You touch your bike in three places: at the handlebars with your hands, at the saddle with your butt and at the pedals with your feet. If these points on the bike are in the right place, and of the right shape, you will be comfortable. If they’re not, you won’t.
A bike that is the wrong size will always be uncomfortable. Always test-ride before buying a new bike and get the shop to help you choose. Different bike manufacturers measure frames in different ways so you can’t assume that if one 18-inch bike fits you they all will. As a guide, stand over the bike with your feet flat on the floor. Lift up the seat and handlebars as far as you can. You should have 7–14cm (23⁄4–51⁄2 inches) clearance between the tyres and the ground. If you have to raise the seatpost above its safety mark to get enough leg extension, the frame is too small. When buying a new bike, don’t just check for frame height. Try different models to find one that also feels a comfortable length, since this varies from bike to bike. You can make small changes to the reach by altering the saddle position and stem length, but it helps to start from a position close to the right one.
Get the height right first. Sit on your bike in the normal way with hands on the bars, leaning against a wall. Turn the pedals so the cranks are vertical, and put your heel on the lower pedal. Your knee should just lock straight in this position. Check the measurement with your other leg too; it’s not unusual to have one leg shorter than the other. Set your seat height for the shorter leg. With this measurement, when you pedal normally – with the ball of your foot on the centre of the pedal — your leg will be almost, but not quite, straight at the bottom of its stroke. Next, set the saddle angle. For almost everybody, the most comfortable angle is with the top of the saddle exactly horizontal. If you find yourself tipping the nose of the saddle down more than a couple of degrees to be comfortable, think about swapping your saddle for a different one. Everybody has a different shape so you may have to try a selection of different models before finding the correct profile. You can also tweak the saddle position until it’s comfortable. Finally, set the fore-and-aft position. Start with the saddle in the centre of the rails. If you find yourself pushing over the back of the saddle when climbing, move the saddle backwards a little. Move the saddle forwards if you feel you need to be closer to the bars – this can be a good alternative to fitting a shorter stem if you feel too stretched out. A popular guideline is to sit on the saddle and use a plumbline to check that the front of your knee is directly over the centre of the pedal. You might prefer to sit slightly further forward than this, but it’s a matter of personal taste.
Don’t fool yourself into suffering an uncomfortable saddle. There are so many different kinds; at least one will fit you. Equally, don’t expect the saddle that comes on your new bike, or the first you try, to be perfect. If you have a saddle that suits you, transfer it to new bikes. Titanium rails are not only lighter but more flexible, giving a comfortable ride. Leather covers breathe better than plastic ones, which makes a big difference on hot days.
Women’s saddles have become comfortable in the last five years; manufacturers have realized that women not only buy bicycles, they also expect riding them to be a pleasant experience. Again, there are different types so try before you buy. Holes and slots cut in the centre of saddles are good for relieving pressure but can be disconcertingly draughty on cold days.
Bars and stem
Reach (the distance between handlebars and saddle) and handlebar height affect how comfortable you are on the bike, as well as how effectively you can use your shoulder strength for control. Threadless headset systems give less opportunity to adjust the stem height than the older threaded version but new bikes should have had spacers fitted beneath or above the stem to give at least some choice. Height and reach can also be altered by changing your stem. Shorter, higher stems give a comfortable riding position for beginners but be careful to avoid cramping your reach. They do encourage you to look where you’re going, though, and the magic nature of bicycles means they go where you’re looking (thus the common warning, “look at the trail, not at the view”).
Short stems liven up the steering and give more control at speed, and in conjunction with wider bars are currently popular on everything but out-and-out race bikes. These tend to flaunt longer, lower stems, which stretch your body weight forwards. This helps to keep the front wheel on the ground whilst climbing steep trails and roads and transfers some of your body weight from the saddle to the front wheel. The aerodynamic advantage found in such a position is irrelevant for mountain bikers, though, as anyone who’s watched the spectacle of a bunch of mountain bikers, with large backpacks and flapping baggy shorts, adopting aero-tucks in an attempt to beat each other to the bottom of the hill will testify. Riser bars give an extra 3cm (11⁄4 inches) or so of height and can be rolled around to match the sweep of the bars to the angle of your wrists, which can make all the difference to sore shoulders. Handlebar material is also important for comfort. More costly bars are usually made of thinner-walled tubing, or even carbon, both of which are better able to absorb the vibration that can leave you with tired wrists though the effect of this is all but completely overshadowed if you’re running a suspension fork, rather than a rigid fork. Bar ends give extra leverage when climbing and provide an alternative hand position so you can shift about on the bars to ease fatigue through your wrists. The easiest way to find the optimum angle for bar ends is to loosen them off so they rotate on the handlebars, sit on the bike, close your eyes, and grip them. Then tighten them securely in that position. Take a bit of care when choosing grips. Your hand is going to spend a lot of time holding them. Match the grip diameter to your hand size. For hot weather, choose a pattern with ribs or grooves so they don’t get too slippery when wet. If your hands get sore, choose a grip that supports the palm, to keep the blood flowing through your wrists.
The third point of contact with the bike is through your feet, and, as with the other points of contact, a little care makes your machine more comfortable. Most SPD pedals are very small so they’re light and don’t snag on the ground. This can cause discomfort, with all the pedalling pressure concentrated on a small area of your foot. Use stiff-soled shoes so that the pressure is spread over the whole of the sole. Alternatively, consider using an SPD shoe with a cage, which can support your foot over a wider area.
Source : BIKE MAINTENANCE TIPS, TRICKS & TECHNIQUES