Bearing Adapters 40mm / 42mm question

I want to get a 26’’ oracle frame and eventually a custom wheel set with disc brakes. Unfortunately, I don’t have the money for this project, so I have to work at it in increments. I have a Torker Lx 26’’ with all upgraded parts except for the rim and hub (40mm). I want the oracle (42mm) because it is lighter, can take brakes, and has a round crown. No more knee bruises.

Has anyone used the UDC bearing adapters 40mm/42mm? Could I use these on the oracle frame in order to accommodate my current wheel set?

I emailed UDC but they unfortunately did not answer the question.

Thanks for your help.


For my 700c road uni with an eBay square taper hub in a frame made for 42mm bearings, I just cut four of them from a scrap piece of ~20 ga steel, saved from the case of a vcr I threw out, I think. Cut out and trimmed to fit with a pair of aircraft snips, rolled into approximate shape with my fingers. (Sharp edges though!)

Sure, you can use them, or you could just make your own shims like LargeEddie suggested. I have a pair of the UDC ones, but they aren’t anything super special.

The Oracle isn’t built to take a brake, really; they just include the dbrake adapter that lets you put a disc brake on any frame. I wish it had proper disc brake mounts. And it doesn’t have have any rim brake mounts at all.

Aren’t these the brake mounts?

Well for now, I plan to get the nimbus aluminum bottom brackets and save the d’brake bracket for the day I decide to do the wheel build.

Thanks for your help!

Nope those aren’t brake mounts. They are guides for the brake line.

As for the UDC shims, they work great. They are nothing special. You can make them easily. I made a set from a galvanized stitch plate that I got from the hardware store. Pretty much any sheet metal that’s 1mm thick can be used.

Those are guides for the disc brake’s hydraulic line (which are nice to have).

(ha ha, ninja’d by 60 seconds!)

This is the biggest reason that I dislike the oracle frame. Why on earth did UDC go to all of the trouble to make a disc brake unicycle and then not put disc brake tabs on the frame? Until the oracle frame has a proper disc tab on it IMO Kris Holm frames are better.

So if there are no disc brake tabs, how do you install the brakes? Do you need to buy more components?

The D-Brake adapter is a bearing cap that has caliper mounts on it. It is a universal part that allows you to put a disc brake on any frame, well, any Nimbus frame (and probably others). So, it’s not actually a part “of” the Oracle.

The oracle frame comes with the d brake mount so you don’t need to buy it separately. The d brake mount works on KH as well as oracle frames and probably quite a lot more frames.

Hi, I am using these adapters on my 36". I bought a UDC trainer 36 (40mm) and a Nightrider (42mm) frame. I was intending to upgrade the hub when funds allow but the present set up works fine for the type of riding I do. I don’t know about the Oracle frame but I’m sure it would be OK. The adapters are cheap enough…I wouldn’t do a bodge.

Have fun,

UDC had frames with a disc tab for a while. They had issues with tolerances and quality control though and I believe Ben had one, but Josh had to dig through a crate of frames to find one that was straight enough, and even then Ben still had to use shims (I believe).

My experience with the D-brake is limited, since I just barely got one. However, if you bend or break the tab on your frame, you’ll either need a new frame, or end up getting a D-brake anyway. If you bend or break a D-brake, you just need to get another D-brake (I ordered a spare). They’re not that expensive anyways.

The only thing I don’t like about the D-brake so far, is the wonky way you have to tighten it up to work properly, and that’s really not a big deal.

Ta-da! Not sure if they ever had the tab on Oracles, but they did on the early Oregon frames.

There’s a disc tab on my 36er with an impulse frame (the impulse frame is just like the nightrider but with a disc tab). This makes me hope that I don’t have serious problems with it when I get a brake.

You should be fine, you just might have to use some washers to shim your brake adapter.

I sure hope so, I was expecting to need to use washers.