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From: AMuzi <am@yellowjersey.org>
Newsgroups: rec.bicycles.tech
Subject: Re: Electric Assist Tandem
Date: Thu, 2 May 2024 08:00:22 -0500
Organization: Yellow Jersey, Ltd.
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On 5/2/2024 4:33 AM, zen cycle wrote:
> On 4/30/2024 8:56 PM, AMuzi wrote:
>> On 4/30/2024 7:21 PM, pH wrote:
>>> I was driving along on my way home and noticed a a 
>>> Jobst-yellow tandem of
>>> some sort.
>>>
>>> I did a double take when I saw a Bosch-like motor bulb on 
>>> the stoker's pedal
>>> set!  I did not realize that there were electric assist 
>>> tandems.
>>>
>>> By the time that realization set in it was too late to 
>>> look and see if the
>>> Captain's bottom bracket was motorized, too.
>>>
>>> I would not think that that would be the case, but you 
>>> never know.
>>>
>>> pH in Aptos
>>>
>>> I think Yamaha and Shimno also make bottom bracket bulbs 
>>> so no idea what it
>>> was.
>>>
>>> I've seen several of the Ba-Feng (sp?) kit's of late as 
>>> well.
>>>
>>> I'll try to do an un-scientific bike survey of what goes 
>>> by sometime this
>>> next month.
>>>
>>> pH in Aptos
>>
>> Yes battery assist tandems are a thing. As you note, 
>> several motor formats just as bicycles generally.
>>
>> https://2022.santana-tandem.com/en/tandem/e-tandem
>>
>> There's no point in more than one motor in a drive train. 
>> Or on both wheels for that matter.
> 
> If we're talking about electric assist bicycles where it can 
> still be propelled with legs in the event of a motor 
> failure, yes. However some redundancy on vehicles without a 
> 'back-up' is indeed practical.
> 
> Turbine locomotives have motors on each drive wheel for 
> exactly that purpose. If one motor fails, 7 more are 
> generally enough to still do the job. If the turbine goes, 
> they're still fucked though.

Well, engineering is achieving a goal with efficiency of 
limited resources; in the case of a tandem, weight, cost, 
complexity and service over the system life.  There's room 
for interpretation and weighing of those factors but a 
single drive unit has been the overwhelming format.

Conversely, for an airliner I agree that multiple engines is 
a reasonable solution.
-- 
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971