I’ve been lucky over many years of motorcycling not to lose the front end on a loose or slippery surface – other than during an off-road training course and that was at a slow speed. I’ve had the back get away on mud and ended up on my arse however nothing too serious.
When these accidents occur, they can can happen very quickly and depending on the length of the changed surface, the situation can be saved – especially if the rider has a lot of dirt riding experience. They key is in where the weight of the rider is, which is the opposite of riding on a sealed road.
Bosch, the German electronics company, has come up with an interesting idea – compressed air. They have fitted a high pressure jet to the sides of a motorcycle and a sensor detects when the front wheel has lost traction and the angle of the bike. The jet is activated to counter the slippage.
It’s a one-off, in that the jet can only work once from the air canister, however it would make sense to carry spares in a pack. As the technology is still a prototype, there has been no discussion about refills and that would depend on the size of the compressed air canister.
I’ve watched the video several times to see what is happening. The patch of gravel used is very small and I would suspect that an experienced rider would be through the gravel so quickly that they would be able to manage the front end. I’ve seen riders get through a small patch of gravel and I’ve seen others not get through unmarked road works where the gravel was more than the length of the bike and the speed was legal for that piece of road.
This is a piece of physics that I’m sure one of my engineering readers will understand more than me. It is the velocity of the air jet that fascinates me – it needs to provide enough counter force for the slide, so it would presumably need to be configured to the weight of the bike with rider/passenger/luggage.
I wonder if we will see this head into production – other safety technology is slowly transferring from cars to motorcycles.
I realised I made a whoopsi in my previous comment, but it is not yet approved and hence un-editable (if it even is then?). Any ‘nana knows the correct equation for rotational force is m x v2 / r yet I didn’t use that. So, the real numbers of my previous example (remembering there are some serious assumptions in this, so have your pinch of salt at the ready!) are 300kg x 27.8 x 27.8 / 50 = 4.6kN, or 472kg force. Much more doable than 1.2t force, but still quite an ask. If our kind moderator wishes to swap out the formula and numbers in my post and just put that edited one up and delete this explanation, that would be tidiest, but heck there is this erratum solution too…
There you are – I knew an engineer would be able to provide the maths!
Gotta say I like the concept, assuming practicalities can be dealt with. I remain a little skeptical about real world application, but those front end slides are a holy terror. All five of the biggies are embedded indelibly in my subconscious, three being fuel spills after a roundabout, another a mid corner stick, and the last a lengthy gravel wash-over that disguised itself ‘beautifully’ (south side of Abercrombie river on Oberon to Goulburn rd). The first four got sorted via the third wheel, kicking the ground extremely hard and fast, and dealing with the hydraulic shock to the leg for a minute or two after – thankfully on an upright bike! The last one knocked me off in ~2006 as I was looking in the rear mirror when I hit the sandy gravelly stuff.
The ultimate (but not first choice) survival trick if you see a slide hazard ‘at pace’ is to flick the bike up so you go over it largely ‘weightless’ as it hits the hazard. You still get upset and chucked off line half a metre, but likely come out OK – had a few of them but not so etched in the memory; it takes two wheel slips to do that! Sticks will roll you a long way. Multiple leaves are pretty bad too – one for you, one for the road, and one to lubricate them. Gravel, as depicted in the video, is pretty bad as it is like a bunch of little marbles. No sooner have you rolled on the handful currently under the wheel than you are transported to the next bunch. That demo patch is enough to knock you over, and more speed it would just be worse. Despite that the inertia equation varies in your favour, the rolling thing on the much higher lateral forces just snaps you over. Could this thing save that? Maybe…
Modelling the behaviour of each of those little pebbles as a tyre climbed on them then got transported by them would be quite tricky, but doable with modern DEM packages. Like anything of this type, getting reliable predicted outcomes all comes down to your base assumptions about how the interfaces and elements behave. That stuff is really complicated, but what you want out of it (nearly) any layman can come to grips with. When a mass is cornering, to let it do that all it needs is for the road to push back with an equal and opposite force, which happens to be mv2/r. Simple. So 300kg is doing say 100km/h = 27.8m/sec and lets say it is a 50m radius circle corner. So F = 300 x 27.8 x 27.8 x 50 = 11.6kN (or divide by 9.81 = 1.18 tonne force, for those that insist on thinking like that).
So if this jet thing can provide a tonne of force, (or thereabouts if we want to fiddle with how the real world rider came across said gravel and allow for a smidge of back wheel support), and do it for the duration it takes you to cross it, you are saved for sure. Alternately, if it can only shove you down into the road a bit harder to try and get a vice-like grip on that bed of marbles, well, you better be a sh1t-hot FEA modeler to save your bacon!
I am going to go with the tried and true method of spotting the hazard, standing the bike up, hitting the brakes as hard as possible (progressively but quickly), washing off the maximum speed possible, letting go of the brakes as you hit it, then tip the bike in once the hazard is crossed. It Works! As I have found out repeatedly. If you can’t do that then a rapid change of direction is often an option – the bike is good for it but your head says no. The ‘weightless flick’ works too if it was a total surprise and nothing else is available / could be done without unsettling the bike in more catastrophic ways.
I regularly counsel people to improve their riding when there are no hazards and hit a few pretend roos / bad potholes and just see how they go with that. Anything other than a dismal failure first time will be a surprise. I also personally feel quite uncomfortable with any new bike I have not done a few emergency stops on, just so I am properly calibrated to what ‘this one’ needs / can do. Surprising how few people do this. Probably, I am accidentally making the case to bring the air jet technology on, whereas my fervent desire is people learn to handle the hazards that are out there by getting better, not broken. Keeps getting me out of the brown stuff, to the point that this whole topic area is just one of technique rather than fear. Can’t count on anything but, and backing off a bit is also a great outcomes creating solution too! Touch wood…