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Old 2013-08-02, 03:31 PM   #1
waaalrus
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3.8:1 geared direct drive wonderhub

Due to my continued interest in freewheel unicycling I read a lot about drift trikes and I came across this interesting photo:

https://www.facebook.com/photo.php?f...&type=1&ref=nf



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JR Drift Trikes

We've got both our prototype trikes running the 3.8:1 geared direct drive wonderhub, aka the game changer! Both have got our custom JR rotors on them, the white one now has a post mount holding the brake calliper
Notice the Nimbus Venture cranks! This doesn't work for freewheel unicycling because it's direct drive but I'm curious if anyone's seen anything like this. Is it maybe a regular bike hub and they mounted the cranks in a special way? It looks like there may be more developments soon and maybe they'll give out more information.
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Old 2013-08-02, 03:46 PM   #2
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Quote:
Originally Posted by waaalrus View Post
Due to my continued interest in freewheel unicycling I read a lot about drift trikes and I came across this interesting photo:

https://www.facebook.com/photo.php?f...&type=1&ref=nf





Notice the Nimbus Venture cranks! This doesn't work for freewheel unicycling because it's direct drive but I'm curious if anyone's seen anything like this. Is it maybe a regular bike hub and they mounted the cranks in a special way? It looks like there may be more developments soon and maybe they'll give out more information.
Interesting. With internal planetary gearing the best you can do, theoretically, is 2:1, and in practice the best you can do is a lot less than that. (The Schlumpf is 1.54:1). Maybe there's a hidden jackshaft in there somewhere?

The big questions are the amount of backlash, and the behavior when pedaling backwards; the NuVinci hub, for example, doesn't really have backwards ability, although Justin managed to modify it to make it possible to use on a uni. (At a weight penalty of 12 pounds).
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Old 2013-08-02, 04:04 PM   #3
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Originally Posted by tholub View Post
Interesting. With internal planetary gearing the best you can do, theoretically, is 2:1, and in practice the best you can do is a lot less than that. (The Schlumpf is 1.54:1). Maybe there's a hidden jackshaft in there somewhere?

The big questions are the amount of backlash, and the behavior when pedaling backwards; the NuVinci hub, for example, doesn't really have backwards ability, although Justin managed to modify it to make it possible to use on a uni. (At a weight penalty of 12 pounds).
I wonder how heavy this hub is. A lot of the backlash in typical IG hubs is due to the need for shifting. Since this hub is a single gear it seems logical that it would have much less backlash (although not completely without).

So, with a 20" wheel this would equate to a 76" gear? That is a huge wheel. I don't know if I could push that with cranks short enough to clear the ground on a small wheel.
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Old 2013-08-02, 04:10 PM   #4
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I wonder how heavy this hub is. A lot of the backlash in typical IG hubs is due to the need for shifting. Since this hub is a single gear it seems logical that it would have much less backlash (although not completely without).

So, with a 20" wheel this would equate to a 76" gear? That is a huge wheel. I don't know if I could push that with cranks short enough to clear the ground on a small wheel.
Whether or not a planetary hub is shiftable, it will have backlash; it's a function of the gear teeth moving from one side of the groove to the other. Harper's hub had more backlash than the Schlumpf does, mostly because Harper's not Swiss (the tolerances weren't as tight).

A 76" gear would not be a problem to ride once you got it up to speed. Getting it up to speed would be a challenge.
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Old 2013-08-02, 04:43 PM   #5
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Why is everyone quoting the post directly above theirs? Isn't that a given?
Sorry... just something I noticed.
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Old 2013-08-02, 04:50 PM   #6
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Originally Posted by tholub View Post
Whether or not a planetary hub is shiftable, it will have backlash; it's a function of the gear teeth moving from one side of the groove to the other. Harper's hub had more backlash than the Schlumpf does, mostly because Harper's not Swiss (the tolerances weren't as tight).

A 76" gear would not be a problem to ride once you got it up to speed. Getting it up to speed would be a challenge.
I know there will be backlash, but much of the regular backlash is designed into the hub to allow the key to move in the keyway. Without having to release the key, and slide it into a new position you would be allowed to tighten up the tolerance quite a bit.
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Old 2013-08-02, 06:30 PM   #7
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Interesting. With internal planetary gearing the best you can do, theoretically, is 2:1, and in practice the best you can do is a lot less than that. (The Schlumpf is 1.54:1). Maybe there's a hidden jackshaft in there somewhere?
Compound gears can be put into a planetary hub. It's only simple gearing that imposes the theoretical 2:1 limit.
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Old 2013-08-02, 06:49 PM   #8
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Compound gears can be put into a planetary hub. It's only simple gearing that imposes the theoretical 2:1 limit.
Fair enough, but wouldn't that require three sets of planets?
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Old 2013-08-02, 08:56 PM   #9
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Fair enough, but wouldn't that require three sets of planets?
I've never looked at space constraints for compound geared fixed hubs. In the case of a compound planet gear, the sun can be big, the part of the compound planet contacting the sun can be small, and the part of the compound planet contacting the ring can be big. the hub starts getting big as the ring gear necessarily expands. There is also a limit to how big the the larger of the compound planet gears can get because they start crashing into the axle.
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Old 2013-08-23, 08:33 PM   #10
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I guess I don't understand the term "direct drive" very well. It sometimes seems to be used in conjunction (as opposed to contrast) with freewheel. Looking at the video it looks like this hub does freewheel which means I may need try one on a unicycle.

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Old 2013-09-17, 04:08 PM   #11
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I checked with the makers and the bad news is that these are custom dropouts so if you want to make a unicycle out of it without a lot of modification you'll need to use their forks which limits the size of the wheel to 20". The good news is that they will be selling these front ends separately so I think the only thing you would need to do is notch the steering tube and put in a unicycle seat post and seat post bolt. Pricing is still forthcoming but I'm excited about the possibility of a 20" wheel geared up to feel like 76".
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Old 2013-09-17, 07:20 PM   #12
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Originally Posted by waaalrus View Post
I'm excited about the possibility of a 20" wheel geared up to feel like 76".
You might be the only one. Well I suppose to be fair I am quite excited about the idea of seeing somebody attempt to ride one
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Old 2013-09-17, 08:59 PM   #13
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You might be the only one. Well I suppose to be fair I am quite excited about the idea of seeing somebody attempt to ride one
My thoughts exactly.
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Old 2013-09-17, 09:38 PM   #14
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You might be the only one. Well I suppose to be fair I am quite excited about the idea of seeing somebody attempt to ride one
I'd ride it to school! I need a faster uni without killing my Muni tire on pavement. The 20" wheel would even fit in my locker!
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Old 2013-09-19, 06:03 PM   #15
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Originally Posted by waaalrus View Post
I guess I don't understand the term "direct drive" very well. It sometimes seems to be used in conjunction (as opposed to contrast) with freewheel. Looking at the video it looks like this hub does freewheel...
If I understand correctly, Direct Drive means you are directly driving the wheel, like a unicycle or a tricycle. I do not know if this allows for a gearing system in between.

Fixed Gear (or Fixie) means there is no freewheel. Whatever the gear is, that's all you get, forward or backward. So those trikes may be direct drive, but they are not fixies.

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...I'm excited about the possibility of a 20" wheel geared up to feel like 76".
It'll be rideable, but very sluggish. Don't listen to the naysayers.
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