All the parts are pretty much sturdy and solid. My friend basically handed me every single part off of it as he changed his bike over time. He finally had only the frame and I took that as well which I'm running now cause I sold all the other parts. The parts can sure take a good beating and still go strong.
The Kenda Kontact tires lasted a while but as they wore down, I started getting flats every couple weeks. The hubs were fine except the axles were a bit weak. The front axle bent after a few smiths and both axles started stripping a little but maybe it's just my fault.
Pretty good bike for the price if you just wanna change a few optional things.