Safe Speed Forums

Generally yes. There may be some designs around that "self limit" in some way rather than actually have a specific rev limiter. One example that's still in common use is old Minis. Most versions self-limited RPM when the "valves bounced".

But no rev limiter will save you if you manage to put it in too low a gear at too high a road speed. When the wheels drive the engine past its maximum design speed something will probably break, and it will probably be expensive.

79 mph is not "considered legal". It is the APCO guidance for the enforcement threshold.

Even 71 mph is illegal

Quite true


Again true, but you don't see many (if any) convictions for travelling at that speed do you?

Since the purpose of the ACPO guidelines is to cover 'measurement uncertainties' we have absolutely no idea.

We may have thousands who were travelling at 71mph true, but were recorded as travelling at 79mph and prosecuted.

Clearly anyone prosecuted at 71mph (recorded) could turn up in court and claim that there was no proof of any offence because legal speeds were within the range of measurement errors. This is why the ACPO guidelines exist, but they cut both ways.

Perhaps I worded my question incorrectly?
Maybe..." but you don't HEAR OF many (if any) convictions for travelling at that speed do you?" is better?

You still seem to be avoiding the main part of my argument....which was...

"....that 79mph is what is CONSIDERED legal by many who campaign against speed cameras with anything above being in NIP territory.
It follows therefore that if the Government raised the National limit for dual carriageways and motorways to 80 mph, that same belief that 80+10%+2mph (90mph) would be the new CONSIDERED legal (although we know it isn't strictly legal) threshold"

It follows therefore that if the Government raised the National limit for dual carriageways and motorways to 80 mph, that same belief that 80+10%+2mph (90mph) would be the new CONSIDERED legal (although we know it isn't strictly legal) threshold"

Even @ 70 mph stopping safely and control of the vehicle during/ after a blow out could well be outside the capabilities of some(many?) drivers.

You'll be enlightened if you spend some time on the derestricted Autobahns

I dont know about cars but a lot of bikes come with slipper clutches. This allows the back wheel to spin faster than the engine.

I've got a Playstation II and a copy of Colin McRae Rally 4. I've played it until my eyes hurt and (I think) become pretty expert at it. But I don't think it improves my driving one little bit, because (in no particular order):

1. Even an incredibly detailed simulation like this is still only a fraction of the whole story, so you are getting all your input from a range of perceptions far more limited than in real life. Thus you become "too focussed",

2. Because the simulation is simplified, when you master it you might wrongly believe you know all there is to know. Eg the physics of the car handling are only a very approximate subset of the real thing,

3. Your sole sensory input is a forward facing screen, so you don't learn to pick up other cues, the "seat of the pants" feel of what the car's doing, tactile feedback through the steering and brake pedals etc. Also it discourages you from looking around,

4. The thing is too predictable. Play it enough times and you know what's going to happen next, thus you learn to drive by rote instead of reacting to the unexpected and crucially anticipating the unexpected.

5. The fact that even the biggest "offs" never hurt or cause any real damage must have a bad psychological effect. In real life it doesn't say "Game Over" when you get it badly wrong.

If you learned to drive first, and have honed your skills over years and years then I think they are a harmless diversion and a lot of fun. But I don't think they represent "good training" in any way for people who don't yet drive.

Oh, and of course you can't "train" your reactions to improve them. Jeremy Clarkson interviewed Michael Schumacher a couple of years ago and demonstrated that their physical reaction times were about the same. What sets the world beating driver apart is NOT his reaction speeds which are in-built and can't be changed, but his level of anticipation and ability to make the correct reactions, not the quickest ones.

Whilst many believe they are driving safely when they exceed the limit as it is now, you cannot account for all the things that could go wrong that are outside the drivers control...Even @ 70 mph stopping safely and control of the vehicle during/ after a blow out could well be outside the capabilities of some(many?) drivers. Now...a blow out at 90+ wouldn't be very safe for either the driver or anyone else I'd wager.

As for the speed vs outcome argument, it is anything but linear. It depends on many factors external to the driver. However, at the top end, it can be put simplistically as "there are no degrees of death".

Is that right? And are bikers happy to give up engine braking? Or is a degree of braking effect allowed with the 'slipper clutch'?

Is the slipper clutch a sprague clutch? Or something that allows 'limited slip'?

So when the gun says, say, 79mph, we are only able to prove in court that the vehicle was travelling between, say 70mph and 88mph true speed.

But if the gun says 71mph we can only prove in court that the speed was between, say, 62mph and 80mph true speed. i.e. we can't prove that there was any offence. THAT's why you don't hear of 71mph prosecutions... THAT's why ACPO issued guidelines.

Getting even more technical that range is also likely to be stated to be at an uncertainty of two standard deviations or 95%, i.e. there is a 95% likelihood that the speed was between 70 and 88 but a 5% chance that it was even higher or lower.