I’m wanting to assemble a 36" unicycle for commuting and distance riding.
What are the advantages or disadvantages of a 36" wheel with a hub that has a bearing space of 100mm vs 125mm? (I have a brand new 125mm spaced cotterless hub and shims to allow it to be used in a 42mm hub bracket. I also have some fairly well worn 100mm spaced cotterless hubs). I may be leaning in the direction of buying a 36" frame with 125mm bearing pitch for the hub. (I think there may only be one on the market that will work - Nimbus Oracle Disc (not the universal disc one though). So that may be enough of a detractor to not want to go with 125mm bearing pitch frame.
CONTEXT:
My main unicycle is a 26" QU-AX aluminum frame with a Magura brake. I’ve ridden that aver 1500km in the last two years. I also have a 20" Nimbus with a 3" wide Creepy Crawler tire for practicing skills. The other unicycle I have is not that rideable as it is a home made piece based on welding an old 20" to the front forks from an old winter bike in which the stem quill broke on a winter commmute - I wasn’t hurt.
Due to lack of finances I will likely build it a bit at a time, similar to the way I build my 26er. (I have some spare parts … lots of rims (not 36 yet though), spokes, I have pedals and saddles and crank arms (both ISIS and cotterless - the cotterless are not in great shape), I also have a brand new 125mm hub which I was going to use on a home build, but have not ended up doing that project. I have a couple of pretty old 100mm cotterless hubs kicking around as well.
What I mean by building it up a bit at a time is that I won’t have to shell out a lot of money all at once. For instance, the first purchace could be a frame and I would simply build a wheel and use some spare parts. Then ride it around. A second purchace would be a 36" rim, spokes, rim tape, tube and build the wheel around some cotterless hub that I have, and ride it around for a while. Next, I would ISIS hub and I’d build a wheel based on that hub and ride it around. Next I’d buy a disc brake and finally I would either take the handle off my 26er and use it on the 36" uni. I realise it is a bit of work assembling and disassembling bits and pieces, especially wheels, but I rather like to tinker and the big draw for doing it this way is I don’t have to buy everything all at once.
wider pitch allows more space for a disc and I think results in a stronger asymmetrical wheel (pretty much required for disc hub).
→ advantage wide hub
pedals forces:
I’m not an expert on this, but from my experience it seems that a narrower hub allows for more efficient pedaling, especially at high RPMs, as there is less side-to-side force while pedaling. Track unis use narrower, I think 92mm, and I feel that the pedaling is less choppy. From the physics I think there is less side-to-side pressure because of the reduced lateral angle, so more force goes in the forward rotation and thus less body adjustment to keep the wheel straight. Note that the pitch combined with the pedal Q factor determines this (for Track you want narrow pitch hub and zero-Q pedals). And with lower pedal spacing (pitch+Q) you also have less lateral movement and thus less “S” tracking of the wheel – so you actually travel a shorter distance, which over many kilometers can become significant and save seconds in a timed event
→ advantage narrow pitch (but mostly for racing, maximum efficiency and top speed)
On the other hand, for uphill or power related activities, I find that higher Q allows me to generate more force. On my 36 Oracle with KH Spirit cranks (high Q) I can still ride relatively steep 10-20 percent inclines (without momentum) with short 127 or 100 cranks. I twist the uni to the side, and I think the wider pitch and Q make this more feasible. The same for off-road muni: with 150/125 cranks I often rotate the whole wheel 10-20 degrees left/right when powering uphill and I think the high Q facilitates this.
→ advantage wide pitch for versatility and slow-speed climbing and power
So… if you’re looking for a 36 with a disc.
Wider is better for a disc pretty much in every way
Wider is better for more power/uphills (while still running shorter cranks)
Narrower is likely slightly better if you want to ride ultra-long distance or racing (but if you’re racing then a Schlumpf is more relevant).
Maybe someone else has more insights as I’m not really a track racer and just bought my first track uni this year. Or maybe Roger has some insight here.
Disclosure: I’m neither a good track racer (as a trainer, my kids and the teenagers in my club now blow me away on the track) nor a top road racer and prefer Muni and commuting, so a hard-core racer will likely view this differently.
I personally like the really wide Q on my 36. Yes, my pedaling is a little less “round” and less maximally optimal because of the high Q, but I can steer more easily at slow speeds and I am much more versatile with an optimal combination between efficiency with maneuverability.
I think the other advantage of narrow pitch besides (probably) more efficient pedaling/less wheel twitching is that it’s probably more ergonomic.
Some people will probably say that they have “wide hips”, but even with 100mm bearing spacing and “zero q” cranks, unicycles already have a wider stance than most bikes. I’m assuming bikes are typically built with the cranks as close to each other as the tires allow for good ergonomic reason.
(It’s also easier to move pedals further out than moving them in.)
I haven’t ridden wide stance vs. narrow on similar setups back to back, but I haven’t noticed any major maneuverability/balancing differences. I could easily see that this may be different with different riding styles, however.
Thank you for taking the time to respond and write your insights on this. About room for the disc. I do recall reading about the Oracle universal disc frame has disc mounts that allow the disc to be on the inside or outside of the frame (this one is a 100mm pitch). Maybe mounting a disc outside the frame was something more in years gone by.
I don’t really plan to do any track racing. So for the 36er I have in mind to do commuting and long distance road, or perhaps some unicycle camping; for muni I’d probably be more inclined to use my 26er.
Thanks for your insight on this as well. You make a good point about cycling as well, where the bottom bracket and crank axle system is much narrower than even the “standard” bearing spacing. I had seen narrower than 100mm on unicycles or maybe just the hubs … I think I had seen something like 92mm, but this is not on any kind of unicycle that I have or have had on my radar. You make a good point about riding styles as well. I never really thought of my riding style before, but I suppose it is just a general commuting / road distance / muni “style”, I’m not doing flatland, nor playing sports with it (like basketball, or hockey), nor am I racing.
For what it’s worth, I measured the distance from the outermost face of the cranks, where the pedal fits, on a mountain bike I have, and also on a Nimbus Oracle (with standard 100mm hub). The mountain bike had a (standard) curved crank to increase the Q and to clear the rear frame, the unicycle had straight sided VCX cranks.
Guess what?.. the unicycle had a NARROWER distance between pedals than the mountain bike!
On a bike, you’re not sitting right above the hub as we do, so you can have your feet closer as it’s more efficient. On a mountain bike, you’re more likely to spend more time standing than sitting, hence a wider stance for balance.
In our world, freestyle unicyclists have narrower hubs, I was told that it makes spinning/pirouettes easier.
Funny thought. For the past years, I have ridden Muni with Qaxle straight cranks. In 2023, I have started to use Spirit cranks on a G29. Guess what? I found my level was better on the G29 with Spirit cranks than on the 27.5 with straight cranks. I can’t say for sure the only reason is the wider Q-factor, but it could be one reason.
For Unicycle Races, use the narrowest possible hub to reduce rolling movements. This makes perfect sense at cadence rates of over 200 rpm. Normal hubs have a bearing distance of 100mm (center-center). However, they require special fork designs to be fit for 3" and 3.25" tires. With a “normal” fork it would be up to about 2.8". That was the reason why I had my own 120mm hubs made for my 4" Fattys. And you know what? The 120mm hub feels more “natural”. I have had problems with my knee (meniscus/cruciate ligament/cartilage damage) for 24 years. With 100mm hubs I tend to have an unnatural leg position. I have the feeling that a width of over 100mm for hubs is closer to the natural posture of adults. Sure, you might be a little faster with a 100mm hub if you try to ride a route at maximum speed. 120mm (or 125) somehow feels more comfortable to me. And I didn’t find any disadvantages. Climbs work at least as well and long distances are more comfortable for my damaged knee.
Ok, I was curious after seeing your message. I thought I’d go and measure the distance between the inside edge of the pedals on a few of my vehicles:
my touring bike with triple chainrings: 188mm
my MTB with thriple chainrings: 188mm
my 26" QU-AX with a 100mm hub (I guess that is all they sell anyway): 225mm
my Junk homebuilt unicycle: 235mm
I can’t measure my 20" as it is at work - I leave it there for practice during work breaks
Thanks so much for your messages. I really appreciate the time you take. Maybe I will even get to visit you in your shop in Switzerland next year as my son is getting married in Germany. (That is a reason I have been learning German)
Anyway, your information is very helpful. Sorry about your knee trouble. By God’s grace I don’t have any body parts giving me trouble. I did have a back operation about 12 years ago and have gone from barely being able to walk even using a crutch to walking, running, cycling, and learning unicycling.
My style of unicycling is not racing, I’ve never been fast, so I don’t think I need a narrow bearing space, and it is good to hear that you found no significant difference in riding between various hub widths, except the feeling of more comfort on 120 or 125mm spaced hubs.
Yes, and I guess it depends on a few things with your MTB, such as if you have a single, double, or triple crank, also how long the shaft is in your bottom bracket too!
That makes sense. Although I myself am not really doing to much in the way of pirouttes. I guess we all do a bit of spinning, if you mean really tight cornering where you twist your hips quickly to shift direction. My unicycling style is not very sophisticated, I mostly do commuting, “long-ish” (so far up to 40km) road trips, and a bit of muni, I don’t do any flatland, and I really don’t know how to do any tricks. So for me, freemounting, riding, navigating the trail, some hopping, a wee bit of idling/backwards riding - just learning how to do the last three) are about all I am able to do right now.
Thank you
The main reason for these knee problems was at a punk concert when someone jumped into the side of my knee while dancing pogo. It doesn’t come from unicycling.
I think it’s thanks to unicycling that I don’t have any arthritis so far.
According to the doctors, I should have had this for at least 10 years. A little bit of unicycling is always good for the knee (except for extreme things). Yesterday I drove about 30km in the dark in the storm and rain. You have to be a bit crazy to do something like that voluntarily But I love feeling the elements and having to fight against them with the unicycle. At least I earned the raclette in the evening.
I would be happy if you stopped by the shop. But you’ll probably be a little disappointed. It is purely a warehouse. There is no showroom, no unicycles to test ride. You won’t see a single assembled unicycle, just boxes and individual components, because I assemble them piece by piece to order.
I just looked up some measurements, the narrowest you can get on a unicycle with 100mm bearing spacing is ~160mm, MTB are ~170mm, so it’s possible.
I guess my head had been a bit overly focussed on road bikes and MTB are similar to many unis.
Either way, while I am pretty convinced that narrower is ergonomically better, I should make clear that for many, this may just be a theoretical advantage. Most people don’t spend all that much time on their unicycle all things considered, so it may not be enough to notice.
Certainly has not made me think about using 89mm hubs, although I have picked pedals on my Muni that put my feet as far in as possible.
I have to say that is the cleanest warehouse I have ever seen in my life. Did you tidy up for that photo? It looks amazing!
Wide vs. narrow hub:
All other things being equal, a wider hub/stance should result in more wobble as you ride, from your feet being farther from the centerline. This will affect some riders more than others, because some are better able to minimize wobble through their spin, while others have trouble mastering this. Also as we get older, our bodies may have issues with a setup that’s too wide (or narrow) depending on the condition of our joints and/or other bodily wear & tear.
Relating to Freestyle, I don’t know that a wider hub would make spinning/pirouetting more difficult, other than for the tendency for more wobble with a wider setup. I spin/pirouette just fine on my 45" wheel. Granted, that basically happens in slow motion (but it looks nice). Probably more of a factor for high-end Freestyle riding is crank length. Japanese riders tend toward very short cranks (89 - 100mm), which make it easier to spin up to high speeds before jumping up onto the fork. It also gives you a smoother spin for any kinds of skills you would do while rolling; less leg movement smooths everything out.
For here-to-there riding, not racing, I don’t think a few mm in hub width should make much of a difference in riding efficiency. Like everything in the world of engineering, you have to compromise. A wider hub generally gives you a stronger wheel, but puts your feet farther apart. Which more important, for you, in the long run? The answer will depend on many factors including your preferred riding style, your knees and physical condition, and what you’re trying to accomplish.
Yeah I got dropped from a stage dive while crowd-surfing about thirty years ago and dropped flat on my back on concrete. So much for crowd support. Ha ha. So we both got concert injuries it looks like.
I also enjoy long distance riding, but I am only up to 40km at this point on the unicycle. I have been a cyclist all my life and didn’t get into unicycling until my late 50s a few years ago. I’m still not very good at riding when it is wet and rainy, although I have been doing a bit of winter riding. It is good to keep active, and unicycling I think is a great skill to have. I think you did racing when you were younger, right?
So, if it works out that I am in Switzerland, I will look you up, it is ok that you might not have a unicycle around the shop or anything much on display. I find that even though I really like unicycling, I enjoy meeting fellow unicyclists when I travel.
I’m going to visit my parents in Edmonton, so I won’t be online very much, I want to visit them while I still can.
Thank you. Merry Christmas to you and yours as well, happy and safe holidays!
So, you have a 45" wheel? I’ve never seen a unicycle with one that large. Wow. You must be pretty tall too! That is fascinating.
For here-to-there riding, not racing, I don’t think a few mm in hub width should make much of a difference in riding efficiency. Like everything in the world of engineering, you have to compromise. A wider hub generally gives you a stronger wheel, but puts your feet farther apart. Which more important, for you, in the long run? The answer will depend on many factors including your preferred riding style, your knees and physical condition, and what you’re trying to accomplish.<<
So, I’m not a racer, and on a bigger wheel especially -although I guess for you 36" is not a particularly big wheel, ha ha - I don’t see myself performing flatland / trick type maneuvers. I’m more of a commuter/road distance/ muni rider (working on that last one). Although, muni can be handled pretty nicely with my 26" wheel. I’m in pretty decent shape and have no real physical issues to complain about at this stage in my life (I’ll be turning 60 in a bit over a year, so I’m not that young).
I really appreciate you and everyone else chiming in to help me understand.
I have to say that is the cleanest warehouse I have ever seen in my life. Did you tidy up for that photo? It looks amazing!
the look of the room is constantly changing. Meanwhile there are still racks in there and stacks of tires. Things don’t look so neat in my 3 adjoining rooms
