San Diego Bike Shop HOW TO FIT A BIKE

HOW TO FIT A BIKE

Professional cyclists could not ride the way they do without being precision fit to their bicycles. Look at
how the rider in front has a slight bend in his knee at the bottom of the pedal stroke. Look at his bent elbows and relaxed upper body. The second rider shows off a perfect aggressive racing position with his straight flat back and super-aero stance.

COMFORT, EFFICIENCY, AND SAFTEY BEGINS WITH RIGHT FIT

How well your bicycle fits you, can mean the difference between comfort and pain, fast and slow, safe and unsafe. Your fit depends on:

- Seat position
- Seat Height
- Seat Tube Length
- Handel Bar Height
- Handel Bar Reach
- Handle Bar Width,

All of which determines your overall correct, riding posture that can translate to comfort, efficiency, and safety.

Keeping in mind that one manufacture makes frame measurements, (Frame size is usually measured along the length of the seat tube, the tube that supports a bike’s seat and seat post,) for example, 15½”, 17 ½”, 19½”, and 21½”, the other makes them in 16”, 18”, 20”, and 22” sizes.

Add other variables such as the slope of the top tube, (The tube between the seat and the handlebar, and one’s body type and mass.

Other important factors:

• Higher quality parts which adjust better for optimized performance, and
• Riding style, (beach cruising, trail riding, touring, commuting, etc, each require a different bicycle type.)

To demonstrate an understanding of a fit, we have put together these general guidelines for checking and perfecting one’s fit. These generalized guideline work for on- and off-road bikes.

Step 1: Level and Centered Seat

A level seat, which is also centered on the seat railings, in general supports full body weight, offers optimum pedaling efficiency and makes it easier to move around on the seat when necessary.

One may think that tilting the seat down or up, will ease pressure on sensitive areas,( and it may actually work for some people.) However, when one does this, it causes the body to slide forward or backward when riding. This could put extra pressure on arms, hands and knees that can eventually lead to injury.

Step 2: Seat Height

To find seat height, one should place his/her heels on the pedals and pedal backwards. The optimum seat height would be when one’s legs are completely extended at the bottoms of the pedal strokes without rocking hips.

With a seat set at this height, when one is actually pedaling with the balls of his/her feet, he/she will have a slight bend in the knees.

Step 3: Fore/Aft Seat Position

One should pedal backwards until the most natural sitting position is reached. The feet must then be moved into the position shown in the photo. The forward crankarm and pedal must be level with the ground. The fore/aft seat adjustment is correct when a plumb line (any piece of string with a weight on the end) hanging from kneecap, touches the end of the crankarm.

However, as with the other adjustments, this is a safe starting position. Typically, people over 6-feet tall, who ride long distances, climb a lot and pedal at about 90 rpm, may prefer to be as much as 1 to 2 cm behind the end of the crankarm. All those less than 6-feet tall, spin at 95 rpm or faster and like to sprint, will probably prefer to be directly over the end of the crankarm.

A recent flatfoot technology introduced by some manufacturers defies the above guideline entirely.

Step 4: Handlebar Height

An incorrect handle bar height effects the weight distribution of a rider over a bike, which can lead to neck, back pain, wrist, or upper arm discomfort.

To find the best height for a handle bar, one must side view the height of the handlebar in relation to the seat height. For a road bike: the handle bar should be adjusted between 1”-4” below the seat height. For off-road and recreational riding, the handle bar may be adjusted to up to 2” bellow the seat height.

It is important to realize that there is a limit to how much one can raise the handlebar. The amount of adjustment depends on the frame and component design. In some cases, it may be necessary to install longer cables and housing to raise the handlebars.

Tall riders with long arms and large hands usually favor lower handlebars and short riders prefer higher ones. However achieving a comfortable back angle of approximately 45 degrees (depending on one’s degree of flexibility) is desirable.

Normally, the bars are the right height, if it feels natural to look ahead. (No neck craning).

It is usually not a good idea to raise the handlebars too much. Once a handlebar is higher than the seat, one’s body weight is shifted more over the rear of the bike, which can mean greater jolts from bumps in the road.

Step 5: Handlebar Reach

If the bars are too close or too far away, you may experience neck, shoulder, back and hand pain.

The optimal position; for a road bike with drop bars: hands on top of the brakes, and looking forward in normal riding position is up to 1” from the tip of the rider’s nose to the center of the handlebar. The same would apply to a flat bar, when hands are on grips, and looking forward, in normal riding position.

Correct reach is normally achieved by replacing the stem of a bike. Stems come in variety of lengths, positive/negative angles, as well as adjustable ones.

Step 6: Handlebar Size

For optimal control and efficiency, drop handlebars should be about the same width as your shoulders. These bars come in sizes ranging from about 38- to 46-cm wide. Therefore, if the distance between the bony protrusions on top of your shoulder blades is 42 cm, which is what the handlebar width should be.

Flat-bar widths vary, too. Usually, riders who enjoy demanding, technical trails appreciate a little additional width between 24”-27”. All-around riders prefer a more standard width of about 22 inches. In addition, if the trails you ride cut through tight spaces such as neighboring trees, one would want to be sure the bars are not too wide to clear the obstacles.

Handlebars come in various shapes, too. Flat bars have different bends and may include rise to help you sit upright. Drop bars often feature anatomic bends in the hooks for more comfort. In addition, they are sometimes bent differently on the tops to accommodate your wrists.

Another consideration with drop bars is reach, the distance between the bar tops and bottoms. Usually, taller riders appreciate more reach.

Step 7: If Riding in Cycling Shoes, adjust the Shoe Cleat

It is important that the cleats on the soles are positioned correctly. There are two important adjustments, A: fore/aft and B: angular. The former is easy to find, the latter takes some careful trial and error.

A: fore/aft

The cleat should be positioned so that the balls of your feet rest over the centers of the pedal axles, photo A.

B: Angular

Ideally, your cleat position allows resting your feet in a natural position on the pedals. Otherwise, you could injure your knees. Usually, aligning the cleats with an imaginary line that bisects the soles provides a safe starting position, photo B.

However, if one feels any stress or strain in the knees, the angle must be changed slightly to eliminate discomfort.

If riding with toe clips and straps, one must make sure the feet must are in the optimum position: balls of the feet over the centers of the pedals.

Note: All adjustments are interconnected and effect your optimum riding position.

Bicycle fitting Methods

Many, universities around the world, bicycle manufacturers, and independent entities continuously conduct scientific studies in bicycle design to better its optimal use, and efficiency.

Major studies are pointed towards both on- and off-road competition, which in turn has broaden the benefits for the general bicyclist community.

However, there are those that want the best and will not settle for less, mostly hardcore bicyclist, in the competition community. For that class of bikers, nothing short of a laser scanner and a computer program that calculates the best mathematical fit will work. For many members of this class of riders; (rightfully so,) incrementally manufactured frames will not work neither. They would want a fit built from scratch right down to the quarter inch of top tube, seat tube, and so on.

Luckily, most bicycles now days are manufactured in many sizes with decent quality frames and components that can be fitted to anyone suitably in a traditional way. Know-how, and few correct measurements are all needed to send you riding with a perfect bike. We are experts in bike fit and strive to help you find the best fit.

Body Scan Laser Measurements

1. Height

2. Shoulder Width

3. Shoulder Height

4. Arm Length

5. Hip Height