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Commuting Bicycle commuting is easier than you think, before you know it, you'll be hooked. Learn the tips, hints, equipment, safety requirements for safely riding your bike to work.

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Old 02-28-07, 08:02 PM   #1
BlindBoar
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Beyond-stupid question about traction...

Sorry for the stupid question; I'm not necessarily new to cycling... er, I guess I am new to cycling, just not to riding bikes. I don't have a ton of experience riding in traffic yet.

You know how many roads are sloped so that the middle of the road is highest and the shoulders of the road are lowest for drainage purposes?

When one is on a slope that isn't "uphill" or "downhill", but horizontal to you, how should you balance your bike to keep traction? Do you stay upright in relation to gravity and trust that you will keep traction with just the side edge of your tire, or do you try to balance so the bike is 90-degrees to the pavement (keeping the middle surface of the tire in full contact) and consequently shift your weight the other way to keep balance?

I'm 95% sure that you are supposed to just keep the bike level in relation to gravity and trust the edge of the tire, but I had a bad experience almost fifteen years ago as a child riding his father's cheapo Costco mountain bike, making a slow turn on pavement and having the wheel simply slide out from under me. Therefore, I always end up doing the latter and trying to keep the bike at 90-degrees to the pavement, even though it always ends up making my balance very precarious.

Can someone reassure me that a good pair of road tires will hold traction even on the side surface of the tires instead of only in the middle? I need to overcome this fear--it's dangerous!
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Old 02-28-07, 08:15 PM   #2
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Stay upright when going straight and lean yourself and your bike into turns. If you are fighting it, you are probably doing someting wrong. A bicycle in motion wants to stay up and will tell you what it needs to do to stay that way.

My suspicion as to what happened years ago is that you were leaning in an odd position during the slow maneuver while not yet having a good feeling for balance and that is why you went down.
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Old 02-28-07, 08:21 PM   #3
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Read the section about halfway down called "Leaning in Turns"
http://www.sheldonbrown.com/brakturn.html
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Old 02-28-07, 08:31 PM   #4
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Check out some pictures of Track cyclists doing "Track Stands" on the steep banking of the curves at the ends of a track. They can stay stock still on bankings of 45 degrees or more. When you went down years ago I suspect it was grease, wet surface, gravel, inexperience, irregular surfaces or any/all of the above.
As was said stay vertical when moving straight and lean for turning. In a turn, except for the tiny move that starts the turn your center of mass/gravity is still centered over your tires. Years back a faired recumbent bike racing a 4-man track team was banking so sharply in the steep turns that it was going below horizontal for a few split seconds twice a lap.
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Old 02-28-07, 08:35 PM   #5
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You were probably running on knobby mountain tires. They have less traction on dry pavement than slick tires, particularly on curves.
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Old 02-28-07, 10:44 PM   #6
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Knobby mountain bike tyres have tall knobs to dig into the dirt when you are in a turn. The downside of this is that these tall knobs will 'squirm' as you corner hard on concrete. Get some cheap slicks if you ride in the city a lot. Horses for courses.
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Old 03-01-07, 12:31 AM   #7
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I would guess the front brake had a part in what happened years ago. There is a very good book called "Twist of the Wrist II" by Keith Code (TOTW I is way to detailed for the average person to read) and it explains the traction circle. For 99% of the time, your tires will give 100% traction, and your choices to use it are acceleration, braking and turning to either side. You can use 50% to turn and 50% to brake but if suddenly turn sharper, you go over 100% and that's what causes the tires to slide. A good example of this: Have you ever been on an icy/snowy road and had to turn into a driveway (in your car) so you applied the brakes and turned the wheel but the car kept sliding straight? Then when you released the brakes, the car instantly followed the front wheels and completed the turn. It all comes back to that traction circle.

When you understand all this, buy the book, it's amazing even for bicycles, we'll talk about how traction can go over 100%.

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Old 03-01-07, 12:46 AM   #8
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Exactly how old we're you 15 years ago? You were riding slow, you are on a bike too big for you to control, and you were much lighter if you are a kid back then. Once you get older and start gaining some mass and strength its much easier to control your bike. I used to fear road bikes because when I was 12 I can not balance one to save my life. But now that I look back at the situation, the bike I was trying to ride was an adults bike and I was simply too small to ride it, hence I fell down. When I got older and bigger I still had a fear of road bikes, but when I finally got on one there really was no difference between it and my mtb's.

Only thing you can do is to practice the turns leaning a little bit, and make sure you have a bit of momentum. Just like any other vehicle you should try to brake before the turn and try not to pedal while leaning and turning. Also make sure the pavement is dry and free of loose debris. No matter how good or experienced you are you will fall/slide down if you lean and there are pebbles between the tires and the pavement.
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Old 03-01-07, 07:57 AM   #9
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In order to ride on such a surface, you can totally ignore it, and act as if it were flat, and you will balance fine.
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Old 03-01-07, 11:08 AM   #10
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Alright, guys--I think I understand now. Now that I know the way it should be done, I just need to go and conquer that fear, trust in the traction!
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Old 03-01-07, 12:36 PM   #11
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The slope across the road is called camber.
Inside camber is like a banked track, the faster you go, the more you stick to the ground.
Outside camber is the opposite, where the ground falls away to the outside of a curve. The faster you go, the less traction you have.
The gradient of camber varies, being steepest near the edges so on an outside camber turn, stay away from the edge.
You have to reduce your speed to maintain traction and avoid simultaneous turn and braking. Wet and slippery surfaces (paint, metal, oil) add to your problems. I have a big outside camber turn at the botttom of a double-lane hill. I take the whole lane and cut the apex of the curve on my lane, as far from the curb as possible.

If you are riding straight with a steep camber its not a big problem but avoid swerving around parked cars, stay out. It is hard to correct a swerve on camber.

High end racing and touring tricycles have correction for camber, one of the wheels is set to a different hiegh but it has to be the correct wheel.
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Old 03-02-07, 12:19 PM   #12
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Just to be contrary, you can steer your bike through turns. Keep the bike upright, lean your body from the waist up into the direction of the turn, and use your handlebars to steer through the turn. Practice on easy turns going slowly until you gain confidence. I will do this if there's a patch of sand on the road in my line through the turn. Otherwise I lean when turning like most cyclists.

I read about this years ago, maybe in a Bridgestone bike catalog. I think the purpose was so you could pedal through turns.
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Old 03-02-07, 12:35 PM   #13
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An intellectual understanding of your balance point on a bicycle will not necessarily make you a better rider only good physical autonomic responses will do that and those, fortunately, can be trained.

Find a big empty parking lot or paved space where you know you will not be bothered by cars or other kinds of traffic or distractions. Make sure you are wearing a helmet and at least cycling gloves, if not the kind of elbow pads, knee pads and wrist guards that skateboarders or in-line skaters wear. Find conditions like you are currently insecure around and build up to those challenges by slowing tackling them in increments. Your body will begin to understand faster than your mind will, if you let it, and soon you'll be confidently riding where once you felt hesitant.
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Old 03-04-07, 03:40 PM   #14
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Also make sure your tires are inflated properly haha :-)
Another reason the tires might have slid from underneath you is because they might have been underinflated a good amount. Just a suggestion.
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