Even with modern mirrors, rear-view cameras, and blind-spot warning systems, the lifesaver over-the-shoulder check remains essential and with increasing use of cycles and e-cycles and ‘micro-mobility’ solutions like e-scooters, even a motorcycle is vulnerable when turning left or right. Technology can alert us to vehicles we might otherwise miss, but it does not remove the responsibility to confirm our blind spots in real time. Combining mirror checks with a brief chin-to-shoulder glance fills the gaps in situational awareness, especially in multi-lane traffic or when vehicles accelerate unexpectedly. Practising these lifesaver checks until they become automatic ensures that riders are less likely to be caught by surprise — No Surprise? No Accident!

Living with Lifesavers

For a lot of riders, the last time they make a lifesaver over-the-shoulder check is the moment they turn back into the test centre in front of the examiner. The reason for making the over-the-shoulder observation is explained early on in CBT – it’s to see into the two problem areas to either side. This area is behind our peripheral vision, yet not far enough back to show up in the mirrors. The blind area is quite big enough to hide another motorcycle and even a car can go missing alongside us. The chin-to-shoulder check ‘clears’ this area with a direct observation. So after all the effort that basic trainers go to, from CBT right up to the moment of the test, why do riders start dropping techniques that are intended to increase their riding safety?

In my article about rear observation, I mentioned that in some cases riders have been told to “forget all that stuff you learned – it’s only for passing the test”. Here’s the really disappointing thing. I’ve heard it from people training advanced riders.

I mentioned that when taking post-test training, the trainee is often introduced to the concept sometimes known as ‘mirror history’. The idea is that if we look in our mirrors frequently enough, we’ll know exactly what’s around us and have complete situational awareness without needing the over-the-shoulder check on basic training.

So the big question is: “can we rely on mirror history?”

Let’s think about what a mirror check achieves. We take a snapshot of the situation that exists at the exact moment we look in the mirror. Two mirror checks are thus two snapshots. Just like comparing two ‘before and after’ photos, we don’t know what happened in the gap between the two. And that means any decision we make on the basis of a sequence of snapshots is, simply put, an informed guess.

How good is our informed guess? The answer is that it’s only as good as our checks.

Hopefully, you can now see that there are three problems with relying too heavily on mirror history:

1. the first is the frequency of our checks. If we leave long gaps in our rear observation, then pretty much anything can be happening behind us and we simply won’t know about it.
2. the second is that we can forget what we saw, particularly when traffic is moving in queues. A vehicle can slide forward into the blind spot and if it sits there long enough, we can forget that it was visible some seconds ago and now isn’t where we can see it – I’ve made that mistake myself.
3. the third is that mirror checks can fail to show a rapidly-changing situation that is about to put us at risk.

It might seem that to solve the first problem we simply need to ‘up’ the rate of mirror checks. Easy to say, not nearly so easy to achieve. The moment that a situation developing in front of us begins to cause us concern, what’s the first thing that goes out of the window? Yes, it’s mirror checks. It’s all very well to say that a skilled rider wouldn’t forget but even experts make mistakes under stress. The answer is not to rely on memory but make a real-time sideways check.

On motorways, riders sit alongside vehicles in their blind spot then wonder why the driver starts to move into their lane. The reason may not be that the driver “didn’t look” as we’re so keen to assume, but in fact “looked, saw and forgot”. So it shouldn’t be a big surprise when we find vehicles in our blind spots that we forgot were there.

And sometimes we’re just looking in the wrong mirror when a situation develops. Some years ago I was following another biker in my Nissan Serena people carrier. We were both in the middle lane of the motorway, and he was looking for a gap in the outside lane to overtake a slower vehicle we were catching. So he was making regular mirror checks to see what was coming up in the outside lane. Meanwhile, we’d just passed an on-ramp and I noticed a car accelerating very rapidly indeed down onto the main carriageway. The Mercedes shot straight through the inside lane, and at the moment the rider made his final mirror check before moving out into a gap to his right, the Mercedes was aiming for the same gap, and crossing through the middle lane behind me.

Naturally, because it was behind me, the rider couldn’t see it in his mirror. He started to move into the outside lane but the car was already in the gap and accelerating. The driver hit the horn, the rider was taken completely by surprise and barely swerved back out of the way.

Now, we can point the finger at the Merc driver but the biker needed to confirm his mirror history – he absolutely NEEDED to turn his head chin-to-shoulder to clear his blind spot. This is the role of the lifesaver. It’s to give real-time information that updates our situational awareness.

Is it dangerous to look over the shoulder at speed? An objection often raised against blind spot checks before committing to an overtake is that it’s dangerous to take our eyes off the car ahead in case it brakes suddenly. I don’t think it should take anyone long to work out that if we’re worried about looking away from the vehicle ahead, we’ll almost certainly struggle to make decent mirror checks too, and it’s unlikely our forward checks will be much better. There’s a simple solution – don’t follow so close and don’t try to force overtakes in restricted spaces. In any case, the quickest and most reliable way to make this final shoulder check is to combine it with a mirror check – follow the glance in the mirror with a chin-to-shoulder check.

We fill in the missing information by combining the two checks, and it only takes a moment longer than looking in the mirror alone.

In the example above, following into the shoulder check AFTER the final mirror check would have taken the rider a fraction of a second but it would have given him that vital update and filled in the gap in his mirror history. His informed guess nearly killed him.

Unusually this is an area where things genuinely have improved for motorcyclists. Improvements in commercial vehicle design, tighter fleet maintenance standards, and just possibly a faster clean-up of reported spills mean that streaks of diesel on roundabouts and bends are now far less common than they were in my courier days, even in the early part of my instructing career. Police collision data has long suggested that fuel spills are blamed for more crashes than they actually cause, and reduced exposure has only reinforced that trend. However, this does not mean slippery contaminants have disappeared altogether. We still need the same level of anticipation, observation, and margin — if anything, newer riders are likely to be less aware of the issue than those of us with a long backstory of dodging diesel. And it’s always worth remembering that ANY liquid will have less traction that the dry or uncontaminated tarmac.

Avoiding diesel and other slippery spills

My first introduction to the slippery nature of fuels spilled on the road came soon after I’d taken my 125 up to London. I stopped at a pedestrian crossing, three bikes came flying past me, turned right and promptly formation-crashed. As I pulled away, the 125 span the back wheel. Even that early on in my riding career I knew that wasn’t quite right and took the corner rather more slowly than the other bikes. A truck was parked halfway up the hill with a split tank and some fireman throwing bags of sand around it. The slick reached right down the hill to where the bikes had crashed. That was a while ago, and on purely observational evidence, it seems to me that fuel spills are much less common than when I was a courier. Moreover, evidence from police accident investigations suggests that despite the popular belief that oil and diesel cause bike crashes, the real crash numbers are low. That might be why in a long discussion on the problems of diesel on one of my favourite forums most of the correspondents had mates “who have crashed on diesel”, yet surprisingly few actually put up their hands and said “I’ve crashed on it myself”.

Nevertheless, it’s as well to be on the alert. As with all hazards, the first thing to consider is where we might find it, secondly how to spot it, and thirdly and to have some idea of what to do if we do spot ANY oil, diesel or petrol spill – they are ALL slippery.

Where might we find diesel and petrol (it’s slippery too) spilled on the road? The obvious answer is where vans, trucks and buses start with full tanks. And that means ports, industrial estates and bus depots, particularly in the morning. Leaving aside the random spills from a split tank, or from the van that had taken off its sump on high kerb round a traffic-calming ‘pinch point’ (it didn’t get far but left quite a slick for half a mile), keep an eye open where vehicles change direction – corners, junctions and particularly roundabouts are likely problem areas.

Combine a roundabout with exits marked INDUSTRIAL ESTATE and we should be on alert. Back when I was a trainer in Lydd, my homeward route took me round the Ashford ring road, which has a dozen industrial estates round it. Just as I was slowing for a right turn at one of the roundabouts, a guy on an R1 flew past signalling right as well. Knee out, he vanished around the back of the island but never reappeared. Going round rather more cautiously, I avoided the big streak of diesel and stopped to lend a hand. Rider unhurt but bike rather sad, having flipped over after sliding into the kerb. I left him arranging a van ride home. If we’re apply the ‘stop in the distance we can see to be clear’ rule, don’t forget it applies to road surface too.

Another good rule-of-thumb is that diesel spotted on one corner will probably reappear on the next. Another courier followed me carefully round one left-hander leading out of one London square as we both avoided the diesel. He overtook me, and promptly crashed on the left-hander leading into the next square just few hundred metres further on. As I stopped to help him untangle the bike from the railings, he said: “I didn’t expect diesel on that bend too”.

Err, right. So where did you expect it?

Most spills either come from overflows on over-filled tanks (much rarer now) or when drivers forget to put the filler cap on. Don’t laugh – I forgot to put the bike filler cap on once, because the tank bag covered it. A lapful of fuel reminded me, but the driver won’t know. The fuel is likely to be be spilled outwards so look for it on the outside of the lane – near the centre line on a left-hander or the kerb on a right-hander. But don’t forget a oncoming vehicle could slosh it our side of the centre line on a right-hander too.

Watching the surface is one reason for not trailing a vehicle ahead too close. If we see temporary slippery road signs or even police SLOW triangles, take care – it could be a spillage or even accident ahead, and there may well be a slippery cocktail of detergent, diesel, engine oil and antifreeze on the road.

See if you can spot the spill. In the rain, oil produces the familiar rainbow effect. It looks scary because the rain washes the oil right over the road, but in fact the rainbow effect is produced by a layer just one molecule thick. A single drop of oil can produce a big circular rainbow patch. It’s slippery but not lethal – the tyres will cut down to the surface. But if we see the rainbow right across the road, then it’s a bigger spill. Try to see which way the rainbow’s being washed – the source is probably in the other direction and that’s the area to keep clear of.

Unfortunately, in the dry, there’s no warning rainbow. The best advice I can give you is that fresh oil and diesel is very wet-looking and very shiny. It’s looks like ‘very wet water’ for want of a better description. A big diesel spill in the dry can often be smelled. So use your nose. A dulled black streak is almost certainly an old spill, and unlikely to be particularly slippery. But it’s worth knowing that if it rains, old spills can be ‘reactivated’, particularly by a short shower after a long dry spell.

Don’t forget petrol can also be spilled. It’s just as slippery as diesel but harder to see – it looks like water. Whenever possible, keep clear of any unusual wet-looking patches.

Interestingly, in that forum discussion, there was little useful advice, beyond declarations that “it’ll will have you off if you hit it” statements.

Ideally, we do want to stay off it if possible. It’s just a matter of having the speed and lean angle in hand to change line and direction. But sometimes we simply have cross a spill. It’s straightforward enough if we can avoid leaning and braking (the usual instinct) as we cross it, and instead keep the bike as upright as possible. For that reason if I find a spill mid-corner, I tend to steer INSIDE it, even if that means sacrificing my view round the bend. Why? I may have to cross it. If I’m on the inside, I can pick the machine up and cross it upright, before leaning over again back on clean tarmac. But if I’m on the outside and need to cross it, I actually need to increase my lean angle. Not a good plan. And don’t forget that the tyres will take a moment to clean off – don’t bang the bike straight over on its side, but ease it over.

Look ahead, think ahead, plan ahead, and oil and diesel should be no more than a minor – if potentially dangerous – irritant.