The first example
Have you ever been to one of those tech museums? If so, you may remember this great exhibit where you sit in a swivel chair with a BMX bicycle rim. The rim has a set of handgrips attached to it. The deal is that you spin the wheel and sit in the chair. As you attempt to lean the wheel in the air, the chair will tend to turn into the leaning wheel. You can get the wheel going fast enough to get you spinning 360's in the chair. You should be careful what you eat before you do this though, it can be a mess for those people watching you. (Do not ask how I know this, but think of a sprinkler spinning in a circle spraying beef stroganoff everywhere.)

If you have not had the chance to do this experiment, I highly recommend it (not the sprinkler thing, but the exhibit at the museum). As silly as it sounds, it is the basis for all your turning and leaning when you ride. Believe me (tree), if you do not lean (tree), or forget to turn (tree), you may run into something you do not want to meet (tree).
Take the front wheel off your MTB and go inside when the spouse is not home. You can do this when your spouse is home, but you may find the wheel doesn't make it back onto your MTB. Sit in a chair which will swivel and spin the wheel like you are going 200 miles per hour. (It is good not to put anything in the spokes when the wheel is spinning, like your tongue for example.) You will immediately notice that the wheel is very hard to get to lean when it is spinning. When you do get the spinning wheel to lean, you will notice that you are pulled to one side. You will also notice that the wheel clearly wants to not be leaned. It will tend to want to stand straight up and down, and it will fight you unless you have it completely vertical or horizontal. The force you feel when you lean the wheel is called "centrifugal force". This force is in effect if your bike is rolling at any speed, and you need to learn to work with this force when you are riding.

Do you fight the basketball when you twirl it on the end of your finger? Of course not. If you do it right, a basketball will stand on the end of your finger as long as it is spinning. In this case, you are working with the forces generated by the spinning basketball to balance it on the same finger you dig your nose with.

Tree Meet
Blazing down the straight, the trail takes a slight turn to the left. It is just enough that you do not have to slow down, you can keep pedaling until you get to the next corner - Dead Man's Curve! As you approach The Curve, you hit the brakes and start thinking about the tree in the middle of the trail. As the road below you departs to the east, you ineptly continue north and meet the tree in the most intimate way. I find I need about 3 or 4 minutes after hitting a tree to recoup my senses and try to assimilate anything that went wrong. Either way, you should take the time to figure out what happened (or didn't happen).

In my example above, hitting the tree (although common for me) could have easily been avoided. It was not the bike which could not make the turn, it was my brain.

The more I ride, the more I understand that turning is a mental thing. Think of most of the places you may have ridden. You probably take corners at speeds which met your personal abilities and not your "hardware abilities." Riding a MTB with any sense of agression requires that you get beyond the personal abilities and start working on finding out the hardwares abilities.

Let's assume I made it through that corner (...after about 10 tries).

As I approach The Curve I look at the line I am going to take and begin to take the bike onto that line. As I start to lean, the bike tire moves from the center tread onto the "transition-tread." This change in forces on the tire causes the tire carcass to deform a little out of round. Based on the tire pressure the contact patch will tend to get a little bigger as the weight of the bike, the cornering forces, and the centrifugal forces start to grow with every degree you lean. As you get to the apex, or the deepest part of the turn, you will take on the greatest amount of external force while in this turn. At this time you are probably on the cornering or "edge-tread." This is the set of tread blocks which seem to stick out the side of your MTB tire. They are designed to better handle the "Blessed Mother of Traction" when the bike is getting attacked by numerous forces of nature. When you are on the edge-tread you are really balancing yourself against the bikes forward momentum, the centrifugal force of the spinning wheels, the force of the rims being leaned off-center, the bike's tendency to stand up in a turn, and the wheel's tendency to want to lay down in the turn. If you are balancing this all correctly, you will turn. If you make a mistake, or the "Blessed Mother" is not on your side, you will tend to meet the ground - post haste.

Cranking up the "how to ride a Mountain-Bike microscope," there is even more going on between the tire and the road when you try to turn.

Another example
Remember those giant hard-rubber ballons you sat on and bounced when you were a kid? They usually had a round, rubber handle on the top. You could sit on them, grab the handle, and bounce all over Grandma's half-acre. This is what you are doing as you blaze down a trail on your mountain bike. As if leaning the bike was not hard enough on you and your poor tires, you also have to deal with the spring effect belonging to conventional, pressurized tires. When you are moving at any speed on your MTB, your tires are repeatedly hitting small irregularities in the trail's surface and bouncing up off the ground for just a moment. If at that moment you try to transition into a turn, or you decide to pull the brake lever into the hand grip, the "Blessed Mother" will laugh at you as you head for your next meal - dirt. This can all be further complicated if the tire bounces while you are in a turn. The bouncing is the reason you and I would always ride at our personal limits and not at our hardware limits; you feel as if you have little to no traction. In fact, your brain is trying to fool you. You have a ton of traction.

Let's say we were going to go for a ride. Find a place where there is dirt, but not rocks or sand. When it is clear of obstacles, take a good run in a straight line - about 20 mph if you can muster it. When you are at speed try to stop as fast as you can without getting out of the saddle. Even for a bike with a geek on it, you will find you can stop remarkably fast in the 2 inches of dust which constitutes the tarmac. The traction you had stopping in a straight line is still there when you turn. Yes, you can actually push the tires as hard on a turn as you can in a straight line, but this assumes you have the tire on the ground 100% of the time you are turning/stopping/skidding/approaching the edge of a cliff or leaning.

As another example, find a fire road which has erosion running perpendicular to the road's surface. Now try the brake test again, and it will take you longer to stop. This is because the tires will bounce on the ruts made by the erosion. Every time the tire bounces off the ground, you are essentially not braking at all. While the wheel is in the air from the bounce, the brakes effect on the wheel causes it to slow faster than when it was on the ground. As a result, the brake causes the wheel to rotate slower than the trail below it. When the tire makes contact with the ground again, the wheel has to accellerate back to the forward speed of the bike before the brakes become effective. Moments later, the tire bounces on another rut, and the cycle begins anew.

When you are turning your MTB the basic effect is the same, but you are not travelling in a straight line. Now the "bounce" has to content with the forward momentum of the bike, and the forces pulling the tire and rim to the earth. The result is a slide everytime the tire encounters any major surface irregularity.

When I am on my un-suspended MTB, I have to ride differently than when I am on the ProFlex because of the differences in traction. I have to setup my tires differently also. When I hit "The Curve" on the hardtail beast, I find that my tire pressure most affects my cornering ability because it determines how much the tires are going to bounce. This is also about the same time you discover if you have crappy transition-tread on your tires. I find with the Beast that I have to run a low pressure, like 35 to 40 PSI, if I want to take turns the fastest. This is a compromise because I have to pedal harder to make up for the spongy tires, and the rear end may tend to squibb out from under the rim a bit more when I snap it into a turn (as opposed to a nice, even arc into a turn).

Since my tire is not filled "tight" it actually cushions the blows from the ground surface to some extent. Also, because the tire is a bit squishy, it tends to hit the ground and get settled in better before it starts to bounce again. This little reduction in the tire bouncing gains a ton of traction. I can come up to a turn trailing the rear brake right up to the start of the turn. Just as I am about to enter the turn, I scan for objects in the trail which could cause "momentus-interruptus". If all is clear and my speed is OK, I look at the exit of the turn right where I want the tire to touch the trail. Keep looking here until you are just leaving the apex of the turn. Next I get off the rear brake and try to lean the bike in to the turn evenly. I usually take a line right through the center of the trail in case the tire slides a bit. This way you have room for a slight slide without hitting any obstacles which are not moving the same direction you are. Letting the bike slide is something you need to get used to. It will slide a bit. If you have good tires and you have correct tire pressure, you can bet that the tire will slide predictably and not suddenly. To best handle a slide, keep your elbows out and relax your arms and hands. When the slide comes, just relax and you will automatically do the right thing - push the front end. If you start thinking about sliding you will not do it right. Practice relaxing and do not practice sliding. Practice cornering and turning and not the disasters that occur when you do so.

My ProFlex is a completely different animal from the Beast. Full suspension bikes are better designed to deal with the laws of the "Blessed Mother", and they therefore allow you to ride more agressively. With a suspension on the bike, the tires will not tend to bounce over the ground. In fact, the suspension allows the bike to soak up bumps like 12 ounces of pimple cream. Because you do not deal with the tire except when it is on the ground, you have a ton more braking power and you can lean until you feel rocks hitting your elbows. When on the ProFlex and I am attacking "The Curve", I use much less caution then the times I am on the Beast. I also use a ton more forward momentum! When approaching The Curve, I will pedal until the last possible moment and then turn my attention to the exit of the turn. Without considering my speed or looking at the center of the turn (beyond looking for logs and dead Union Leaders) I put my pedal down on the side of the bike on the outside of the turn and lean until I get to the place on the exit of the turn I am looking at. When leaning you should slighly crouch down and keep your elbows out to handle a slide. RELAX!

Once you are on track with the exit point on your turn, then you should look as far forward down the trail as you can and head for that. If you can manage to get out of the turn with relaxed arms and no slide, you will be flying on the way to the next turn - And I mean HAULING MAJOR BUTT here!

And man can you lean!!!!!!!!!!
With no bumps deflecting the tire from its course, you will be able to perform feats of anti-gravity that will amaze even you. I cannot tell you how many times I have been in a turn when one of the wheels went away a little and I just hammered on knowing that it would hook up again, and the "Blessed Mother" would help me escape the snake-of-a-turn with little change in my forward speed. I still find myself coming up to a turn going so fast that I have to not think about it or I will hit the brakes, and break what I hit.

There are a million variations upon actually taking a corner. But cornering on a MTB essentially boils down to two methods - the arc and the apex. (They may have official, bike-geek, in-a-book-somewhere names, but I do not know them).

The apex method of turning is probably the hardest to master, but it will save your butt the most. With an "apexed" turn, you are dealing with a line which is not smooth and even. You want to drive into the turn to a specific point, change what your bike is pointed at, and exit on a different line than you entered on. The hardest part of this is changing the dirction of in which your bike is pointed. Generally, this is done with the rear brake and your pedals. If one was to apex "The Curve," it would actually be the slow way to get through it. "The Curve" is about a 100 degree turn which is round enough to carry speed through. But, to apex The Curve you would want a slightly different approach whether your bike had a suspension or not. The key to the apex is how much room you give yourself to "adjust" your line, and how well you use that line. In a perfect world you have as much room as the trail is wide, and you will use every square inch of that room to make the corner. I have never ridden in "perfect-world," but I hear it is nice this time of year.

As you approach "The Curve," you will want to be in the middle or all the way to the inside of the upcoming corner. Adjust this based on the amount of room you have when you are in the corner. If you have a ton of room for error on the corner, then take the turn tight and inside. If you have little room for error and you do not want the directional change to be as radical, stay farther from the inside if you can. (With some trails you do not have a decision here. You will take a line based on where you can put your wheel) Just as your tire starts to enter the turn look at your "pivot point." This is the place you want to apex the turn at. You want to start the apex as the front rim of your bike passes over the pivot point. When you get to the right place, you have two choices: heave the bike over into a slide, or hit the rear brake just enough to goose the rear rim into a slide. If you want to carry a ton of speed, you will need to slide without the brakes. Using the brakes to slide can sometimes be the only way into a tight turn if you want to keep the collarbone count to just two. Either way, you need to get loose to change where the bike is going to go. If you get the bike to slip just the right amount, you will be able to oversteer to stop the slide. When you get it all back together, you are on a different line going out of "The Curve" than the one you took going into it. If you get real lucky, the line you chose will actually be in proximity to the trail you were riding on.

It does take practice to master apexing a turn, but it is worth the time to learn if you do not have a fully suspended mountian bike. Arc'ed turns, on the other hand, are what make Motorcycles, BMX, Motocross, or Mountain Biking so much fun that you would spend a ton of money on one of these pursuits, and get up at 7:00AM on a Saturday even when your spouse has this thing about sex in the morning.

There is only one secret I know of to arcing a turn - RELAX! You want to find a line which can be made into an even, or widening circle. It helps if the surface you are turning on has been tested with one's tires and has a nice positive camber to it. But this is not as critical. As you approach "The Curve," make sure you are on the line to enter your turn. You better not be on a hot approach when you realize you forgot to take time to find a line. If you have to, take the turn on your bike a few times at walking pace. Once on your line, look at the exit of the turn - the place you want your tires to cross as they leave the turn. As you move deeper into the turn, look farther and farther ahead and adjust how far you look relative to how fast you are going. The faster you go, the farther ahead you need to be looking. Tune out the corner itself, forget about any minor irregularities you saw. Do not think about how much you are leaning. Do not think about sliding or crashing, just concentrate on keeping to the line you took. By doing this, you will relax your arms and hands. If you are relaxed and the bike starts to slide you will automatically handle it (it just happens). Let it happen. Next thing you know, you will be through the turn in half the time you thought it took, and on your way to crashing into the next turn. (Learn to walk before you run, ya know!)

You may have to adjust your line, but eventually you will get it. Like golf, when you get it right, it takes the minimal amount of effort to really fly.

The keys to cornering extend beyond the way your tires are made, the weight of you or the bike, or even what surface you are cornering on. To corner you need to know the safest and fastest way through a turn, and you need to be looking at where you will be and not worry about where you are. I cannot stress enough how much it helps to have a place to practice. You used to always hear me going on about Campbell-park "this" and Campbell-park "that," but I was able to try things with the same bike on the same surface to see how they affected my ride. The ability to analyze yourself will result in safer riding, more speed, respect for the "Blessed Mother" and a definite understanding of your incremental improvement. To me, this makes MTB's both a challenge and a reward everytime I throw a leg over to just have fun.

Flyin Al

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