IMO, 121 with a 1.25 inch lug track and 1.325" studs is ideal for trails. If you ride where is real bumpy maybe a 136.ripperd said:Why would you long track it and then make it narrower, negating some of the benefit of long tracking it?
They make thinner lighter tracks in 136. But if you are looking for lightness why on earth would get a big lug and stud it?
You don't need a 136 for a "sick trail sled". Trails are packed. You want a 121 ripsaw with lots of studs if you want a go-fast trail sled.