How to prevent scratching while riding a bicycle?

Riding a bicycle not only has the ability to burn over 300 calories in 30 minutes, depending on the type and exertion rate, but spending time in fresh air with family and friends can help you to release stress. Having a bicycle properly fitted to your body is important for riding comfort and maneuverability. Seat height, in particular, is important to ensure proper leg extension while also preventing the handlebars from scratching your knees.
Step 1
Straddle the bike; place both feet flat on the ground, one on each side of the bike. There should be at least an inch of space between the crossbar and your body. Less than 1 inch means that the frame of the bike is too big for you will be more difficult to maneuver.
Step 2
Sit on the seat of the bike and place one foot on the ground and the other on the pedal. If your foot cannot reach the pedal when it is at its lowest point, then the seat is too high, whereas if your foot does reach the pedal but your knee is more than slightly bent at a 20 degree angle, the seat is too low.
Step 3
Take the bike for a test run around the block or store and notice the bend in your knees during the rotation. Optimal maneuverability and oxygen use occurs when your knee is only slightly bent, at around a 20 degree angle, at full extension. A locked-out knee at full extension can lead to injuries and means that the seat is too high; a large bend in the knee, at a 90 degree angle, while at full extension is an indicator that the seat is too low.
Step 4
Determine the comfort of your knees during the rotation of the pedals; knees can be vulnerable during physical activity, so it is important to protect them from injury. Knees scratching or hitting against the handlebars means that your seat should be lowered. Alternatively, if you have the proper alignment during extension, yet your knees are still hitting the handlebars, then it may be that the handlebars are positioned too low and they should be raised.