Safe Speed Forums

The usual argument for favouring understeer is that all you need to do to correct it is (usually) lift off the throttle, whereas oversteer takes much more skill to catch it (as long as you have more than 2 wheels so balance isn't an issue).

Cars have a system for limiting the rear brake force so you can't lock the rear wheels up without the fronts, this used to be a valve linked to the rear suspension so the brake force was regulated by the load on the rear wheels, brake hard and the weight balance shifts to the front, the rear rises and the valve reduces the rear brake effort. Today I would guess it's all controlled via the ABS.
We had a works vehicle (a Maestro van) where the rear brake limiter wasn't working. A colleague managed to spin it 180 stopping (in a straight line) at a set of traffic lights.

A locked wheel has less grip than a turning one, this is why the rear end of a car will try to overtake the front if the rear wheels lock up. In this scenario the car has more in common with your rocket than you think. The front and rear have the same force driving them forward (momentum) but the rear has no lateral control. The same would apply to any other situation where you were attempting to slow but for some reason the rear wheels had less grip.

On the bike, you lock the rear wheel it squirms around, trying to overtake the front, the effect is the same in a car.

Lock the fronts in a car and all you will do is plough straight on. You not only lose much of the braking effort, you also completely lose the steering.

Give that gold star back. Bikes break when their brakes fail

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

Are you sure of that? In aviation and railway it is well known that sudden deceleration is more survivable if you are facing backwards. That way you are pushed back into your seat rather than been thrown out of it.

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

In a lab, I'd be inclined to agree. You could be sure that the impact was spot-on rearward and the backrest and head restriants were adjusted correctly. On the road, I can't think of a way of making sure a car impacts facing exactly backwards (leaving aside someone running into the back of you). If it's facing anything between 45 degrees either side of "backwards" when it hits, that's probably down to luck more than anything else. I guess that's the thing with trains and planes, they generally crash in a straighter line than a car? If you're going to fall off and you've locked the brakes, as Homer says you've lost the steering too and are therefore more likely to go straight on.

Of course, with ABS and electronic stability control, you don't loose the steering (as much) and I accept that leaves my theory with a bit of a hole in it! I guess the number of KSIs avoided by having ABS / ESC might be greater than the number of KSIs resulting from NOT ploughing straight into something, but hitting them obliquely as a result of having some steering capability? Dunno!

Hmmm. I (think!) I beg to differ?
For me, tyres seem to grip best between 1/3 and 1/2 way through their lives (wet or dry). Between half worn and the legal limit, I think they're worse. I'm sure Auto Express did some wet grip test (not deep standing water, just ordinary wet test track) and found that the grip dropped off considerably below about 3mm tread depth. As the tyre rolls on a wet road, it "squeegees" the water away from the contact patch - some of which ends up in a rolling wave ahead of the contact patch and the tyre is always trying to ride up it. You wouldn't be able to drive on (say) a 2mm deep continuous puddle with 3mm of tread and expect to aquaplane at the same speed as you would with (say) 6mm of tread. We just compromise on 1.6mm as a minimum 'cause otherwise we'd end up throwing away a hell of a lot more tyres!

I'm sure that I've read this somewhere and don't the Germans have a min legal tread depth of something like 3mm (perhaps in winter)?

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My views do not represent Safespeed but those of a driver who has driven for 39 yrs, in all conditions, at all times of the day & night on every type of road and covered well over a million miles, so knows a bit about what makes for safety on the road,what is really dangerous and needs to be observed when driving and quite frankly, the speedo is way down on my list of things to observe to negotiate Britain's roads safely, but I don't expect some fool who sits behind a desk all day to appreciate that.

I've a feeling theirs is 2mm, but am not sure.

Stop arguing!

Tyre depth doesn’t matter anyway, apart from the legal angle...

Wet or dry roads, whether you are going up or downhill, whether you are on the mobile phone heading towards oncoming traffic or driving in snow or pissed/drugged as a fart, past parked cars with children present, or going home at 3:00 a.m. mid week there is a safe answer and an answer which trumps ALL other logical arguments... Thank you and good night. Take it away Scaffold...


We'll drink a drink a drink to
Scamera the NIP a NIP a NIP
The saviour of the human race
For Gov invented medicinal compoun££££
Most efficacious in every cas££££

Mr Tears drove around in fears
And it made him awful shy
And so they give him medicinal compoun£££
And now he's learning to take to crime

Brother Weepey was notably speedy
He would drive as he saw fit-for-the-conditions
And so Gov gave him medicinal compoun£££
Now they move him, around behind-a-man-with-a-red-flag-and-he feels-very-safe-now... (Artistic licence there )

Chorus..

We'll drink a drink a drink to
Scamera the yellow a yellow a yellow (See what I did there )
The saviour of the human race
For Gov invented medicinal compoun£££
Most e££icacious in every case...

Well Ebenezer thought he was Julius Speeder
And so they put him behind bars
Where they give him medicinal compoun£££
And now he’s an emperor with no home

Chorus...

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.

Nice poem/song ,Tone.

You are absolutely right though, so long as I have that 1.6 mm of tread and don't go above the posted limit, I am obviously driving as safely as I possibly can and no harm will come to me, no matter how icy or wet the roads may be....I should have known that or at least asked the resident road safety expert...GREENSHED!

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My views do not represent Safespeed but those of a driver who has driven for 39 yrs, in all conditions, at all times of the day & night on every type of road and covered well over a million miles, so knows a bit about what makes for safety on the road,what is really dangerous and needs to be observed when driving and quite frankly, the speedo is way down on my list of things to observe to negotiate Britain's roads safely, but I don't expect some fool who sits behind a desk all day to appreciate that.

Oh ta Grabs

Every now and then I feel compelled to 'go off on one' and yesterday was yet another prompted by my trip out...

It was like the first day of spring for bikers yesterday so off I went on my favourite run for the first time this year and what do I see.. 'New speed limit in force' complete with the scamera sign below a

It was last year and no accidents have ever happened there. How do I know? I use it all the time on nice days; no flowers no nothing and as we know there would be some remnant even six months after or longer. It’s just lowering the speed for lowering sake.

I tentatively followed the car in front, thinking if there’s a hidden traf pol he’ll get it first, both of us doing the speed it was last year in perfect safety.

Going abroad to live is appealing to me more than ever.

Say, I’ve just sent my licence off, the old pink one for a new card and picture type. I had categories A, D & E, (Sounds like a vitamin supplement ), and I’d better get the same back. Well, I have heard stories...

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.

There's been a lot of talk about our resident safety expert - and as a compliment to his naval background ,I found a suitable avatur -

-perhaps in absence of his proof of nit being SCP ,mods can award him this

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lets bring sanity back to speed limits.
Drivers are like donkeys -they respond best to a carrot, not a stick .Road safety experts are like Asses - best kept covered up ,or sat on