I'm not much of a car driver, and...

[Twanger]

..most of the driving I have done has been with diesels so I really don't know, but why are cars so slow off the mark at the lights? When I am behind a line of traffic at lights (which happens a lot when I don't think it's safe to filter) I am always p****d off by the way these motorists just don't seem able to get their cars in gear and movng when the lights change. Now, diesels don't have wonderful acceleration, generally, but I thought petrol engines did. So is there something mechanical with cars that just reduces their acceleration, or is it something to do with the way car drivers perceive the road, or is there something wrong with the drivers?

 

[Will1985]

I know what you mean - I notice quite a few are fiddling with the radio/something in their bag/their mobile and aren't concentrating.
I think I could out-accelerate most vehicles from a track stand start up to about 25mph. The difference is that I only have to shift a total weight of about 75kg (body and bike) compared to the 2 tons of car and passengers - at a guess an engine doesn't hit its power band until 15-20mph. It's something I can ask automotive engineer flatmate later today.

 

[tordis]

I believe it might have something to do with the energy required to move a bulky, heavy object, and the rules of acceleration. I was never very good at science, though, so I'm not entirely sure.

 

[skwerl]

it's better for everyone if cars do pull away slowly. less polution/CO2 etc.

 

[addictfreak]

I more likelyput it down to the fact that people have different reaction times, which are influenced by many factors.
When stopped at redlights I usually apply the hand brake and select neutral. Red and amber are the sign for me to engage gear and be ready to move on green if all is clear. Perhaps those slower of the mark are waiting for green before engageing gear.
At the end of the day who knows, and is the saving of a couple of seconds so important?
At times I tend to think we all need to 'chill' at little, which is sometimes easier said than done.

 

[Bristol Dave]

Acceleration is force divided by mass. A pedestrian, from a standing start, accelerates quicker than a cyclist.

Unless the car driver is holding the car stationary by careful application of clutch and accelerator then there is also a reaction delay caused by debraking. (I may have made that word up!).

I'm sure if you were on the Top Gear track up against with the Stig in a Vanquish you would be out accelerated.

BD

 

[Dan B]

It's intereting, isn't it, that car drivers are perfectly content to wait behind a queue of slow-off-the-mark vehicles because the drivers ahead are dopey, or in heavy cars, or have trouble with their clutch control, or are fiddling, or chilling, or saving CO2, or not in their power band, or lost, or whatever, and yet put a cyclist at the front of the queue and they'll all be muttering about "lycra nazis holding up the traffic"

 

[addictfreak]

I think its called 'human nature'

 

[thomas]

If people put their car in first gear, found the biting point and were ready to pull the handbrake up they could pull away much quicker. At the few traffic lights on my route I'd get off the line before nearly anyone else, partly because I'm ready to go...also because I'm lighter.

 

[Twanger]

At the end of the day who knows, and is the saving of a couple of seconds so important?
At times I tend to think we all need to 'chill' at little, which is sometimes easier said than done.

Sometimes it is....lights on some streets in central London often have very, very short duration and a long wait on red. If anyone knows the junction of Black Prince Road and Albert embankment, for example, they'll know a place where nippiness can save you, literally, five minutes.

Though in general terms, I agree with the suggestion we chill.....

 

[I am Spartacus]

I cant trackstand and dont particularly want to, but I will creep slowly forwards at 0.01 mph awaiting the green light unwilling to unclip.
Yes, drivers who dont make progress/dawdle when lights change do get on the pecs from time to time.. and was in Manchester yesterday and heard a few 'get a move ons fer Chrissakes'.
It's like those drivers who pass then box you in 5 yards up the road....