I’m an attorney myself, and I could care less about patenting this. I’m more interested in pushing the designs, and I’d like to see more folks try stuff like this. My only issue is that no one try to take credit for what I’ve actually made, as this is, by my reckoning, the first compact chain-geared 36 in the world. Yes, others such as Tommy Miller (and another guy whose name escapes me) have chain-geared smaller wheels, but not quite like this. And I give all due credit to Harper, Schlumpf, & Unifrank for their incredible internal gear designs.
The commonality here is that once you get used to the dynamics of a geared wheel for purposes of speed, you’ll never want to go back to direct drive. Granted, it’s not the most manueverable uni, but if it’s a fast ride you’re after, I can easily see gearing soon exceeding 1:2, especially with the 36" application.
As for shifting, that remains the holy grail. But without these prototypes, we’re leaving ourselves in the 19th century of unicycling, and it’s about time we “gear up”!
Unisk8r, thank you! I hate it when people tell others to patent stuff like that. It is likely that others have thought of this before you, so if they had patented it, you would’ve been unable to build it. That just seems pointless.
I must agree, geared uni’s are the holy grail for speed. Even if they aren’t actually faster (although they are faster), they are lots more fun to ride. I have a hard time imgaining gearing past 1:2, since that just seems excessive. Kind of like Brian’s 40mm cranks… (not to say it didn’t look like a fun idea)
Gearing in excess of 1:2 makes perfect sense. The goal should be to have a cadence of about 90 to 100 rpm at the speed that you wish to maintain. Spinning at 150+ rpm is crazy and not efficient. So if your goal is to set the 1 hour time trial mark at 20 miles then gear the unicycle so that you can go 20 mph at 90 to 100 rpm.
The 1 hour time trial record and the 100 mile record are beatable with a properly geared unicycle and a strong, fit, skilled rider. So when are the records going to fall?
I’m not so sure that the 36" Coker wheel is the best wheel size for these high speed geared unis. A 29er might be better. The 29er is lighter and you can find better suited tires. Gearing a 29er up past 1:2 will get it going plenty fast.
A few of us today were trying to figure out how that French geared uni would work, with the final conclusion of it shouldn’t, due to the fact that you can’t shift the deraillers with the chain going backwards. Has anyone experimented with a Continously Variable Transmission design of somesort? If some one designed a CVT system which gave a smooth, even shift throughout the entire gear range, that would be awesome… The Holy Grail of geared uni’s…
I think the issue with a CVT (if I uinderstand them correctly), is that it’s difficult to retain adaquate belt tension, and also where to put one. You could run a cvt right above the crown , but I think it would be rather difficult, and would need to be extrememly compact.
BTW, my understanding of a CVT is that it has two cones pointing opposite directions and a belt running between them. The movement of the belt effectively shifts gears. Is there any other way to do this? I like the idea because it would be somewhat possible to make it work on the fly, whereas other shift-on-fly methods seem to involve nasty freewheeling or locked wheels. Freewheeling may be possible, but a locked wheel will just smash the seat into the ground, possibly taking the rider with it.
On Mon, 22 Nov 2004 21:32:44 -0600, “evil-nick” wrote:
>A few of us today were trying to figure out how that French geared uni
>would work, with the final conclusion of it shouldn’t, due to the fact
>that you can’t shift the deraillers with the chain going backwards.
I’m not sure but from the pictures it seems that one of the
derailleurs is mounted ‘the other way around’, so that both chains fun
forward with respect to the derailleur.
I was wondering where the seat will be. On the site it says (in
French) above the pedals. Initially I thought he meant it to be on an
extension from the (about) vertical tube you see, but then it would be
in the wrong place, balance-wise. So it’ll probably go on top of an A
shape of frame extension mounted on the studs visible in photo 2. Of
course the seat axis should point roughly to the centre of the wheel.
So it would be a geared giraffe.
But, why a knobbly tyre for a geared fast uni?
Klaas Bil - Newsgroup Addict
“Deflating pi does not reduce calories, it just concentrates them. - billham”
I think high revs are actually quite good for distances. I know that my legs feel better after a unicycle ride at high revs than a bike ride at lower revs when riding at the same intensity for the same length of time. But I agree- 150+ is probably excessive, maybe 120-130rpm would work well.
I have plans for the 100 mile and 24hr record early next year. I’ve got a hundred mile race this weekend but it’s not suited for the record- with 1500m of climbing, I’d be happy to get in under 7hrs30. I’d love to try the geared uni for the record though.
well I am no mechanics but I have been googling like mad on this subject for months: there are CVT without belts
that rely on direct contacts with rollers with strange shapes.
I’ve shown a design of my own to an engineer but he told me the friction will lead to inefficient transmission … so still enquiring.
and, just to clarify, I didn’t tell anyone to patent anything so that it could never be made by anyone else ever again. I suggested that unisk8r thought about it to make sure that no-one could exploit his idea
He obviously has thought about it, which is plenty good enough for me
mgrant, if there was any uncertainty in my choice of wording, then feel free to copy my design and see if I sue you! LOL!!
Understand that almost everyone who has seen this says that same thing (you should patent that), without thinking about the limited uni market, or the problems of worldwide patent enforecement.
This design could not be patented in the UK, once something is in the public domain (e.g. putting a photo on this forum) it would be too late to apply for a patent. I believe there are subtle differences in the US.
The cost of getting a ‘water tight’ patent in a single country is not particularly cheap, the annual cost & costs fighting an infringement would probably be to big for the size of the unicycle market.
As an aside I wonder how many active patents still exist for bicycles nowadays?
Can’t wait to hear the long term reports on this design, it looks great.
On Tue, 23 Nov 2004 01:01:34 -0600, “GizmoDuck” wrote:
>I think high revs are actually quite good for distances. I know that my
>legs feel better after a unicycle ride at high revs than a bike ride at
>lower revs when riding at the same intensity for the same length of
>time.
Then why don’t you switch to a lower gear on the bike?
Klaas Bil - Newsgroup Addict
“Deflating pi does not reduce calories, it just concentrates them. - billham”
It’s harder to spin high revs on the bike because the cranks are generally longer. So even if you did switch to a lower gear to allow higher revs, you legs are still doing a lot more work, because your limb movements are much greater.
I’d like to try shorter cranks on my bike to see if the theory is correct.
There’s lots of stuff out there about low vs. high cadence, and what crank lengths are better for spinners vs. pushers. There’s also info on selecting a crank length proportional to your leg length/inseam…Captain Bike (Sheldon Brown) has a good article: Bicycle Cranks
I’ve already ordered more cogs to increase my gear ratio, and am considering a slightly longer crank (155mm) to preserve what (little) wheel control I have. But even if I went super high on the gearing, I wouldn’t violate the proportional crank length rules, which for me means never exceeding 170mm.
Beautiful prototype, Pete, and an innovative design. It will be interesting to hear your reports about performance as they come out.
Spinning rules for bicycles may not be relevant to unicycles. I have found that spinning on a bicycle is much different than on a unicycle; it uses different seat heights, the body is in a different position, the foot-pedal connection is very different, the balancing needs are different, the stability of the body-seat connection is different.
I have found that different muscles get sore/tired.
As uni speed increases, air drag will become more of a factor and then leverage on the pedals will become an issue in crank length. However, we have a ways to go in that department, except for outdoor time trials which may include a headwind on one leg.
It is also important to remember that your specific intention with this beautiful machine is to set a unicycle speed record. It is not designed for touring, or for mixed-slope trips. So your crank length would have to be optimized for max speed, not average speed, or ride-all-terrain, or city manueverability, or climb-the-Sierras, or any of the other situations that 36" unis find themselves in.
Although there is a lot of literature on crank length for bicycles, it may not be relevant to unicycles. It may take semi-controlled timed experiments with different length cranks to develop a sense of what kind of overlap there is between the two fields.
Thanks for weighing in, Dave! Actually, I’m not saying that I’m gonna the rider who breaks a speed record, but it sure seems that this machine would do it for just about anyone!
As for the applications, I feel that having different crank lengths (i.e. the triple pedal holes) allow use of a geared wheel on a moderately hilly route. I’m going up some grades with the pedals in the 150mm position that surprise me. With a bit more speed output in the slower cadences, it almost seems easier to balance on a grade than a direct drive. I haven’t yet tested a hill in the 170mm position, but I’ve got a big hill nearby to try it.
So far, I really like the geared feel, and now look at the direct-drive as “undergeared” for normal riding.
Happy holidaze!
I’m wondering about the cost to build and if the design is adaptable to a non-Hunter frame. It seems to me this would be less expensive to make then the internally geared hub.
Yes, that’s possible, and maybe easier than the dual downtube frame. All you’d have to do is weld on twin vertical dropouts on the back side of a single frame leg, then drop in the same jackshaft assembly, using the same chain tensioning system. Due to the single leg, you wouldn’t need a full jackshaft housing like I have. Just the dropouts themselves could support the jackshaft axle. The frame leg would still run between the 2 jack cogs. And if you have a single frame leg like on the std. Coker frame, it would be even better because that leg is vertical, not angled in.
