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,