) Joe, what rpms does your kit see when I am doing long mileage touring?

Answer)My clutch kit offers 350~400 rpms Lower than stock calibration. Clutch kit is about 6200 rpms, stock calibration is 6500~6600 rpms under sustained throttle position - The reason why is the clutch kit uses 23g of flyweight compared to the 18g of stock pinweight.
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  Gearing - XP 800 - My gear is 27 top, how low can I go without a new chain?
Question) I have a 27 top gear on my sled, what is the lowest gear I can go without changing the chain?

Answer) The 27:45 and 26:45 use the 106P chain. To go to a 25 gear you must reduce the chain size to 104P.
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Gearing - XP 800 - My gear is 25 top, how low can I go without a new chain? Question) I have a 25 top gear on my sled, what is the lowest gear I can go without changing the chain?

Gearing - REV / MXZ SPROCKET and CHAIN chart

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  XP Sprocket & Gear chart

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  Gearing - Lowering ratio and effect on flyweight

Here is what happens when you change a gear ratio to a lower ratio
or
When you change the overall ratio (aka smaller drive sprocket diameter)

The term(s) tuners use "gearing too low" or "geared lower" is a "label", a descriptive marker that is attached to a result of reducing "overall drive ratio"

Gearing commentary

IF you can remember the theory "The law" of how the parts work, then you change your overall drive ratio and see "X" result...
THEN you can apply other theory "the law" of how the parts work to compensate for the lower gearing.

An example.
You can run a gear set with 21:49 as stock with a 413 ramp and reveal "rated rpms" (8150) right to full shift.
If you were to run a 20 or 19:49 then make the same run down a road to full speed, there is a great chance that you'll observe rpms that will stay at 8150 until the load changes (bumps, cycling throttle for a corner, snow getting slight deeper) then the rpms will reduce. [remember the lever is doing more work being farther out on the ramp]

Alright...
You reveal lower rpms under re-applying full throttle.
Ramp example illustration ( i will get a picture of 413 vs 410 vs 417 and post)
You can take the 413 ramp out and install a 410 or a 417 as each of these ramps have an increased angle towards full shift compared to the 413.
Law - If ramp angle increase; Then rpms increase. Then rpms quicken from one rpm to a higher rpm / time.

You reveal lower rpms under re-applying full throttle.
Example question arises - what spring force is being used at an example 45mph track speed? (look at track speed at bottom of chart)
You can look at your primary spring final force. The rpms reduced with a xxx/260.
You can remove the xxx/260 and install a xxx/290 or a xxx/320.

Each time you raise the final force then you will be adding more spring force at-the-moment-during-upshift where the rpms start to diminish or become sluggish.
How much spring force you add at-that-point-on-the-up shift will determine 1)how much the rpms will drift low. 2)how quick the rpms will recover.

there is always an easy way to get around drifting rpms due to a gear change.


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Gearing - Commentary 2

Aaen give us ultimate facts which some are actual and some are alleged.  The alleged are proven with evidence from testing.

Pg 14  (Aaen Tuning Handbook)
*Belt loss is influenced by turning radius.
*The tighter the belt has to turn, the higher the loss of power.
*Line A shows the increase in efficiency with the 15 degree angle sheaves.
*In a low ratio the belt speed is low but the turning radius around the driving clutch is tight and the belt tension is high, giving lower efficiency.  As the transmission moves towards 1:1 ratio the belt tension is reduced from the torque feedback giving higher efficiency.

Remember this track speed post from 2008?
I did not come up with this 29~45mph track speed range, you guys come up with it, not me.  I started to study what happens in this range that mountain riders said they use and range they said they don't care about.

Knowing Aaen's mixed actual and alleged facts about efficiency, then also looked at gearing. 
Gearing low; 1)Where is the highest belt loss in which clutch and 2)What is the time component is spent there at that track speed?
Gearing higher; 1)Where is the highest belt loss in which clutch and 2)What is the time component is spent there at that track speed?

Aaen) as the transmission moves towards 1:1 ratio the belt tension is reduced from the torque feedback giving higher efficiency.
Comments - If we geared with the drive belt closest to 1:1 in mountain sledding, then where would the belt be in both clutches at the range of track speeds mountain guys told me?
How could I push the belt higher in the primary to the more efficient range that Aaen promotes in the usable range of 29~45mph track speed range?
We kept changing the gear at the bottom of the hill (takes 10 minutes with an xp on its side and you don’t even spill a drop) and watched the marker get wiped off the primary.  The lower we geared the higher the marker got wiped off. 
Now another subject arises, belt slip in the secondary.  Ok tackle that by changing out only the helix and do it again.(takes 10 minutes on a rev chassis and 20 minutes on an xp with bolts instead of hex)

The alleged fact here is going by seat of the pants.  The rider is running by himself with nobody to go against.  The rider says "feels stronger, nice track speed” Now how to do prove an actual fact?  Count seconds at full throttle to measure, temperature, track speed lowering as time increases.  Then go test against the similar stock sled using the orange ball test.

Clutching requirements for mountain riding is somewhat set-aside from any other discipline I have ever seen other than watercross oval racing.
The most usable track speeds are lower than any other discipline.  The time at the usable track speed can be for long periods of time.  So then would it not be more suitable to gear the sled to have the belt at or closest to the most efficient locations on BOTH the secondary AND primary clutch sheave?  Where is that?  According to Aaen, it’s at 1:1 ratio.
Ok then if it is at 1:1 ratio then there should be no problem gearing lower to push the belt to the most efficient position on BOTH clutches.

I tell ya, if I could make a 60 tooth bottom gear, I would, and that would bring the 1:1 ratio to 56mph for a peak overdrive at 62mph.  And that would bring the drive belt to the most efficient location on BOTH sheaves.

19:51 @ 65mph (2012 skidoo stock 163)
19:55 @ 61mph
19:60 @ 56mph (wouldn't this be fun to try?)

 Guys say "that won’t work" or "that would be too low” Really?  How do you know that?  How far have you chased out that subject?

I've made a good living at going against the grain, I mean I love it when guys say "you can’t do this" or "this is required" or "you need this" or "you need that", "that won't work", "that helix angle is too small".  "Joe, i don't' like your spring with 350 finish, its too strong" Umm, gee it has come stock in skidoo summits for a few years now, maybe to talk to them about it."  So, I’m still here, doing what people tell me I cant do.

When there is a problem grabbing the belt as you start to gear lower, this is one of 2 explanations on how to solve it. (helix angle change)

In the final analysis it boils down to figuring out the correct forces to grab the drive belt.  Skidoo in 2012 has gone in the best direction for grabbing the belt on their new summits.  The 2012 calibration is grabbing the belt harder than the previous year calibrations.

With my kits, If you want, you can change the gearing higher or lower.

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