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In article ,
says...
On 25 Nov 2005 04:41:19 -0800, wrote:

T i m wrote:
On Fri, 25 Nov 2005 11:08:15 +0000, Andy Dingley
wrote:

On Fri, 25 Nov 2005 11:00:20 +0000 (GMT), "Dave Plowman (News)"
wrote:

Very interesting article about this flawed concept in Autocar this week

There's nothing wrong with the concept, we just need better batteries.

'Any' battery that needs charging, unless charged environmentally
friendlylyly simply moves the pollution / problem elsewhere .. hence
'flawed' ...

A hydrid car that only charges it's batteries via energy initially
input from an IC engine (that should cover the 'regen braking' fans)
is an IC engined powered car. If it's charged from the 'mains' (in the

AIUI the point is that it is (or can be) a more efficient IC engine
powered car since the IC engine can always be run under the most fuel
efficient conditions instead of being geared to the road wheels.

Oh, indeed, and there is no question that different transmissions have
different efficiencies (and why a bicycle has 21 gears when it only
(typically) has a top speed of 20 mph .. it's because the 'engine' is
so low powered and has a restricted rev range?) 'and' that running IC
(and other) engines at specific rev ranges / temperatures allows
better efficiencies.

The large number of gears on bikes is as much to do with the mechanism
as the need for many ratios close together. A lot of the ratios in a
21/24/27 speed setup are either duplicated or useless (you shouldn't use
the larger rear sprockets with the large chainwheel, the largest or
smallest sprockets with the middle chainwheel or the smaller sprockets
with the smallest chainwheel because it causes excessive wear and loss
of efficiency).
Many years ago when building my "dream bike" I spec'ed a 14-17-20-24-28
block with a 32-52 chainset, which gave a wide spread of evenly spaced
gears with no duplication - I soon realised that using ratios around the
middle of the range (which is where you usually spend most of your time)
required a lot of double-shifting, which just isn't convenient.