A secondary coating line for producing a secondary-coated optical fibre or bundle of fibres, the line including a feeding apparatus with a feed roll for feeding an optical fibre or bundle of fibres; an extruder for extruding an oversize secondary jacket around the fibre or bundle of fibres; a cooling apparatus for cooling the extruded secondary jacket, the distance between the extruder and the point where the cooling apparatus starts to cool being adjustable; and a winding apparatus for winding the finished secondary-coated fibre or bundle of fibres on a take-up roll. To maintain the high quality of the final product even as the line speed changes, the secondary coating line of the invention further including means for determining the point where the cooling apparatus starts to cool, means for determining the speed of the finished secondary-coated fibre or bundle of fibres, and means for adjusting the point where the cooling apparatus starts to cool in accordance with the speed of the finished secondary-coating fibre or bundle of fibres.