If you have knobby tires on your mountain bike, lose them and get some slicks 26x1.25 or 26x1 (no wider than that). Pump them up to their stated limit or a little past it. You want to mimic the feel of a road bike as closely as possible. You might also want to drop your handlebars down too. An upright riding position is a significant drawback to good cornering technique.
Find a corner and go around it as fast as you can then go faster then faster then faster still. You do need to be particular about what corner you use. Be safe. An office or industrial park on a Sunday morning might be ideal or a VERY quiet residential street. Make sure the corner is free of gravel, glass, small furry creatures, UPS trucks and land mines. Check to make sure that the pavement is smooth.The Physics
To corner correctly, you need to have a low center of gravity. Have your body centered on the bike. Lean the bike as opposed to steering it and take a correct line around the apex of the corner. Low center of gravity is achieved by getting your upper body as low as possible while maintaining control. Do not however put too much weight over the front wheel as that will compromise your body being centered on the bike. You want your weight low and between the wheels. Lean the bike, don't steer it - think Formula 1 race car, not tractor-trailer. Watch racing motorcycles on a road course and notice that they do not turn the handlebars but rather they lean way over and, voila! The bike corners. Also notice how they use their outside knee as a counterweight. You want to brake as little as possible as braking not only slows you down but can also radically change your line around the corner. Approaching the Corner
Adjust your speed and make sure your inside pedal is up.
Press down on the outside pedal, lean the bike over slightly.
Its better if you can use the whole roadway because you can start on the left side of the road.
Drift across both lanes to reach the apex of the corner and drift on through to the left lane to exit .
Use the whole road (this is the reason I recommend a NO-traffic situation).Find the local roadie scene and watch a criterium. Look at the body position of the riders and look at the lines they take. Also make note of the speed.You are only going to learn by doing some fast cornering. It is about feel and (lack of) fear. Trust yourself and your bike. You build trust by practice.
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