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From: Frank Krygowski <frkrygow@sbcglobal.net>
Newsgroups: rec.bicycles.tech
Subject: Re: Electric Assist Tandem
Date: Thu, 2 May 2024 10:53:23 -0400
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On 5/2/2024 9:00 AM, AMuzi wrote:
> 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.

Right. Benefits vs. detriments.

Detriment of a single motor failure on a tandem: Riders have to pedal a 
bit harder. Versus detriment of engine failure on a single engine 
airliner: 100+ fatalities, years or decades of litigation and penalties, 
loss of future customers, etc.

-- 
- Frank Krygowski