I think you mean concentricicicity 
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I umm, don’t know what you mean 
It doesn’t help that my spell checker doesn’t understand the word concentricity, so concentricicity looks identically wrong when checking messages
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Awesome! Please share a link!
First a plea. Please don’t everyone go out and try and work out how to get hold of one yet unless you’re prepared for possible disappointment.
So far nobody has tested them on a unicycle, and I’ve no idea about availability (probably poor with the pandemic situation and the other issues right now in the cycle manufacturing world).
@rogeratunicycledotcom is going to enquire.
With that out of the way, it’s the 1:1 freewheel hub of the bicymple (https://shop.bicymple.com/)
Some info got posted on the Facebook group.
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What about the geared hub from the penny version?
Super dangerous! Rolling at 25km plus per hour and freewheeling…
Is that a real issue? I can top at 27+ kmph on a freewheel with a good brake. A geared freewheel hub would certainly need some time to be used to it but it can be great.
What about the geared hub from the penny version?
It uses/used a freewheeling Schlumpf hub.
As they were custom engraved with bicymple, they clearly had a production run done for them, but I had previously presumed that they were square taper hubs.
Based on these 1:1 hubs being ISIS I’m now thinking that they had a custom run made of freewheeling ISIS Schlumpf hubs, which with the BrakeFast Schlumpf Brake Adaptor would allow a 2 speed freewheeling unicycle with a disk brake.
They apparently enquired about another run and got nothing, so clearly Schlumpf isn’t making custom freewheeling hubs or unicycle hubs.
Now someone just needs to find a 2 speed bicymple owner who wishes to part with it…
Super dangerous! Rolling at 25km plus per hour and freewheeling…
Honestly I don’t think it’d be that bad. I’ve done 25kph on my freewheel downhill and it felt fine.
Because you’re not spinning your cranks around madly, if you’re doing brake assisted freewheeling then that speed doesn’t feel all that bad.
There’s a 3.8 ratio on some geared hub
The JR Game Changer hub is 3.8x geared, but it’s single speed so not all that useful, and it requires a custom frame.
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The only other way I know of getting this right now is the MC² driving wheelset but it would require some custom frame work and I don’t think anyone’s got hold of or tried one of these yet.
However based on their prototype, I think that the MC² wheelset might allow you to vary the friction that enables the second gear effectively giving you a rudimentary CVT.
The prototype used a second disk brake to lock the gearing for the second gear. Not sure what they’re using now.
When I was fond of freewheeling I measured a Nightfox to have an acceptable legs bend to accept an MC2 hub. Maybe I should have old emails with them. However it was like 127mm or 123, just a few mm in difference, enought for a small bend in a 26-29 build
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My thoughts around the custom frame work was more for the gear change mechanism than the spacing, as I had also presumed that for my large wheel interests I could easily bend a frame to be whatever required.
I put a message on the facebook group (thanks Robin for your answer), but I should have put it here. While disassembling and reassembling the hub, I’ve broken the pawl spring on a nimbus hub several times (Jeanbute sent me the pawl springs of the many hubs he broke while riding uphill, but I broke them one by one…). 
I did some research on the internet (google/aliexpress) and the most common pawl spring size is 26mm diameter and 0.8mm thick. I ordered one, although I’m a little worried that it’s too big… I tried to take measurements of the broken spring, but it’s not so easy… I would have thought it was more like 24mm, but that’s not a size I was able to find. I’ll let you know if it does the trick. 
Quick question for those experienced in freewheeling, do you find you can go faster on road once you master freewheeling as compared to a fixed unicycle?
Does exist anyone who could master a freewheel right now?
There are various who can ride a freewheel.
I have a freewheel uni myself, but never mastered it. I had a hard fall off the back and am reluctant to put time in learning again. UW ended up being easier to learn
As for going faster on a freewheel uni, I don’t think so, unless you go downhill. On flat your speed depends on how fast you pedal. When you stop pedaling, naturally you continue, but you won’t pick up speed.
There are a bunch of videos linked in this thread, e.g. go back up to this post
https://unicyclist.com/t/freewheel-unicycling-megathread/267800/4?u=ruari
Also more recently
But (in most countries) terrain varies. On a given route there will be uphill, flat and downhill. If you are the same speed on the first two but faster on the downhill on average you have the potential to be faster, don’t you?
I should make it clear I have never ridden a freewheel uni (@UniMyra has offered to lend me one of his but I have yet to take him up on that). Anyway my assumption was that overall, if you master it, you could be faster.
Also, even if you are not faster, it does look like a lot of fun! 
(well… apart from the falling on your back part, obviously 
)
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