Cycling shoes have a number of distinctive features - they generally have very stiff soles (with screw fixings to take shoe plates that clip to pedals), and often have exotic fastening systems (shoe laces are so last millennium!). Common fastening systems include velcro straps and a variety of ratcheting designs. Personally, I dislike velcro straps, and prefer the ratchet systems, as these are more amenable to adjustment while riding.
A couple of years ago, I bought a pair of Specialized S-Works shoes (see left), which featured a ratchet system that tightens up a criss-crossing string across the upper, and which fastens the shoe very effectively. Unfortunately, the other day, the string snapped, leaving me to compete with a shoe held together with gaffer tape. I disassembled the ratchet this morning and was struck by how the string resembled plaited dental floss. I repaired the shoe with three lengths of dental floss, and it seems to have worked. At least, it's stood up to full tightening with no sign so far of giving way!
I shall no doubt regret this repair when the string pops many miles from home!