It wasn’t that long ago every trail sled had a 121 or 120-inch track (actually, both are the same length but there’s a difference in the pitch of the track where the drive sprockets engage it and the measurement on the snow can vary by less than an inch).
All quibbling aside, in the last decade there’s been a big shift over to baseline track lengths that measure 129-inches. It began with Arctic Cat first, then with Yamaha, then Ski-Doo and today the only OEM not offering a 129 is Polaris.
In reality, the on-the-snow footprint of a 129-inch track is about 3 to 3.5 inches more length compared to a 121. It’s not a lot but given the fact many sleds continue to drop weight, it can make a significant difference in the way a snowmobile handles powder snow and in its ability to accelerate and bite into packed snow.
One thing that’s made the 129 transition so successful is the fact it doesn’t appear to compromise handling. This may not necessarily apply to those multitudes that are choosing 137-inch trail sleds over either 120 or 129ers.
There’s a pretty big difference in the contact patch of a 137 compared to a 120 (between 6 and 7-inches on the snow) and this additional track length will numb down the sharpness in a sled’s steering response.
We’ve talked to many riders who tell us they are opting for a 137-incher as their first choice because a 129, although their second choice, doesn’t give them the off-trail versatility they’re looking for. The compromise in handling is acceptable to them for the deep snow benefit they gain.
Another interesting development is the crossover market appears to be a jumping ship from 137-inch tracks to 141, 144 and 146-inchers. New sleds like Cat’s High Country (141), Ski-Doo’s Renegade Back Country (146) and Polaris’s Assault 144 all offer excellent handling and great trail suspensions with longer tracks.
We think trail sleds will all be 129-inches soon and the crossover market will be exclusively 140-plus. We do doubt however, true crossover (trail and powder) track lengths will exceed 146-inches.