The truth about countersteer

(First of all, sorry for the clickbaity title)

The other day I shared a video of a big slam I'd had and received some critique from a fellow MTBer for not countersteering through the turn. This guy was very confidently telling people they need to countersteer through corners – albeit with mixed responses, but a few MTBers took the advice and that's potentially a dangerous situation. Looking around a bit more it seems to be a topic that lots of people struggle with, so if you're confused about countersteer or just interested in the physics of it, hopefully this post is for you.

For info I'm an engineer who specialised in tyre physics & suspension design for about 15 years, and have been a multi-discipline cyclist for a good 25 years. I'll speak plainly and avoid jargon as much as possible, because I want this to be understandable to anyone.

I'll reference to this excellent Pinkbike video because it has some really good shots of cornering in it, as well as a huge amount of great advice:

(Edit – vid moved to end due to post being snipped)

First of all, what is countersteer? Very simply, it's the action of steering in the opposite direction to the one you want to turn.

Also note that steering = the direction you point the front wheel in and turning = the direction in which you travel; the two are not always the same.

What was wrong with the advice given in my post and others like it is that countersteer is not something you do always when turning in order to corner better: it is something that is used in very specific circumstances. I'll explain the main reasons when and why you will want to use it.

1 – Initiating a Turn

The most common use of countersteer is when you want to start turning – or more precisely, just before you want to start turning.

What countersteer does in this instance is use the difference in inertia of your body (high inertia) and your bike (low inertia) to get you and your bike ready to start turning. Note that inertia is an object's reluctance to start moving, so if your body's inertia is higher than your bike, your bike will always want to move before your body does.

What you do is steer in the opposite direction to the turn, so if you want to turn left then you steer right, and vice-versa. As you steer away from the turn, your bike will start to move out from underneath you due to the difference in inertia. This effectively leans the bike over for you, ready to start turning.

This is where confusion starts to creep in, because weird stuff starts to happen. You have steered in the opposite direction to initiate a lean, yes, but then you need to steer in the correct direction to start turning! Otherwise your bike is going to continue moving out from underneath you and you're going to have a bad time.

So where are we? We have:

1 – Steered in the opposite direction to initiate a lean

2 – Steered in the right direction to initiate the turn

What's next?

3 – Steer in the opposite direction again to maintain the turn?

No.

This is where so many people get mixed up, so I hope this is really what clarifies things!

At step 3, some weird physics interactions happen and if you don't act against them the bike is going to take over and either stop turning, fall over, or eject you. Bikes want to be vertical when they're moving, and they want to move in a straight line. When the bike is leant over it will want to steer itself further into the turn (see: weird physics stuff) so you need to resist this by applying a counter-torque to the handlebar – i.e. trying to straighten them up. Notice I said counter-torque, not counter-steer – you will still be steering into the turn, you will just be stopping the bike from steering itself further.

If you try steering in the opposite direction in the middle of a turn, guess what's going to happen? Your bike is going to fly out from underneath you in the middle of a corner and you're going to slam into the ground. If you don't believe me, find some soft grass and try it.

Just because you are applying a torque to the bars, it does not mean you are steering them: you still need to steer into the corner a little to maintain the turn, the amount depending on how much you lean. More lean = less steer, but you are always steering into the turn.

That probably sounds horrendously complicated and impossible to remember, but don't worry! Your body already knows how to do all of this stuff and you have been doing it ever since you learned to ride a bike. It is muscle memory and does not require thinking about or debating on the internet.

So why is countersteer a problem? It's because there is another time when you may want to use it.

2 – Beyond the Limit

I'm sure everyone knows that if you're going to pick an end of the bike to slide out first, it's the rear. If I could have one wish from an MTB genie it'd be that my front wheel never washes out on me again. You just have so many more options when the rear end loses grip versus the front, and one of those options is countersteer.

So let's imagine you're turning a corner on loose ground. Within the limits of grip all of the rules in section 1 apply: you countersteer to initiate the lean, then lean the bike over and steer into the corner. Watch any MTBer at any skill level turn a corner, and provided they don't lose grip this is what they'll do.

However, beyond the limits of grip things change. Like I said, and like you all know, you want the back end to slide first. The critical point is: you do not make this happen by using countersteer! Instead, countersteer is what you do to deal with this once it starts to happen. You make sure the back end slides first by careful use of body position / weight balance, braking, and praying. This all comes with practice.

Once the back end starts to slide, if you were to continue to steer into the corner you would spin out and most likely crash. So what you do is the same as if you were drifting a car: you apply some "opposite lock" and steer away from the corner again, allowing the slide to continue until you regain grip, at which point you can turn into the corner again. OR.. you can slide all the way round the corner and everyone is going to think you're an elite pro badass. (Did I mention I am an engineer and not cool)

Conveniently, because of the weird physics stuff we discussed in section 1, you're already applying a counter-torque to the handlebar while you turn a corner, so switching to countersteer is something that happens fairly easily and most of us will do it without thinking when the back end starts to let go.

Summary

So if both of the main circumstances for using countersteer are things you do completely naturally when riding a bike, why is it so confusing for so many people, and why do bloggers / vloggers / magazines / engineers with too much time on their hands talk about it so much?

Because if you talk about it people will listen to you I guess, and our world is driven by engagement.

If you have ever ridden a bike in anything but a straight line, or done a really long skid, then you already know what countersteer is and do not need to think about it any further! Get out of your head and practice riding your bike, and it will all come naturally.

Do not under any circumstances try to use countersteer in the middle of a corner unless you are already sliding.

If anyone tells you to do that, do not listen to them!

Hope that helps

Pinkbike – How to Corner Properly

Bonus short video on countersteeer