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From: AMuzi <am@yellowjersey.org>
Newsgroups: rec.bicycles.tech
Subject: Re: Only 14 gear ratios? Primitive!
Date: Wed, 4 Dec 2024 10:16:59 -0600
Organization: Yellow Jersey, Ltd.
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On 12/4/2024 9:39 AM, Zen Cycle wrote:
> On 12/4/2024 9:54 AM, AMuzi wrote:
>> On 12/3/2024 11:05 PM, Frank Krygowski wrote:
>>> Bike transmissions: Derailleurs are easy to understand. 
>>> Internal gear hubs are more complicated. (When I was 
>>> teaching, I had our machinist do a cutaway of a Sturmey- 
>>> Archer AW hub and mount it on a display stand near an 
>>> explanatory poster, so interested students could see what 
>>> made it work.)
>>>
>>> Rohloff 14 speed gear hubs are an order of magnitude more 
>>> complicated than AWs. But this new gizmo makes a Rohloff 
>>> look like child's play. It's a true continuously variable 
>>> transmission, with an infinite number of gear ratios, 
>>> that is completely gear-based. No slipping surfaces, and 
>>> supposedly minimal friction losses.
>>>
>>> Here's the link to the half hour explanation video:
>>> https://www.youtube.com/watch?v=mWJHI7UHuys
>>> You may want to start at about 14:30 before returning to 
>>> the beginning to digest the super-complicated explanation 
>>> of it's operation.
>>>
>>> No info in the video about prototype weight, efficiency, 
>>> etc.
>>>
>>
>> Brilliant and clever! Thank you.
>>
>> I can only see complexity, cost to fabricate and weight as 
>> downsides, none of which would be deal breakers for some 
>> applications. Motor power for example.
> 
> It actually seems to me to be significantly less complicated 
> than a standard automatic transmission
> 
>>
>> Sort of the inverse of fixed, which are dirt cheap, light 
>> and reliable at the cost of zero gear variance.
>>
> 
> Nothing a good pair of legs can't handle :)
> 

I have to admit I don't know much about modern electronic 
control slushboxes (except to avoid them) but the geared CVT 
is much more complex than what I drive* and infinitely more 
complex than what I most often ride (fixed)


* https://corvair.com/user-cgi/catalog.cgi?show_page=130

-- 
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971