Never seen a problem with them breaking spontaneously and I'd worry more about someone else carrying a cable cutter. But I've been using only a combination cable lock for my local shopping trips for years without any problems. Your post just reminded me that I bought mine for our daughter to use when she rode her bike to school in 5th grade. I ended up getting it back after she finished college. She's a pediatrician now. So this lock has been in regular use for quite some time and hasn't lost a bike yet (but is supplemented by a U-lock when in riskier areas).