How I can know the efficiency of a pulley system

Hello to all!!,  I’m wondering what’s the overall efficiency of a pulley systems to make a reduction of the motor’s RPM of a shredder machine if I have as reference a motor of 1500 W with 3490 RPM and a pulley system of 49 : 1, that allows having 71 RPM in the shaft. The pulley system has two two-inch and two 14-inch pulleys.

I read in some places that the overall efficiency of a gearbox is 90 %, Is that value valid for the system I mentioned to you?

Searching “efficiency of pulley drive”
Lots of good info and design guides out there such as
So it depends on your design. Handbooks provide the minimum pulley size and separation to avoid slippage.

Thanks for the resource!! 🙂