Thursday, March 15, 2007

Stopping quickly in a curve ( Part III )

The most efficient method to stop quickly in a curve is to straighten the bike then brake. The qualifier to that statement is "if there is room". We're not always going to have the space to pull this maneuver off. Which means we're going to have to brake while the bike is leaned over.

It's amazing how many students come into our classes with the notion that braking while leaned over will automatically cause them to crash. On the flip side, not many know about the straighten-then-brake technique, either. With such a lack of accurate information combined with wrong information being passed on, it's a wonder more riders aren't injured or killed. A lot of the information is passed along with the best of intentions. Riders faithfully parrot "accepted" wisdom like "don't use the front brake hard or you'll throw yourself over the handlebars". This is one example of many. The sad part is that others begin to believe the same thing. Sooner or later someone pays the price. I guess that's one of the reasons I have such a passion for training riders. I'm a small voice in the wilderness but at least every rider I touch in a class goes away with accurate information. The chances of them being able to take care of themselves has gone way up. When I train instructors it magnifies the effect. They go out and reach even more riders than I can reach alone.

My enthusiasm must be contagious. We conducted an instrutor prep workshop last weekend. There were two of my former students starting on the pathway to becoming instructors with us. Cool, huh?

Anyway, I digress. Sorry for the soapbox diversion, but sometimes I just can't help myself.

It is entirely possible to brake in a lean without crashing. The key is to keep in mind what's happening with our traction requirements and manage things accordingly. My graphics didn't survive the transfer from my word processing program so I'm going to paint a mental picture.

Put yourself back into the corner. Visibility is somewhat limited so we've planned a late apex. This curve is to the left. For most of the curve our bike is fairly close to the right hand edge of the roadway. This increases our line of sight and keeps us from committing ourselves before we have all the information about the curve. After all, it's at the apex where we're the most vulnerable, isn't it? That's where we're asking the bike to lean the most. It's also where we're using up the greatest amount of traction. To round out the picnic basket of disadvantages, it's also the point where we have the least amount of resources to take any sort of evasive action. Never commit to the apex until the exit of the corner is in sight. Only then do we have all the visual information available.

That's the situation I was in with Katie as passenger. We were in the right hand third of our lane. I kept the path of travel wide until I could see the exit. In this case, the truck was helping to block my view. As the truck started to move I realized I couldn't straighten the bike immediately. We'd of been off the road in a couple of heartbeats. The only other recourse was to begin braking while we were leaning.

Think back to the two budget accounts. Say my total available budget for traction is a hundred dollars. Most of the funds are being eaten up by the traction account. We're close to the apex so the expenditure is increasing all the time. The good news is that not all the funds are in the traction account. There's a small amount in the braking account that can be spent. I applied the brakes accordingly. Gently. Ever so gently. Enough to cause an effect but not so much as to make the check bounce, as it were.

Gently applying the brakes doesn't do much by itself towards stopping the bike. The magic happens in what this gentle braking initiates. Guess what the bike is going to do once the speed is reduced? You guessed it. The bike will begin to straighten up. Little by little the funds that were being demanded by the traction account are freed up to be deposited into the braking account. At first the amounts are small. Like 5 bucks or so. Each successive transaction gets larger. Next time it's 15 bucks. Next time it's 30 bucks. Next time it's 70 bucks.

It's like a mud dam starting to leak. First there's a trickle. That opens up a channel for a larger flow which, in turn, opens up a channel for a torrent. Think about the traction dynamics.

The contact patch of the tire has an important but limited role here. That's not really the contributing factor we might think it is. The biggest difference is the change in side forces. Remember that formula from the previous post on stopping in a curve? The traction required is proportional to the square of the speed. In other words, increasing our speed by a factor of two means the traction appetite quadruples. 2 times the speed squared is 4 times the traction required. The great thing is that it also works in reverse. It's the reduction in speed that has the biggest effect. Halving the speed quadruples the amount of traction available for transfer into the braking account. Letting the bike gradually straighten up allows it to take advantage of the situation.

Is that too technical? Basically it's a gradual transition from leaned over to upright. The more we reduce speed and the straighter the bike is the more braking traction becomes available. Our braking needs to follow the same progression. Start out gently and increase pressure as traction allows. We're managing the flow of funds between accounts. By the way, there's a reason we're stopping quickly in the first place. While I use the word "gradual" I don't mean to infer that a rider can be all day about it. It's relatively gradual compared to the immediate action of straightening the bike. It will still need to happen fairly quickly.

Go back in your mind to our corner to the left. We are near the apex and to the right side of the lane. During this more gradual braking and straightening process the bike is still moving through the curve. This will normally mean that at some point the bike is going to head towards the center of the lane. That's the whole purpose of spreading the transition over a longer distance. It lets the bike continue on its path which increases our chances of staying on the road.

A lot will depend upon where the hazard makes itself manifest, where we are in the curve, what comes after the curve, as well as other factors. Your technique may need to be modified accordingly.

That's why I urge everyone to practice and become proficient at skills before the need arises to use them. Once a rider truly understands how to manage traction in a variety of situations they can use a little finesse to increase their options. It's quite possible for a skilled rider to move the bike's line a little, for example, while still executing a quick stop. Technique can't be refined, however, until the technique itself has been perfected.

In some perverse way it reminds me of my bodybuilding days. Arnold had a great quote:

"You can't define bone!"

A lot of guys were at the gym doing "sculpting" exercises. The trouble was that you can't really sculpt and define muscle until you actually have some muscle. Better to stay with the basics until they are solid and then worry about refinement. It's the only way it works well in motorcycling. Like I tell some of the young hot dogs in my classes. First you get good. THEN you get fast.

There's also a couple of small differences here in our head turns and what we do just before the bike comes to a stop. In the straighten-then-brake method we need to snap our head and eyes forward right away. In the gradual transition method our head and eyes will move forward at about the same pace as the bike's angle. Leading a little but not too far ahead. Here's another really important thing to remember.

Just before the bike comes to a stop, SQUARE THE HANDLEBARS! What holds a bike up when it's moving? The motion of the bike. What holds the bike up when it's not moving? We do! Do yourself a favor by not letting the bike come to a stop with the bars turned. That will lead to a lesson in picking up the bike. There's more constructive ways to burn off the extra adrenaline, I assure you!

So there's the story on the two techniques for stopping quickly in a curve. I would feel totally remiss as a trainer if I didn't include a couple of parting thoughts. These are physical accident avoidance skills. It is far better not to get into situations in the first place by using mental skills. Have I shared with you my definition of an expert rider?

"An expert rider is one who uses expert mental skills to avoid using expert physical skills".

Sometimes crap just happens. Take me, for instance. Of all the folks who should be able to avoid situations I found myself in one. Then I called upon expert physical skills. The more powerful skills are mental. Find trouble before trouble finds you and deal with it while it's small.

The number one determining factor in how fast to take a corner is how far the rider can see through the corner. I have people tell me that they were surprised by gravel in a corner. It wasn't their fault that they crashed. If you can't see all the way through a corner what do you have to assume? Be prepared for the worst and be pleasantly surprised when it doesn't happen. Speeds will obviously need to be slower than if you can see all the way through.

If you do see gravel in a corner what do you do? Yeah, slow down and move to avoid it. So if a rider crashes in the gravel what went wrong?

What do you do when you see a potential hazard by the side of the road?

The saving grace in my encounter was that I was aware of the truck. I saw a person in the driver's seat. I wasn't going to just stop in the middle of the road. However I had started to roll off and had hands ready. I also changed my line slightly to avoid the possibility of having to begin braking in the gravel that was thrown onto the road. The movement of the truck was a surprise, as was the mentality of the driver, but it didn't prove to be costly. Keep the mental skills sharp.

What are you waiting for? Go practice!

Miles and smiles,

Dan

14 comments:

Theresa Hogue said...

Just wanted to let you know we're doing a Lifestyles piece in the Mid-Valley Sunday paper (Democrat Herald and Gazette-Times) about local blogs, and your blog is one of those we're highlighting and recommending as a good read.
Thanks!
Theresa Hogue
Features Reporter

Krysta in Milwaukee said...

(Straighten, then brake) "If done properly, the bike will stop before it runs off the pavement."

That's what I _tried_ to do last Oct. But I ran out of road before I ran out of momentum. Then the trees did a loop-de-loop, I ended up looking at the sky, and poor Olsa ended up in the ditch. (There's a funny story about that... Tell you below.) Repair bills for each of us have been in the $7K range, but we could both have been hurt much worse.

Karl has tried showing me the "come up straight and brake for a second, then lean around the curve again" technique. I need to practice that, as well as your gentle braking while leaning. (Aw, shucks... I have to go play on the twisties?)

Any words of wisdom regarding the proverbial "getting back on the horse"? Not literally - I was on my own on 2 wheels by mid-Dec. (yes, in Wisconsin) - I mean getting my head back to where curves are fun again. I've noticed I'm considerably more cautious now. I am signed up for a basic MSF course in May.


Now that story...

While I was lying there on the road, I dialed Karl, handed my phone to someone who had stopped to help, and asked him to explain where I was and that Karl needed to come take care of the bike. (The phone wouldn't go inside my helmet.)

By the time he arrived, the ambulance was there (I think 4 EMT's around me) and a deputy was also kneeling by my shoulder, asking questions.

When Karl asked what happened, I burst into tears and said, "I'm sorry! I killed Olsa!"... never thinking about how it'd sound to anyone but Karl.

When he & the deputy walked up the road a little ways to survey the scene, the deputy asked "so who's Olsa?" Karl pointed to the ditch. Fortunately, the deputy rides, so understands that bikes have names.





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Combatscoot said...

Funny, the two exercises I had to do during the skills test for my motorcycle endorsement were swerving and stopping in a turn. I did swimmingly, though the CB 750 I borrowed from my dad was the biggest thing I'd ridden to date.
John

bobby said...

I am a bit confused. The options I have heard are:
Front Brake
Light trailing rear brake
Both, let it stand, scrub speed , lean
what is the best to do if I have Linked brakes,ABS or the old separate brake systems, or does it not make a difference?

Steve Williams said...

Thanks for sharing these techniques Dan. It's funny how everytime I read about braking in curves I always picture in my mind a curve to the right. I guess I want to give myself as much room as possible to stop. Glad you specified a left hand curve.

Riding within your vision and the resultant slowing of speed is essential though I see a lot of riders who don't do it. They rocket through blind curves with the certainty of clear roadway ahead. I have faith, but not in clear roads.

Steve Williams
Scooter in the Sticks

irondad said...

theresa,
I'm honored!
Just make sure to mention that I am a TEAM OREGON instructor and not an MSF instructor. Small but significant difference.

krysta,
Once again, let me say I'm really glad the damage was repairable to both parties involved.
The straighten, brake, lean thing requires flawless execution. There's no magic bullets, we just do the best we can.
By coincidence, one of the next few posts will deal with getting back on the horse in an indirect way.
I'll bet the deputy was real excited for a while, thinking he had a murder to deal with!

combatscoot,
Swerving is pretty standard since most departments use the MOST template. I've never seen the stopping in a curve used. How do they measure your performance? Is it just pass / fail? Do they give you a signal when they want you to stop?

bobby,
Good questions.

Anytime on the streets when a rider needs to stop or significantly slow always use both brakes at the same time.

Use firm, progressive pressure on the front, light to lighter on the rear.

Once a rider has a high level of proficiency they can move into techniques like trail braking. Even then, I would still hold that when there's a need to stop quickly always use both brakes at the same time.

In a corner, there are two choices.

Straighten then brake if there is room.

If not, begin gently braking while leaned and then use progressively firmer pressure on the brakes as the bike straightens and slows. Still using progessively firmer pressure on the front brake and light to lighter on the rear.

Realizing that we're talking about a need to stop quickly, once the braking process has begun, stay with it until you're stopped.

The only time I would suggest the "let it stand, scrub speed, lean" method is when a rider has gotten into a corner way too hot. Rather then give up and go off the road, a rider could try this. It's pretty tricky and the execution has to be perfect. This should be considered as a weapon of last resort.

Linked versus independent brakes makes a difference in brake application but not in the actual technique. No matter what brake system a bike has, the two methods for stopping in a curve hold true.

I am planning a post on linked brakes and ABS in the next few days.


Steve,
Riders are paying a high price. About 85% of our fatalities are riders in corners. We don't have accurate figures for accidents as most aren't reported. You can figure there's a lot of them.

The big factor is not looking far enough ahead. Visual information sets lines and entry speeds. I don't see how riders can not want to look but it happens all the time.

Dan

lobsterman said...

Thanks for an excellent series. Fortunately I have not had to emergency stop in a curve since the first installment. Now I can practice and be ready.

I know we covered braking in a curve during the MSF basic rider course I took, but I don't think it was part of the test at the end. If I remember it right we only covered the straighten out and then brake method. I know from experience that can't always be done.

Combatscoot said...

I had to accelerate to 25MPH, do the swerve exercise going out, then complete a 180 degree turn and stop in a box. The box was close enough to the turn that I had to begin braking while leaned-over. If I stopped in the box, I passed. This was 1991, in Gainesville, Georgia.
John

Allen Madding said...

A suggestion I'd offer to my fellow riders. Consider changing your mindset to this: Whenever you see an automobile (at a red light, at an intersection, on the side of the road, or in another lane), assume they are going to pull out in front of you and be surprised when they don't.

By doing this, you see an automobile and you instantly develop an escape plan. If they suprise you and don't pull in front of you, nobody gets hurt and all you have done is waste a little mental processing time.

irondad said...

lobsterman,
Rider courses can only teach so much in the time allotted. Most of the students take the beginner type classes. There's only so much they can process. Most are doing good to get a grasp on the basics. This blog gives me a good place to pass on other techniques to riders who are able to absorb them. Isn't it great to add more weapons to the arsenal?

combatscoot,
I ride the DMV test a lot. The examiners there need training in how to properly score the test and in what to look for. So I'll volunteer to ride it over and over while they practice. Sometimes I wonder how a new rider passes at all. Most of the test areas seem way too small like you experienced.

allen,
Sage wisdom, Sir!

Dan

Bryce said...

Very interesting reading.
As to the braking situation, I tend
to look waay ahead, usually try to see as far round the curve as possible.
It's not the curve that kills, it's what's at the end of the curve!
Ad when one is riding a motorcycle
that 25 years old, in good nick, and which rides much taller than the current editions of machines, one can see well beyond the perimeter of the curve.

American Scooterist Blog said...

Man this is great advice! The only time I "bogged" in a turn my offroad riding mindset took over and I plowed down into a ditch, rode it through and popped up on someone's country driveway. Scared the bejeezus out of me. I was simply going way too fast. There are times though, especially on these country roads where riding it through is a real possibility but the rider has to change their whole mindset. I'm grateful for what you showed here. I also believe riders who learn off road skills can find another option for saving themselves if not their bikes. Naturally I agree that a person who can't keep it on the road is going too fast. In some cases I do think there is a "last ditch" possibility of staying upright and finding a path out of the initial harm's way by tracking the bike off the road and riding it like an enduro. I would like to hear your thoughts on this.

balisada said...

In Basic Rider Training they said to use gentle pressure and then gradually increasing pressure on the brakes. This must be the concept that they were alluding to.

Thanks for the info. I will have to add that to my list of things to practice.

Balisada
2006 Black Rebel

irondad said...

bryce,
If there's any one key to success in corners it what you said. Looking as far as you can see. That information is the foundation of everything else like lines and entry speed.