hate to say it but inboard means inside the frame attached to the hub , outboard means outside the frame attached to the cranks
Yeah, inboard, like the Oregon, but for a frame that is not currently designed for a disc brake, which means a 100mm bearing spacing, which means a disc hub that is not “yet” available 
Think Spring.
So UDC says it allows you to use a disc brake on any muni. But you would also need a disc brake hub, too, right? I couldn’t install a disc brake with this mount on a regular isis hub, can I?
nope, you can use your old hub with a d’brake. Although not specified it works just as well with outboard brakes as inboard. All you need is a pair of spirit cranks, the disc calliper and some washers.
However be careful when choosing the calliper as most mechanical brakes are too wide and would hit the crank. There is a thread of what brakes people have used/are using.
Also do not be afraid to spend $10 on a brake line for a mechanical brake. Look at BMX brake lines rather than mountain bike ones.
You’d have to use either KH spirit or Sinz cranks, then you could use your old hub. In fact, since sinz cranks can be purchased in either ISIS or square taper it doesn’t even have to be ISIS if you can get a brake mount that will work with the larger square taper bearings. (There may be others but those are the main ones)
With some washers or adpaters or at least some grinding or rasping ist will probably work at any unicycle. Just make sure, that it has a planar contact surface to the frames bearing housing so that the brake force is lead into the frame and not into the bearing. With bearing housings that are not machined (sheetmetal) you’ll need an adapter to provide this planar face for force transmission. I just made one for my Muni, look here at the german forum for my project with d’Brake and adapter. But also some modified washers will make fine like shown here.
Just installed a nimbus dbrake on oracle frame with KH spirit cranks and external rotor. I used Tektro Augira SUB caliper and I had to place 2 small washers between the dbrake mount, and the caliper mount. Works great!
Eric aus Chemnitz brings up a good point. The MU UCM has a flat top compared to the D’brake’s staggered surfaces. Where the D’brake is tightened on the side with the arm first then snugged up on the other side the UCM would be installed like a normal bearing holder.
I still use both UCM and D’brake with both styles of outboard disk (KH and MU). I now use a washer under the arm side of the UCM to transfer the force to the frame like the D’brake does and both need to be shimmed out to work with the KH cranks as the Spirit cranks place the disk a bit further from the frame than bike cranks with a MU disk would.
I had brought up the spacing issue with Roger when touring in Uzbekistan and he said that the KH cranks with a 6mm spacer puts the disk about 1.5mm further over than the bike standard. Presumably this was done for clearance reasons at the bearing holders.
I did not know, that the UCM does not provide this staggered shape. So thats plus for the d’Brake. It’ll make no sense to tighten the bearing holder with a defined torque for not deforming and so damaging the bearing and on the other side let the whole brake force go radial right into the bearing just to deform it to egg shape.
I wonder if riders with the UCM therefore do have damaged bearings a bit more often. Did anyone have issues with that?
Before I got the D’brake I used the UCM without a spacer, it was like that for at least half a year and I had no issues. These adaptors really should have a firm surface to push on though.
EDIT: I just clicked on your links, nice job. I especially liked the adaptor, did you make it yourself?
It looks much more elegant than just a flat chunk of steel with a hole in it (what I would have done)
Yes, I designed it myself after measuring the bearing housing and the d’Brake and hat it produced by a friend. The major purpose was to guide the sheetmetal bearing housing of the frame to prevent it from bending when tightening the screw. It fits the sheetmetal bearing housing of the QU-AX, if other unis have the same, then it fits them too. I can provide CAD data or manufacturing drawing if needed.
I have a 24" Impact frame with a 24" KH wheel set. Have yet to put anything together. Desire to have internal disc brake. Any idea’s if d-brake will work? I know the KH disc brakes are mounted externally, why? If d-brake would work, what would be best brake?
Thanx
If you want a internal disk you would need to get a new hub and completely rebuild your wheel, as well as a disk break adaptor and break. If you decide to go external you just need some new cranks with the brake and adaptor, and as a bonus you get strong light dual hole cranks.
Very nice. What type of shop could produce it? What type of material would be suitable? I would like to have the information to have one made. Could you pm the info?
Thanks!
I had it produced via SLM (Selective Laser Melting … 3D printing with metal) out of steel (don’t know which alloy). I think any sort of normal steel would just be fine (e.g. S235JR) or even aluminium. It must only take compressive forces, not more. It can be produced by any manufacturer that has a small cnc milling machine out of 6mm flat steel.
I PM you the CAD data and drawing. I did this construction for a Qu-Ax steel frame. I’m not 100% sure if it fits any other steel frame. Just plot the drawing 1:1 on paper and check if the groove will fit your frame.
Please post a photo when you have it produced.
So here it is: we now have the first broken frame caused by the UCM Caliper:
http://unicyclist.com/forums/showthread.php?p=1662619#post1662619
I think this belongs to this thread but was not mentioned here yet:
To avoid broken d’Brakes, Hugo from the german part of the forum designed a strut to support it. We call it “Hugo Strut”. Many riders have installed one to their d’Brake yet. It also helps against vibration noise
This is how it looks like:
I’d like to figure out something like that for my Oracle frame, which doesn’t have the magura mount to use as an attachment point for the strut. The stock brake worked fine, but I had to replace it after a crash, and I’ve had a terrible time trying to make the new brake stop shuddering.
I’ve tried things like cleaning, sanding, replacing pads, replacing rotor, no help. I finally stopped it by forcing a little bit of toe-in on the pads, but I don’t like the solution, so I’d love to find something better. Has anybody tried something similar to this, but just clamping it to the frame leg somehow?
Yes. A strip of flat steel, a m6 bolt and nut, and some aluminum tube (I believe I used 9mm diameter) will do the trick nicely.
Bend the steel around the frame leg, drill 2 holes through it. Hammer one side of the tube, drill a hole large enough for the bolt on the brake mount to pass through. Shorten to desired length drill another hole through the tube for the frame clamps screw to go through. I used a different pickup on the D brake than the one Eric posted (the one where the post mount adapter is bolted to the bearing holder) I can dig out pictures if you want.
It really helps a lot, much less vibration under braking now.