Overtaking on left-handers - experts only or best avoided?

I've been generally very impressed with the clarity with which Andy Morrison has put the case for advanced riding techniques in his series in Bike, but in my opinion "overtaking in left handers" (Bike February 06) goes the proverbial 'bridge too far'.

He states plainly enough that it's dangerous but then goes on to assert that it's a manoeuvre within the grasp of the expert rider. Well, perhaps. I'd certainly not say I've never overtaken in a left hander but I can certainly say there's a few cases I wish I hadn't bothered.

One thing that is much understated about overtaking in general is the difference between "need" and "want". Overtaking comes far towards the "nice to do" rather than the "must do" end of the scale. There are very few overtakes that you actually need to do; the safer option is nearly always to choose not to pass.

To say that we might as well be in a car if we don't overtake is to overlook the risk factor involved. Something like 50% of out-of-town fatalities are overtakes that go wrong. Even in a straight forward overtake on a straight road there are variables over which you have no control and may not even be aware of - passing on a left hand bend to my mind has just too many "what ifs". Do a calculation on a risk-benefit scale. To my mind here we have Risk 10, benefit 1.

Andy has pointed out problems of dead ground but I think he's missed a number of other considerations, which need re-emphasising given the risks of the manoeuvre.

One is that with overtakes is that you have no control over the driver you're passing. On a straight you at least have a chance of him knowing you are there. In the middle of a bend even if the driver is aware you are there - people tend to check their mirrors on straights - there is little chance the driver will be expecting you to pass mid-corner. Neither will the driver you are about to pass or the driver coming from the opposite direction be looking for an overtaking bike - on bends you tend to concentrate on staying on the road, not looking at the furthest point you can see - which is why we spend so much time on lifting riders' view on training courses. It's also easier to steer on a straight, but even there drivers swerve when they go for the mobile phone or the cigarette lighter. You'd hope they'd not do this in a bend and swerve - but I wouldn't rely on it - I followed one weaving all over the road just this week!

Andy talks about the need for a view far enough ahead to allow you to visually sweep a clear space for oncoming traffic. There are some neatly drawn diagrams in the magazine which show the road visually swept for a couple of lorry-lengths ahead of the vehicle you're setting up to pass. This hugely understates the distances you're likely to need. Say you aim to pass a lorry doing 50. First hitch is that to get the views you need, you have to hang back from the vehicle you're about to pass in the first place. You really need a view ahead of many hundreds of metres - 800 metres or a half of a mile isn't overstating it. The temptation of course, is to nail it once you've decided to go - but the faster you attempt the pass, the more difficult it is to bail out when it starts going wrong.

Andy mentions the danger of a car doing more than the limit and the need to consider just where you might meet head-on in deciding if you have enough space. What he hasn't mentioned is that the vehicle most likely to be exceeding the speed limit, and by a considerablely margin at that, is of course another bike. And if the rider coming the other way is hugging the white line rather than the hedge, you'll see the bike much later than you would a wider car or truck. That space that looked clear might not be nearly so big as you thought.

When you think about it further, the type of bend you'll be looking at whilst considering the pass will almost certainly be shallow or you wouldn't be trying to pass. And shallow bends invite high speeds not just from you, but from other road users. So what if the bike coming the other way is doing 90? Even if you only speed up to 70 to make the pass, that's a closing speed of 160mph. You're now trying to mentally juggle closing speeds of 160mph with distances of hundreds of metres, something that quite frankly any normal human brain struggles to deal with - we never evolved for doing time/distance calculations at that speed. What happens when the brain runs out of processing power is that you revert to "best guess" based on previous experience - so you are likely to underestimate the oncoming bike's speed, overestimate its distance and think you have more time than you really have to complete the overtake. And as suggested it's quite easy to get even higher speeds which need even longer distances.

Andy mentions the brown underpant factor of getting it wrong. But what about the effect on other road users? You emerge from behind the truck and the oncoming driver suddenly sees you. Even if you've timed it perfectly, you're likely to scare the wits out of him - he's not going to have the time to sit and make the same rational calculation you just made - he's just going to see a mad biker heading straight for him on the wrong side of the road in the middle of the bend. Can you guess what he's likely to do next? I can't and don't want to have to. Or alternatively what about that speeding rider hogging the white line? Whilst you might be good enough to brake or swerve to miss the oncoming rider, you'll be swerving to relative safety - to the inside of your turn. He'll be swerving OUTWARDS towards the hedge. Do you want to be responsible for sending him into the hedge? Meanwhile, what's the lorry driver likely to be doing when he sees all this unfolding in front of him?

And onto another issue that gets scant attention when riders overtake. Where are you going next? You're now accelertating through a bend through the area you have visually swept, but ultimately into a blind spot - by definitiion you can't see what lies beyond the area you have swept at the point where you commit yourself. But that view will continue to develop - what if your developing view as you commit to the pass shows you that the bend tightens? Or blocked completely? You are now committed to accelerating towards a hazard and you CAN'T slow down until a much later point than you would normally because you have to complete the pass first - you need MUCH more space because you need to be able to STOP IN THE DISTANCE YOU CAN SEE IS CLEAR not when you start the overtake but at the moment you COMPLETE it! This is much further ahead than the article makes clear.

What about machine control? You're placing accelerating and braking demands on the bike mid-turn. Not ideal for grip, stability or holding a smooth line easily. Whilst you've almost certainly got grip enough in hand on a decent surface, what if there's diesel or even a wet patch ahead? Given the speeds and distances involved, you're going to be relying on the surface hundreds of metres ahead of the point you commit yourself. Are you good enough to spot loose gravel at a quarter of a mile? I don't think I am. Although the issues of poor surfaces have been mentioned previously it's not stated explicitly in the feature. And it's far easier in terms of machine control to accelerate and brake hard in a straight line - by committing to an overtake mid-turn, you're compromising your ability to play these vital get out of jail cards. What if the braking zone for that tighter kink ahead co-incides with a slippery surface?

So, back to "need" and "want". What's left pretty much unsaid is that a better opportunity will be along in a minute. I intensely dislike this "press on at every opportunity" approach to riding and once again I say it may be appropriate to police pursuit riding, but question its validity in civilian riding in general. Even if you do decide to teach it as part of your training, it's one thing to teach it to riders whom you have watched ride and believe are up to the job but I'm certainly concerned at its publication in this series where Andy has no control over the riders attempting to apply it. I'm very aware of this problem wihen writing tips of my own..

So, what's my take on this? Don't underestimate the risks and don't underestimate how far ahead you need to see. In reality, only the shallowest left hand bends with the very best views allow a safe overtake. By all means set an overtake up on a blind left hander, but you're far better off waiting for the next straight to actually pull it off.