I've broke 3 chains over the past 12 years on my Dyno Zone and have only ever had to replace my tires, tubes, and chains and never had a broken bone in my life. Been in plenty of crashes (usually from trying to do a jump that is just to far/high for me), but never had a crash or major failure from a chain. You can usually tell if your chain is to the point of breaking and any time I am getting ready to do major riding such as a 20-30 trail ride on either a BMX or MTB I do a basic check, but other than that, I ride it till it goes and so far has never failed me. Granted, I've just started riding on my first ever road bike this week and that may change things going at higher speeds.