The Nimbus Oracle has set a standard for disc brake equipped unicycles. From its simple yet strong aluminum frame, to its time tested disc hub. It will allow you to escape deep into the woods from smooth to rough terrain.
Saddle: Nimbus (black/blue) with front lift handle and brake mount
Seat post: 25.4mm x 300mm aluminum, welded rectangular mounting bracket, 4 hole
Seat post clamp: Nimbus (blue) double-quick release, aluminum, 31.8mm
Frame: Nimbus Oracle 29" (black) 6000 series aluminum with 42mm machined maincap bearing housings, with D-brake mount
Hub/axle: Nimbus Disc ISIS all steel (black) 36H, hardened CrMo splindle,100 mm center bearing to center bearing
Spokes: 14G. stainless black (Disc side 282mm 3x, Non-disc side 284mm 3x) with silver nipples
Rim: Nimbus Dominator 2, 29" (blue) 36H, 42mm wide, aluminum doublewall, reinforced eyelets, ERD - 492mm
Rim strip: Rubber
Tube size: 700c x 52/47 (29" x 2.3")
Tire: Maxxis Ardent 29" x 2.4"
Crank arms: Nimbus Venture2 (black) 150mm, ISIS splined, aluminum
Pedals: Nimbus Venture black, reinforced plastic body with steel removable pins, backing plate for added durability and CrMo axle with 9/16 threads
Bearings: 22mm x 42mm
Brake: Tektro Auriga SUB, 180mm rotor, mineral oil, white
Approx. cycle weight: 14lbs with brake
Oracle 29 - a muni you really can't live without
Posted by Matt H. on Apr 30th 2015
I was excited to try the Nimbus Oracle 29. I have ridden a few other 29 inch models but never this one. The Oracle 29 completes my collection of unicycles - having at least one of each size - 20, 24, 26, 29, and 36 inch.
The Oracle 29, much like the Oracle 24 I have, looks very nice right out of the box.
The Dominator 2 42mm wide rim has earned a reputation for being strong, and has a nice ride characteristic. Coupled with this Maxxis 2.4 inch tire, there was no noticeable tire roll. It is worth noting that the wheel feels decently rigid, even with the internal disc hub on this fairly large wheel size.
I love the double seat clamp that comes with the Oracle line - it holds tight but can be adjusted without a tool. Brake assembly attaches cable to frame nicely.
I tried a 6 mile ride with 2 different setups on the Oracle 29. One setup used 125mm KH Spirit cranks, and the stock Nimbus saddle. The other setup used 137mm KH Spirit cranks, and the KH Fusion Zero saddle.
The 6 mile ride consisted of about 3 miles off road on dirt sections and gravel sections, and a short patch of flat grass. It also had a section of flat dirt path that had a high density of roots. 3 miles of the ride were mostly flat pavement, with one hill climb that is about 400 feet long with about a 19-20 percent grade. The off road portion had about a quarter mile long descent with gravel that has a slope of about 24 percent. The off road portion also had a foot high drop into a sloped bank of a creek bed. There was some intermittent mud on one of the days from fresh rainfall during the night. I also did a fair amount of hopping up onto and off of curbs on the paved portion.
I rode both setups for a total of about 15 miles before writing this review.
The overall feel of the Oracle 29 is very light. It is very quiet to ride - I did not notice any creaks. The Maxxis 2.4 inch tire says that it can hold 65psi. I do not recommend riding it with that pressure - I did try 60, and although the resistance was nice and low, it made the wheel wiggle a bit on pavement. I am a 220 pound rider, and for the riding I did, I found that 33psi gave the muni a nice aggressive feel both on and off road. You could probably go about 40 psi fairly well too - 33 was slightly low but nice for a wide range of riding conditions.
I also set the stock seat so that it tilted up in the front as much as it would allow. For the Fusion Zero saddle, I used it in the recommended muni configuration.
While figuring out the setup on this muni, it can feel really wrong before you get it dialed. Too much tire pressure and seat too high on this somewhat narrow tire and it can feel very twitchy and the 29 inch wheel size will exaggerate that motion.
However, as I got it all dialed in, it really really felt very right. Basically just fill the pressure up close to max and keep releasing air until it makes you happy, and hopefully you haven’t let out too much to add too much rolling resistance. When it was dialed in right, It felt like how you close your eyes and imagine muni feeling. It has a very smooth momentum with very minimal effort, and turns very smoothly. It is light enough to be responsive. The 2.4 inch tire did not feel like it was going to roll over the rim when I side hopped.
On the 20 degree paved hill climb, both setups climbed extremely well. This is probably my favorite setup for a climb like that. I have done this same hill on 24, 26, and now 29 inch munis, and this was by far the smoothest and most comfortable climb of the 3, which surprised me.
Probably the most noticeable quality of this size and model of muni is that when you find a flat section after doing a climb, and want to keep going but do a relaxed ride, the Oracle 29 does that exceedingly well while keeping the momentum high enough still to even generate enough breeze on you to cool you off. It is probably the most efficient energy-wise at covering ground for all the sizes. Also, with the Zero saddle, I noticed that I did this ride with the least saddle soreness of any unicycle I ride - something about the way this setup spins seems to be very comfortable not only for energy but for saddle soreness.
Descending hills: I found that with the 137mm cranks and the Zero saddle, I was able to do the long 24 percent grade gravel descent with the highest amount of speed of any muni I have, while maintaining very nice control. This gave me a chance to try out the brake. The brake couples nice with either saddle. It simply works great. I put enough pressure on the brake to allow me to avoid using much if any back pedal pressure, which allowed for a very fast controlled ride. With the 29 inch wheel, you can have the lever out farther in front without fear of it hitting ground when you crash, and for this reason I do not feel compelled to use a starfighter lever on this size of muni. NOTE: If you are not used to 29 inch wheel, you really do need a brake if you want to do steeper descents, especially with shorter cranks. You can crawl down hills without brakes on 24 or 26 inch models, but you need to consider a brake for certain hills on a 29, and if you are new to using a brake, make sure you are using larger cranks at first and not depending on the brake technique until it is solid.
This setup is also one of the best I have used for covering flat grass, which is my least favorite riding surface. .
The root section: The Oracle 29 did the root section exceptionally well with both the 125mm cranks and the 137mm cranks. It turns well where I chose to go around a particular root obstacle, but when I went over them, if there was even a moderate amount of momentum, it rolled over the roots very well. This is a strength of the 29 inch wheel - it’s roll-over ability.
The drop section: I was less consistent in rolling the drop on the Oracle 29 with the 125mm cranks, but the 137mm cranks were a more consistent setup for drops. At first my seat was a bit too high for the drops and the roots, so I lowered it until both were more consistent. I continued riding it with that height, and it seemed to work ok for the rest of the ride. The 29 inch size requires a bit more finesse to do drops effectively than other sizes, especially with smaller cranks, but it can do them.
I did try a little bit of riding with 150mm cranks on it and this made doing rolling hops up curbs easier.
If you are looking for a muni that does muddy sections well, I would recommend a fatter tire and/or one of the smaller Oracle models. I have ridden these muddy sections on Oracle 24 and KH26, but on the Oracle 29, after trying out one or 2 sections, I chose to walk the rest of the muddy sections I encountered.
One thing that is important to know about the Oracle 29 is that the frame crown is narrower than some of the smaller wheeled Oracle model muni frames. That means that a 3.0 inch tire will not fit onto and Oracle 29 with a decent amount of clearance for more aggressive riding - like it would on one of the smaller sized models. This caught me by surprise, but the reason for this is that this frame is designed to not let the crown of the frame hit your legs/knees as much, as that is more of an issue on larger wheels where the crown comes higher, where the gap between your legs is narrower. So an Oracle 24 which comes with a 3.0 inch tire has a frame crown that is actually wider than an Oracle 29 frame crown, which comes with a 2.4 inch tire. If this is a serious problem for you and you want a 3.0 inch tire, you need to consider purchasing an Oregon 29+ frame (which is the same frame that is used on the Oregon 26 by the way).
In summary, my preferred setup for the Oracle 29 was to ride the Maxxis tire with with 33psi, 137mm cranks, and Zero saddle. It covers distance very efficiently. It is light, rigid, and responsive for some basic trials use. It excels at smooth climbs up to about 20 percent grade - keeping them smooth and controlled and with a fair amount of momentum. It also does very well on flat grass. You can tweak setup to be more aggressive feeling for muni, or indulge in its capabilities for riding smooth distance rides with shorter cranks and higher seat, and some higher air pressure in the tire. It looks very nice, and has great value for the price.
Amazing Mountain Unicycle
Posted by David on Jan 15th 2015
I am a newbie when it comes to unicycles but I have to say that I am in love with my new Oracle 29"! My wife bought it for me for Christmas 2014 (I was on a borrowed 20" before that). It was a big change from 20 to 29 but I have found I am learning faster and getting better with each ride. It is a bit of money, but when you think of a top of the line mountain bike, it is cheap! I also highly recommend the upgrade parts. The KH Freeride seat is amazingly comfortable and the spirit cranks are going to add some additional flexibility for all the hills around our home.
Thank you to my lovely wife and to Unicycle.com!
Posted by AlanM on Apr 17th 2014
My 3rd unicycle, learned on a 20, then rode a QUAX for a few years, then got this one. Seems a bit pricy at first, but very well built. At first it seemed a bit twitchy, but after a few days of practice it settled down. Rides very smoothly, is fun to ride, and looks really cool. Very glad I got it!