I weigh about 230lb. and I often stand up on the pedals when riding. This is now the second time I've had this problem: the teeth on the cog wear down and break off and then when I'm pushing in a high gear the chain will slip and jerk my feet around. It's like $50 or something to replace both the crankset and the rear gears, which the bike mechanic told me I have to replace together... First of all, is that B.S.? And is there a crankset you'd recommend that's a little tougher and might stand up to the torque? I don't really use anything but the middle chainring and I wouldn't mind getting a leg guard for the outside ring either, anything you'd recommend? I have a Kona Dew Deluxe, by the way.