I had the exact failure on my 36er RGB. It took work to drill the broken bolt out. I changed also the other bolt for avoid further issue
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It’s good to hear I’m not alone in this, but also a bit worrying. Do you think you could have overtightened the screw?
Does Qu-Ax provide torque specs for it?
Yes, if a bolt snaps while you tighten it, you overtightened it. Grease helps get rid of some friction in the thread, which will make the bolt more “effective” - more of the stress in the bolt is axial and less torsional (for the same torque applied), which means more clamping with a bolt under similar stress.
I’m not a fan of the bolt size they use either, mostly because the small hex heads have a habit of wearing out quite quickly. I think they are probably able to provide plenty of clamping force, if you don’t overtighten them…
The nerd in me loves impact seat clamps, or pretty much any seatclamp where the bolt goes into a steel cylinder, not the aluminium- no weird bending of the bolt happening that way, and also threads into steel 
If the bolt doesn’t also come with precise instructions on how the bolt should be lubricated, it’s pretty safe to use feel instead of a torque wrench.
Yes! A much better design.
Obviously raises cost, though, and the monolithic aluminium design is “good enough” that better options are a luxury item.
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There are plenty of fasteners out there though that simply have not been made to high enough specifications. I see it most commonly among cheap screws provided with small hinges and hasps, but I’ve seen it with bolts too. I wouldn’t want to blame a unicycle maker for it though, as even if the bolt actually was defective, it was almost certainly sold to them as meeting industry standards.
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Thanks, this makes sense. I was having problems with the seat post rotating a bit after impacts, so I might have overtightened at some point, weakening the screw. I will grease the screws and double check with a torque wrench next time I have one handy. Howard Zinn’s book recommends 7 Nm for a generic M5 steel bolt into aluminium, that can’t be too wrong.
Regarding alternative seat clamps, I would switch mine for another, if it weren’t for the fact that Qu-Ax went for a non-standard seat post diameter (which I also find annoying).
Also it’s additional weight to make it that way
A quick google search returned plenty of options, you just have to look outside of unicycle retailers… You can probably even get 34.9mm seatclamps at your local bike store.
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Thanks, I realized this yesterday. Ordering one now!
34,9 is a typical size in bikes, there are a lot of options actually.
The smaller the bolt, the less torque it takes - 7 Nm is too much. I’d recommend 5Nm. If the seatpost still twists, some friction paste (used in bike-shops for carbon-parts) helps a lot.
Providing a torque is quite theoretical - since the fewest customers have a torque-key, unfortunately. Also, on the road, if you adjust height (or angle after the saddle crashed), you will also not have a torque key at your disposion.
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It is, but the idea of over-torquing a bolt is also quite theoretical if there’s no figure to aim for.
At least with a torque spec, those of us with such tools can have things tightened as recommended and then can also then know if something failed within spec.
I know that somewhere around 4-8Nm is pretty typical for clamps on bikes, and some people use friction paste, but we put far more force through our seats than they do (especially with seat mounted bars) so I think most people generally expect to be able to keep tightening things up until nothing moves, even on a UPD.
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Wow, tightening a unicycle’s seat post clamp has become pretty complicated. Torque specs, which aren’t torque specs, pastes and grease, 7 Nm too much, 5 Nm good, whatever that is, go by feel, you break it it’s your fault. 
I like unicycles that I can lend to any clumsy friend without worrying too much or having spares and repair tools ready.
I have heard about too many RGB muni frames being 
broken by riders.
I wonder, is the Qu-ax RGB the least sturdy muni frame currently on the market? 
(I mean, it looks great and still appears to be a perfectly fine option for either light or somewhat more gentle muni riders… doesn’t have to be right for everyone.)
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Too many? So far isn’t that number 1?
It does feel a little bit too much like that for my liking. I’ve now dug into my selection of trusted machine screws to find replacements for my clamp.
I’ve honestly always been kind of surprised that once you get past the basic unicycles, basically every unicycle is designed and rated for use by anyone. I could almost certainly get away with losing a few hundred grams from most of the unicycles I ride and have zero issues as they’re also designed to hold up when ridden by someone twice my weight.
But, if that’s going to change, it obviously needs to be set out very clearly.
I’ve heard about two QX RGB frames.I’ve also seen a broken KH, and multiple Triton frames with cracks, I think riders at the upper end with big brake disks and rough riding will break frames at some point. I haven’t seen a broken Mad4one frame yet (might be coincidence, but they are really high grade aluminum, so they might just be the strongest).
So is that too many? Maybe, maybe not. I hope future iterations of this frame will be slightly stronger (because I don’t care about weight much). Maybe it’s me being used to the old trials/street/flat days, where frames breaking was just a thing that happened from time to time, but as long as it’s only “hardcore” riders with big brake disks managing to break one, I think that it is a pretty succesful first generation.
(And there have always been people who managed to break seatclamps by overtightening them, that really isn’t new…)
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I seem to remember seeing something about the disk mount being welded differently in the future.
Clamps, or machine screws in clamps?
You’re right.
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Yup! After repeatedly damaging the thread in the busses of my Impact 2 bolt clamps, I’ve realized the bolts were to short to fully use the thread. So I replaced them with longer bolts and then my clamp broke 
I’m definitely not using anything near 7Nm, probably around 10-15 (estimate) since I really put a lot of force on it and I dont want it to move (trials uni)
What’s that supposed to mean? American-made is the only good thing?
I think it’s the politically correct way to say “shit made in China”… 
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