129 to 137?

[fxnytrortxkid]

Hey all, time to update track and rails are little beat up from center shock back when bolt came apart. So question is has anyone gone to a 137 from 129? Did you need to change the rear tunnel extension? I’d just do diff rails so would keep the 129 mounting locations, even tho I do need to change the drop brackets as they egged out when the locktite failed and one of those backed out on the last ride. Just getting idea to see how involved and if it’s worth messing around with. Thanks

 

[Big_Phil]

The tunnels and mounting locations of of the rear skid mounts are different. The 137 literally does everything worse than the 129 sleds, and they are slower. Just an FYI

 

[fxnytrortxkid]

Which is why I’m not changing any of that, it would be all the same aside from rails and track if I did it

 

[jonlafon1]

The tunnels and mounting locations of of the rear skid mounts are different. The 137 literally does everything worse than the 129 sleds, and they are slower. Just an FYI

129 is not faster then a 137. Not even close in 1000' ... 137 will out dig any 129.. the 141 will beat the 137 also..
If were talking a one mile race on ice or a road MAYBE the 129 wins

 

[Fast]

The tunnels and mounting locations of of the rear skid mounts are different. The 137 literally does everything worse than the 129 sleds, and they are slower. Just an FYI

I would have to say a 137 would be faster, going from 121 to 137 is so much better in the trails

 

[cannondale27]

ProCross chassis the XC sled went back to 129 from a 137 last year because the 129 is faster. Other makes like Nytro always thought 141 was faster so it all depends.

 

[jonlafon1]

in 1000' I will stand with my above post. In a straight line no 129 will win. Procross with 1.25 track.

Running tight twisty trails sure the 129 might be slightly better.

 

[rtx moose]

Difference in speed would be impossible to notice between the two!!your body will thank you for the 137 on long days though!!

 

[fxnytrortxkid]

Speed an all isn’t s main concern. All mounting points would stay same as 129 so transfer would remain but 137 for bit more traction and mostly for better bump spanning

 

[fxnytrortxkid]

But mostly curious if anyone made a transition and if the rear tunnel and bumper had to change for 137 or not.

 

[Big Ugly]

Loose or deep snow the 137 has the advantage but hard pack or ice the 129. 129 weight transfers better and on real rough trails the 129 is better.

 

[fxnytrortxkid]

Again 0 change to geometry it’s just a 129 or 137. Those that have done it are the rear tunnel abs bumpers needing to be swapped or the 129 ones work well?

 

[Big_Phil]

in 1000' I will stand with my above post. In a straight line no 129 will win. Procross with 1.25 track.

Running tight twisty trails sure the 129 might be slightly better.

Maybe if youre talking fully chiseled race sleds, and in that case the 141 skid is far superior to the 137 or 129 skid. For trail sleds, the 129 will be faster just about all the time in all conditions due to better transfer and less rotating mass. Is what it is. Ive never lost to a 137 winder or t cat, my brother had 2 137s that I used to spank. Now he has a 129 and he beats me by a length.

 

[DGZRT]

If you go from a 129" to a 137 " you will have to add on to the tunnel for coverage but the bump stops should be ok .

 

[snoprof6]

I have seen riders do it both ways. It seems the racers who do tail stands all day long clip studs on the end of the tunnel, where the snow flap mounts. Most tame trail riders seem to have no issues running the 129 tunnel with the 137 track.
There was a gentleman on HCS who installed a 137 tunnel extension and used the stock 129 heat exchanger. No issues he stated.
Here is a few images of 137 extensions with stock tunnel. One with a 137 extension and tunnel extension.