leaning vs. turning... unscientific experiment results

I was pushing a wheelbarrow full of firewood this morning. (It's that time of year already!) and I noticed that the wheelbarrow was a LOT like a motorcycle. very odd... It got me thinking about lean vs. steer, and what lean does and blah blah blah.
This is what I came up with. I noticed that when steering a wheelbarrow, if you don't lean the wheelbarrow in the direction of the turn, it has a tendency to tip over in the opposite direction. then I realized that the wheelbarrow's handles are much like the front fork of a motorcycle. If you think of the handles as the fork, at an extreme rake, you realize that in order to turn the front wheel you have to change your direction of travel at the back of the wheelbarrow. and to make a lean on the front tire, you have to "twist" the wheelbarrow's handles. very interesting...

So, this is what I decided to do. I wanted to see if it was possible to make a high speed turn, without leaning. keeping the bike straight up in the air, and turning seemed like it shouldn't be that hard. at low speeds, I tried it without anything added to the bike to prevent me from leaning (which seemed safer). I found it hard to not inadvertently lean in the direction of turn, but it was possible at very slow speeds. The key thing was keeping balance. You almost have to lean to gain your balance on the bike. Next, I tried some high speed turning wihtout leaning. 25mph was about my limit because the ground is pretty dry and hard this time of year. I did everything in a cut down hayfield, and kept off of the roads, for the obvious reason. When traveling at 15 mph I was able to fight the urge to lean somewhat, but after a few milliseconds, the inevitable happened... broken visegrips... (my shifter is long gone, so I have a pair of visegrips clamped to the shaft) I got a few grass stains, but otherwise, I was ok.

nothing really changed at 25 mph. as soon as you get into a turn with the handle bars, your body will want to lean the bike subconciously. Maybe this is something we learned, when we learned to ride a bicycle? anyhow, I bit turf about 6 times and gave up, and deemed it impossible to turn a bike without leaning into the turn. Leaning out of the turn was really stupid (read: broken tail light). All in all, I have come to the conclusion that, in order to maintain balance on the bike, you must lean in the direction of the turn, as your bike/body keeps the centrifugal force created by a turn from making the top of the bike fly out of turn, ahead of the bottom. Also acting on this would be Newton's first law. when you turn, the bottom of the front wheel is the only thing that changes direction, the top wants to remain going straight, unless you lean on it to counteract this.

Was it worth it? sure! I don't fear broken bikes, and I am pretty good at falling, as I have been doing it for years! Did I really prove anything? I guess not. Unless you were looking to prove that I was a bit "loose." Does this help anyone's understanding of how a bike turns? I hope so!

again... recap... as you turn the front wheel, the top of the bike follows Newton's first law of motion, and tries to remain on a straight path, except the bottom of the bike decides to go in the direction of bottom of the front tire(the back tire usually follows the front tire, if not, check your welds). Without anything except balance and a slight amount of gyroscopic action (which is disturbed when you break it's rotational path by turning the handlebars) there is nothing but the rider to counteract this natural tendency to remain traveling straight. By leaning the bike, you are essentially changing the direction of the top of the bike to match the bottom/front, relative to your ability to balance the bike. I'd guess that you'd have no trouble turnign a bike without leaning, if you affixed a pair of training wheels tight to the ground at the footpegs. This would keep the bike from tipping over out of the turn

I'll try a few experiments with countersteering tomorrow. I don't mind putting a few dings in the bike, I have a bunch of NOS parts coming in the mail for it! If you are bored and not afraid of a little dnager, try to lean the bike hard to one side while remaining upright, and try to steer the bike as to prevent it from turn in the direction of the lean. I was thinking of tryign this tonight but the grass is pretty wet with dew, and my front tire is flat, so I'll have to wait until tomorrow.


giddy up!

"And remember kids... just say "nope" to dope!"

Maybe I should start drinking again. When I drink, I think to myself, "self, you will look like an ass if you do something like this, people will know you are an alcoholic." Without beer, that thought never crosses my mind. :blush:

Been trying some mental visualization...

Slow speed...moving forwards

force from front to back of bike exceeds side to side force
this makes the bike want to lean MORE in the direction it's already leaning. Balance the forces...

Notice this effect when you come to a hump with your wheel barrow while in a gentle turn. You have to 'counter steer', that is you have to push down on the right handle...or your gonna be reloading wood or shoveling up a mess of wet concrete...

It's the transition from gravitational force dominant at slow speed to lateral force dominant at slightly higher speed and the transition is going to be a function of both rolling resistance and rake angle. I'm betting you will experience an increase in the amount of 'counter steer' required and transition speed if you accelerate with some front brake applied....probably easiest to crank up idle a little and use clutch and brake rather than throttle and brake.

This is all based on a mental visualization. If you report back that this is indeed the case, I'll try to get fired up enough to draw a diagram with circles and arrows (alices restaurant?)

-Duck

Years ago, I read an interesting description of how motorcycle steering works. Basically, because the front forks have rake (like the wheel barrow) when you turn the handlebars to the left the contact patch of the front tire (where the tire is in contact with the road) shifts off the center of the tire to the left side. When this happens, the centerline of the 2 contact patches (an imaginary straight line between the contact patches of the front and rear tire) moves to the left of the mass of the bike. This results in more mass on the right side of that line than on the left. This imbalance of mass causes the bike to try to fall to the right side, and the bike will actually turn to the right.

Try this, driving down a straight (wide) road at about 30 mph gently try turning the handlebars to the left, The bike will steer to the right.

Steer left to go right and right to go left. Of course, we actually steer be shifting our weight and don't really turn the handlebars much during normal driving (except me when I was 16 in an experiment that left me and my old BSA stuck on the side of a big elm tree). Ed