d'brake with external rotor?

Would it be possible to make this mod? Would it be any good?
I have a steel frame, one of those with the cheap stamped bearing holders, and it has nothing wrong to me, except the absence of any brake tabs.
I’m wondering if something could be done without changing frame.
I already have spirit dual hole cranks, and i don’t like the idea of a dished hub/spokes.
I don’t have the gift of welding, so it would be nice.

yep, d’brake and external disk work fine. Just make sure you stock up on washers to space the disc away from the crank and the calliper towards the rotor.

People have done d’brake with pressed housing. I would assume its ok as long as the bearings are 42mm (isis bearings basically) and not two small bearings and a shim.

Is what I have on mine, though with Oracle frame. Works fine. No spacers between disc and crank, but a fair amount between d-brake and caliper (it’s an IS rotor, so spacers are the only way to align it).

Ok, thanks a lot… what about the cracked d’brakes some people had?
Has this problem fixed or it’s still the same design?
Is there a different adaptor to choose over the dbrake?
Can i buy any caliper?
Too many questions? :o

Not sure about the cracked d-brakes. I have 2 and have not had an issue, even on the one I had to file down (knock wood).

There are also the Mountain Uni UCM adapters. They were the original.

You can use most hydraulic calipers I believe, but the only mechanical one that works is the TRP Spyre which is my favorite brake. You will however have to shim the rotor a bit.

Hope this helps.

It will work fine!!! I ride the same setup with steel frame and pressed sheet metal bearing holders. Never had any issue.

You just need a little adaptor piece or some filed shims.

See his thread where we discussed this issue. You need a planar contact face so that the brake force can go into the frame and not destroy the bearing. And this will also prevent you d’brake from cracking early.

See also my build with the adaptor (bad translation via google). I can also provide technical drawings and CAD data for the adaptor in nearly every CAD exchange file formate.

If you want it simpler, refer to Hugo’s build, he used shims instead of the adaptor and it works fine. (bad translation via google )

Eric also posted a reinforcement bar to avoid vibrations, common with D-brakes apparently.


d’Brake is quite weak solution. It is better to weld IS brake mount onto steel frame.

Surly Conundrum with welded IS mount: http://unicycles.ru/viewtopic.php?f=7&t=4880&p=32539#p32539 (will be painted soon), there was d’Brake and it has been broken :slight_smile:

Guy says he does not have the gift of welding, and is told to weld it. Wow.

Lots of people use dbrakes without issue. They are designed to be a weak link so you don’t mess up your frame. Carry a spare.

works great!

Yeah, works great. I’ve had the dBrake on my old steel frame Koxx 24" for almost a year and it works great. As Eric describes, I did mine like Hugo’s Build using washers: Euer setup

I was scared that I was going to squish the bearings and thinking I might have to replace them, but I’ve had the unicycle apart twice and everything looked great! So totally satisfied!

You need to set the washers just right so that the screws on the side where the disc are can be tighten down tight without crushing the bearings, as in Hugo’s photo:

I also have the dBrake on my Oracle 36 and it works great to. While I guess it is possible to bend the dBrake, it seems pretty strong to me, as I’ve done some really big downhills and drops on the 24" as well as light Muni on the 36 (ok, I only weigh in at 160lbs).

Good, thanks to all!
I’m going to look for all the parts then.
Maybe i will just start using the dbrake until i find someone to do the welding for me.
Do you think Avid juicy 5 can be fine? I found a cheap second hand set, but it has 200mm rotor.
What rotor size is used the most?

Juicy should be fine. Basic but that’s all you need. I’ve got a 160mm on my 24" and my 36er came with 180mm. I would say these sizes are good enough unless you’re doing long downhills or are very heavy. Larger rotors give more braking power and also dissipate heat better so they don’t fade or overheat as easily. I think 200mm sounds a little big for a 24 (also increased chance of bending it), but for 29+ sounds great. But then I haven’t been riding disc so long (on my various bikes for years), so maybe others have different perspectives. If you do decide to downgrade, on ebay you should probably be able to sell the 200 rotor and adaptor for more than what a smaller rotor/adapter costs.

With 200 mm rotor you will probably bend b’brake.

Welding can be done in local machine shop.

Rotor size doesn’t really make any difference to forces through it. You won’t be braking any harder, so the braking forces transmitted will be the same - just that the force on the disk itself will be lower due to the longer lever arm.

It is not the forces, it is where they are applied. The IS adaptor for the 200mm moves the position of the calliper. So the forces are applied in a different place… and less good.


200mm is way too big for just about anything IMO. I run a 180 on my 36er Muni and could easily get away with a 160.

I ride G36 with 200 mm rotor, it works much better (smoother) than 160 mm one.