The above quoted thread is illustrative of the confusion surrounding the ISIS standard. I think you should worry about the small space. Your new unicycle could last for a very long time, but not if parts get loose. If I were you, I’d order a crank puller, more/different spacers and a new set of ISIS hub bolts. I added the last item because it’s possible the hub bolts that came with your unicycle are not of the highest quality and might deform under serious tightening.
If I detach everything from my 20" frame, grab the top of it and tap the fork against my knee, it resonates nicely, like a tuning fork, though it gives an A flat instead of an A. I don’t think I could bend it a whole centimeter, though, unless I were trying to destroy it!
They say 2 inches minimum, but I wouldn’t mess with that too much just yet if I were you. The more seat post you have in the frame, the less likely it is to swivel, and the less likely the seat tube is to break. Also, in your first year of riding, you are going to want to experiment with a lot of different seat heights, so right now, you can’t be sure how much you should saw off. You can always saw off more later, but if you saw off too much, you can’t put it back!
Is it possible the company forgot to send you spacers? My concern would be that dust and crud might get into the bearings or something.
Yeah, I think press-fit bearings are the cheap kind. I forget what the better kind is called, You seem to know more about a lot of this stuff than I do, though, maybe because of your trials bike background, and maybe because you do lots of research, but in any case, hopefully at least some of what I have said is helpful.
But now it is time for you to take action. This instructional video was posted recently by another user on this forum. If you do what it shows 50 times or so, you will most likely find yourself going on longer and longer rides. Note that the fall shown in the instructional video is a worst-case scenario. Most of the time you will just end up on your feet.
Kind of like the New Coke thing from 1985, for those that are old enough. Except Coca-Cola managed to (after a while) turn that into a triumph.
Yup, back in 1999 we thought John Drummond was insane to spend $5000 US on the unicycle.com domain (before that they were unicyclesource.com). They were pioneering the idea of selling unicycles online, and it was a very much unproven thing at the time. But he got it oh so right! Someday I will offer unicycling.com to the highest bidder… if there are any…
Pretty amazing for them to recommend someone else’s product over theirs. Probably said “China” based on your location, or just on knowing that if you’re serious about unicycling you’d be back pretty soon. 
I would expect KH to recommend his own products; he probably assumed you wanted info about them specifically (and they’re good stuff). I love the Mad4One unis; beautiful colors and great builds, but a little expensive, especially when adding shipping to the US.
Stealthy is a relative term; you’ll only be stealthy at night. But it should make a nice, sinister Bat-Uni!
That sounds pretty flexy, but the true test will be riding. I’m pretty sure my handmade Wilder 6160 frame wouldn’t flex that much. The unknown with “off brand” unicycles will tend to be in the hub and cranks. They’re either good or they’re not, but even if they’re not great, they will probably last you through a lot of learning, and be a really good starter uni.
To be fair, Trials forks are purpose-built for Trials bikes, so are probably extra burly for that reason. I think the biggest stress on a Bike Trials fork would be from being bashed from the front, either from riding up against things or hopping on the front wheel (if that’s a thing; I’m not a Bike Trials guy). Unicycle forks get their share of abuse, because they carry 100% of the rider’s weight 100% of the time; no “sharing” with a large frame and another wheel at the other end.
I recommend zero shortening. The only reason to do that would be if you couldn’t get the seat low enough. Extra seat tube is extra structure, which is especially a good thing on a cheapish uni.
Uh, enough to do what you just said. Unless the tube is a non-standard size, you can always replace the clamp. Double-bolt clamps tend to be the strongest, but are a bit more hassle every time you change seat height.
I agree with the advice on having spacers in there, especially if the frame likes to flex.
Thanks John and Song for the thorough replies, all points noted. BTW that gif looks scary but indeed probably the quickest way to learn.
Regarding fork flex, it’s literally 1cm (just measured it), but that’s both ‘prongs’ combined, i.e. I can reduce the spacing between them by 1cm. The mad4one frame is even lighter than this one (alghouth it’s 7005-T6 aluminium), and the Impact Gravity is only a tad heavier so it seems they are all in the same ballpark.
Regarding the crank spacers, I need to ask the seller if he forgot to include them, but I don’t think so because the axle looks like it’s not designed to hold a spacer there, see pic below:
The blue stuff you see on the spindle is Loctite ‘threadlock’. I know what you are thinking: of all places, why would anyone would that stuff there? I have no idea either, that’s how the uni was supplied. I’ll bring it to the attention of the seller though. They also applied copious amounts of threadlock to the crank bolts; here one could argue there’s a valid reason to do so, but when you remove the bolts and see small metal shavings coming off you know that thread should have been greased, not locked.
Anyway, back to the spacers, a 9mm spacer is needed for this particular axle+crank combination. The widest one available from UDC, the KH one, is 8mm but I can buy some very thin 22mm stainless steel shim washers to fill the gap, which might turn out to be better than a single spacer that’s the right size should the gap narrow over time.
For me the spacer serves three purposes:
- To ensure both cranks are symmetrically spaced
- To increase crank stability by acting as a shoulder
- To prevent overloading the ISIS interface if bolt over-tightened
Sounds like this spacer is a good thing to have in place!
I’m also putting some M6 shim washers between the frame and the bearing clamp. I realise the clamp doesn’t need to be crazy tight especially with the ‘nyloc’ nuts, but with the shims in place I can tighten a little more to help stiffen the assembly without fear of deforming the bearings.
Yes, Loctite on the splines is definitely weird. When I first saw that photo, I assumed the blue stuff was some sort of exotic bicycle grease that I hadn’t seen before. A bit of bicycle grease on the splines (and crank bolt threads) is a good idea.
The only place I ever used Loctite was on the bolts on the underside of my seat. All my hopping was loosening them. Some people’s crank bolts come loose chronically, so they use Loctite or they have some sort of enhanced hex wrench to twist them until they scream, but I have never needed to resort to these measures.
There’s clearly a market for bolt-locking technology, say a grove across the threads with a strip of nylon to create friction whilst the the thread can be greased.
It’s the only way to learn! Some people postpone it by clinging to a fence and pedaling slowly along, and insist that it helps, but I don’t think it does, and sooner or later, everyone who rides a unicycle does what is shown in that gif. As long as you always fall forward, rather than back, the worst injury you are likely to get is a pedal bite or two. Enjoy!
BTW my uni frame rings out an A flat 
Thanks for the mention Song, that was my gif.
Here’s a link to all the other videos from the day. Most of them aren’t very dramatic as you can see.
I haven’t shared Google Photos using a link like that before so let me know if it works. Also if I thought anyone would be watching them 13 years later I might have kept my shirt on!
Yeah, the link works. Recording your learning process was a wise move. Whatever anyone thinks of unicycles, learning to ride one is something you only do once. Last year I saw an old guy learn to unicycle for the second time, but it wasn’t the same, even though he had gone more than 40 years without riding.
You’re grabbing at the air for balance in one of those videos- I did that for a little while too! I had thought it was because of my prior experience on a slackline, where hand and arm movements are more important, but maybe it wasn’t. The thing I did learn from the slackline that was applicable to unicycling, though, was that you could only learn it by pretending you already knew how and falling off again and again. The people who tried the slackline with a parent or friend holding their hand never got anywhere at all!
Very true. I still get surprised when people try and learn something by doing things that don’t really resemble what it is that they are trying to learn, but then I suppose I was once that way too.
I’m in a very specific part of the Navy and we do lots of learning, all day every day, even (especially) the very experienced guys. The only way to really know a system, routine or operation is by touching it, operating it, practicing how to use reversionary modes or drilling the procedures. This cannot be learned from a book alone, even though trainees often think that it will work for them. It’s easy to tell if someone knows the book answer or whether they actually understand something simply by asking questions which expose their level of understanding of how multiple complex systems interact.
Let go of the fear, allow yourself to be wrong in the training environment for as long as it takes but make sure the training environment has been designed appropriately. Would anyone who persisted long enough to be successful regret letting go of the wall too early during their learning? Clearly not. So the logical inference is to let go of the wall immediately!
The knowledge that people can learn at different rates is neither uncommon nor contentious.
The knowledge that many people enfeeble themselves by overestimating and avoiding risk is less common, more controversial but true nonetheless!
Hi again guys! Just thought I’d give an update. I finally managed to get my unicycle built up, got some KH 8mm crank spacers from UDC China (thanks Alex :)) and added a 0.3+0.5 mm stack of M22 shim washers to achieve the total spacing needed. Also got some 7075 alu crank bolts and transparent pedals. Looks pretty sick.
My learning experience started on Friday. Did two 30 minute sessions in my building’s corridor, managing a couple of 3 full crank turns towards the end (my best for the day). Despite the advice of “just going for it” given in rich’s gif above, I found having walls within close reach was an incredible time-saver. Constant dismount-mount cycles consume a lot of time and waste energy if what I’m trying to do is get a feel for balance. However the corridor was too narrow at 120 cm and that was preventing me from progressing. I gave up for the day. That night my legs felt as though they wanted to keep pedalling, it’s as though my legs were still on the unicycle. I could feel the unicycle under me even thought I was just lying in bed. Groin area slightly sore.
Yesterday (Saturday afternoon) I found an alleyway about 20cm wider than my stretched arms can reach. I found this to be perfect for learning. It allowed me to launch off whilst still having the option of a friendly wall to either side to prevent UPDs. Any time I was definitely going to fall, I would just lean onto the nearest wall, straighten up and try again. Within about 15 minutes I was able to ride half the length of the alleyway without walls—about 10 metres. Once that happened my courage went up quite a bit, especially because I realised bailing was relatively easy, landing on my feet 100% of the time. I know that’s what everyone told me, but you have to experience it for yourself before the brain buys it.
With the fear of falling gone, I then went to a nearby road, and holding onto a wall, launched off into the open, no side walls. After a few attempts, I managed about 50 metres. Felt friggin’ awesome 
The ride was only 30 minutes, and it kicked my ass. My whole body ached by the end of the day.
This morning (Sunday) I went out again, for about one hour this time. Towards the end I was able to ride for about 100m with not much arm waving and managed to turned a 90 degree bend in a more or less controlled way. I was also able to free-mount once.
Hopping was trivial, maybe coming from a bike trials background helped.
Overall I’m pretty happy with my progress so far, and I’m finding unicycling to be very addictive.
I encountered a few setbacks though, advice needed:
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Groin discomfort: This is the second biggest roadblock I’ve encountered thus far. According to various threads here on this forum, it’s caused by a combination of poor moisture control, inadequate padding, pants material, whether underpants are being worn or not, saddle geometry (width, etc), saddle orientation and saddle height. That’s a lot of variables with one common denominator—a sore groin. Just few minutes into my first attempt, my inner thigh area was already hinting at the problem, and the end of the ride was clearly marked by my groin’s ability to endure the burning. One thing that helped make the situation better was to adjust saddle height correctly. As it turned out, my saddle was initially about 5 cm too low. Will padded cycling pants eliminate the chafing?
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Diamonds: We’ve all seen the picture. I have to literally grab and pull my diamonds up before every mount. Doesn’t look particularly classy and the extra step is a bit of a chore. Will tight-fitting cycling pants make this better or is it an issue with the saddle?
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Sitting on perineum: Biggest roadblock for at the moment. I want my sit bone to be directly above the seat post. That requires the widest part of the saddle—the rear of the saddle—to be positioned also directly above the wheel axle. Unfortunately, my saddle is already is adjusted as far forward as it can go and it’s still inadequate. Currently the only way round this is for me to lean further forward, which brings the back of the saddle to where it should be (good) but the back of the saddle ends up sloping downwards and forward. As a result, I tend to slide forward into the saddle, further sliding prevented by my perineum hitting the upslope of the saddle. Sitting on the perineum is incorrect and very uncomfortable. Eventually I just end up semi-sitting and semi-standing, which is very inefficient. I am convinced this is a seat ergonomics problem. I know KH does a flatter saddle, that seems like it might do the trick. I would love some advice on this as it’s preventing me from enjoying my rides.
I’ll post some pics of my machine later 
Unlike many people on this forum, I don’t even wear cycling shorts, just gym shorts, (preferably of thin, stretchy material), and I have gone 50 km in one day with no significant discomfort in my crotch. Every 20 minutes or so, I do have to rest, either by standing up on the pedals for a minute while riding, or by dismounting, but the various kinds of extreme discomfort you describe from such short rides sound more like the result of a poorly-designed seat. You might adapt to it somewhat, but replacing it may be easier. I once rode someone’s Avenir (cheap) unicycle that had a seat that seemed to have been precision designed to keep your bodyweight directly on top of your nuts at all times, no matter what.
The seats on both my unis are some sort of KH/Nimbus joint project, and not flat. I have tried one of the KH flat seats. They are easy on the crotch, but painful on the ass! It feels like you are sitting on a board. People do get used to those seats, though, and really like them, but as far as I know, they are usually for distance riding rather than trials.
Sounds like you are making good progress. Riding without sitting on the seat (SIF we call it here) is also possible, and allows for some very big hops, but you might not be ready for it just yet, and in any case, sometimes you have to sit down.
Flat you own saddle
I had a spare saddle from an old style uni. Reading on the forum I flattened it: removed the cover and the foam, used an heat pistol and pressed the base. Than, I decided to use a thinner foam… found an old foam I used when younger to build miniatures buildings: firm and light weight. Cut the form, cut a deep hole for diamonds and glued it to the base… I was luck: it’s my choice for every kind of riding! Without handlebars the flat seat implies front leaning and more speed to keep balalncing. With handlebars it’s really great (I prefer it to the KH fusion which however is also good too).
The most important thing is to create a deep, long, big cutout to securely store family jewels (as we say in Italy referring to diamonds) https://imgur.com/a/9EsawZP
I think cycling shorts might help with inner thigh chafing though but not so much with diamond-related issues. My current goal is to replace my commuter folding bike with a unicycle. Uni trials is a possibility but I first want to focus on general riding so I need a saddle that will enable me to ride, say, up to 10 miles fairly comfortably. Just now I came back from my longest ride thus far, I was able to go about a mile down a trail without any UPDs and had to dismount only because the trail was narrow and there was a big SUV driving towards me. Pressure on perineum still a problem, the diamonds problem only happens when mounting and is partially solved by initially sitting slightly forward and then sliding back to ensure things end up in the right place… if that makes sense.
That Avenir saddle sounds like some sort of medieval torture device 
I’m willing to hack my saddle. The worst thing that could happen is I bugger it up and need to buy a new one, which I’m already prepared to anyway. On my saddle the cover is stapled to the plastic base, how’s yours made? How did you put the cover back? Or did you just buy a removable cover and pop it over the foam? Would putting the saddle in boiling water work for bending it?
Otherwise I could choose from the following saddles:
Nimbus Flat
Nimbus Stadium
KH Fusion One
The two Nimbus ones seems similar, one having more padding than the other, and the KH is especially flat. Seems the KH one might be a better option, don’t know… I assume I’ll also need a matching seat post. I’m not keen on spending too much money on stuff that might not do the trick.
It is not really the forward and back position of the saddle that will determine where most of your weight is. The angle of the saddle will determine this with the nose of the saddle higher and the rear lower then rider will tend to stay back on the wider part of the saddle. Shims can be added in the front to raise the front more and the shape of the saddle comes it to play also. If the saddle has too much curve then very sensitive body parts may start to get in the way before the rear part of the saddle is at the lowest part. Just try different angles to see what happens.
Jim
Scoox, congratulations on your super-human progress! OMG, it took me several weeks to progress to the point you are already! I suppose the trials bicycle background helped?
Your issues with the seat sound pretty typical. I suggest you try solving the problem with bike shorts before moving onto a newer saddle. Since you’re such a fast learner, it may not be long before you learn to ride with one hand on the saddle, and you’ll be able to orient your sit bones and your junk better when that happens. Of the three saddles you mentioned, I only have experience with the Stadium saddle. It’s not really designed for holding onto the seat in a variety of ways, so it might not be the best for general purpose learning on the 20", but it has been great for longer distance. We are all so different, and the right saddle is a matter of personal taste.
If you’re thinking of going on 10-mile rides, you really need a larger wheel than the one you bought last month. I have taken 5-mile trips on a 20, and it was OK, but it is not something I would do regularly. There are millions of threads here about 29 versus 36 and so on.
I have only really had inner thigh chafing problems when riding on the horrendously bad seat that came with my cheap first unicycle, but yeah, maybe you can solve your current problem with biker shorts, I don’t know. Before you spend lots of money on biker shorts or a new seat and seatpost, and before you spend time carving up and boiling your seat, try following the advice posted just above by JimT and elpuebloUNIdo. When it comes to unicycling, problems with your balls are often just from sitting in the wrong position, while chafing on your inner thighs is usually due to some fundamental structural flaw in the seat. General numbness in your entire crotch during long rides is pretty much inevitable, but very easy to get rid of just by either rising up off the seat for a while or taking a break for one or two minutes. Some people also resort to installing handlebars on their large-wheeled unicycles, but again, that’s a topic that I’ll leave to someone else.
All has been said…
But in the beginning, chafing is made worse because one tends to “squeeze” the saddle between your legs out of tension. And also because the skin there is thin and hasn’t been attacked ever.
Though on long rides, shorts and chamois cream do help for sure.
To get the family jewels out of reach, you can go for a full cycling bib, that will hold everybody up. Or get a pair of Aussiebum underpants, their EnlargeIt series was suggested here as an interesting special pouch bring the family kit further front. Just be warned it’s a very popular brand in the gay community, so be ready for an upfront website.
Commuting 10 miles on a uni… why not, but rethink the wheel size, and make sure there are showers on arrival.
All replies noted and appreciated I didn’t think about using shims there, probably because my saddle is held in place by closed end nuts, not bolts. But reckon I can squeeze at least a couple of them in there to see if there’s some improvement, and then go from there.
Might grab a pair of cycling pants. I’ve just looked at the gay pants, they might work, might grab a pair just to check them out. They are a little expensive for a pair of pants though.
The problem with cycling shorts, IMO, is that you can’t just grab your uni and go, you have to first change into “uni clothes”, which kinda kills the whole simplicity vibe. I’m a briefs kinda guy but switching to some kind of tight-fitting boxers might help at least with the inner thigh chafing—maybe? I am convinced that saddle ergonomics can take care of most problems.
The other option would be to make a saddle by Frankensteining my existing saddle bumpers onto a CNCed piece of carbon fibre board, a matching piece of CNCed EVA foam to go on top and around, and then finish it all off with a layer of soft foam plus a saddle cover from UDC. I can order the CNC bits, I just need to design the parts in Fusion 360 and send the CAD files off. Of course the saddle base would be flat but I could design it in such a way that tilt and backward-forward position could be adjusted. In addition, EVA foam can be 3D machined to give it a bit of a contour like regular saddles, plus a groove down the middle for the jewels. It can even have holes to allow it to breathe.
Quick question about larger wheel size, UDC China have the KH 26" on sale (from 4970 to 3970 CNY), maybe because it’s a discontinued model. Would this be a good choice or is 27.5 inch a more versatile size? Maybe 26 inch was discontinued for a reason. Just been reading up on this and it seems 27.5 inch is now quite a common size for MTB, so tyre choice should not be a problem. If 27.5 inch is better then I’ll pass up on this offer.
My intended use is metropolitan commutes in a medium-busy city where traffic rules are often ignored (China) and pretty much anything can happen on pavements (street sellers, middle-aged women dancing in the evening, parked cars, etc). That means there will be a fair bit of mount-and-dismount, obstacle avoidance, slow riding & idling, and at the same time there are dedicated bike lanes where one can enjoy a bit of speed for short periods of time.