When unicycles fail

I’m interested in what it looks like when unicycles fail and what those examples teach us about the limitations of parts, materials, designs, etc., for different scenarios. Examples:

  • Rider size/weight/aggressiveness
  • Unicycle disciplines: muni, trials, …
  • Extremeness of usage

I’d be fascinated to see photos and videos to learn about different unicycle models and what their limits are (but not to see people get hurt).

Part of what I’m interested in are examples like:

  • “I tried [fill in radical maneuver] and it was too much for my [brand/model] and parts Y and Z broke (see photo). I’d recommend this other build level if you want to do that sort of thing.”, or
  • “I tried using my street designed [brand/model] on trails and it worked for a couple months then my rim cracked (I weigh [X] lbs.)”,
  • Or even when a uni [brand/model] was pushed beyond expected limits and handled it without problem.

My goal is not to push the boundaries but rather to hear about your hard-won experiences on where the boundaries are so we can safely respect them (while still having as much fun as possible).

This could be helpful for newer unicyclists, like myself, get an orientation on when to get a more capable piece of equipment, considering their weight, demands of their maneuvers, and limited budget.

Many thanks!

I guess you could also add “wear and tear”. I’ve had a few seat post clamps fail on me after being untightened/retightened many times. Usually it’s the aluminium of the clamp giving up on being attacked by the steel bolt, and often a lack of grease.

I had a Shadow base break on me a while back. It was an older version the design has since been updated.

The piece which interfaces with the seatpost is a solid machined piece. The front and rear tubes fit over stubs on the machined piece and are welded in place. It snapped right where the machined piece ended inside the tube - an obvious stress riser.

The new version has no separate tubes. It’s one single machined piece. No real weak points in the design.

Of course, there’s always going to be a weak point in the whole (uni) system. I wonder what will break next?

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Hi mroze,

You should start your quest in the broken parts thread:

You will get a sample of parts failures over the years with some background information when the reason of the failure is not obvious.

Unicycling being cover by a handful of brands, a vast majority of the design updates (sometimes not as obvious as others) are driven by these known weak spots that only a few dedicated riders ran into.

You top list of disciplines that are bringing the most mechanical stresses: trial, muni and street.

I remember also a couple of times somebody posting a CAD screenshot to discuss mechanical simulation of a part to visualize where a part would be most vulnerable (but cannot remember the discussion enough to find it myself).

So far I consider myself very lucky to have not really had any failures.

I’ve broken (a plastic) part of a brake lever after a fall but it was not catastrophic and I could still ride and use the brake (albeit in a non-ideal fashion).

I’ve slightly bent some pedal axles, probably again related to falls and always seemingly dropping the unicycle onto its right side.

In repairs for other people the most common has been spokes, generally through lack of maintenance and non-ideal truing from the factory. One case of eyelets pulling through the rim but I think that was also a wheel tightness issue.
Unicycle club unicycles also tend to get bent pedals and sometimes cranks with being cheap and cheerful square taper setups, many falls, and riders having a go at hopping.

Excellent photos! Both show clearly where the problem was and how to correct it (reinforcing right out to where it supports all the weight). A great example of what to look for.
Thanks,

See the broken parts thread for pictures. Most failing parts are rather unspectacular (seat posts are common for me). I usually feel or hear it creak before the final failure, flatland/trials/street riding, and one on my muni. Clearly fatigue failures.
Two 19" rims bent for me, to the point where I retired them (landing sideways on gaps). A lack of maintenance and improper tensioning didn’t help them, but it’s also just something that happens over time.
I broke a plastic based seat (or well, the metal plate in it), when practicing crank flips, which is why most flat/street riders have a carbon base. Some seat handles too, also victims to do flips.

I’ve seen examples of every component of a unicycle failing by now, but the majority of riders doesn’t have to worry about that. Most failures are fatigue failures, and it seems like they mostly occur for “extreme” riders, that put a lot of stress on their parts regularly. (I am talking about “good” unicycles/parts here, not the no name brands.)

Seat posts? I’m surprised to hear that, but now that you mention it, I see a lot of examples of seat posts in the broken parts thread.

Perhaps some failures are related to welding the post to the plate holding the saddle (and repeatedly stressing the weld when dropping the uni with the saddle striking the ground)?

Perhaps the seat tubes bend because they are made somewhat thinner in order to provide a little flex for comfort?

Are their brands/models or materials that are known to be extremely long-wearing?

Thanks,

Aluminium has a habit of stress fracturing over time, welded or otherwise, especially if you try to bend it.

You pull on the seat when jumping, which means the seat post is under high stress.
Mad4one has a super beefy seat post, which seems to last for a long time. (If you don’t jump much, or have a long T-bar, breaking seat post is a rarety, just like it is on bikes.)

The more and more you improve your uni and make it stronger … the more it’s gonna be you :wink:

So true. Better to break a part then to break you or the frame.

February, bad giraffe dismount… I failed, not the equipment!

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I destroy bearings… I think it must be the North Moors. They mud is very abrasive and successful in getting to my bearings.

How’s your feet now?
I sprained my ankle 2 years ago (I remember a “crack” sound) and couldn’t ride for 3 months. The pain faded out after more than 6 months.

Your injury seems nasty.

And how’s the giraffe? :smile:

Hi @Canapin, Ouch for you! (Sorry, I have to figure out how to make a quote work!) I just have a habit of ankle rolling so when I tried to land on my foot, I landed on the outside side of it. Wearing flat but open at the top Mary Jane shoes didn’t help.

Anyway, had ankle had dorsiflexion issues for quite a while, and foot inversion strength is lacking (which meant riding a pushbike with road cleats was a real issue)… no ankle strength to disengage. Took me around 5 weeks before I could drive my car, as it’s a manual. You don’t realise you need a reasonable amount of ankle strength to operate a clutch, till you have this challenge.

Riding unicycles right now is pretty good though, but the first few times I went on longer rides, my ankle felt blocked in dorsiflexion and the first couple of times dropping off a kerb, depending on crank position, it would hurt my ankle when the uni landed.

The giraffe now? I sold it :slight_smile:

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From my experience uniycles are unbreakable.

Leaving apart replacing seats, tyres/tubes and pedals, the only failures I have had on a unicycle with over 67,000 kms (metered) is a fractured axle and a bunged up crank and that was due to me riding it a long distance while it was loose.

I did have to replace the bearings at around 60,000kms when they became clogged with Australian red dust from driving thousands of kms of outback dirt with the unicycle on the bike beak. The bearing surfaces were still in good condition.

It is a Nimbus. But I hasten to add that it is a very old Nimbus dating from the time when they had skinny seat tube, square taper cranks and steel rim equating to a no-brand internet purchase with a better seat. So on my experience, for just plain riding without the stresses of street, stair jumping, hopping etc, even a basic cheapy with competent welding should not break. Ever.

I exempt plastic wheel jobs. And I’m only talking of commuting and touring. Of course more extreme use like street will need heavier duty rim, splined hubs and so forth.