Hello! I am looking at buying a new or used uni. I would like it to be as versatile as possible. I’m leaning towards a 29 muni. The goal would be to have two different wheels so that I can easily swap it out between on and off-road riding. It would be ideal that each wheel have its own dedicated cranks and brake disc to make the swap as quick as possible.
I would like to build the second wheel using a KH Spirit Hub and cranks. Will this wheel/crank/disc combination work on an Oracle frame? Or any other disc compatible frame? Or is this setup specific to KH frames?
Also, if anyone has ideas on what would be a better “all-around” setup I’d love to hear them. I’ve even been thinking about getting an Oracle 32 and building the second wheel as a fat 29er for when I want to go off-road. Any downside to this?
Kris Holm is the only manufacturer using the disk brake on the right (mounted to the crank), so Oracle frames will not work. The only alternative to KH are mad4one frames to mount the disk brake on the right.
29" is a good choice for an on/offroad hybrid, although it seems to me that most people end up with two complete setups rather than swapping out wheels at some point - on and offroad you might also want different seat heights and handlebar setups.
If you want to use a Spirit hub and cranks the disc brake will be on the right hand side of the unicycle. KH frames therefore have the mounting tab welded on the right hand side of the frame.
Oracle frames on the other hand have the brake mounting tab on the left hand side of the frame, so you can’t use that with an outboard brake with Spirit cranks. You could use a Spirit crank with an outboard brake on an Oracle frame if you mounted the brake on the right hand side using a d’Brake adaptor as far as I am aware. You can’t just put the cranks on the opposite sides – the pedals would unscrew unfortunately.
Oracle frames have 100mm bearing spacing on all frames except the 32" and 36" ones which are 125mm. So you wouldn’t be able to use a Sprit hub in an Oracle 32" frame.
Some frames (eg some Mad4One frames) have disc tabs on both sides so you are not restricted to KH frames if you want to use the direct frame mount with an outboard disc.
If you want something that gives you most options for fitting different sized wheels perhaps consider a Nimbus Hatchet frame – you’d need to go with a 125mm hub and inboard disc but you could run that with a wide variety of wheel sizes and tyre widths.
Thanks for the info. I am noticing the caliper mounts now. Maybe it’s best if I just aim for a KH frame to simplify things.
I’m sure as I learn and grow I will want more specialized equipment and end up with plenty of unis lol. However, I’ve only been at it a month or so and I really need to move up from my Sun trainer; the frame tubing is scary thin and the wheel is garbage. I figured that trying to stick to one uni for as long as possible would be more economical. Also, I live in a van so space is limited.
Yes, the same caliper can be used for inboard or outboard disk brakes. The caliper just needs to have the disk to the right of it, which is why inboard disks are on the left side, and KH has it mounted on the right side.
Two wheelsets one frame is a definetely a good plan to save some money. Although I’d personally recommend to start out with a 29" and a relatively mild tire, that would work okay on and offroad. As a Muni beginner you probably won’t push the limit of your tires traction too much (at least if you don’t live somewhere super muddy). Would give you some time to figure out where you enjoy riding and what wheelsizes might work best.
I tend to think you’d get more compatibility options and “swapping wheelset ease” using an inboard disc system rather than outboard. You’d certainly open up all your options in cranks at least by using an inboard disc, and not have to use Spirit cranks.
As a beginner myself I think this is a really good advice. I regularly ride blue (easy) MTB trails and I’m limited by my skills (and courage) not by the traction of my tire. Also using the same tire but with different tire pressure for road and trail could significantly change the ride characteristics and the dual-hole spirit cranks could be used for changing the gearing.
@Rob86 If you want to build two wheels then I would suggest a 27.5" for Muni. Slightly easier to manage, lower to ground and you will dismount more often on a trail if push your limits (which is part of the fun…). And then a 29" wheel for road use. Also note that a high volume 27.5" tire is quite close to 29" road tire in actual diameter so height of the ground will be similar.
For light Muni use I don’t think strength is an issue (but my few days of use proves nothing). But if you start to really abuse your equipment doing jumps and landing with your brake locked then this is likely not for you. But then you will also start to break other parts… all metal parts will wear out at some point no matter what.
Anyway I don’t see a reason for using a d’brake unless you wanna upgrade an old frame. It also looked a bit odd with the d’brake because it moves the caliper away from the frame compared to a welded mount.
I probably would end up going 27.5 for muni. I totally agree with you. What I’m wondering now is how the 32" Oracle frame would do with a 27.5. Maybe I’m crazy but a ride that could go from a 32" road tire to 27.5 dirt tire in a few minutes seems pretty cool. Frame may be too big though?
Just be aware that an Oracle 32" frame has 125mm spacing so you need to build two wheels with 125mm hubs (and inboard brake disc). There are no issues* in having a smaller wheel in a larger frame except that it looks slightly off with the extra space above the tire.
I have a KH36 frame and I could put my 27.5" wheel in there for sure… even my 19" trials would fit.
* as 32" and 36" tires only exists in 2.25" means the frames are designed to be more narrow than the smaller frames. So you may not be able to fit a 27.5x3" tire in a 32" or 36" frame. I just did a rough measurement of the inside of my KH27.5 and KH36 frame and the KH36 has approx 1cm less width than the KH27.5 frame at the top near the crown. Also note that many frames are widest near the crown but will bend inwards to reach the bearings.
(I don’t know if Oracle 32"/36" and Mad4One 36" follows a similar design pattern but I think it’s likely)
I don’t know about the oracle frames, but I’m pretty sure my nightfox frame would have no problem with 3" tire. If he’s tall enough and a 125mm hub isn’t a problem I’d just go with a 36" frame. That way he can put anything other than a fatty on it.
He might also consider the m41 sonic bang. That’s got 100mm spacing and dual brake tabs.
Absolutely – unless there was some other feature of the Oracle frame you really wanted (like the rounded crown) and you really wanted the Spirit cranks and outboard disc. The d’Brake now comes with a bracket to stop vibration/juddering when you brake but unless you have a compelling reason to go that way, and are buying a new frame, get one with a tab of the correct side for whatever brake system you choose.
Anyway, here is a link to a reasonably close up photo of the outboard brake on my KH26 with a Hope brake and 200mm floating rotor. I’ve also got a Hope E4 brake on my Hatchet (inboard) with a Hope 200mm floating rotor so you can hopefully get away with any brake you want regardless of if you choose an inboard or outboard brake.
I’m 6ft with long legs so height shouldn’t be an issue. You really have me thinking about the 36er now. For what I plan to do with it, I don’t see a downside.
