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!
For those of you that ride motorbikes as well (like me), corning is different than on a push-bike, this is mainly down to weight distribution. On a motorbike you'll go faster round a corner if you hang off the inside - a la Casey Stoner, this is because the bike weighs more than you do and if you hang off you can keep the bike more upright and the COG more over the wheels.
On a bicycle, it's the other way round, you weigh far more than the bike does (usually), so you need to stay upright (ish) whilst you push the bike down towards the road. You still trying to achieve the same thing, it's just done in a different manner.
Thanks Phil that's a good point. I think 'hanging off' is also about the fact that motorcyclists, particularly circuit racers travelling at 300Kmh plus tend to be leaning further and find as you say moving their body inboard means the bike leans slightly less, which maintains a larger tyre contact patch and also maximises ground clearance. On the road it's a moot point that has more to do with guys emulating their track heroes than any real benefit at road speeds in my opinion. Going back a few years interesting that Isle of Man TT champions Phil Read and Mike Hailwood broke records for many years without resorting to the technique.
Yeah thanks, maybe I should draw some vector force diagrams and make it a blog post! Like you say though it is so true that many riders dont keep their heads up. Maybe there is a good case for a Bike SA style advanced riding skills course? Could save a lot of embarassment, money and gravel rash! These are just things I've picked up over the years and most of us do but avoiding learning the hard way would be good.
In Apr-2012 I met a MTBiker who once trained police bike patrol officers how to fall off a bike while minimising injury. Met him while at physio for my broken shoulder, hence the offer, and it will be a while before I can take up the offer. I asked him if he would like to teach AC members, and he hesitated over insurance. I explained that City of Sydney during try-a-bike, ask participants to sign a waiver. Also common in some extreme sports.
I figure prevention is better than cure but should you 'step off' at some stage then knowing how to fall could pay dividends. Sounds like hell fun anyway!
Sorry about your shoulder, not cycling related I hope?
Sorry about your shoulder, not cycling related I hope?
What else? :) Did it in Oct-2011, still discomfort (pain at first was awful) and still going to physio.
Ian, so you would be interested? If Mick can be persuaded to give a group class.
Personally yes though it would depend on the interest on here I guess, could always put it out there and poll for a response.
Will wait until my shoulder has healed and I can participate. You could remind me in a few months.
On a motorbike, to turn right, you push left on the bar, that sounds weird but that is how it works.
Good points above, many people cranks thebrakes on midcorner and a very messy exit appears.
look through the corner, in slow if you must and roll through, weight on outside pedal as said and use a good line too, like cutting the apex or from outside in so you can see through corner better and have to wipe off less speed.
Best thing is to watch some pros ride downhill.
Anyone wanting these words put into pictures, watch the man in black from about 1:55 in this, although not quite sure if his butt ever leaves the saddle.
It's also probably easier to throw one's body around when leaning into a corner if one uses clips/toe straps rather than cleats, as the foot can twist a bit on the pedal while crooking the knee over the seat.
A good description. I was instructed in the art of cornering many years ago by a motorcyclist friend.