How to adjust your bicycle seat height
Riding your Giant road bike is supposed to be fun and enjoyable. Everyone has a different body shape so you need to think about getting those little adjustments made to your bike before you do yourself an injury. As you ride your road bike over time, you may start to feel pains and stresses on your body which tends to spoil the experience of being out on the open road and enjoying the ride.
Seat height adjustment is very important and even the slightest adjustment to your seat can make a huge difference to your ride. The adjustment screw is located at the bottom of the saddle tube. Simply loosen the screw until you can move the saddle height freely.
Adjusting a saddle is a trial and error process and it may require a few attempts to get the ideal position. What you have to do is gradually raise the saddle and ride your bike for a few seconds between each adjustment until it feels right.
How do you know when you have reached the correct height? – good question!
It’s best if you can get someone to help you by holding your bike by the handlebars whilst you make the adjustments. If you don’t have anyone to help you, put the bike close to a wall, and get on it.
Hold the brake lever firmly so that the bicycle can not move. You should be able to rest on the bicycle with your two feet on the pedals. Slowly turn the pedals in reverse until one of the two legs is at its maximal elongation position.
Your knee should flex very slightly (making a few degree angle, not more). If your foot ankle flexes down as you reach that point, the saddle is set to high. The foot should rest in a flat position with respect to the ground.
Some people set their saddle so that their ankle flexes a few degrees downward. This enables you to use more muscles when pushing on the pedals and gives extra power, but be careful as this may cause you to use excess energy and you could find yourself miles from home exhausted. Nothing worse than that – I know, because it happened to me many times.
A simple way to know if your saddle is set at the correct height is to pay some attention as you ride the bicycle and the way you sit on the saddle. If you are moving, slipping left and right on the saddle, it is definitely set too high. On the other hand, if your seat is too low, your legs will rapidly hurt because the lactic acid will form up more rapidly in your muscles.
Why? Because you are constantly using your leg muscles inefficiently and that forces them to work harder to create the same power. This has to do with the lever effect.
The more you flex your legs, the less strength they can develop.
Image source: http://www.giant-bicycle.com
The above illustration gives an idea of the ideal body position on the bike. Notice the red lines showing the slight angles at the joints.
Why the small angle flexion at the joints?
This is mainly to act as natural shock absorbers, dissipating high stress energy coming from bumpy roads and uneven surfaces. If you don’t set your saddle and handlebar correctly, you may end up in a position where your elbow and knee joints are totally locked (no angle at all). This situation is not recommended as the high energy shocks will directly transmit over all your body, possibly causing you pain and premature fatigue.
Before the adjustments are completed, you can also adjust the saddle slope (the angle of the saddle with respect to the ground) and forward position (You can move the saddle forward or backward a few centimeters). To adjust these two parameters, you need to loosen the screw located under the saddle, at the top of the seat post. Only loosen the screw so that you can move the saddle but it should not move easily if you are not applying undue force.
With the bike in a stationery position, the saddle angle should be almost parallel with the ground. If you feel like you are drifting backward of forward as you ride the bike, readjust the saddle.
Pay close attention to signs of back pain and such as you ride. After many rides you make, you should periodically adjust the saddle distance until the pain and such symptoms are reduced.
Another great resource on how to adjust your Giant bike to fit your body is the Australian website called CycleBuzz. http://www.cyclebuzz.com.au/size.asp . There is good information here about measuring your inseam, checking for proper leg extension, setting the saddle for and aft position and an important factor that keeps your posture aligned (and prevents bad backs), determining the top tube/stem length relationship. I hope this helps you in some way with your Giant bike fitting.