Since I am not a mx racer, I was going to use my stock 19" as a dunes wheel and get an 18" wheel with a Pirelli Scorpion Pro Enduro Rear Tire - 140/80-18 for trail riding in steep mountain terrain. Since I ride both places often, I don't want to be breaking apart the chain and adding or taking away links. I think the 13T front with a 50T rear sprocket is about right for trail riding. Right now I can switch rear sprockets on the rear between 50T and 48T (dunes ... but would like to go less) What is the max difference I can go between rear spocket sizes and still keep the same chain? Also, is a 14T front too crazy on these bikes since I do ride some steep sand trails when I'm out there?