Roller Brake squeeking, even after body replacement

Question

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.

Answer 1

Only a small pool of potential causes remains since you've completely replaced the brake.

One reason bike brakes squeal sometimes is something about the mechanical condition of the system is allowing a grab-and-release feedback loop. A classic example is on a front cantilever brake with a housing stop in the headset area and a long run of bare cable running down to the brake. With a sufficiently flexible fork, it's possible to get very loud squeal. The mechanism here is this:

1. The fork flexes backwards.
2. Cable tension is increased because the input force at the lever remains the same while the distance between the housing stop and the brake has increased.
3. The increase in cable tension increases the application of brake force.
4. The bike slows down that much more.
5. The fork springs forward some amount.
6. Repeat.

Anything being loose or flexible within the structure of a bike brake or the parts it's attached to can hypothetically cause some amount of this. In this case I would look carefully at the adjustment and condition of the hub, since while the length of exposed cable you have is small, looseness or other issues with the hub are one of the few variables left after having replaced the brake. If the bike has other sections of exposed cable along the frame, look carefully for anything that might cause the effective length of that run of cable to change as the bike flexes.

I'm not an expert on Bakfiets steering linkages, but check to make sure everything is adjusted properly with it as well, in case there's some relationship possible where brake forces can move it around in a way that creates a feedback loop. Also make sure both headsets are properly adjusted.