Nimbus (disc brake) Oracle MUni

Why not? :smiley:

I believe we both wanted to build a lightweight MUni, I come from riding a ridiculously light Single Speed MTB (it was only 1.5 kg heavier than my KH26 and about the same as my KH24) so was keen to apply some weight weenism to my MUni

The light rim (which I don’t think is too narrow) is pretty strong and light and for XC and light MUni rides fantastically and spins up effortlessly so is a dream on the climbs. As I said in the Project thread the Rim Tyre ratio is almost the same as my 3" Duro on a Nimbus MUni rim on my kh24 (same as old KH I believe) and nobody stresses that that is a horrible combination?

I am very new to Uni riding but have two decades in MTB and come from an Engineering background and am a whore for new parts and tech so am not walking into this totally blind. To me the advantage of a light wheel is going to outweigh any stability issues which I am not a good enough rider to notice. I understand the nature of how we ride a single wheel effects a tyre differently to a bike and that ideally a wide rim is better but for me and my skill and type of riding the weight factor is more important.

So far this MUni is everything I could possibly want which is all that matters

At the end of the day it would be boring if we all ran the same setups:)

Yeah, but skinny rims look queer :stuck_out_tongue:

I almost went skinnier, but the KH rims just look so macho, and when I ride a unicycle i just need that little bit of extra ego boost, know what I mean :roll_eyes:

The only advantage of a wider rim is in maximizing tire volume, but it’s not that significant and if I had a second wheel for my 29er I might built up a skinny and run a narrower tire like 2.0

You should try running a Large Marge and a Duro 3", that Unigeezers 24" set up, I tried it on a 26"and it was a big ride and a nice flat profile, so super stable.

By that rationale just call me Seabiscuit :stuck_out_tongue:

I almost did get a LM on Oracle hub for my KH24 (although with the spoke holes so widely staggered from the center of the rim and the narrow Oracle disk side flange spacing the dish must almost be massive on that combination) but as the cost was almost the same as building a second KH26 which I thought would be better for my type of riding and was interested to see how it would turn out.

A LM setup does look monstrously cool though

With a wider rim you get a wider tire. This ultimately means that the agility of the unicycle will not be as high. The more muni I ride the more I like to be able to turn on a dime. This allows me to be able to ride super steep trails with lots of turns and technical terrain. Also you can find a lot stronger and lighter rims, unicycle rims seem to gone to shit with how strong they are. You constantly have to baby them so they can stay true. Nothing is wrong with higher pressure I say, you get less tire fold and its easy to roll and go fast. I find that speed is a lot better for getting over things than anything else.

So, when removing/installing the wheel, is there anything special you need to do with the disc brake? Like move or adjust?

nothing, disc is on the hub and D-brake is fixed on the bearing which is on the hub

so, put taking the wheel on and off is just like a uni without a d-break?

Yes, almost same; D-Brake needs some small caution while tightening.

As it’s planned for different frames (Nimbus, KH, QX, …), holes for bolts are oval, so needs first to find the right position by approaching the bolds and then needs to tighten first the bold on caliper fixations side; but this is not a big issue. I use blue Loctite glue to secure bolts tightening

I think I may have missed an important detail somewhere along the way.

One thing confused me a bit about the Oracle (and other disc break related threads). It almost sounded as if the day had finally arrived where people could get disc breaks for their unis. Couldn’t help but think… but the Impulse already has a disc break.

So is the Oracle a first in the sense that disc breaks are now available on smaller wheels or first in the sense that the break is much improved over the model featured on the Impulse?

Maybe I misread the whole thing and the anticipation was over the arrival of new stock and not necessarily due to the arrival of something totally new - with respect to breaks. I recognize that the Oracle with the new frame et al is something totally new.

Just trying to see if I missed a detail where a newer, better model of disc break has become available.

This is the first standard 100mm disc hub width the Oregon and Impulse were non standard 125mm so not retrofit-able to peoples existing frame.

I got mine the month the Hub was released and it is awesome :slight_smile:

Ah. Thanks for the info.

Having owned an Impulse (swapped to a geared 36er) I knew the disc brake was for me so I waited until the Oracle was released (almost bit on the Oregon, glad I didn’t) before I got into MUni. Then again, I buy whole kits and don’t customize much. Because, as Fiesty said, the real BIG deal was the release of the Oracle hub which could be retrofitted on other mountain unicycles.

Yeah, the retrofit is the big deal, though now KH has an external disc hub crank set that is really the true retrofit because you don’t need to change hubs; yes, MountainUni was first.

Disc brakes are good, I have four set ups, two on the 125 mm Oregon Hub and two on the 100 mm Oracle hub.

Kris added some very insightful comments on this thread: Announcing the new KH gear for June 2012

Note that he suggests getting a more powerful brake vs getting a bigger rotor.

Also, he suggests that Maguras would be a better choice for unis that get thrown down a lot in super tech DH scenarios. This comment gives me mixed feelings as I have broken a Magura hydraulic slave fitting from a rock hit and two levers from rock hits, so lever wise it’s a push in terms of durability, and it seems to me that having a brake exposed on two sides is more risky than having one exposed on one side…

One comment that I’d make is that having crank mounted disc brake is not only easier to retrofit, it is also easier to remove/adjust, and you will have a stronger wheel. Not that I have had any wheel failures with the Oracle hubs, but the disc brake side spokes are very steep.

Re my comment, above, about vulnerability of the brakes. Yes there are pros/cons to each. There’s no difference in vulnerability of the lever between disk or rim brakes, and the caliper is probably in a less vulnerable position with a disk brake, tucked behind the crank and with no brakeline over the tire. It’s just that with trials riding if you jump up a sloping rock surface and slip (a common enough scenario), you’re uni usually instantly goes sideways (along with yourself) and grinds its way down the sloping rock surface. Not a good situation for a disk rotor if it’s on the side facing the rock.
And with super tech DH - I can imagine a rotor getting dinged if you chuck your uni into a rock garden, but I should admit it has never happened to me so far (damage to rotor).

Unlike maggies, which have an adjustment to bring the pads closer to the rim to compensate for wear, I can find no such adjustment for the Oracle’s [bengal] disc brake. Only adjustment I could find is a small screw in the lever but that only changes the lever’s up/down position. It doesn’t move the pads closer to the disc. If there is such an adjustment, please let me know. Thanks!


The Bengal is a basic disc brake, most disc brakes are designed to have a small tolerance and thin pads that wear slowly, so no adjustment is needed like on a magura. There are some high end brakes that have a measure of pad adjustment, but in my experience it is not necessary.

If you have rubbing, look first to see if the rubbing is in specific places on the rotor, in which case you may just have a rotor that is slightly out of true. They pads will often rub momentarilly after going through water or snow as they shed the moisture and any grit they pick up.

You can move the position of the brake mount holder to the left or right very slightly. I did this with disc brake i have. there is still a slight amount of rub but nothing that is bad, (at least I do not think its bad).

Loving disc brakes sooo much! Its like you can actually use them and still be in control.

Oracle 26 Review

Christmas came early for me this year, and I’m excited to offer some first impressions of my new Nimbus 26" Oracle!

First, a bit of background…I started riding in 1998 and was very active for about four years, and then drifted back into road cycling for several years, and then came back into unicycling this summer. In the past my focus has been on building my skills and some distance riding. This year marks the first real experiences that I have had riding muni, and I’ve really been having such a great time. It’s the best! I’ve been riding a 24" Torker LX with the largest tire I could put on it (1.95) and it functioned fairly well, but I really wanted to get a full fledged muni and I figured while I was at it, I might as well get one with a disc brake.

I debated back and forth between the Oracle and a KH with the crank-mount set-up. I decided on the Oracle because I think the hub mounted disc makes more sense (and just looks better) and because the Oracle is a better value than the KH - with comparable quality. When the Oracle went on sale at UDC at $100 off, I decided to get one now instead of waiting until next spring like I had planned.

First impressions: This is the first “new” unicycle I have purchased since the 700c Semcycle that I bought around 10 years ago. Wow - unicycles sure have changed A LOT since then. The quality of the equipment is amazing! The first thing I saw when I opened the shipping carton was the KH saddle and black graduated Nimbus seat post. Those items alone looked 10X better than the equipment I’m used to. As for the rest of the unicycle, I wasn’t sure if I was going to like the red rim of the 26" Oracle, but after I had it out of the box and saw it first hand I was totally happy with the appearance, quality, and design of the wheel and frame. Everything is just beautiful. The only thing that I would want to be different is the color of the brake, being white, but it’s not really an issue. The design, decals, color scheme, and quality of the components are all very nicely done and I love it. Oh, the other first impression: this unicycle is much heavier than I expected. That Duro Leopard tire is MASSIVE. I’m definitely going to be putting on something lighter next season.

Assembly: I’m no stranger to working on bicycles and unicycles, so that was no problem at all…install the seat, the pedals, and the brake lever. The instructions are generic and do not refer to setting up the braking system of the Oracle, so that might be an issue for someone that has little experience. For example, I was careful to position the brake lever so that it wouldn’t protrude beyond the seat handle and get struck on a drop. I also adjusted the angle of the lever to bring it closer to the seat. Then I noticed that the disk brake was rubbing a bit in one area as I spun the wheel so I did some research and learned how to adjust it. I checked the torque on the cranks and they were fine. None of this was difficult and I actually enjoyed setting it all up but for someone inexperienced it might be more of an issue.

Riding: I brought it to work today and had a short ride at lunch time on a local trail. I was really curious to see how it would feel to ride on that humongous tire and use the brake. I had no problems mounting - I’m used to a 24 but a 26 is so close in size - but once I took off I really noticed a difference in the pedaling effort due to the weight of the wheel. It was a good workout, that’s for sure…I’m glad that I stuck with the 165 crank length! On the other hand, the weight of the wheel provides really nice momentum and I was able to roll over some roots really easily, although this trail doesn’t have many challenging obstacles on it. (that will come tomorrow). I’m sure that I will get used to the weight and pedaling effort, I think my seat may be a bit too low as well. The Duro tire had a bit of pull on tilted areas of the trail but not too bad, and I adjusted to it quickly. Hopping on that big tire was fun!

Disc Brake: The trail has a nice long sharp descent that I was eager to test the brake on. I fully expected to have a UPD the first time that I used the brake so I practiced with it several times to get a feel for the modulation while I was off the uni and pushing it around, and a little bit when I was riding on the flat. I found it easy to carefully apply just a little bit of brake and it seemed very smooth. No UPD! Then I came to the hill and really had my first experience using it, and it was completely natural and smooth. No problems at all! The brake is going to be very handy on some steep trail sections that I ride on and I’m eager to try it on some sections that I’ve never been able to ride down.

So that’s my little review, coming from a fairly experienced uni rider, but as someone pretty new to muni and very new to the modern equipment that we have now. I’m completely happy with the Oracle and I’m looking forward to my next ride!

Don’t dismiss that 3" Duro too quickly. I replaced mine with the Maxxis HighRoller that Kris puts on his new KH26. It did save some weight but my 26" Oracle is still quite a bit heavier than my new KH29. And, since my KH29 (47mm drilled rim) came stock with a Maxxis Ardent 29 x 2.4" tire, I am seriously considering switching my Oracle back to the 3" Duro to differentiate the two rides a little more. I will admit, when I was customizing my Oracle, I was thinking it would be my only MUni so I wanted it to be great for XC as well. But, now that I have my KH29, I want my Oracle set up for tech DH and the Duro is really a very nice tire.

Get a pair of red Deity Compound pedals and one of those new Nimbus Double QR clamps. All I’m missing now is an adjustable seat post and my Oracle will be totally pimped out. Now I just need to pop a spoke on my KH29 so I’ll ride it more.

Ditto on the disc brake learning curve. Of course, I knew that when I got my Impulse (sold) 36er. I’ve gone back to Magura rim brakes on my 36er due to incompatibility with the Schlumpf hub.

I’ve ordered a Hans Dampf but I’m going to keep the Duro on until Spring to give it a fair trial (and build up my legs!).

I was curious what the weight difference between the Oracle and the KH would be if you take the tire and tube out of the equation. If the weight specs on UDC are accurate the Nimbus Dominator 2 rim is just 160 grams heavier than the KH rim. If you add up all the weights of the seat post, frame, rim, hub, and cranks, the Oracle adds up to be only 68 grams heavier than the KH. Of course the disc brake adds a little too.

I took the Oracle on a 4 mile trail ride this morning and had a blast!