Has anyone ever made a carbon uni frame? Before we go down the carbon can shatter etc route yes I know but we make modern MTBs out of them and I’ve seen bikepacking bike with carbon forks.
We have a bias in our brains where if we can easily picture something bad happening we’re liable to think it is more likely to happen.
This just to say, yes there are some ways in can go bad, but of the frame was intended for unipacking or road (not muni packing) there might be some benefits.
For example a KH or Nimbus 29" frame is 500-650g or so, and a carbon fork for a fat bike are about the same weight.
There would be some differences in the design but it may be a nice option to have.
In a niche market though where the current frame are about the same weight though I can see why it’s not available.
Indeed @rogeratunicycledotcom made some in 1997 or 1998? I am sure he could confirm and say why their are no carbon Nimbus frames. In addition IIRC @johnfoss has one.
There used to be a koxx one trials frame commercially available, but they were heavier than aluminium frames and expensive, so few were sold. However, they were apparently decently strong for the time.
EB used to make aluminum lugged carbon frames too. Which would be the way I would go about making one, if I wanted to. Atherton bikes make a compelling argument for using bonded carbon tubes with 3d printed titanium lugs, easy custom geometries and using the strength of each material in a place that suits them. Not very cheap either, but at least that is a process that would work at a lower scale.
Development cost would be astronomical, as would resale price. You need a new mould for each size, the interface areas (bearing caps, disk mount, seat clamp) are notoriously tricky to get right, so there is high initial investment and high risk.
Sounds like Finnspin has the most accurate short answer to that question. Yes, I have a Roger Davies carbon frame that was probably made in 1997. Three examples of his frame were also present at the world’s first Mountain Unicycle Weekend (Auburn, CA 1996). Roger, Constance Cotter and Andy Cotter all had them at the time. This page inculdes a (tiny) photo of them.
They were made with very sturdy (thick walled) carbon tubes, using machined aluminum lugs for the bearing holders, crown and probably where the seat clamp attached. Simple design, extremely light and very strong. The only downside I can think of in that particular design was that the round tubing would make a wider frame than many people would want. And this was before Mountain Unicycling started using 3" tires; they wouldn’t fit them later on, which is why my beautiful carbon frame hangs in the garage and is rarely seen on a trail, it only fits tires up to about 2".
The most beautiful carbon unicycle frame I’ve ever seen was made by a guy from Japan, who brought it to Unicon IX in 1998. The thing was a work of art, with teardrop-shaped legs, monocoque construction and just overall good looks. I unfortunately don’t have any scans of those film-based photos; a future project…
The Karbon Koncept carbon frame was still lighter than available aluminium and titanium frames at the time, the KH shortneck was close but has a reasonably shorter neck.
Potentially the new impact gravity or the hydroformed impact gravity could be lighter, but I am unsure.
The difference in weight in comparison to the lightest aluminium frames is still small so I am guessing most would prefer not to sacrifice durability for 10 or 20 grams. That would make the market pretty small.
You can still buy 20" carbon frames, I believe it is likely the company that made the Koxx Karbon Koncept back in the day.
I stand corrected, but I guess you pointed out the main issue: it wasn’t enough weight saving for people to spend the price for something with unknown durability.
For fun I found some carbon 160 mm carbon ebike cranks online too. They similar in my mind to my VCX cranks. So apparently our current stuff is not too bad and there’s good reason to stick with aluminum
100%, the main usage case would probably be trials but I’d struggle to trust a carbon fibre frame that has fallen off a high pallet and hit things on the way down
The cheap aluminum Qu-Ax one say they are about 245g for a 100mm so quick math makes my estimate for a hypothetical 160 maybe 392g or so.
It’s not one for one but I feel like there’s some further weight saving we could make in the aluminum as the sport matures or maybe Ti or another metal.
To me the 100g savings are good with the carbon but there’s other area (rims, spokes, hub, tire, tpu tubes or tubeless) I’d want to save that 100g first.
Tyres and rims are the cheapest reduction in weight you can get. Tyres and rims for sale at unicycle.com are objectively heavy compared to what is available and for general riding are more than strong enough. They wouldn’t necessarily hold up to muni though.
Paying money to get light parts is only worth it if you need extra performance though. Wouldn’t be worth it for general riding on the basketball court.
Agreed, I run carbon and light stuff for road and Unipacking mainly and some light muni.
It’s nice to have the weight savings after an 80km day lol
There’s some pretty beefy carbon and aluminum bike rims you can get that are MTB specific that hold up well with the guys that do muni near me. But I’m with you that a Dominator 2 rim is stronger than your average bike rim for good reason.
I wouldn’t say “extra performance” but “more comfort”. A carbon 36 rim is way more comfy than an alu rim: it’s easier to accelerate, turn and stop. That can make rides more enjoyable
It indeed offer more performance, but that may not be the only goal.
Yep, also getting dehydrated on my most recent unipacking trip I was very happy to have removed 1.5lbs of wheel weight. It def makes a difference for climbs and when I’m dieing. Also I find it lets a smaller crank be more versatile. I can still have my higher rpm but less wheel weight means climbing, stopping, and slowing down are much easier
“Paying money to get light parts is only worth it if you need extra performance though. Wouldn’t be worth it for general riding on the basketball court”
Yes you are right.
36ers are more specialist than riding around on the basketball court and being rare in bikes lightweight aluminium rims don’t exist for them.
36ers are one of the key Unicycles where a carbon rim saves a bunch of weight in the rim and with the large diameter of the rim it makes a big difference in inertia and feel when riding. To be honest you’d probably get improvement in feel (but reducing with each size) on 29’s and 26’s.
In comparison 20 and 24 carbon rims are not really any lighter than light racing bmx rims so for normal weight people doing regular riding, the carbon fibre rims don’t add too much more.
I thought about talking about 29er, but I’m rot sure how much improvement you get there. Certainly a little, but that’s a lot of money for not a big comfort increase - and I ride a carbon G29
