Even the humble crank bolt hasn’t escaped the evolution in bike components. For many years a steel bolt with a 14mm hex head was sufficient for cotterless cranks. But we have since seen; 14mm hex bolts in aluminium/titanium, 6mm allen key bolts in steel/aluminium/titanium, self-extracting crank bolts in a variety of materials, and numerous proprietary examples such as the solution proposed by Magic Motorcycle.
Crank manufacturers have often produced their own crank caps, some purely functional, but others also ensuring a perfect symbiosis between cranks and caps – Cook Bros Racing spring immediately to mind with their crank caps completing the dog bone profile of the cranks.
Self-extracting crank bolts – those which enable the user to install and remove their cranks with the aid of just an allen key – have been around since the early 1980’s with the Shimano One Key Release, but it was only after the Syncros Crank-O-Matic bolts were released in the early 1990’s that the popularity of these bolts really took off.
Shimano One Key Release