I need more low end for my 240 lbs in the tight and steep moutain single track I ride here in Utah at times. Should I just put a 12 tooth front sprocket on and keep the 47 tooth rear or should I go with the stock 13 tooth up front and a 50 in the rear? I found where it was advised to change to a 12 tooth up front for more low end but then recommended going with the 13x50 if you were replacing a chain. What is the advantage?
It seems to me that it is easier just to change front spockets depending on riding conditions.
In theory, the 12 tooth countershaft is harder on the chain than a 13t. So chain and sprokect life would be better with a 13t than a 12t. Howver, you might need a longer chain to run 13/50 or 13/51.
If your chain is in decent shape, just put on a 12t. It is much cheaper to experiment with this. If you like the change, you can go to 13/50 or 13/51 with a longer chain next time you need to replace the chain and sprockets.
I agree with dirt bike dave above. The problem with the larger rear sproket is you need a longer chain and many have chain guide problems. You will like the 12t sproket and you might want to consider a flywheel weight. If you are riding at high elevations, your jetting will be critical to your enjoyment. Cheers John
Thanks for the input. I installed the 12 tooth and it seems to be the ticket for the low end enhancement. I will try this for a while and possibly lean out my pilot jet some. I currently run my needle in the leanest position, a 38 pilot (and it is just a tad rich at 8500' elevation) and a 143 main.