As a road cyclist, mountain bike rider and advanced motorcyclist, the subject of the best way to get around a bend on two wheels is something I have considered from time to time. There are almost as many theories as there are cyclists but for what it’s worth here’s my two pennies worth.
Sunday’s UniSA ride in the wet was a timely reminder for me and after witnessing the aftermath of an unfortunate failure to make it around the bend I feel moved to put up something here that maybe some might benefit from reading. The secret to safe, confident cornering on a push bike is not something generally well understood by most of us who ride one. The more I ride in various groups the more I realise that there are a lot of us out there who really have no clue how we actually get around a corner. This is hardly surprising as riding a bike is something most of us learn at a very early age and then becomes automatic as we get older with little further conscious thought to the mechanics of what is actually going on when a cycle goes around a curve.
The first very important thing to understand is that you are never actually cycling in a straight line and that cycles are inherently unstable! But then you’ve fallen off before so you knew that didn’t you! The whole time you are riding you are constantly making very small but sub conscious corrections in order to balance. So what is balance? Well simply you are trying to keep your body and cycle’s combined centre of gravity immediately over the tyre contact point on the road. As soon as the centre of gravity goes to one side or the other of the contact point, unless corrected, you will go off course and eventually fall unless a correction is made. (imagine a plumb line hanging down from the centre of gravity)
So how do you get the bike back in balance? You steer towards the direction you are falling. This causes the bike to turn and the reaction forces make the bike stand up and balance again. The thing is we are not very good at knowing when to stop steering and generally overdo it. This then makes the bike unbalance and fall back the other way, hence my initial statement that you are never riding in a straight line.
Well so much for balancing in a straight line, how do we deliberately turn the bike? This is where it starts to get interesting. Most people will say ‘well it’s easy I just lean the bike and round we go.’ This is not quite true. What you actually do without thinking about it is deliberately unbalance the bike by turning the handlebars (very slightly) in the OPPOSITE direction to the way you intend to turn and this makes the bike fall towards the direction you want to go in initiating the lean angle and then you steer in the intended direction to maintain a course around the corner with further small corrections for balance of course as this is going on all the time. The most important thing to realise is that to deliberately turn sharply you can consciously COUNTER STEER to initiate a turn. This is essential knowledge for a motorcyclist but also very useful to know on a push bike as it is amazing how much quicker you can turn to take avoiding action when you are aware and have practised it.
Finally, what makes a bike skid and fall when cornering. Well obviously loss of sufficient adhesion with the road surface but as always in the physical world there is a bit more to this than meets the eye. Without getting too technical; when you corner as opposed to balancing in the usual upright series of small turns the bike and your body are deliberately leaning into the corner in order to counteract the forces which are acting to stand the bike up again (centripetal forces). These competing forces react through the contact patch of your tyres with the road. It’s easier with diagrams but suffice to say you will happily remain upright as long as the friction of your tyres is enough to overcome the outward (sideways) force trying to push the bike back into a straight line again. Now this is a key point. The higher your centre of gravity and the further inboard (towards the centre of the corner radius) the greater this outward force is to counter it and the more sideways force there is trying to unstick your tyres from the road. Therefore the last place your bum should be in a tight cornering situation is on the saddle!
In the dry, there’s generally no problem but when it’s wet there is a much reduced margin… So the best way to reduce these unwanted bad forces trying to unstick your tyres is to get your centre of gravity as low and as close to over the tyre contact point as possible. Therefore for example when going around a fast RIGHT turn get your bum out of the saddle and stand most of your weight on the LEFT pedal (outside pedal) in the downmost crank position (you’ve stopped pedalling!). This gets your body weight reacting with the bike at a point much closer to the road and moves your centre of gravity both lower and in over the wheels. You will find at the same time you will be tilting the bike more steeply into the corner while your body is in fact more upright. (and over the wheels) This will actually feel safer and you will have good steering feel and control of the rate of cornering. You will find that you can steer the bike more accurately into the bend and if necessary have the confidence to counter steer and turn sharper if need be. If you have ever watched Motor Cross or mountain bikers riding on mud, this is how they get around corners while sliding their back wheel without falling off! Because you have lowered your COG and got it closer to the contact patch the sideways reaction forces trying to unstick your tyres are much reduced. In addition if the worst should happen and a wet cow pat just can’t be avoided there is more chance that you can still save the plot.
Finally, always remember only brake in a straight line and you tend to go wherever you look so whatever happens if it’s gone wrong and you have an ‘oh shit’ moment don’t be transfixed by where you think you might end up but keep looking around the corner, don’t touch the brakes, stand on the outside pedal and tip the bike into the bend…most times you will make it round…
Try to practice these techniques in the dry so they become automatic and you will become a safer and happier rider. Good luck!
Thankyou for a great post, have been thinking about this for some time trying to get my mind around the physics.
Is there a way to "star" a post to enable reference to it at a latter date?
Thanks for the positive responses, will be happy if this helps someone improve or get over a hurdle. Fast cornering can be safe, doesn't have to be hairy to be fun, being smoother and faster is way more satisfying. Don't run away with the idea that you need to be climbing all over the bike either, the main improvement comes from lifting your weight off the saddle and transferring it to the outside pedal. Another advantage of this which I didnt mention before is if you should hit a bump mid corner you will be in far better shape to absorb the shock through your outside leg which should be slightly bent and will allow you to soak up the hit without the wheels jumping side ways, something which will surely happen if you have your weight on the saddle.
Get out there and give it a go you wont be disappointed and it will soon be natural.
Thank you so much for this (pretty) simple explaination. I came down the veloway this morning to work and remembered to put into practise what you'd said. Amazing how much more stable it felt cornering. I wasn't going fast, just cruising down the hill, but the difference to the stability of the bike (and my heart rate) was amazing. Thank you.
Descending is something that many people enjoy but if it goes wrong can get ugly very quickly.
Road bikes with their narrow tyres can be very unforgiving if things go wrong.
Great post, counter steering is the way, push left, go left, push right, go right. You can feel this for yourself by removing your front wheel, holding both ends of the spindle with wheel vertical and getting someone to spin the wheel for you - now push your left hand forward, the wheel leans sharply left, try it.
A note on braking only in a straight line, it is a good safe starting point, however you can brake safely at even quite high lean angles if you must, it just requires some touch. Think of your total available grip equalling 100%. If you use 101% of available grip you lose traction and (possibly) crash. So the key is to remember that if you are "spending" 80% of your grip on braking at a given moment, you only have 20% left for cornering grip or vice versa.
And as has been said, where you look is where you go - every time, and if you look down, you go down, so look up and past the obstacle to the clear path you wish to take, don't target fixate on the scary ditch-tree-car-puddle where you don't want to go, look through the turn, pucker up, push on the inside bar, weight the outside pedal, and rail that turn like you never thought you could.
Another thing you learn when doing crits, is how fast you can corner and keep peddling before scraping a pedal... particularly useful in the finishing laps! In this case you'll be trying to keep the bike as upright as possible.
Somewhat ironic but considering what was being discussed here.... Maybe a link to this excellent footage might serve to help reinforce the message if you don't mind RD6 and poor Brian?! Glad you came out of it so well mate you will be back on a bike in no time. Better get that frame checked too!