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

For the original version of this post see Richard Fennell's personal blog at Why has my L-Twoo GRX Shifters stopped working and how do I fix them?