New chain length... 12-47

I run 12/47 and an o-ring. Anew stock length chain will fit just fine - as the size change from 13 to 12 is very small.

There is no way anything other than an o-ring would hold up with my riding. For many - good chain maint will allow standard chains to last all season. However, a 100 mile enduro will shred any chain no matter the maintenace. They are constantly in the muck, sand and grime and just grinds the thing to pieces.

I am firmly on board with he WD-40 only crew. One o-ring lasts all season under som pretty tough rides. I cant really ask more than that. With chain lube - it just seems to hasten the wearing ans I could only get 1/2 season at most. I ran the stock chain on my KDX when it was new and went to the back clicker in one 70 mile ride.

You can get decent o-ring for $50. Anything lese just inst worth it IMO. I hink you drop 1/4 HP - but on a 30 HP bike, who really cares.

As Moridin said the stock chain length (108) will work with 12/47 or 13/47.

If you are happy with 12/47 and are buying new chain/sprockets then I would suggest 13/50 with a 110 link o-ring chain. The 13/50 is very close to 12/47 but the 13 lasts longer IMO.

The o-ring chain will take alot more abuse without as much stretching or required maintainance. The stock non-oring chain streches like a rubber band.

The o-ring chain is a little fatter so you need to either get a new rear chain guide or modify the existing one with some washers.