I took my C5 up and down the close earlier to check if it was good for another 200 miles + over the next few weeks and at applying the brakes before entering the garage, I heard a snapping noise and lost all brakes. Lucky it was on entering the garage and not when approaching a junction at rush hour tomorrow.
I rang my local cycle shop to confirm their opening times, "We shut at 5 sir, that's in 2 minutes" Oh, bugger. You see, I really need to source a brake cable tonight for my Sinclair C5. Mine's just snapped and I have no replacements at home. "Ah, yes. I remember you. Give me a ring when you get here and I'll open the shop up for you"
Result! Now I have brakes that can hopefully be trusted for another 6 months.
Worst of all is that the cable showed no signs of fraying anywhere along it's length prior to snapping and it was replaced about 6-8 months ago.
Check your cables the next time you're near your C5. If they show any signs of fraying anywhere, especially if they're frayed at the lever end, simply replace them.