The Problem

About 18 months ago I built up a road bike ago using an L-Twoo GRX wireless electronic groupset, and I have been very pleased with it.

I planned to ride it this weekend, after not using it for about three weeks, so I charged the battery that drives both the front and rear derailleurs, but stupidly did not do a quick test ride. That was a mistake.

I drove to my starting point and started my ride, but I found that I could not shift gear. Luckily the ride was very flat and the bike in a reasonable gear, so I was able to complete the ride with no problems.

When I got home I checked that I had in fact fully charged the battery. I had. So I then tried the L-Twoo app to see if that gave any clues, but this also failed to connect.

I decided to check the CR2032 batteries in the shifters. Turns out these we down to under 3 Volts, given they were 18 months old this was not unexpected, something I should have considered sooner. So I replaced both of them, but I still could not shift, or manage the groupset in the app.

The Solution

In the end, what I needed to do was to first re-add add the groupset in the L-Twoo app (deleting the old registration).

I then had to follow the process to re-pair the shifters with the derailleurs.

Once this was all done, everything was working as expected. I could shift and manage the whole system.

I am not 100% sure why I had to do all this, but it seems that (effectively) flat shifter batteries must cause all pairing information to be lost. Hence, requiring re-scans and re-pairing.

The moral of the story is to do some preventative maintenance on the shifter batteries