Re: Dual-Chain drive train

On 12/28/2024 2:52 PM, AMuzi wrote:

On 12/28/2024 12:05 PM, zen cycle wrote:

On 12/27/2024 2:11 PM, AMuzi wrote:

On 12/27/2024 12:32 PM, Frank Krygowski wrote:

On 12/27/2024 10:35 AM, Zen Cycle wrote:

https://www.bikeradar.com/news/buffalo-utility-s2
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Made for developing countries to allow for easier transportation on cargo bikes, without the exposure and complexity of an external derailleur or hand-operated shifting (for an internally geared hub). It was developed and patented with the help of SRAM.
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It appears to engage one drive train or the other through a back- pedaling action, forcing the pawls in the freewheel to toggle from one side to the other.
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It's been tested for over two years in the field with great feedback (according to the article) and is now being marketed in 3rd world countries.
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The design won the Eurobike Gold award in 2024 for "excellence in design and innovation within the cycling industry"
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More information at https://worldbicyclerelief.org/s2/

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Thanks, that's more info than I was previously able to find.
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ISTR a 1960s hub gear with coaster brake that also shifted gears when backpedaled slightly. I never had a chance to ride one.
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Many similar.  Cheap and effective, famously robust too. I made that comment the first time we discussed double ($$) drive chains on that vehicle.
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The original 1950s Bendix two speed had a cable to change gears. In 1960 it was replaced with the three 'automatic' versions whose mechanism is directly analogous to a Parker ball point in-out mechanism.
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https://www.youtube.com/watch?v=MhVw-MHGv4s
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[nice clear graphics]
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Fichtel & Sachs (later SRAM) made a very nice automatic unit as well and there are smaller volume eastern European variants too.
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Two of the Bendix 2-speed CB designs are currently produced under the Eagle [SOMA] brand.
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https://www.bicycleretailer.com/product-tech/2021/03/17/ merry-sales- helps-bring-back-eagle-2-speed-coaster-brake-hub
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Can you think of any reason why those versions haven't made their way into this application? Serious question....

 My totally unsupported and uninformed guess would be that the 'designers' know next to nothing about the bicycle industry, prior art, previous solutions to their problem, etc.
 Again I do not know that but it fits the data as far as we know it.

A couple of problems with that - the first being that WBR has a joint patent with SRAM on the design, meaning there had to be research into the design specifically to check for prior art.
Also, According to the article the lead designer was a SRAM engineer who had developed some version of Etap and of course the WBR has a rather extensive legacy with their own design team. It seems to me the supposition therefore that there was no knowledge about the bicycle industry is not very well founded.
I was actually asking from the perspective of the inherent qualities of the other designs. Do you know of any reason the earlier designs you mentioned might not have been deemed appropriate by WBR such that they had to invest some amount of NRE into something completely new?

 Example:
I once fielded a call from a gentleman who wanted to have bicycle-type dynamos for household power produced. He was willing to pay for the project from his own funds, and have them sent "to Africa". I listened, then paused and asked, "Where in Africa?"
 Well, that stopped the conversation dead. After a long silence I suggested that Ghana is not Sudan and South Africa is not Mali, etc. I ended up having a nice rambling conversation as he was an accomplished person and had made and saved plenty of money but had absolutely no idea of any specific nation in Africa.