According to my research, the bike comes stock with a 13 tooth front and a 49 tooth rear. I just ordered a 50 tooth rear and a 12 tooth front. I would like to try some combinations (perhaps order some more rear sprockets); what do you guys run/have you run? I am building an mx track at my house. The track will be about a 1/2 mile long on 5 acres, so not a lot of long straightaways, thus my thinking of going bigger in back and smaller in front for more low end. I will also trail ride and stuff too so just looking for some opinions. Thanks in advance.