Thanks. I didn’t hit 40 kph yet, just 30kph, we’ll need shorter cranks than the 150’s which are currently on there to do 40+, and probably a braver rider than myself!
Anyways, we got the new steel planet carrier all machined up:
And now the backs of the pins are welded in place, so no more concern about the planet carrier being a weak link in the mechanical system.
Since reassembling it with these fixes it rides amazing. The new strain gauge system holds the zero torque point much better so I’ve been able to dial up the responsiveness, and the mechanically things feel tighter.
There have also been a few rounds of firmware enhancements. I’ve now got it so that you have an up-down push button for the setting the bias torque of the motor in Nm, and a potentiometer knob for adjusting the gain amplification of your pedal effort.
Riding along, I would first dial the gain up to a value that makes it much easier to balance the unicycle but doesn’t overshoot on each down stroke of the cranks. Then whenever there was an up hill ahead I would hit the “up” button a few times to give the desired level of hill climbing torque, and similarly on the downhills I’d hit the “down” button until the braking force was just right.
It works freaken amazing. Now we’ve got to pack it all up for travel to Spain and realllly look forwards to letting the wider community test this out and see what it’s good for.
Hope to see many of you at Unicon in just a few days.
You repair parts and make modifications faster than most people can post on the forum. I was just going to suggest that you peen the pins into the aluminum plate and you’ve already machined a steel one and spot welded them. You rock, Justin.
Well, it turns out that I did have problems with my flight to Unicon but not related to the unicycle, rather my passport went missing at the worst possible time! So had to get a rush/replacement on that and had an extra couple days in Vancouver to do some more upgrades before the event.
Rather than have the batteries hanging from a bag in the handlebar, I welded up an extra set of tubes to the frame so that they could be properly supported behind the unicycle. This also linked the two frame tubes together which increased the overall frame stiffness a good amount.
I found a perfect sized seat bag from a bike shop to fit in this area which can hold up to 4 of the small 100Wh packs, and the result is pretty clean.
It also gave us some time to make a little film showing the unicycle in action
So far it’s generated a lot of interest at Unicon but nobody has broken 40kph yet, I’m still working to convince the skilled riders to put some more faith in my engineering here
Some fantastic engineering there. Impressive work!
I wonder if you can answer a question for me? I have been thinking about how unicycle hubs are constructed, specifically, how the axle is connected to the flanged hub part? I am currently building a little Arduino based CNC machine with the first goal of machining some bearing parts so that I can construct my own frame. Beyond that, I would like to look at making my own hubs. Any thoughts? Thanks for any information
On the all-steel nimbus hubs like this they are welded on, and you need to be a bit careful about that detail when machining them down. Not only is there a risk of removing too much of the weld bead, but the material properties are different on the welded area and sometimes that results in damage to the cutting bit.
Other hubs are made with interference press-fit parts, and aluminum hubs (like mad4one) would typically be machined either from solid bar stock or from a forging.
Machining the hub and hub flanges is the easy bit, but the spindle with the ISIS splined taper would be a real challenge. I’ve never bothered to attempt this and have always hacked up old spindles (either from bicycle BB’s or from other uni hubs) or doing these custom unicycle hub projects.
A square taper spindle seems easier to machine than ISIS, but would have to be a strong metal like steel or titanium.
Well sorry that you didn’t get a chance this time around, but if you are in the US I’ll have it (or a future model) at the 2017 NAUCC event in Seattle next summer. The good news is that lots and lots of people at Unicon did get to give it a go and the feedback was super useful and for the most part positive. For anyone who had significant Schlumpf experience it was no problem to hop on and ride, but there were even a few people who had never ridden a geared hub before and managed after just a minute or two to be pretty comfortable on the machine.
Here we were at the city where the downhill competitions were held. The guy coming off the unicycle Christoph has also built his own internal geared hub with the ring and sun gears reversed so that it has like a 2.5:1 ratio, which unfortunately I didn’t get a chance to see but he’ll be racing with it in the marathon ride tomorrow.
Katja from Germany had visited our Vanuni club in Vancouver several years ago and really schooled us in hockey, and it was nice to see her again.
I was also really in Roger’s opinion on this project, especially as he’s known for spinning fast with short cranks on big wheels. He found the automatic assist a bit weird and preferred having the pedal torque multiplier turned way down and using the up/down button for steady power assist. While for most people, the torque multiplier from the motor is what is needed to make it rideable.
And Finally, Anne-Sophie has grown quite skeptical of testing any my unicycle creations since getting injured on my earlier prototypes some 5 years ago. But after sooo many people at unicon were giving the thumbs up on this one she at last gave it a go and cracked a smile too:
So I used it on the 10km street race early in the event, but since it was wet and raining outside and this was the first real ride for me on it in Spain it took a good 4-5 minutes on the course before I really got comfortable. I finished the 10K in exactly 22 minutes, so not nearly as fast as the top riders who were right around the 20 minute mark. And my top speed was 36.3 kph, so still a ways from 40.
Martin who won the 10K race by a huge margin also gave a spin on the geared electric unicycle after the uphill event, but I think he was more interested in playing around with the assist and regen levels than breaking any speed barriers, or he didn’t want to have a nasty crash before the final competetions had all wrapped up.
I took it to the track and field oval hoping that this might be the right spot to find someone with the balls and protective gear to crack 40kph, and Josselin proved a willing participant
And he came soo close repeatedly hitting 38 kph on the straight segments of the oval, but it wasn’t getting any faster than this.
Then at last I caught up with Scott Wilton at the unicon village on my last day there. Scott had tested the first prototype non geared electric unicycle at the 2010 muni weekend in Vancouver, is pretty much fearless of speed on 1 wheel, and I was hoping would find this one a comfortable fit to push to its limits.
He disappeared up the road beside the stadium, came flying back a couple minutes later, and smashed my best expectations, getting 45.2 kph (28mph) on the flat run while also dodging people mingling on the street.
Anyways for me the main personal use and goal for this unicycle is not speed records so much as having the ability to cover distances and commutes that I normally otherwise wouldn’t have considered.
Where we were staying in San Sebastian there was what looked on the maps like a nice ride westwards with some good elevation climb to the town of Orio, which made for a ~40km return trip going from sea level to 1150 feet each way along a ridgeline overlooking the water.
Corbin was game for this ride so we did it together with him on the Schlumpf 36. Of course I had a big advantage on the uphill climbs but on the flats we were pretty well matched for speed, while going downhill I tended to keep in the <30kph comfort zone generating 300-400 watts of power into the battery via regenerative braking, while Corbin would fly forwards at 40+ kph.
Most of the ride was on nice country roads but on the return we ventured up what looked like an alternate crudely paved path that became a section of the Camino de Santiago hiking trail, where rideable sections were few and far between.
Corbin shot some video footage and uploaded it here:
The total regen stats were pretty good, but part of that is because we hiked rather than rode up most of the elevation gain on the return trip when were were on the Camino trail. Had we taken the roads it would have been more like ~30% regen.
One other detail that I found interesting is that the human watt-hours and electrical watt-hours have almost always matched up nearly exactly 1:1 every time I’ve taken this unicycle for a ride. It’s the same riding on the flats in the city or going on this long tour with plenty of up and down. At the end of the trip, half the energy came from my legs and half from the battery, and that’s a ratio I’m pretty happy about.
Thanks Terry for revising this thread. I missed the Unicon updates.
The uni weights like several unis but still it rides nicely. The feeling at the beginning is bit like starting in high gear on Schlumpf, but then when you add the assist it rides so well. I tried it only for a little while and corners were troublesome for me, but I guess it’s something you can get used to.
Thanks Justin for the opportunity to try such a cosmic uni (even if this one looks so much casual than the machine you had in Montreal).
And whoa Scott, you are fearless!
but still it rides nicely. The feeling at the beginning is bit like starting in high gear on Schlumpf, but then when you add the assist it rides so well. I tried it only for a little while and corners were troublesome for me, but I guess it’s something you can get used to.