CHART FOR COMMON GEAR RATIOS, AND "AT TRACK" RATIOS FOR 7 Tooth 3" PITCH DRIVERS.
With the arrival of the X3 tracks and the 2.6 Powerclaw... 7 tooth Drivers have become common place.
Many of our members are curious about gear ratios with this driver, so I thought I'd put together a list of Comparative (realized) drive ratios... That is, what is the real ratio at the track taking into account the correction factor of .92 for the smaller diameter of the 7tooth 3" pitch driver.
EDIT: Comparative (realized) drive ratios are ALSO listed for 2.86" pitch 7 tooth sprockets.
To calculate the comparative 'final' drive ratio for a 7-tooth, 3" pitch driver equipped sled, use this formula (B ÷ T)÷.92=Final Ratio. Where B is Bottom gear tooth count, T is top gear tooth count and .92 is the correction factor for the difference in the diameter of the sprockets.
I will not list the 18t top sprocket as I'm not at all a fan of that small of a sprocket.
Now...For the STOCK 2013/14 owners with the QuickDrive™ belt drive equipped PRO RMK's, you are limited to a final drive ratio with 7tooth 3" pitch at 2.27:1 (ie 2.09 ÷ .92 = 2.27)... Which is not bad... I personally prefer, as does my "Gear-Guru" TRS... around 2.35:1.
I'm running the 19/41 gearing with a stock 72 link (pitch) chain and AVID 7 tooth 3"-pitch combo drivers for a realized ratio of 2.35:1
As a comparison, the factory 8 tooth x 2.86"-pitch drivers ... a gearing combo of 19/45 gives me approx the same ratio of 2.36:1
For the same approx 2.35:1, the 20/43-74p may be more "ideal" as it puts more teeth in contact with the chain... but heck... I'm cheap and have plenty of 19/41 tooth sprockets on hand... and stock chains (72p)... and none of the others.
Chaincase PRO RMK models:
Factory gearing 20/42-72p
A) Gearing top/bottom
B) Ratio (gearing alone, factory drivers)
C) Realized (at the track) 7t, 3" pitch Ratio
D) Realized (at the track) 7t, 2.86" pitch Ratio.
E) Pitch count (IE... How many links in the chain)
--A-- -> --B-- -> --C-- -> --D-- -> --E--
================================
20/41 -> 2.05:1 -> 2.23:1 -> 2.33:1 -> 72p
19/41 -> 2.16:1 -> 2.35:1 -> 2.45:1 -> 72p
20/42 -> 2.10:1 -> 2.28:1 -> 2.39:1 -> 72p FACTORY
19/42 -> 2.21:1 -> 2.40:1 -> 2.51:1 -> 72p
20/43 -> 2.15:1 -> 2.34:1 -> 2.44:1 -> 74p
19/43 -> 2.26:1 -> 2.46:1 -> 2.57:1 -> 72p
20/44 -> 2.20:1 -> 2.39:1 -> 2.50:1 -> 74p
19/44 -> 2.32:1 -> 2.52:1 -> 2.64:1 -> 74p
20/45 -> 2.25:1 -> 2.45:1 -> 2.56:1 -> 74p
19/45 -> 2.36:1 -> 2.57:1 -> 2.68:1 -> 74p
20/46 -> 2.30:1 -> 2.50:1 -> 2.61:1 -> 76p
19/46 -> 2.42:1 -> 2.63:1 -> 2.75:1 -> 74p
.
With the arrival of the X3 tracks and the 2.6 Powerclaw... 7 tooth Drivers have become common place.
EDIT: Oct 2016....
Most people base their "feel" for gear ratios based on stock gear ratios of the sleds when they were 8-tooth 2.86"-pitch drivers on the drive shafts... now that we have many 3"-pitch tracks... and using 7-tooth drivers... a "translation" for comparison... has been posted here. That is, if I change out to a different pitch driver or track... how would that compare to my ORIGINAL gearing.
BUT... if you are keeping you stock driver diameter...then this is a moot point as you are NOT changing the diameter of the drivers on the driveshaft.
. For example, you have a 2016 AXYS with the 3"-lug with 3"-pitch-drivers... and you switch out to a Conquer 280 track... which also has 3"-pitch drivers... then your gearing will NOT change... unless you change the sprockets on the drive/jack shafts... easy to do on a chain drive.
. If you have a QuickDrive™ equipped sled (belt drive on the jack/drive shafts), for those with the series 6 (2.6"-lug) or series 5 (2.4"-lug) that has the 2.86"-pitch, you will need to change drivers to the 3"-pitch, then you will need a kit like C3 or TKI etc on a
Many of our members are curious about gear ratios with this driver, so I thought I'd put together a list of Comparative (realized) drive ratios... That is, what is the real ratio at the track taking into account the correction factor of .92 for the smaller diameter of the 7tooth 3" pitch driver.
EDIT: Comparative (realized) drive ratios are ALSO listed for 2.86" pitch 7 tooth sprockets.
To calculate the comparative 'final' drive ratio for a 7-tooth, 3" pitch driver equipped sled, use this formula (B ÷ T)÷.92=Final Ratio. Where B is Bottom gear tooth count, T is top gear tooth count and .92 is the correction factor for the difference in the diameter of the sprockets.
I will not list the 18t top sprocket as I'm not at all a fan of that small of a sprocket.
Now...For the STOCK 2013/14 owners with the QuickDrive™ belt drive equipped PRO RMK's, you are limited to a final drive ratio with 7tooth 3" pitch at 2.27:1 (ie 2.09 ÷ .92 = 2.27)... Which is not bad... I personally prefer, as does my "Gear-Guru" TRS... around 2.35:1.
I'm running the 19/41 gearing with a stock 72 link (pitch) chain and AVID 7 tooth 3"-pitch combo drivers for a realized ratio of 2.35:1
As a comparison, the factory 8 tooth x 2.86"-pitch drivers ... a gearing combo of 19/45 gives me approx the same ratio of 2.36:1
For the same approx 2.35:1, the 20/43-74p may be more "ideal" as it puts more teeth in contact with the chain... but heck... I'm cheap and have plenty of 19/41 tooth sprockets on hand... and stock chains (72p)... and none of the others.
Chaincase PRO RMK models:
Factory gearing 20/42-72p
A) Gearing top/bottom
B) Ratio (gearing alone, factory drivers)
C) Realized (at the track) 7t, 3" pitch Ratio
D) Realized (at the track) 7t, 2.86" pitch Ratio.
E) Pitch count (IE... How many links in the chain)
--A-- -> --B-- -> --C-- -> --D-- -> --E--
================================
20/41 -> 2.05:1 -> 2.23:1 -> 2.33:1 -> 72p
19/41 -> 2.16:1 -> 2.35:1 -> 2.45:1 -> 72p
20/42 -> 2.10:1 -> 2.28:1 -> 2.39:1 -> 72p FACTORY
19/42 -> 2.21:1 -> 2.40:1 -> 2.51:1 -> 72p
20/43 -> 2.15:1 -> 2.34:1 -> 2.44:1 -> 74p
19/43 -> 2.26:1 -> 2.46:1 -> 2.57:1 -> 72p
20/44 -> 2.20:1 -> 2.39:1 -> 2.50:1 -> 74p
19/44 -> 2.32:1 -> 2.52:1 -> 2.64:1 -> 74p
20/45 -> 2.25:1 -> 2.45:1 -> 2.56:1 -> 74p
19/45 -> 2.36:1 -> 2.57:1 -> 2.68:1 -> 74p
20/46 -> 2.30:1 -> 2.50:1 -> 2.61:1 -> 76p
19/46 -> 2.42:1 -> 2.63:1 -> 2.75:1 -> 74p
.
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