This past weekend I was graced with a visitor from the Pacific Northwest - none other than Mr. Harper, the inventor of the uni.5 and Blue Shift geared hubs. My house was his first stop on a cross country journey to NAUCC - driving a car completely loaded with unicycles of all kinds.
We’ve colaborated a little bit on the design of a geared unicycle that, hopefully, will be available in the near future at a reasonable cost. My part of the project is the frame and Harper’s part is, naturally, the hub.
Last week Harper received some sample frame parts from the overseas manufacturer so he sent them to me along with a prototype hub, also manufacturered overseas, so I could check them out and make sure the frame was what I had in mind and that the hub fits the frame.
I wanted to try and assemble the parts into a ridable geared hub unicycle before Harper arrived Friday night. I was able to get a 29" wheel laced to the hub and hub guts installed by Friday. Saturday afternoon (after a morning MUni ride where Haper showed my how MUni is REALLY done) we finished putting the frame together, installed the tube and tire, cranks, seat, etc. and took it for a spin around my neighborhood.
I put 170mm cranks on it mainly because that’s all I had available to use but I also had the idea it would make the thing easier to ride in 43.5" mode. Harper took the first ride and said that it was “10,000 times easier to ride than Blue Shift” with the long cranks. I thought that was an exaggeration though … it only seemed several hundred times easier than what I recall about riding Blue Shift with 150mm cranks.
Harper rode the new geared hub uni and I rode my non-geared 29’er along a paved bike path. I was pedaling like a demon while Harper was just loafing along. The plan was for Harper to ride the geared uni “out” and I’d ride the geared uni “back”. Unfortunately it broke … a weld failed on the frame … so we both got to walk “back”. Oh well - that’s what prototypes are for and I’ll have it fixed and ridable again this week.
The attached picture is Mr. Harper with the new geared hub uni on his right and my 29’er on his left.
So, any secrets as to how it works? Is there a chance of getting a nice portable 20" geared to 36"? When you say ‘reasonable cost,’ is there a ballpark figure of what that means?
That sounds like a great idea. I hope it works, 'cause the world needs a good geared uni!
Steve:
Your frames look really nice. It’s a shame you didn’t get to ride back but at least it was the frame and not the reproduction hub that broke.
Greg (on the road):
Had you ridden on the ‘overseas’ prototype hub before Steve laced it to a rim or was this your first go at it? Also, does this mean that you’re close to relasing a production epicyclic hub equiped uni? Steve, maybe you can answer this since Greg’s out on the open road?
When I first saw that pic, I thought that was blue shift on the left. I was wondering why it was silver. So is that a frame that was made overseas? It looks great! Can’t wait for the production models to be released!
You do need to dismount and fiddle with a bolt to change the gear.
There is a short lever arm that is part of the hub. When the end of that lever arm is connected to the frame the hub is geared to 1:1.5. When the lever arm is disconnected from the frame (and bolted in place to the hub itself) the hub is in a 1:1 gear. Changed the gear is a matter of removing a bolt, positioning the lever arm in its new position, and putting the bolt back in. It takes a minute or so to change the gear. With practice you can get faster at the gear change process.
Oh, and there are pictures of Greg’s original version of the Uni.5 hub in the gallery.
<http://gallery.unicyclist.com/albun23>
You can see the lever arm on the hub and how it bolts to the frame to put the hub in to the high gear.
The hub that is being made overseas is slightly different in design but basically the same.
The geared hub uni is Harper’s thing so I don’t know anything about cost or when they’ll be available. I think the hub is very close but the frame has some problems that still need to be worked out.
Greg made two epicyclic hubs - one was built into a 24/36" uni dubbed “uni.5”. His other hub is what Blue Shift is built around. The hub and frame I have are the first overseas version that have been assembled into a ridable unicycle. The big difference between Greg’s first two hubs and the new one I have is that the new one can be disassembled without having to remove the spokes. That’s a good thing! Other than that it’s just the same as the original version.
As John explained, the hub is shifted by changing the position of a screw. The question that has been asked before is “can a hub be made that will shift on the fly?” Anything is possible but shifting a unicycle hub on the fly is a very difficult problem. One of two things must happen when changing gears. Either the hub must be completely stopped while BOTH ratios are momentarily engaged (thus locking the hub) or the hub must free-wheel BETWEEN the two ratios. Either one would be a problem on a unicycle. I’m sure someone somewhere could learn to shift a unicycle while it freewheels but …
Another problem with a shift on-the-fly unicycle would be shifting gears in the rider’s brain. The difference between 29" and 43.5" modes is dramatic. I find it takes some time to get used to the difference after shifting the hub. Again, someone, somewhere could learn to deal with the instant change in ratio but I’m not sure I ever could.
Naturally, shift on-the-fly would make the hub more complicated and expensive to make too.
I’m sure Harper will run the prototypes through the gauntlet to be sure they hold up.
The 29er frame has a hole machined for the fixing bolt. The original uni.5’s Torker frame was just drilled in the right place. I have no idea what the plans are for frame sizes but unless you plan on gearing up a Coker the 29er frame should accomodate all the other wheel sizes.
The hub by itself would probably fit most unicycle frames. It is about 1/8-1/4" wider from bearing center to bearing center and most main cap bearing frames are somewhat forgiving along the axle. Those frames could use the production hub and be strapped to run in 1.5 gear mode full time rather easily. The frame that will accompany the production hub has holes bored in strategic locations to relatively high tolerances that will make it easy to shift from one mode to another. This is the way Blue Shift is made. It also has machined bearing holders and, as such, must fit the axle to length quite closely.
The bent axle on the original uni.5 hub was made of 1018 or 1022 soft steel. The latest oversees prototype that I received was made of heat treated 4140 Stainless hardened to Rockwell C-37. I think it is hard enough to accept any steel cranks and tough enough to resist bending and twisting especially since the primary use is as a road unicycle, not a MUni or trials rig.
The weld that broke on the prototype frame connected the seatpost tube to the crown. When Steve and I looked at the frame before it broke we agreed that the weld was unnecessarily stout. Little did we know that it would be the point that failed. Had the manufacturer adhered to Steve’s tolerances, the tube would have been a nice, tight press-fit into the crown. After the weld broke, it was clear that this fit was sloppy and the only thing holding the pieces together was the weld itself…not good practice. The frames that Steve has made himself are not welded at all but use the press fit and a roll pin to anchor the parts. I have had no trouble with either of his frames that I own.
Meeting Steve and staying at the Howard household was a real treat and only serves to reinforce my belief that unicyclists are the finest of folks. The Howards were kind, generous, and tolerant hosts. Especially Brenda who had to accommodate the first of perhaps many eccentric “loony-cyclists” who make the pilgrimage to Pocatello, Idaho, the home of Kinport Cycles. Fortunately for me, Steve has no local riding partners so all I had to do to look good was any one thing on his “home court” trail that he couldn’t do. I just showed him how to handle the flat parts.
I agree that Steve is an excellent human being. He was very helpful in building my MUni, and saved me a LOT of money!
So Harper, what is different between your new hub and the Blue Shift? Why is it so much easier?
Can we get an estimate on how soon this will be available (this year, next year, five years?) and approximately what it will cost (hopefully less than the ring Kobe bought for his wife)?
I second that motion, though a 50% speed increase while Cokering is a frightning, but exciting, proposition. Imagine a cruising speed of 22MPH?! Might have to start riding in full leathers . . .
