This guide is to show you how to complete a front gear repair with a twig when your gear cable snaps.
Your front gear cable could fail for any reason and the mechanism will shift the chain to the smallest chainring. This annoying problem won’t end your ride. It will slow you to a snails pace. You can resolve it temporarily by manually moving the chain onto your desired ring. Once the chain is in position you should poke a bit of twig, pencil, pebble etc into the back of the front gear mechanism to stop it returning. This will make it stay in position until you get home. You will not be able to shift gears until the job is resolved properly but this trail side solution will not cause any long term problems.
The worst this quick fix may cause could be a snapped chain. If the bodge fails unexpectedly whilst you’re half way through a pedal stroke the chain could jam. This scenario is so unlikely that the front gear repair with a twig should always be strongly considered.