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Old 2018-02-06, 08:44 AM   #7
Vogelfrei80
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Join Date: May 2017
Location: Italy
Posts: 273
Quote:
Originally Posted by rich View Post
Agree with you about input and output for one set of fixed planetary gears.

But freewheeling is integral to how these hubs can have changeable ratios, with some gears overdriving others.
The freewheel is not totally its own entity; the clutches that allow such a large variety of engagement of individual ratios also act as freewheels therefore don't engage in reverse.

At least in my understanding of how for example a Rohloff works.
https://www.youtube.com/watch?v=s4UpwoDmOb4
12:45 mentions the freewheel as a specific part. Even if you deliberately seized this in place, because of how the other clutches work you still wouldn't be able to drive it in reverse in most (any?) of the ratios.

I suppose this is to avoid complexity, if the clutches were made to be more complex than engagement pawls and a spring then it could perhaps be made to work.

The old Sturmey Archer 3 speed works in a slightly different way, you can hear the clicking when pedalling in the the higher ratio as the other ratios are overdriven and are effectively freewheeling. It still doesn't work in reverse without modification (I believe these can be converted to 2 speed fixed?)

Don't get me wrong, I'd love to see it! Build me a three speed fixed hub and I've got thousands of pounds you can have!

Motor windings and strain gauges on the input side would be essential though, there is not much point gearing these things down!

Edit: Justin LE's solution is probably the best one. http://www.unicyclist.com/forums/sho...d.php?t=119436
One ratio with variable assist. If you've ever ridden a half decent electric bike with a strain-gauge based proportional assist you quickly realise it doesn't matter which gear you are in as long as it's tall enough so you don't spin out!
I'm also inquiring Bimoz http://www.bimoz.ch/ to power a Huni-rex http://unicycle-c-1/roadtourbasket-c...ack-p-650.html
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