The gains are more obvious, however, with the front derailleur, which moves the chain between the two large, toothed rings on the bicycle’s crank.

That is partly because the electronic front derailleur is able to make constant readjustments to reflect changes in the chain’s position caused by shifting with the more frequently used rear derailleur. That allows the electronic front derailleur to use a more efficient shifting mechanism, one that would drive riders to the point of distraction with fiddly readjustments on a mechanical system.