Compact Road

Giant's Compact Road concept was developed in conjunction with Mike Burrows, one of the world's most innovative and prominent bicycle designers. His designs have proven themselves in the real world, including a gold medal at the 1992 Olympic Games and many stage and overall wins under Team ONCE. For further inspiration, check out our shop-on-line for over 5000 items with pictures and descriptions.

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The Giant Compact Road design addresses two very important aspects of a road bike's characteristics, weight and stiffness. Critical to its success in achieving both of these traits is the frame's inherently sloping top tube and larger diameter, thin wall tubing. Because the rear triangle is more compact, rear end flex (which occurs most under acceleration) is significantly reduced. It also reduces weight because there's less material overall. At the same time, larger diameter tubing makes the front triangle stiff to reduce front-end flex while accelerating, cornering and descending. Consequently, a Giant Compact road frame accelerates faster and corners more confidently than any other bike on the road. All this, and the lightest frame as well!

Critical Sizing Dimensions
The Giant Compact Road design is amazingly simple. Burrows realized there are two critically important sizing dimensions for properly fitting a rider to a bike: the bottom bracket-to-seat distance and the distance from the seat to handlebar. These measurements create a triangle of three points; the Seat, the Handlebar and the bottom bracket. The relationship of these three points determines if the bike fits properly. This means that it really doesn't matter what connects the points, as long as the measurements are correct for the rider.

Four Sizes Fit All
Burrows compiled geometry data on a variety of different size bikes to evaluate the positions of the seat, the handlebar and the bottom bracket. He was able to distill this array of dimensional information into four frame sizes that would accommodate a full three-point range of seat and handlebar positions. These four sizes, small (44cm), medium (50cm), large (55cm) and extra large (58cm), coupled with seven seat posts of varying lengths and the wide variety of stems that currently exist to fit virtually every rider from 5'1" to 6'7" with the accuracy of custom-made frame.

Easier Fit
The Compact Road concept allows you to more easily choose a precise fit. Each frame provides a much broader range of sizing possibilities than traditional style frames, so a variety of riders can be fitted quickly and easily.

Step 1  Bicycle Inseam Measurement

a) Locate an uncarpeted hard floor surface.

b)   Dress in cycling shorts with chamois and thin cycling socks. It is important to use shorts with a chamois liner because the thickness of chamois material will affect your inseam measurement.

c)  Measure inseam in centimeters (Use any inseam-measuring device -  Fit KitÒ, "L" shaped level, a large, hardcover book, etc.).

1)   Stand tall and straight on an uncarpeted hard floor surface, feet slightly apart with both heels, buttock, back and shoulders firmly against the wall, facing out into the room.

2)    Place the measuring device between your legs and apply enough upward pressure to the measuring device to simulate sitting on your bicycle.

3)   With a centimeter measuring tape, measure the distance from the top edge of the level/book, to the floor. Repeat this step several times until you are satisfied with the final measurement.

Step 2  Frame Size

Once you've determined your bicycle inseam measurement, multiply that number by .67 to determine conventional frame size (center to top). Convert to Compact Frame size as follows:

CONVENTIONAL                                                             GIANT COMPACT

FRAME SIZING (cm)           RIDER HEIGHT                      Defy / TCR FRAME SIZE

49 - 53                             5' 1" - 5' 6"                            SMALL

53 - 59                            5' 6" to 5' 11"                         MEDIUM

59 - 63                            5' 11" to  6'3"                         LARGE

63 - 67                            6' 3" to 6' 7"                           EXTRA LARGE           

Step 3  Overall Saddle Height Measurement

a)      Multiply your bicycle inseam measurement by .883 - this will give you a centimeter measurement for your saddle height.

b)      This measurement is the overall distance, in a straight line parallel to the seat tube, from the center of the bottom bracket to the top of the saddle at the cupped area where you actually sit and not at the highest points of the saddle that rise off the back or tip of the saddle.

c)       Remember that this measurement is a good starting point and may not be your final overall saddle height measurement.  You will need to determine your pedal position first, found in step four, and ride the bike making slight adjustment before you can arrive at your final measurement. You need to raise the saddle high enough to achieve 96% to 98% full leg extension.  

Step 3.  Shoe/Cleat set-up

Position your cleats with the ball of your foot directly over the pedal axle, and in line with any natural "toe-in" or "toe-out" foot position. Most pedal cleats provide a reference mark on the cleat side.

Step 4. Pedal Position

a)      Before you make any measurements, loosen the seat binder bolt underneath the saddle and gently slide the saddle back as far as it will go - taking care not to force the saddle back beyond its maximum, where the rails start to narrow. Once you've positioned the saddle as far back, (without forcing it), tight the seat binder bolt.

b)      Next, prepare a plumb line. You can purchase an inexpensive Mason Plumb Line from the hardware or make a plumb line with a heavy key on the end of a three foot piece of string.

c)       Place your bike on a trainer with wheels level or on a flat, level, hard floor surface next to a solid and secure wall that you can lean against while seated on the bike.

d)      Dress in your cycling shorts, with your cycling shoes on.

e)      Once you are clipped in the pedals and comfortable on the saddle, pedal several revolutions (slowly backward if using the wall/lean method) while adjusting your position on the bike to find a comfortable riding position.

f)        Once you've situated yourself on the bike to a point where it feels comfortable, stop the cranks parallel to the floor or in the 3 o'clock - 9 o'clock position.

g)      While seated on the bike with the cranks in the proper parallel position with the sole of your shoes parallel to the ground as well, drop a plumb line from the front of your kneecap (just under the kneecap) down to the pedal.

h)      If you're in the correct pedal position, the plumb line should bisect the center of the pedal spindle or axle.If not, measure the distance between the plumb line and the pedal spindle in centimeters. Loosen the seat binder bolt just enough to allow the saddle to slide forward. Using the measurement of the plumb line/pedal spindle difference just determined, slowly slide the saddle forward that same distance. Re-tighten the seat binder bolt.

i)        Get back on the bike and repeat the pedaling position measuring process until you are satisfied with your new position.  You should end up with a plumb line measurement that bisects the center of the pedal spindle falls millimeters behind the spindle, depending on personal preference. If the saddle is pushed back as far as it can go and your plumb line falls to far ahead of the pedal spindle, you may need to re-evaluate your frame size.  Seat setback is affected by the seat tube angle and the size of the bike. Your femur length will play a key role in your final pedal position. Longer femurs tend to require more relaxed seat tube angles or larger frame sizes. While short femurs tend to require steeper seat tube angles and smaller frame sizes.

j)        Remember, this is a starting point. You will need to ride the bike and make subtle adjustments to both the overall saddle height and pedal position before you arrive at your final riding position. Also, keep in mind that most bicycles are not built with a 90-degree seat angle. As a result, the pedal position, or fore and aft position of the saddle will change when you raise or lower your overall saddle height.  Both are dependent on each other.

 

Step 5  Handlebar Width/Handlebar Height

Holding on to the handlebar with hands in the drops, arms should be roughly parallel. Handlebar height and saddle height should combine to give a relatively flat back with hands in the drops. Ultimately, this is a compromise between comfort and efficiency - a lower position is more aerodynamic, but isn't comfortable for low mileage riders because it requires increased flexibility and puts added weight on the hands. In general, less experienced and riders with decreased low back flexibility will be more comfortable with a higher stem/bar height.

Step 6  Stem Length/Reach

Proper reach gives you easier breathing, better neck and lower back comfort, and better weight distribution and bike handling. That "ideal position" varies here more than anywhere else for cyclists, depending on riding style, flexibility, body proportions, and frame geometry, among others. And, your upper body position will evolve with more hours in the saddle. That is, you may find that you develop a lower, longer position as your fitness and flexibility improves. Unfortunately, there is no formula for sizing the top tube and stem that works as well as the inseam method.

Determining stem length: With hands in the handlebar drops, there should be a slight bend to the elbows, with about 3-4 inches of separation between elbow and knee when the crank arm is in the 3 o'clock position. Another indicator comes from glancing down at the front hub while riding in the drops or on the brake hoods; your view of the front hub should be obstructed by the handlebar.

If proper top tube-stem length combination cannot be achieved with a 105-135mm stem, try the rider on the next frame size.

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