Originally Posted by
bobotech
Something else to consider, riding style. A lot of people are mashers, they keep their bike in a higher gear which makes them pedal harder but slower. The problem with that is if the person pedaling is overweight, they put a LOT of torque on the wheels. My son killed more than 2 rear wheels with his mashing style of pedaling. He would be in the smallest cog in the rear and the middle on the front and start off from a dead stop going up a hill at his 300 pounds. That is going to put tremendous twisting torque on the rear wheel.
What I taught my son was to downshift the rear derailleur all the way while coming to a stop. He finally listened and even said how he found it much easier to ride now that he downshifts.
Bobotech, you got
torque confused with
force. Being in tallest-gear (smallest cog in back) will generate the lowest torque on the rear-wheel, but you have to really stand on the pedals and exert more tension
force on the chain to generate any torque and acceleration at all (try starting a stick-shift car in 3rd gear). Starting out in the lowest-gear (biggest cog) will generate more torque on the rear-wheel for the same chain-tension, like starting a manual car in 1st gear.
What was happening with your son's bike was probably due to his mashing/stomping motions. This causes uneven lateral-loading on the frame and lots of rocking back and forth. Wheels are extremely weak in the lateral-direction. If he hits any bumps or pothole while standing out of the saddle, rocking the bike and stomping on the pedals, this can easily tweak a wheel and rim permanently. Heck, that can happen if you're a light tiny rider as well.