I was looking the UDC website, and noticed the 24" “racers”, which have the super narrow 23mm wide rim and 1" wide tires, similar to road bikes. It dawned on me, why can’t they make a 36er with a narrower rim and tire? Wouldn’t It would be much lighter and more efficient for riding long distances, including centuries? The current stealth rim width is 38mm.
If they could make the same 24" racing rim in a 36er size, along with a 1" wide road tire, (not a solid rubber tire of course!) I would think the weight savings would be substantial, not to mention much less rolling resistance. But maybe a rim and tire that narrow would be impractical for a 36er, and would be too flexy or unstable?
I’ve thought this for a while too. Most of my riding is done in smooth clean roads, and I don’t need the beefy wide tire on my coker for anything, really. I would love to drop another 500+ grams from the outside of my wheel, especially with a schlumpf hub in the mix.
You just need to convince someone, perhaps KH or Coker or UDC, to do it. I assume the problem is low sales volume: they will not sell many and will need to charge a lot to recoup their investment.
A narrow rim and light road tire would be fun. There is a lot of weight that could be saved over the standard setup.
The other option is to go with a 29", which already have lots of options and combine it with a Schlumpf hub.
semcycle makes a thin 43" with a hard, thin rubber tire. That’s probably what you’re looking for, but keep in mind, that big tire is there for a reason, I hear the thin tires are uncomfortable for long rides, too much vibration. http://store.semcycle.com/product_info.php?cPath=5&products_id=21
As I mentioned in my first post, I don’t want a solid rubber tire. That would be extremely impractical for road riding. I think the only real use for those might be in parades or on a gym floor. My thought was to keep the same 36er size, but make the rim much narrower with a much lighter, folding bead tire and a much needed LIGHT weight tube. The weight savings would be huge and distance riding would be greatly improved.
The only negative I can think of would be that the narrow tire would be at a fairly high psi, which might make the rider feel more road imperfections, bumps and so on. The current nightrider tire absorbs a great deal more and would probably have a way more “cushy” ride than a thinner racing tire would, so I’m not sure how a really narrow, high psi tire would feel on long rides.
Terry,
This is a topic that keeps surfacing and just won’t go away. I agree, a skinnier and lighter tire and rim is a much needed improvement in the field of long distance riding and road racing. For some reason the makers of 36" wheels and tires used muni tires as their reference points rather than 700 cc racing bike wheels and tires. Why? We’ll never know. Now it has become the industry standard and no one wants to gamble on the investment in retooling for light and skinny wheels.
I talked to a bike tire sales rep a couple years ago. He said that the tire factories in India require minimum orders of 500 tires, maybe even 1000. I don’t know what sort of minimum a rim maker would require. I’m no metal worker, but I could imaging that it would be possible to cut down the walls of a 36" rim and modify it to fit a skinnier tire. But If you’re going to the trouble of getting a mold made for a new tire then you might as well get a standardized skinny rim into production too.
Fabricating your own sew-up tire is much more reasonable than making your own regular clincher tire. Good luck on that project.
As far as ridability and comfort, until someone makes a skinny tire, it’s all conjecture. My conjecture though (thanks for asking), is that a tire somewhere around 4-5cm wide, fairly thick walls and tread, and with a pressure of about 60-70 pounds would give enough road contact and bounce to function quite well without fatiguing the rider too much. Just a guess.
Geoff, my guess is that they took a “one size fits all” approach, with the [correct] assumption that the wider rim and tire would serve double-duty for both street and off-road riding, making it more appealing to potential buyers who could use it for either, although not the ideal setup for either. The narrow, racing type setup would obviously preclude 36er MUni or even xc. Just a guess on my part.
What’s the difference between a high pressure tire and a solid rubber tire? Semcycle mentions it’s like riding on 85 psi (so like low pressure in a racing bike)
I could see a 1.5 or 1.75 tire making a considerable difference. Much thinner than that and you have the same problems as a hard rubber tire.
A kevlar bead sounds like a FANTASTIC idea actually. I’m not sure if you’d have a lot of trouble seeding a tire that big, but a folding bead on my 20 inch saved half a pound off the old tire!! Probably couldn’t run it with a low pressure on a 36er though, which I guess wouldn’t matter if you’re exclusively on the road.
Those tires are used with smaller wheels, how would the large wheel with a thinner rim hold up to crashes or substantial bumps? Doesn’t the larger-size make it weaker in general?
Road bikes/racing bikes generally have extreme high profile shaped rims for optimum strength and aerodynamics.
A 36er rim made this way would probably be much stronger than the current, much more square shaped stealth rim.
The older “airfoil” 36er rim had a fairly tall profile, and it was amazingly strong. I did tons of good sized drops with mine and the wheel never went out of true. It’s like an arched structure; they are incredibly strong and can withstand far more weight and resist downward force much better than a flat structure.
As I understand it, making a new tire is very expensive, unless you know you’ll sell 10,000 or more. And I don’t doubt this, based on the fact that the only specialized tires unicycles have had in recent years have been 36" (and those are expensive). Does anyone know of other unicycle-specific tires?
Indeed. Most of the weight of a 36" is in the wheel, and the bigger the wheel, the more it magnifies the effect of rotating weight. I would love to try one, but I know it wouldn’t be as comfy of a ride.
As Scott said, the easiest way to go light and fast today is probably to marry a Schlumpf hub with a road bike wheel. You could use 125mm cranks or maybe shorter and spin really fast; the lightweight wheel would make it easy.
But what about all the early cyclists? That’s all they had and they did cross-country and round-the-world rides. The same in unicycling; most of the riders that did crossed-continent and longer rides before 2000 did them on solid rubber tires. They were manly men indeed!
I know this because I have a 45" unicycle with a hard (gray wheelchair rubber) tire. I’ve ridden it in some March of Dimes charity rides (75k) and 5-Boro Bike Tours, but that solid tire gets old pretty quick. Once I got my first Coker in 2002, my Big Wheel was permanently relegated to parades and shows.
Yes it would. It would not be as harsh as my 45" wheel, but probably closer to it than to the 36" tires of today. That would be something you’d have to be willing to give up for the lightness.
My understanding of the history of the 36" wheel is that Coker first made them for a cruiser bike. So they made pretty much exactly the scale of wheel they wanted. I’m sure they didn’t know what MUni was in the late 90s, nor did they associate their unicycle project with offroad riding.
But then we can blame all the makers of the later rims and tires, right? Why be compatible with all of that when your seatposts and bearings aren’t interchangeable? So we have half a dozen choices of 36" tire that are extremely similar to each other. Huh.
But maybe they were also thinking what Coker was also thinking. As bike wheels get bigger, they are inherently weaker. Build your novelty wheel beefy, and people will enjoy it for many years without having to replace the rim, spokes or tire. We have to remember that 36" unicycles are still a novelty to most riders, and it’s only a fraction of owners that use them for long and/or hard rides. So if you’re thinking about the economics of having a special tire made, you need to consider that it will appeal to maybe 5-10% of owners of 36" unicycles. At the most.
Probably a few hundred, but I think way less than what would be required from most tire companies. For rims, I think it’s not too hard to make an existing rim into different sizes. That’s how we got the Airfoil rim. At the time, it was a huge improvement over the original, steel Coker rim, but huge numbers of them were not made. I can’t remember who spearheaded that project, but it was more about convincing a rim-maker to do a custom size of an existing rim, than about designing something from scratch. I think.
4-5 cm is about the same size as the 1.75" tires many of us grew up with. I think you would have decent comfort, but still a lot of rubber and rim. The trick would be figuring out the right compromise between weight and ride comfort (and strength) for a wheel people would want to ride.
Since we don’t race our 36" every day, comfort is more of a factor. For those of you that have ridden racing bikes, you know what I mean. They are not built for comfort. If you’ve never ridden one, they are twitchy, stiff and mean. Built for speed, not for comfort. I definitely would not want the equivalent of that on my road machine. But something around 4 cm, as Naturequack suggested, would probably be pretty nice. You would have to run high pressure, but not as high as with a 1" tire or similar.
It kind of is, but it’s more like riding on 150 psi. The Semcycle red rubber is also softer than the wheelchair rubber on my 45" But on the ones I’ve ridden, the tire is also not as tight on the rim, so I’d be worried about it rolling off if you did aggressive turns & things; stuff that you couldn’t do indoors, and shouldn’t need to do in parades.
Yes. Got to factor that in as well. If you make a 36" out of one of those 24" racing wheels, one sloppy ride off a curb will make a big flat spot in the rim. As the wheel gets bigger, it becomes more prone to flat spots unless you make the rim more substantial, but this can cancel out your weight savings so again it’s going to be a compromise. If you don’t go skinny/light enough, it might not be worth the effort. If you go too skinny/light, it may not hold up well. You can’t fix flat spots by truing.
That’s why I got a new wheel for my 45" when it was about 10 years old. The original rim had flat spots, and a lot of scars around the edges from clipping rocks (the rim is wider than the tire and low to the ground). Those divots translate into cuts on your legs whenever they brush the wheel.
If you’ve read this far, I’ll throw out a simpler, more doable solution to the weight problems. Along with using a 29" tube (which I haven’t tried; I prefer reliability), maybe we can get one of these tire makers to do a tire with thin sidewalls? I wouldn’t want to take away more than a tiny amount of the tread, as I like tires that go for huge amounts of miles. But do we really need all that sidewall? For a “performance” tire it may be a fair compromise, and something I think would be much cheaper to do. I’ll buy one.
I think a lot of weight could be saved if they made a folding kevlar bead 36er tire, AND a super L I G H T weight tube!!! A new gen drilled stealth rim reduced in width to about 30mm (from 38mm) would save even more weight and I would think it would still work with the current nightrider tire.
Well also with considering that these types of tires are usually used with smaller (stronger?) wheels, but also the riders weight is displaced by two tires normally
Concerning the tube though- given the number of riders who use 29-er tubes, it’s obviously an effective way of saving weight. However, there’s also lots of posts on how difficult it is to install a 29" tube on a 36" rim, along with reports of instability.
Presumably, it’s a lot cheaper to manufacture a new tube than a new tyre, so it would seem a good idea to produce a 36" tube with similar weight to a 29", but made for a 36 so it doesn’t need to be stretched on.
Plus, there’s be a guaranteed market as virtually every 36 rider would, assuming the tubes good/reliable, prefer it to the current heavy tube.
I too would love a much lighter 36" tyre and I agree that a narrower width would make the best progress on this. I think the rim is less of an issue; we could use 40mm tyres on current Stealth/Airfoil size rims and it would be a massive change. The rim needs to be extra strong at the large diameter size; it’s the tyre that’s really overweight.
I understand that the reasoning behind keeping 36" tyres so thick is to maintain a bigger contact area for riding stability (avoid squireling etc.) and minimise the side-to-side deformation that thin sidewalls would give you (which bikes don’t worry about, not steering/driving/braking with the same, single wheel).
I do mean to (some day) try building a normal width (about 40mm) tyre for a 36" wheel - possibly out of two touring tyres and a pair of beads cut from an old 36 tyre. That would ensure that the bead would fit (as opposed to making new bead loops from other wire/kevlar cable). The two bike tyres could then be stitched on to the old beads at each side (obviously this wouldn’t have the weight benefit of kevlar bead!). I’m sure that part would work, I just don’t know how good a join could be made at each end of the half-tyres. It may be possible to get a nice, smooth ride, but I suspect it would be quite hard to! Bumpmmmbumpmmmbumpmmmbump?
Only when we have a good prototype of a thinner tyre can the questions about ride quality be properly answered. But real production tyre prototyping is hugely expensive.
Anyone running Titanium spokes and a drilled rim? I believe that coupled with a Ti hub and 29er tube would yeild a very light 36er wheel that one could actually acquire with easy.
That’s an interesting idea, sam. eric (saskatchewanian) has made his own tire before, using some kind of glue and long strips of thick nylon material. He then glued a tread down the middle which he’d pulled from an old mountain bike tire. I think it was only a 24" tire but the concept is the same - he said it was rideable, though I’m not sure for how long!
I’d never thought of using the beads from a 36 tire though, that might make this kind of idea possible for a low-profile 36 tire. Summer only, of course
