What is the max weight an MTB bicycle with a freewheel can handle until it starts putting high stress on the rear axle? Of course the riding style matters. How hard you go on jumps etc.
I don't drive my bicycle that hard. Sometimes i do when im in the mood. My issue is that i am constantly braking my rear axles. It all started a year ago while i was getting heavier and started going off road. I weight 95 kilos (210 pounds). So far i've broken 4 axles and my current one is bent. I don't get the hollow ones with the skewers(quick release). I get the solid ones. I've heard that bikes with cassettes have more durable axles. But i am not planning on buying a new wheel.
So what is the max weight an MTB bicycle with a freewheel can handle until it starts putting high stress on the rear axle?
Is there any way to reduce the chance of braking and bending axles?
Axles break for various reasons - weight is only one of them. Miss aligned dropouts, flexing in the frame, tension of the QR all play a big part. Different axles with slightly different materials will also have an effect - some are stronger overall, some more brittle, some more prone to fatigue.
As you identified, riding style also affects the axle loading.
While the manufacturers probably put a number on this for their axles, I suspect its very conservatives and more reflective of there policy around warranty and brand value.
As far as regularly breaking freewheel axles, they are known to be weak compared to other options. A freehub wheel will probably solve your problem, but also check your frame dropout alignment.