The same principles extend to cyclic exchange processes (Figure ); at equilibrium steady state there is no net flux around the cycle and all individual equilibrium constants are satisfied. More generally, if multiple pathways connect species in a reaction network, at equilibrium steady state there is no net flux over any single path, which is the condition of "detailed balance". A simple example is the rotation about a C-C single bond connecting stereogenic and prochiral centers (Figure ). Detailed balance holds even when the potential energy surface for the rotation resembles a macroscopic ratchet, as shown by Kelly and co-workers, 6 who demonstrated that rotation about the triptycene-helicene bond of 1 (Figure ) occurs at equal rates in both directions. That barrier height and microscopic reversibility win the day rather than the shape of the potential surface is reassuring as, if it did not, it would be possible to use flux around the cycle to perform work at equilibrium steady state, violating the second law of thermodynamics.