The MTB clutch tightens the chain when riding on bumpy trails.
The clutch acts as a tensioning device that will tighten up the chain. This significantly reduces the chance of the chain falling off the chainring when riding rougher terrain. It also reduces the chain slap on the frame, causing less noise and damage to the paint. However, the clutch can be turned off with a switch to make it easier to change gear if the child struggles with shifting.