The extension for the fourth bike is inserted between the second and third rails of the multi-cargo 2 family. The fourth bike is attached to the third bike using a double frame holder.
If you have a load of 4 bikes, you must use the strain relief strap. The strap is attached to the retaining bar of the bike carrier and then hooked onto your trunk or tailgate.
The extension increases the weight of the carrier by +4.5 kg.
New total weight of multi-Cargo 2 family for 4 bikes: 25 kg.