Di2? On my last ride the Front Derailleur stopped working for about 20 minutes, then started working for an hour, then stopped working for 10 minutes, and has worked fine ever since. I can't see that this is a cable issue, unless it is an internal break. I'm putting it down to the evil Garmin Gods. The 810 persistently told me the Di2 battery was low, and when the front derailleur 'came back' the Garmin shifted into an adjustment mode I didn't know it had ...
Good point. Top tips for Di2 users:
- make sure the system is all charged before the start
- (If you have the D-fly ANT+ accessory, make sure it has up to date firmware to fix an evil battery draining bug)
- always carry the system charger with you, not rely on it being in a drop bag
- in cold weather, the battery voltage will drop faster (which does indeed cause the FD to stop working first)
All 4 points were learnt from a single character-building experience on the Colorado High Country 1200km. We survived, but 200km on a tandem with strictly rationed rear-only gear shifts in sub-zero conditions on high-altitude climbs in the dark was not our finest hour.