I'm just wondering if anyone knows the logic behind combining 13 and 15 gears. I think some of the newer race sleds are running like this? Does anyone know how and why they are set up like that ?

Well I just found out it's the 2004 Polaris Pro XR 440 that has a 15 wide chain and top sprocket and a 13 wide bottom sprocket.

Anyone know the logic behind this?

less weight (than having 15 wide bottom), but stronger set up than 13 wide chain. It's not exactly new- the 15 wide top, 13 wide bottom concept.

Hey! Thanks for the insight. I was guessing it had something to do with less rolling resistance as it is over a slightly narrower surface. But, Your suggestion of less rotating mass sounds better. I guess that's why, the 13 wide I saw was made of aluminum?

Aluminum is just crazy, unless you're replacing gears all the time (read racing).

The top gear is the one that brakes toots, very often compered to the bottom......
Top gear got veery few toots "in" the chain compered to the bottom.
witch is way the top gear brakes. (of corse the 15chain is stronger to)
I agree with FIII_151, don't go aluminium unless "racing only"
Lars

Never ever have i heard of a top gear breaking, in snowcross anyway. Bottom ones yes, but never a top. All Ski-Doo race sleds have a 15 wide everything. Go with a solid steel gear on bottom, not aluminum as it will just wear faster and give you problems.

Originally posted by skidoo175@Feb 22 2004, 07:47 AM
Never ever have i heard of a top gear breaking, in snowcross anyway.* Bottom ones yes, but never a top.* All Ski-Doo race sleds have a 15 wide everything.* Go with a solid steel gear on bottom, not aluminum as it will just wear faster and give you problems.
Well, i got at least one broken gear in my garage right now... :hallo1:
what can i say..... (Arctic cat and Polaris stock top gear) :confused: :crazy:
w00t
And that the guys at bombardier uses more toots on top (and bottom) than the other brands....for example mach-Z 26-44, while the thunder cat is geared 24-39, this give a toot in chain advance to the doo!
Bottom gear breaking, that newer happen to me.....yet! :D
Lars

Just pulled my top out of snopro and she is cracked.