roller brakes (ergh)

my bakfiets cargo bike has roller brakes front and rear. When they were new they worked passably, but the front now is completely gone – good enough resistance to the lever, the arm is moving fine on the hub, but there is almost zero retardation – I can easily pedal along with the thing fully on, which when you’ve got a 50kg bike with 40kg of kids onboard is a bit scary. The rear brake is alright (won’t lock up but slows me down ok)

I rebuilt the brake in the summer with fresh grease, but it didn’t help much. Given the braking surface is pretty un-destroyable I wonder if I’ve killed the ‘power modulator’ – but I don’t know where it actually is. I don’t want to buy a new brake, fit it and find the modulator is in the hub, so thought I’d ask around and see if anyone knows how to test it.

Incidentally, there’s a new, more powerful c-6060 brake coming out at some point, which might be an upgrade, but I can’t find any sellers.. https://bike.shimano.com/en-EU/product/component/nexus-c6000-int8/BR-C6050-F.html

They are a type of cam operated drum brake.

There are no parts of the brake in the wheel hub.

I THINK the power modulator is the cam – which is the component at the centre of this image. It rotates to push the rollers and thus push the brake shoes in to contact with the drum.

If the cam is worn then the force you can apply to the rollers, and therefore to the drumbrake shoes, would be reduced and may give the symptoms you describe. If that is the case then a new brake would resolve the problem.

Useful information here; Sheldon Brown page

Urban Arrow?

Im amazed they specced them, the Shimano documentation states they are only for use on a combined bike/rider weight of 100kg. (iirc)
they are totally unfit for purpose.

I bought a disk brake mount and had a local fabricator weld it onto the fork, built a new wheel and put a proper brake on the front end.
The only thing i would say is the “light” front end of an empty bakfiets makes it very easy to lock up the front wheel and slide, which is scary!

Probably just needs new brake shoes. I presume it’s 100kg per brake. Never had a problem with the ones I had on a Dutch bike. Only me and shopping on it though.

its a gazelle – i’m also amazed they specced them, and given all the nice other bits they put on the bike they didn’t weld a front disk mount onto the fork so people could upgrade later. I guess it is flat in holand 🙂

I found this page https://bike.shimano.com/en-EU/technologies/component/details/power-modulator.html which suggests there is some sort of clutch on top of the cam setup. I guess if its in the hub then the finned thingy would stop spinning whilst the wheel continues which doesn’t happen, so either way its pointing to the brake.

anyone got reccomendations for tandem-length brake cable (may as well do them at the same time)?

You can just replace the roller brake bit.

Remove the wheel, swap the brake bit (I recall it being a tool-free job apart from unbolting the cable), rebolt the cable, refit the wheel and ride away.

Something like this:
https://www.sjscycles.co.uk/brakes/shimano-nexus-brc6000rdx-rear-roller-brake-with-38-x-72mm-washer/

Oops – that’s rear but I bet it will work on the front too 😉

As other/s say it could depending on your load and usage be unfit for purpose.

I used mine beyond their limit (living in very hilly country, coasting on them, 200kg all-in, etc, and the front has seemingly been killed by my hangable-offence-levels of neglect (got some grease in there only once in about 8 years 😬)

I like them, though. Enough to treat with grease and a little more sympathy next time around. I’ve seen some with cooling fins…

As mentioned check out Sheldon’s pages before making new plans This bloke is really useful too, for all things cargo:

Not “No Maintenance”, But “Low Maintenance”! Roller Brakes, An Idiots Guide!

thanks for the tips, I’ve bought a new front brake and new cables for it. I’ve no idea why its so weak – if the grease was blown it’d surely have more friction, not less.

Our setup is probably ~170kg and I have taken it down ditchling beacon (after getting up there, very very slowly), so I haven’t been kind to it either. Maybe its just too much

any idea what the DX version does differently? it says for larger wheels, so I guess it offers more power than the small wheel version..?