Safe Speed Forums

[ This topic has been split from another, slightly imperfectly I'm afraid because some replies covered both topics.

The other topic is here: http://www.safespeed.org.uk/forum/viewtopic.php?t=11006 ]


Wasn't there a pretty successful 1-armed rally driver in the 70s / 80s?

I'm afriad I too think it's rubbish that one doesn't have proper control of the vehicle with one hand on the wheel.

If you REALLY believe this is dangerous, then it should never be alloed to happen. Accidents often only take a few seconds from start to finish. If having one hand on the wheel was a significant cuase of accidents, everyone would be forced to drive automatics (with no radios).

I think the reality is that it's a bit like never hooking your thumbs over the spokes of the wheel in case you hit a pothole and the kickback breaks your thumbs. This is part of mtoring folklore that MAY have been true in the days of the Model T Ford but things have moved on a bit since then!

Mole the kickback still holds true for off road driving we had a LandRover trained instructor run a course when I worked on a gas pipeline. and very effectively demonstrated it. rather than have two styles of stering I have one where I don't put my thumbs inside the wheel.

Would this proposed system then dtect that I did'nt have my hands on the wheel and cut power???

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Gordon Brown saying I got the country into it's current economic mess so I'll get us out of it is the same as Bomber Harris nipping over to Dresden and offering to repair a few windows.

Chaos, panic and disorder - my work here is done.

http://www.wildcrafts.co.uk

I alos avoid putting my thumbs through the wheel. On the road getting your thumb broken in the first impact may prevent you from avoiding the second impact.

I think it's especially relevant if your front wheel is struck, or strikes something during a crash. I don't see much risk from potholes on made up roads.

Some track driver trainers recommend putting your thumbs on top of steering wheel spokes and through the wheel, claiming that it 'improves sensitivity'. I don't agree with them.

On the skid pan it's well worth keeping your thumbs out of the wheel.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

No, I think it demonstrates the lack of awareness of advances in vehicle technology since the 1950s!

(- excepting off-road vehicles when driven off-road, SE)!

Are you still on about thumbs? Did you read my post?

Huge torques are transmitted upwards through the steering column in some crashes in modern cars.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Yeah. I'm going to put my neck on the block and question the assertion of "huge". Does anyone have any statistics for numbers of broken thumbs as a result of this in accidents on cars less than (say) 10 years old? I know it's a pretty difficult one to ask but maybe even broken / dislocated thumbs on drivers - however caused?

My belief is that most modern (i.e. in the alst 10-15 years at least) cars (and I mean ordinary run-of-the-mill roadgoing passenger cars!) have steering geometry (and componentry) that minimise feedback by this mechanism. They also have steering wheels that are generally too chunky to "hook" your thumbs over the spokes in any case. I could believe that inadvertently clipping the kerb might wrench the wheel out of one's hand but as far as breaking digits is concerned, my feeling is that this is nothing like as common as we might believe. In fact, one of the vehicles I'm dealing with at present, has a steering lock whereby if a thief tries to burst it by wrenching the steering wheel, the wheel just slips on the column. That ought to give an idea of the sorts of maximum torques the manufacturer expects to see in normal useage!

Fair enough. I'd love to see some data too.

However, even if the risks proved to be small or occasional, I've never found a drawback to keeping my thumbs out of the 'line of fire'.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

thumbs have probably been overtaken by broken wrists from airbags

It depends on which way the wheel kicks and how badly. If the wheel kicks clockwise and there is a spoke within striking distance of your right thumb, it will tend to drag you thumb further in, and vice versa for the other side

When I took my tonka toy for MOT a couple of months ago, I had the "thumbs out" theory reinforced. I sat in the car while the tester did all the outside things. When we did the front brakes, he brought the rollers up to speed and told me to hit the brakes. I did, and the steering wheel spun well over half a turn as it was wrenched out of my hands and the front of the car leapt sideways a few inches. I was very glad that I didn't have my thumbs in the wheel. (FWIW, I sat on my hands when we did the other side!)

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Will

I think you are wrong. Suppose the wheel has one horizontal bar and your thumbs are rested on it. If a sudden force on a front road wheel jerks the steering wheel clockwise your right thumb tends to 'fall through' the wheel. Once the wheel has turned best part of 180 degrees the spoke from 9 o'clock hits your right thumb hard in a direction where it is weakish and constrained by physiology.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

I tend to drive with the heal of my hand resting on the wheel, fingers curled round and thumbs resting on the wheel. I just find it more comfortable that way. In town and when making tight menoeuvers I tend to palm the wheel anyway (yes I know, so shoot me ), so having thumbs out of the way makes the transition between steering 'properly' and palming much quicker.

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Science won over religion when they started installing lightning rods on churches.

Off roaders are taught not to put their thumbs through the wheel, and that's on vehicles with PAS and steering dampers. It's just as important on a road car, it's possible for the wheel to be ripped out of your grip and having a broken thumb doesn't put you in a very good position to stay in control.

I've missed the discussion about steering with one hand or two. I think it's generally safer to steer with both hands, but that doesn't mean that it is inherently unsafe to steer with one hand. There was a famous and very successful Mini rally driver who steered with the right hand, changed gear with the left, applied the brakes with the left foot and throttle with the right. It had a crash box and the clutch was just used for starting. At a more mundane level, I would have said that I steer with both hands most of the time, but my in-car video shows that when I make sudden steering inputs I make them almost entirely with my right hand. It's ugly to watch but very effective and enables me to get from lock to lock in under a second, shuffle steering has its advantages but when speed is of the essence other techniques are better.

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Peter Humphries (and a green V8S)

I'm still sitting slightly on the side of the fnece that says in a modern road car, it shouldn't be a big problem. That said, I DO completely agree that you can have the wheel pulled out of your hand if you're not concentrating and you hit something with one tyre whilst holding it loosely with one hand. I think this is a separate argument though. It IS obviously, better to have two hands (firmly) on the wheel , pretty much equidistant either side of the centre of the wheel (10-to-2 or 1/4 -to- 3 etc). But, human nature (and manual gearboxes) being what they are though, this won't always be the case!

What I'm questioning is whether, in a modern, roadgoing car, this phenomenon will ever be bad enough to break (or dislocate) a thumb.

I can always remember lectures from mentors and articles in various motoring mags about the danger ---clip the roadside - in my area it was a grass verge ( without power steering - wheel got taken out of hands ) or gravel verge - same treatment ---thumbs inside - wheel takes them out.

Not sure of the in modern cars, but if thumbs out is taught then it covers both on and off road driving.

I've never had a steering wheel wrenched out of my hands when 'thumbs out'. So I would say that I have a good enough grip to maintain control of my vehicle on or off road.

_________________
Gordon Brown saying I got the country into it's current economic mess so I'll get us out of it is the same as Bomber Harris nipping over to Dresden and offering to repair a few windows.

Chaos, panic and disorder - my work here is done.

http://www.wildcrafts.co.uk

Imagine a glancing accident - perhaps we're on full steering lock starting to turn right when some nutter overtakes. Said nutter hits our OSF road wheel at say 40mph.

Or perhaps we're waiting to turn right at a green light, but just as we're moving off with full lock applied, someone coming from our right shoots the red and strikes our vehicle in the front right quarter. He hits the road wheel first.

Either of these could easily put enough force into the steering to break your arm, never mind your thumb.

There's also a 'hammer effect' where the wheel picks up speed over perhaps half a turn before your thumb gets caught. See my reply to DeltaF.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Only just caught up with this one. I think for low-geared non-assisted steering the mechanical advantage is so low that either the rack or pinion would be stripped or a track rod end/steering knuckle pulled ouy before it sent the steering wheel spinning that visciously. For the higher geared assisted systems more commonplace today... I think it depends if the assist mechanism bottoms or gets defeated. If it does, Paul is right - and it will be even worse than the old systems due to its more direct gearing.

I don't know what experience that is based on, but I don't think it's realistic. The steering systems used on production cars don't eliminate kick-back, and are easily strong enough to cause physical injury. I know a former rally driver who has broken both forearms because he could not train himself to let go of the wheel, and production cars are no better. The steering is easily capable of transmitting forces higher than the driver can resist even with a firm two handed grip, and in a crash it is almost certain that the steering wheel will be ripped from your hands if the front wheels hit anything.

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Peter Humphries (and a green V8S)

i think the point here is that by it's very nature steering assist systems will help the driver resist such kickback meaning the driver (or his thumbs) will feel less force for a given input than the same ratio system without.

(this is why in part any assist system reduces road feel)

this is probably only true within the bandwidth of that system, which will vary on what kind it is.

in most of the emergency or impact scenarios above, the speed of the input may be high enough to negate this effect.

i also agree that power steer systems allow manufacturers to choose more direct ratios and hence allow higher torque's back up the steering column than a higher geared manual system.

I drive a Lancer Evo6 in National Gravel Rally competition. The streeing gearing (PAS) is direct ( about 2.2 turns lock to lock )

From in car video it seems on straights and at high speed that I hold the wheel with two hands but with fingers extended behind and thumbs aligned with the wheel circumference. A palm grip effectively. On tight corners the same but with only one hand on the wheel.

Thumbs definitely out of the way of the spokes. I do know of those who have injured their thumbs in the spokes and looking at i/car vid of other top drivers ( those who win at this level, I can only manage to finish in the teens ) they seem to do the same.

Of course motor sport is extreme but much of what I've learnt at a car control level I apply every day.

And the proposition that one needs both hands on the wheel is a technical artefact which is nonsense. If it was phrased as " One needs one's primary attention on driving " I could not agree more.