From: boltar2003 on
On Thu, 22 Jul 2010 22:00:01 +0100
"DavidR" <curedham(a)4bidden.org.uk> wrote:
>"Jethro" <krazykara0(a)googlemail.com> wrote in message
>news:6842a0c5-6d67-4d78-a6b5-7ce0b485caa7(a)q35g2000yqn.googlegroups.com...
>> Having just watched a number cars grinding up a hill near me (I was
>> walking) because a cyclist was at the head of the queue, and it was
>> too twisty and narrow to safely overtake, I started wondering about
>> the OVERALL effect cyclists have on carbon emissions.
>>
>> Does all the extra carbon produced by cars having to crawl behind
>> cyclists cancel out, or exceed the carbon saved by the cyclist ?
>
>The loss of mechanical efficiency from using a lower gear is probably
>cancelled out by the reduction in aerodynamic loss. The biggest effect is

No it isn't. Cars have an optimum speed at which they use the least fuel
for a given distance and its usually somewhere around the 50-60mph mark.
Above and below that fuel economy starts to drop off a cliff. Thats what makes
all these "green" initiatives by local councils slowing traffic down to 20mph
such a joke. It just generates more CO2 and probably causes more bad driving
when drivers get back onto a main road and floor it to make up lost time.

B2003


From: GT on
"Jethro" <krazykara0(a)googlemail.com> wrote in message
news:6842a0c5-6d67-4d78-a6b5-7ce0b485caa7(a)q35g2000yqn.googlegroups.com...
> Having just watched a number cars grinding up a hill near me (I was
> walking) because a cyclist was at the head of the queue, and it was
> too twisty and narrow to safely overtake, I started wondering about
> the OVERALL effect cyclists have on carbon emissions.
>
> Does all the extra carbon produced by cars having to crawl behind
> cyclists cancel out, or exceed the carbon saved by the cyclist ?

My wife is a driving instructor and one of her pupils failed a driving test
this morning for 'failing to make good progress'. He was doing 20 in a 30
zone and causing a queue to build up behind him. He should have either
speeded up or stopped at the earliest convenient spot to let the queue pass.
This regulation applies to all road users and is fact.


From: mileburner on

<boltar2003(a)boltar.world> wrote in message
news:i2bkgp$i15$1(a)speranza.aioe.org...

> No it isn't. Cars have an optimum speed at which they use the least fuel
> for a given distance and its usually somewhere around the 50-60mph mark.
> Above and below that fuel economy starts to drop off a cliff. Thats what
> makes
> all these "green" initiatives by local councils slowing traffic down to
> 20mph
> such a joke. It just generates more CO2 and probably causes more bad
> driving
> when drivers get back onto a main road and floor it to make up lost time.

OTOH the 20 mph limits encourage drivers to drive at a speed where they are
not continuously (and often aggressively) speeding up and slowing down.

In urban areas, how long can 30mph be maintained before reaching a set of
lights, pedestrian crossing or other give way, stop etc?

Lost time from travelling at 30 is often gained by less time waiting in
traffic queues, so the overall time of the journey can make little
difference and fuel economy can be better.



From: mileburner on

"GT" <a(a)b.c> wrote in message
news:4c496349$0$22743$c3e8da3(a)news.astraweb.com...
> "Jethro" <krazykara0(a)googlemail.com> wrote in message
> news:6842a0c5-6d67-4d78-a6b5-7ce0b485caa7(a)q35g2000yqn.googlegroups.com...
>> Having just watched a number cars grinding up a hill near me (I was
>> walking) because a cyclist was at the head of the queue, and it was
>> too twisty and narrow to safely overtake, I started wondering about
>> the OVERALL effect cyclists have on carbon emissions.
>>
>> Does all the extra carbon produced by cars having to crawl behind
>> cyclists cancel out, or exceed the carbon saved by the cyclist ?
>
> My wife is a driving instructor and one of her pupils failed a driving
> test this morning for 'failing to make good progress'. He was doing 20 in
> a 30 zone and causing a queue to build up behind him. He should have
> either speeded up or stopped at the earliest convenient spot to let the
> queue pass. This regulation applies to all road users and is fact.

I bet he would of failed if he had just stopped where there was nowhere to
pull over too.

"Earliest convenience" is the key phrase.


From: GT on
"mileburner" <mileburner(a)btinternet.com> wrote in message
news:i2bpeq$bvv$1(a)news.eternal-september.org...
>
> "GT" <a(a)b.c> wrote in message
> news:4c496349$0$22743$c3e8da3(a)news.astraweb.com...
>> "Jethro" <krazykara0(a)googlemail.com> wrote in message
>> news:6842a0c5-6d67-4d78-a6b5-7ce0b485caa7(a)q35g2000yqn.googlegroups.com...
>>> Having just watched a number cars grinding up a hill near me (I was
>>> walking) because a cyclist was at the head of the queue, and it was
>>> too twisty and narrow to safely overtake, I started wondering about
>>> the OVERALL effect cyclists have on carbon emissions.
>>>
>>> Does all the extra carbon produced by cars having to crawl behind
>>> cyclists cancel out, or exceed the carbon saved by the cyclist ?
>>
>> My wife is a driving instructor and one of her pupils failed a driving
>> test this morning for 'failing to make good progress'. He was doing 20 in
>> a 30 zone and causing a queue to build up behind him. He should have
>> either speeded up or stopped at the earliest convenient spot to let the
>> queue pass. This regulation applies to all road users and is fact.
>
> I bet he would of failed if he had just stopped where there was nowhere to
> pull over too.
>
> "Earliest convenience" is the key phrase.

Never been disputed by me. No one has ever suggested (refering to the OP)
that the cyclist should have just stopped in the middle of the road where he
was as soon as someone arrived behind him - we have all said that he should
have pulled in to the side of the road. We have also all said that this
should be at the earliest convenience. The argument seems to be that you
think that he didn't need to pull over at all and the car drivers should be
more patient and just wait until the cyclist has finished his journey. This
stance is wrong and the above proves it.