If you run a good synthetic like Motul, Redline, Amsoil Dominator, Etc, there is no good reason to run less than 50:1, especially if you are just riding trails. Each of these oil companies recommend 50:1 + ratios for non-racing and they have no incentive to do so. Jeff Fredette runs 50:1 Golden Spectro - he has never lost a top end in 20+ years of racing the ISDE. In fact, he claims he has very little top end wear after 40 hours of absolutley hammering the motor in an ISDE. Pick a good oil and ratio, and jet accordingly.