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From: GT on 23 Jul 2010 08:47 "Brimstone" <brimstone(a)hotmail.com> wrote in message news:cpGdnZJvGoeLGNTRnZ2dnUVZ8vednZ2d(a)bt.com... > > <boltar2003(a)boltar.world> wrote in message > news:i2brj4$ubu$1(a)speranza.aioe.org... >> On Fri, 23 Jul 2010 10:43:17 +0100 >> "mileburner" <mileburner(a)btinternet.com> wrote: >>>> What a load of drivel. >>>> >>>> Stop bike. >>>> >>>> Get off and stand next to wall/bush. >>>> >>>> Let cars past. >>>> >>>> See , not hard is it? >>>> >>>> B2003 >>> >>>The only thing is that if you all-of-a-sudden stop, and get off you bike, >> >> Why would you do a sudden stop? Stick your arm out so drivers know you're >> stopping and coast to a halt. > > Most car drivers don't know hand signals. You have to know them to pass the driving test, so those car drivers without a driving license and insurance should be arrested and given a prison sentence. This does occasionally happen. >>>It is far better to wait until there is an appropriate shoulder, lay-bay, >>>side exit etc. where you *can* stop and get out of the way and let them >>>pass. Even better, just wait for the road to widen (or otherwise be safe >>>to >>>pass) and pull over and wave them past. Then there is no need to hold up >>>the >>>traffic or put anyone at risk. >> >> In an ideal world yes. In a narrow road that you might be puffing your >> way up for the next 10 minutes its only good manners to let other traffic >> pass. > > Why should people sitting in nice comfy overpowered cars get precedence > over people using muscle power? No one gets precedence over anyone else - there are rules governing road craft and conduct - everyone has to comply with the same rules. If a person sitting in a nice comfy car is driving too slowly, then they will fail their driving test and not be allowed to drive on the road unsupervised!
From: GT on 23 Jul 2010 08:50 <boltar2003(a)boltar.world> wrote in message news:i2buq3$491$1(a)speranza.aioe.org... > On Fri, 23 Jul 2010 12:15:56 +0100 > Albert T Cone <a.k.kirby(a)durham.ac.uk> wrote: >>> 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. >>On the flat, without a headwind. And the peak can be anywhere from >>25-60mph. On a hill, the optimum speed can be very different. > > Possible , I'm not an expert in this. But I was under the impression that > IC engines have an optiumum rev range and if you keep within that range > then no matter what the load you'll achive the best possible fuel economy. True if maintaining a constant speed at a certain revs. If we take 2000 revs as an example, one could be accellerating hard in 1st gear as you hit 2000 revs - this would not be very fuel efficient. You could be slowing down on approach to lights in 4th gear as you hit 2000 revs - in a modern car this will be using zero fuel at all! 56mph is supposed to be the most fuel efficient 'cruise' speed. The varying example elsewhere does not take account of road conditions, gradient, acceleration and other forces. At a constant speed, 56mph is the most efficient if one is happy using mpg as a measure of fuel efficiency - I know some people don't like this industry standard measurement of efficiency, but lets not go there again!
From: boltar2003 on 23 Jul 2010 09:10 On Fri, 23 Jul 2010 13:03:26 +0100 "Brimstone" <brimstone(a)hotmail.com> wrote: >Why should people sitting in nice comfy overpowered cars get precedence over >people using muscle power? Well since you're so fond of quoting the highway code when it suits you: http://www.direct.gov.uk/en/TravelAndTransport/Highwaycode/DG_070314 "169 Do not hold up a long queue of traffic, especially if you are driving a large or slow-moving vehicle. Check your mirrors frequently, and if necessary, pull in where it is safe and let traffic pass." It should be interesting to see you try and wriggle out of that. B2003
From: Albert T Cone on 23 Jul 2010 09:33 boltar2003(a)boltar.world wrote: > On Fri, 23 Jul 2010 12:15:56 +0100 > Albert T Cone <a.k.kirby(a)durham.ac.uk> wrote: >>> 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. >> On the flat, without a headwind. And the peak can be anywhere from >> 25-60mph. On a hill, the optimum speed can be very different. > > Possible , I'm not an expert in this. But I was under the impression that > IC engines have an optiumum rev range and if you keep within that range > then no matter what the load you'll achive the best possible fuel economy. It's horribly complicated when you look at it in detail. You are balancing the frictional losses in the engine (which increase with rpm, and hence drop with higher gears) against the gravitational (on a hill), rolling frictional and air-resistance losses (which increase with speed (and hence drop with gearing. Moreover, for a normally aspirated engine, the peak efficiency (energy produced/volume of fuel) corresponds roughly to the peak of the torque curve. However the peak of the torque curve depends on the throttle position. General wisdom suggests that you should run the highest gear you can pull at any given speed to minimise engine speed, however running a lower gear can result in you running closer to the peak of the torque curve and getting better nominal efficiency. Things get much more complicated if you have forced induction... Finding the best speed for economy depends on the engine design, gearing, frontal area, body shape, mass and gradient of the road. The "56mph" rule is fine as a rule of thumb, as long as you bear in mind that it can be out by more than 50%...
From: Mike P on 23 Jul 2010 09:44
boltar2003(a)boltar.world wrote: > On Fri, 23 Jul 2010 13:03:26 +0100 HC states..... "........pull in where it is safe and let traffic pass." > It should be interesting to see you try and wriggle out of that. Mileburner says "It is far better to wait until there is an appropriate shoulder, lay-bay, side exit etc. where you can stop and get out of the way and let them pass. Even better, just wait for the road to widen (or otherwise be safe to pass) and pull over and wave them past. Then there is no need to hold up the traffic or put anyone at risk" Now, where's the difference? *Safe to pass* being the main thing here.. Mike P |