Electronic vs mechanical gear systems

Let’s take a look at gear systems. Specifically, the difference between electronic vs mechanical gear systems.

The “Big Three” bike part manufacturers each have an electronic gearing system:

  • Shimano has Di2 for both road and mountain bikes;
  • Campagnolo has EPS; and 
  • SRAM has Etap which, along with being electronic is wireless! 
Left: Electronic rear derailleur (Shimano Dura-Ace R9150 Di2). Right: Mechanical rear derailleur (Shimano Tourney RD-TY500), note the electric wire going into the electronic derailleur vs the steel cables into the mechanical model.

There are, of course, the pros and cons of electronic gear shifting. 

The pros:

  1. No cables to stretch, rust or replace.
  2. Cable routing isn’t an issue, whereas mechanical cables don’t like to go around sharp curves, but digital wires can go anywhere. This frees up bike designers to make frames and handlebars weird and wonderful, which is especially evident in aerodynamic time trial and triathlon bikes.
  3. The shifting is done by a servo motor actuated derailleur rather than a cable actuated derailleur. This means electronic groupsets can cope with ‘heavy’ shifts and weird chainring combos better than mechanical groupsets. For example, sometimes when you’re on a steep climb (like Arthur’s Seat or Devil’s Elbow) where it’s more difficult to move to an easier gear under strain.
  4. There’s less hand strength needed to shift gears, which is great for people with smaller hands or arthritis.
Left: Electronic shifter (Shimano Dura Ace R9170, Di2). Right: Mechanical shifter (Shimano Acera 7 Speed ST EF500)

The cons:

  1. There is a battery to keep charged (or several if you have SRAM E-tap). If your battery goes flat the system automatically shifts you into the smallest chainring and the smallest cog on the cassette.
  2. It’s expensive. Typically electronic drivetrain parts cost 2.5x or more than the mechanical equivalent.
  3. The feedback from the shifters isn’t the same, think typing on a touch screen vs typing on a proper keyboard where the tactile feedback from the keyboard makes typing easier. This is especially true when wearing gloves.
The battery does need to be kept charged and in this case, is done via a USB charger.

Both systems are affected by chain and cassette wear as well as the derailleur hanger being straight and aligned correctly. So, regardless of which system you run, it does need servicing!

If your bike is due for a service you can book in at 1 of our 3 hubs, Monday to Friday.

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