I have a Bakfiets with a roller brake system from Shimano (BR-C6000-F-DX).
The Front started making squeaking noises in the winter, so I bought the special Shimano Braking Lube, opened the brake, cleaned it and filled it up with lube. But it did still squeak.
So I bought a brand new BR-C6000-F-DX brake (front), put it on the bike - but it still squeaks.
Whenever I brake it makes the noise of metal rubbing against metal, getting louder and squeakier the harder I brake.
The back break only squeks occasionally and a lot less noisy.
I tried adjusting the brake tension from low to high, made sure it is tightly screwed on, but nothing helped.