Rollers carry the door through the channel track. Nylon runs quieter than steel and will not rust, which is why we fit it as standard rather than as an upgrade.
Signs it needs replacing
A grinding or squealing noise as the door moves
Flat spots or chips on the wheel
The door catching in the track
Fitting notes
Replaced as a full set. Mixing worn and new rollers puts the load onto the new ones and they go early.