Bike Fitting Guidelines

Bike Fitting Guidelines – Rules of Thumb by bikedynamics

Maximum knee angle

Knee Angle – Maximum

The ideal saddle height is best described by the angle of the knee at full extension. Typically, men will be close to 145° and women 150°. The difference is due to flexibility, with looser female hamstrings allowing the knee to extend further. Tight hamstrings will inhibit the extension of the knee, so many people find that being closer to 140° may suit them better. The key to finding the ideal saddle height is to use knee angles and hamstring flexibility to get close, then fine tune (up or down 1-2mm at a time) until in the ‘sweet spot’. Please note that these are dynamic measurements, i.e. whilst pedalling and that static measurements may be different.


Minimum knee angle

Knee Angle Minimum

Once the maximum knee angle has been established, the minimum should be checked. Avoid an angle less than 70° as this can put high shear forces into the knee joint, exaggerates the ‘dead zone’ at the top of the pedal stroke and can cause discomfort in the hip and lower back. If too tight, you will need shorter crank arms.


KOPS Knee over pedal spindle

Saddle set back

The simplest method for establishing saddle fore aft position is to hang a plumb line from the tibial tuberosity (the bony bump below your kneecap). This should pass straight through the pedal spindle when the crank arm is at three o’clock. This is called the Knee Over Pedal Spindle (KOPS) rule, but contrary to popular opinion there is absolutely no biomechanical justification for it. In fact, if the saddle height is incorrect the knee will be too far forwards or back and it will be wrong!
It can work very well though because it is a good predictor of the hip position relative to the seat tube axis. If the hip joint is along this axis, the rider will tend to be well balanced without too much weight on their hands and as the bike designer intended. Finding the precise point on the Greater Trochanter to signify the hip centre of rotation can be tricky though, which is why the KOPS technique is more popular.


Torso Angle - Fast

Torso Angle – Fast

Torso angle is very dependent upon the cyclists choice of performance and comfort. A lower position is more aerodynamic as frontal surface area is reduced. 30° to 40° is a good compromise of performance and comfort but does rely on reasonably good flexibility to lower back and hamstrings.


Torso Angle - Touring

Torso Angle – Touring

A more relaxed torso angle will take the pressure off the lower back, hamstrings and the neck and distribute loads from hands to seat. 40° to 50° is a suitable angle for longer distances where comfort is the priority over speed.


Minimum Hip Angle

Minimum Hip Angle

Torso angles significantly less than 30° can only be achieved using specific Time Trial or Triathlon bikes. Although being much lower at the front will reduce aerodynamic drag, the minimum hip angle can tighten to a point where both comfort and power are compromised. Note how there is a difference between the ‘actual’ hip angle measured between the body reference points and the ‘real’ hip angle due to the curvature of the spine. The ideal ‘real’ hip angle will vary between individuals and is dependent upon their flexibility and duration of events.
The ‘actual ‘ hip angle is easier to measure and men of average flexibility should be able to sustain 45° to 50° for some time. Whereas very flexible women such as World Champion Duathlete Helen Russell shown here can hold angles of less than 40°.
The minimum hip angle can be affected by saddle height and fore-aft position, crank length and the position of the bar extensions and elbow pads. Moving forwards onto the tip of the saddle will open up the hip.


Upper arm to Torso

Upper arm and elbow

On a road bike, the upper arm should always be between 80° and 90° to the upper body. This puts the shoulder in a relatively stable position and distributes loads directly into your skeleton. If ever fitting a shorter stem, care should be taken to check that knees do not hit the bars when riding out of the saddle.A small bend in the elbows will help dissipate road induced shock load into your upper body. If you feel you need to ride with locked elbows, you are probably too far away from the bars.


Hand Position

Hand Position

Dropped handlebars are designed to offer a number of holds to facilitate both alternative torso angles and a variety of hand positions. This is to suit different road conditions and prevent discomfort due to staying in one position for too long. Once saddle height and set back has been established, stem length should be set such that the hands fall naturally to the hoods. This offers the alternatives of a more relaxed position up on the bars and a more aerodynamic position on the drops. If riders spend nearly all their time up on the bar tops, either their top tube or their stem is too long for them. The hoods should be adjusted such that the wrists are straight (as when shaking hands).


Cleat Fitting

Cleat Position

The cleats should be positioned such that the ball of the foot is over the pedal spindle and to accommodate the natural toe in or out of the foot. The ball of the foot can be defined as the end of the first three metatarsals bones which can be found with a bit of light prodding. Alternatively just use the bony lump on the inside of the foot at the base of the big toe.

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About swimbikerun1
Devoted Father, Husband and Employee.Endurance sports fanatic (running,cycling,swimming).Triathlon athlete and coach.If only days had more than 24 hours.

5 Responses to Bike Fitting Guidelines

  1. Reblogged this on the5krunner and commented:
    Note to self: read this one!

  2. Sandra says:

    Reblogged this on A Promise to Dad and commented:
    Thanks to a fellow blogger who pointed his readers here. Great tips! The next thing you will hear from me is my prerace jitters report, then a preliminary race report, followed by a race report with photographs. Keep up your hard work, everyone–but don’t forget your family. They come first (I am reminding myself). . .

  3. Sandra says:

    What a great post! I just reblogged it, I hope you don’t mind.
    Like a fool, I altered my seat position a week and a half before my triathlon (yes, I’m a little newbie, sort of). So far no problems. It’s just a sprint 😉

    • swimbikerun1 says:

      Wish good luck and enjoy the race. In sales, where i work, we have an expression, for those who go to an interview: You only have one chance to make first impression. That goes for your first race. The first races is only once, so enjoy it, don’t try for a world record, save it for the races to come. Good luck!

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