During the course of your bike's ownership, it may become necessary to access the internal controller of the bike. This silver box holds some base-level programming for the bike, connects all the electronic parts together, and is vital for the bike's functionality. In this article, we will go over where to locate the controller, how to access it, and show the different wiring configurations. 

Step 1: Locating the controller

On both the Road and the Gravel the controller is located at the bottom of the downtube under the trapdoor. 

Step 2: Accessing the controller

To gain access to the controller one has to remove the back trapdoor on the bottom of the bike. This is held in via one fastener on the bottom of the trap door. After they are removed it will lift off.  If one does flip the bike over to access this door; it is important to not rest the bike on the display.

Step 3: Remove the crankset

The crankset and the bearing cover need to be removed to fully access the controller and connections. The following photos go over how to remove the crankset. The process is identical to the process of removing a Shimano Hollowtech 2 crankset. Please pay attention to all the spacers on the crankset to avoid losing them. 

Step 4: Remove Bearing Shield

Once the crankset is removed the bearing shield can be removed. This piece serves to keep the cables away from the spinning crank spindle/ bearings. The shield is spring-loaded and once compressed can be removed from the bicycle. The following video shows how this piece works. The shield can be retracted by pulling on the bolt and once the shield is compressed, tighten the bolt to hold it in that position. The installation is the opposite. 

Step 5: Working on the controller

Once the panel, shield, and crank are removed; the controller is easily accessible. The controller is held in place by one bolt on the downtube which is shown it the image below. While they may vary slightly the following tips are true for all controllers: 

  • Each connector is unique for each part. For example, a display unit cannot be plugged into where the motor cable would go.
  • Pay attention to how the controller was originally sitting in the bike. The cables come out one end of the controller and for ease of reassembly, it is often best to put it back in the same configuration. 
  • When changing out a whole controller it is best to move the connections over one at a time until complete. 
  • Mark the new controller with tape or marker before starting. That way there are mix-ups during the switch. 

Controller connectors:


To reassemble, repeat the steps in reverse order.