The most important feature for cycling comfort:
The bike fits you!
Dave Moulton, one of America's greatest bicycle frame builders, is my source for bicycle sizing guidelines. The fit suggestions below are starting points, based on averages, for optimal riding comfort and performance.
"There is so much information available on bike riding position, it can be confusing to both beginners and experienced riders alike. A whole cottage industry has sprung up dealing with bike fit, and one can spend a great deal of money, and often be no better off.
To find a position that is both efficient and comfortable, there are really only two main issues we need to concern ourselves with. Those are saddle height and position of your arms in relation to your legs. Whether you are looking for an extreme aero racing position, or a more upright leisure riding position, the same principle applies. You need an efficient position, whether your goal is to go fast, or ride in comfort.
1) Saddle height.
Imagine you are doing squats. When doing squats with a weight it is hard to lift from the lowest position. It would be much easier if you started from the half way position. In other words, leg muscles work more efficiently near the top end of the lift. So if you can ride a bike with the saddle as high as it can be, you are pedaling with more efficiency than with the saddle set low. How high would be too high? Well, if you are stretching for the pedal at the bottom of the stroke, and your pelvis is rocking side to side, it would indicate your saddle is too high. With one crank at its lowest point, your toe should be pointing down, but not stretched. You should be then able to lift your butt 1/4 inch (6mm) above the saddle. If you can lift yourself more than that, your saddle needs to go higher. When riding, it is easier to tell by feel if a saddle is too high, but not so easy to tell if it is slightly too low."
Mr. Moulton has put forward a simple formula for bicycle frame size based on his records of hundreds of custom frames built over many years. The frame sizes below assume that the top tube is horizontal and frame size is measured as the distance from the center of the bottom bracket to the center of the top tube. If you are sizing a bike with a sloping top tube, the 'virtual' frame size would be from the center of the bottom bracket to the horizontal line extending back from the top tube/head tube junction.
Bicycle Frame Size:
If you are 5’ 3” to 5’ 5” frame size
equals height divided by 3.3.
For people 5’ 6” to 5’ 10” frame size
equals height divided by 3.2.
If you are 5’ 11” to 6’ 4” frame size
equals height divided by 3.1
A example would be someone 6’ 2” = 74” divide this by 3.1 = 23.87 in. (61 cm. measured center to top. i.e. 59cm. center to center. A person 5’ 7” = 67” divide this by 3.2 = 20.93 in. (53cm. center to top. i.e. 51cm. center to center.)
Mr. Mouton goes by the reasonably well researched 109% rule. The distance from the top of the pedal to the top of the saddle should be 109% of the distance from the rider's crotch to the ground.
2) Position of arms in relation to the legs.
"When pedaling at maximum effort we are pushing down with more than our body weight. The only thing holding us down is our hands grasping the handlebars. Power is transmitted through the arms, shoulders, and back muscles to the legs.
With the crank arms horizontal and the pedal
on its downward stroke, a line drawn from
the hip joint to the pedal is approximately
parallel to a line drawn from the shoulder to
the hands on the drops. In other words arms
are in exact opposition to the legs.
Many recreational riders make the mistake of
raising their handlebars higher and higher to
achieve a more upright back angle, when a better approach might be to fit a shorter stem and raise it less. (The resulting back angle is the same.) If the arms are not opposing the legs, backache can result, or you find yourself constantly sliding forward on the saddle.
Weight distribution too comes into account. Weight should be distributed between the pedals, saddle and handlebars. If the bars are above the saddle then all the weight is on the saddle."
Reach: the horizontal length from seat post to handlebar is frame size center to top plus 12.5-13 cm. It is a pretty constant number, because on most bicycle frames the length of the top tube is proportional to the height of the seat tube.
Handlebar Drop: The difference in height between the top of the saddle and the highest point on the handlebar.
Frame size Reach Drop
(center to center)
60 72.5 11.9
59 71.5 11.2
58 70.5 10.6
57 69.5 10.0
56 68.5 9.3
55 67.5 8.7
54 66.5 8.1
53 65.5 7.4
52 65 6.8
51 64 6.2
50 63 5.5
49 62 4.9
48 61 4.3
47 59 3.6
46 58.5 3.0