A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » General
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

"Continuously variable" electric transmission



 
 
Thread Tools Display Modes
  #1  
Old December 8th 03, 04:43 AM
Richard Schumacher
external usenet poster
 
Posts: n/a
Default "Continuously variable" electric transmission

My searches have not turned up anyone selling a bicycle with a
continuously variable electric transmission. I don't mean an electric
scooter: I mean one in which the crank turns a generator/alternator,
whose output through an electronic controller then drives an electric
motor on the wheel rim(s) or in the hub(s). There would be no chain,
derailleur or gears, except perhaps for some fixed-ratio gearing inside
the generator/alternator or motor assemblies. A control equivalent to a
shift lever sets the ratio between crank torque and RPMs, which can be
varied over some wide range. The rider sets the speed by changing this
ratio and/or the crank RPMs as they find comfortable. Scooter-type
assist would be possible through use of an optional battery. (Earlier
threads on the subject addressed mechanical CVTs and auto-shift
mechanisms, not an all-electric transmission.)

What's the point? Mostly geekiness, I suppose, but the effectively
infinite number of "gears" while reducing the number of moving parts is
appealing. Also appealing is the notion that a battery in the system
would provide load-levelling (hill assist) but with the rider still
ultimately providing all of the energy, unless of course the rider
cheats by re-charging the battery from an external source. For
non-cheaters :_ the battery need only be large enough to help climb one
hill. Efficiency would not be as good as with a conventional drive, but
that's not really a concern for commuters or pleasure riders.

Surely by now someone must make such a thing?

Ads
  #2  
Old December 8th 03, 05:19 AM
David L. Johnson
external usenet poster
 
Posts: n/a
Default "Continuously variable" electric transmission

On Sun, 07 Dec 2003 21:43:10 +0000, Richard Schumacher wrote:

My searches have not turned up anyone selling a bicycle with a
continuously variable electric transmission. I don't mean an electric
scooter: I mean one in which the crank turns a generator/alternator, whose
output through an electronic controller then drives an electric motor on
the wheel rim(s) or in the hub(s).

snippage
*Efficiency
would not be as good as with a conventional drive, but that's not really a
concern for commuters or pleasure riders.


Efficiency would indeed be a concern for commuters and pleasure riders if
the efficiency is low enough, as I would presume would be the case. You
have three separate sources of energy loss: the inefficiency of the
generator, the power transmission to the motors, and the motors
themselves. Do you ever notice an electric motor getting hot? That's
wasted energy, and that gets worse as load increases.

The engineers can give reasonable estimates on the energy losses.

--

David L. Johnson

__o | Deserves death! I daresay he does. Many that live deserve
_`\(,_ | death. And some that die deserve life. Can you give it to
(_)/ (_) | them? Then do not be too eager to deal out death in judgement.
-- J. R. R. Tolkien

  #3  
Old December 8th 03, 01:58 PM
David Kerber
external usenet poster
 
Posts: n/a
Default "Continuously variable" electric transmission

In article ,
says...
My searches have not turned up anyone selling a bicycle with a
continuously variable electric transmission. I don't mean an electric
scooter: I mean one in which the crank turns a generator/alternator,
whose output through an electronic controller then drives an electric
motor on the wheel rim(s) or in the hub(s). There would be no chain,
derailleur or gears, except perhaps for some fixed-ratio gearing inside
the generator/alternator or motor assemblies. A control equivalent to a
shift lever sets the ratio between crank torque and RPMs, which can be
varied over some wide range. The rider sets the speed by changing this
ratio and/or the crank RPMs as they find comfortable. Scooter-type
assist would be possible through use of an optional battery. (Earlier
threads on the subject addressed mechanical CVTs and auto-shift
mechanisms, not an all-electric transmission.)

What's the point? Mostly geekiness, I suppose, but the effectively
infinite number of "gears" while reducing the number of moving parts is
appealing. Also appealing is the notion that a battery in the system
would provide load-levelling (hill assist) but with the rider still
ultimately providing all of the energy, unless of course the rider
cheats by re-charging the battery from an external source. For
non-cheaters :_ the battery need only be large enough to help climb one
hill. Efficiency would not be as good as with a conventional drive, but
that's not really a concern for commuters or pleasure riders.

Surely by now someone must make such a thing?


I doubt it. The loss in efficiency over a mechanical
transmission would make most any ride a real chore.

--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.
  #5  
Old December 8th 03, 03:38 PM
Pbwalther
external usenet poster
 
Posts: n/a
Default "Continuously variable" electric transmission

I doubt it. The loss in efficiency over a mechanical
transmission would make most any ride a real chore.


A good point. Bicycles lose only a fraction of 1% in friction losses. The
above proposed bike would probably be lucky to lose say 30%. Think of it this
way, you are pedalling 3 gears higher then you are going.

Another point is that all that stuff would weigh something. I think the
proposed bike would weight considerably more then the 18 or so lbs for a good
mechanical bike.

A final point is all that added stuff is fairly complex and I think it would
have a certain failure rate. The mechanical bikes are pretty reliable - except
for flats, one sees very very few mechanical failures on bikes.
  #6  
Old December 8th 03, 04:12 PM
Mike Farnes
external usenet poster
 
Posts: n/a
Default "Continuously variable" electric transmission

Richard Schumacher wrote
My searches have not turned up anyone selling a bicycle with a
continuously variable electric transmission. I don't mean an electric
scooter: I mean one in which the crank turns a generator/alternator,
whose output through an electronic controller then drives an electric
motor on the wheel rim(s) or in the hub(s).sure riders.

...

Surely by now someone must make such a thing?


I don't think you'll find anything in production but there's an
article about such a thing he

http://petrix.dreifels.ch/fb/images/1_wsj_shorter_1.pdf

Regards,
Mike
  #8  
Old December 8th 03, 06:32 PM
Jeff Wills
external usenet poster
 
Posts: n/a
Default "Continuously variable" electric transmission

Richard Schumacher wrote in message ...
My searches have not turned up anyone selling a bicycle with a
continuously variable electric transmission.

SNIP
Surely by now someone must make such a thing?


Search through the IHPVA archives at www.ihpva.org . I believe
Andreas Fuchs was designed such a device and has built working models.

Jeff
  #9  
Old December 8th 03, 09:01 PM
Bill Hennessy
external usenet poster
 
Posts: n/a
Default "Continuously variable" electric transmission

I've been thinking the same thing. But, I know of no one who makes such a
thing. Yes, I've looked.


  #10  
Old December 8th 03, 10:49 PM
F1
external usenet poster
 
Posts: n/a
Default "Continuously variable" electric transmission


"Richard Schumacher" wrote in message
...
My searches have not turned up anyone selling a bicycle with a
continuously variable electric transmission. I don't mean an electric
scooter: I mean one in which the crank turns a generator/alternator,
whose output through an electronic controller then drives an electric
motor on the wheel rim(s) or in the hub(s). There would be no chain,
derailleur or gears, except perhaps for some fixed-ratio gearing inside
the generator/alternator or motor assemblies. A control equivalent to a
shift lever sets the ratio between crank torque and RPMs, which can be
varied over some wide range. The rider sets the speed by changing this
ratio and/or the crank RPMs as they find comfortable. Scooter-type
assist would be possible through use of an optional battery. (Earlier
threads on the subject addressed mechanical CVTs and auto-shift
mechanisms, not an all-electric transmission.)

What's the point? Mostly geekiness, I suppose, but the effectively
infinite number of "gears" while reducing the number of moving parts is
appealing. Also appealing is the notion that a battery in the system
would provide load-levelling (hill assist) but with the rider still
ultimately providing all of the energy, unless of course the rider
cheats by re-charging the battery from an external source. For
non-cheaters :_ the battery need only be large enough to help climb one
hill. Efficiency would not be as good as with a conventional drive, but
that's not really a concern for commuters or pleasure riders.

Surely by now someone must make such a thing?



Unlike a gas fueled internal combustion motor, an electric motor's peak
torque is 0 rpm, so no transmission is needed. A single gearing is used for
whatever your primary speed will be.


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Should I get an electric bike? Help! The Real Lee Casey General 9 August 30th 03 09:48 AM
Ego-2 electric bike faster than car in city commuting race Electric Bike & Scooter Guide General 0 August 9th 03 01:44 AM


All times are GMT +1. The time now is 06:41 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.