The objective of this entire treatise is to help set up a road bike properly, either for racing, touring, or more relaxed riding. What we are actually talking about is a riding position in which the rider contacts the bicycle at three points: the seat, the handlebars and the pedals. In the most basic sense, making a bicycle fit involves adjusting these points in relation to each other. Once the locations and specifics about those points have been determined, there are other issues that must be addressed to fully adapt the bicycle to its rider, such as frame flex, maneuverability vs. stability, durability vs. weight, etc. The bicycle must support the rider’s weight, and hopefully do so without causing discomfort. One might presume that it’s the seat that supports the rider’s weight, but on a typical road bike that would be an incorrect presumption. With the correct setup, the rider’s weight is divided between his feet, his seat, and his hands. On a road bike, the torso will be angled forward and there will be some weight on the hands when coasting on level ground. To fully understand this setup you need to understand the balance involved. The intention is to make the bike feel comfortable in the type of riding to be done. On a properly set up racing bike, a rider will feel quite comfortable in his head-down, body-forward position as long as he is pedaling hard, but if he tries to take it easy he will find the weight on the hands a little uncomfortable.
If you want a bike to fit right, the best thing to do is to start with the right size frame. The reason for selecting a particular frame size is to establish the height of the handlebars. Since the top tube stays horizontal in all but the most unusual road bike, the frame size determines the range of height of the handlebars above the ground. We would expect that any formula that bases frame size on inseam length is probably a good guideline.
The width of the bar should be equal to the distance between the forward rounded edges of the shoulder joints. Too narrow bars inhibit breathing. Too wide bars decrease aerodynamics. That being said, some riders like wider bars to gain greater leverage while out of the saddle. Road style bars give the rider a variety of hand positions. Mountain style bars are less aerodynamic than road style bars, but are more practical for urban cycling because the rider sits more upright. On these bars, the distance should be shoulder joint distance on the point on the bar where your hands will be placed. Handlebar angle or Bar end angles The angle should create a neutral position for the wrist. For road bars, grip in the drops and on the brake hoods. On straight bars, rest on the bar ends. Neither position should cause extreme bend of the wrist.
(the part that connects the handlebars to the frame.) To get an approximate length for your stem, first ensure that your saddle height and position (front to back) are correct. Now place your elbow against the front of the saddle with your hand outstretched, the center of your handlebars should be approximately 3cm (two finger widths) beyond the fingertips of your outstretched hand. With the bike on a level surface, take a broom handle and place it across the saddle and the handle bars, ensure it is level, the top of the handlebars should be approximately 3cm below the lower edge of the broom handle. If you are going touring, or are new to cycling, you may want to start with the bars a little higher and as you get used to them gradually lower the bars to find your preferred position. For racing you will probably want to lengthen the stem and lower the bars as it will be more aerodynamic, but remember that you will probably spend most of your riding time with your hands on top of the bars resting on the brake hoods. The top of the stem should be no more than 4 to 6 cm below the highest point of the saddle. If your thighs contact your abdomen then your stem is too low. The more upright you are the less aerodynamic you will be and the slower you will go. This determines the horizontal distance between the handlebars and the seat. Assume your normal riding position with your hands on the hoods. Drop a plumb from the tip of your nose handlebar. while you are looking down at a 45-degree angle towards the road surface. If you do a long ride and you ache in the neck and shoulder area then your stem extension is too short. These two must be chosen together. The purpose of a “cycling shoe” is to hold the foot rigid. Everything below the ankle should behave as a stiff link. If the arch of the foot is allowed to flex, then the rider must expand energy in foot muscles holding it rigid when applying force to the pedals. Most purpose-built cycling shoes are very stiff indeed; some even have metal beams in the soles. You need to be deciding what type of riding you intent to do. The more serious rider will want the dedicated cycling shoe with an attached cleat that mates to the specific type of “clip-less” pedal he intends to use. Recently, pedal designs have changed in response to complaints of sore knees with the development of pedals allowing varying degrees of float. This form of transmission is intended to enhance power transfer from rider to bike as well as minimise trauma to the legs by permitting the foot to rotate during the pedalling cycle in a toe-in/heel-out or heel-in/toe-out movement pattern. Recent evidence suggests this type of pedal design does reduce trauma and maintains power output. Just exactly what this means depends on the choice of pedal/shoe type you have chosen. It refers to the fact that some people’s feet are wider than others, and the pedals must vary to match. In the case of a casual pedal/shoe setup, the pedal simply needs to have a wide enough platform for the shoe to sit on. It’s best not to be too wide, however, since that would decrease cornering clearance. In the case of clip-less pedals, the cleat assembly on the shoe will be the same width for whatever rider is using them, but it will need to be relocated according to the width of the shoe. For optimum cornering clearance, the inside edge of the shoe needs to be as close to the crank arm as possible without touching it. The adjustment for this typically in the cleat-to-shoe attachment; the cleat itself can be slid side-to-side and tightened down in the proper location. The ball of the foot needs to be located correctly on the pedal to apply force without tilting the pedal forward of backward. With cleated shoes, this positioning is controlled by the location of the cleat on the bottom of the shoe. Without a cleat on the shoe, this location is controlled by the length of the toe clip – where the point of the shoe runs into the clip and won’t go any further. This varies not only with the size of a rider’s foot, but also with the configuration of the shoes he is wearing. Note: The precise configuration of the toe clip is also important, besides just its length. Some provide more room for a thicker shoe, while others will only allow a pointy without crushing the toe. It is important that the shoe is properly aligned on the pedal, toes pointed forward. Riding slew-footed or pigeon-toed misaligns the knees. Slew-footed can cause the heel to contact the chainstays. With cleats, the way this alignment is adjusted is by rotating the cleat on the bottom of the shoe. Some of the modern clip-less pedals are deliberately designed to provide a bit of “slop” in this positioning, allowing the rider to twist his feet a little while riding. Without cleats, the typical way of adjusting this alignment is by adjusting the toe clip side to side. As the toe clip moves inward, so does the toe of the shoe, and the shoe is rotated inward. It is convenient to adjust the toe clips or cleats while sitting on the floor next to the bicycle and inserting a shoe into the pedal. As a final test it is important to take it for a test ride, but for the most part you can tell it’s adjusted nearly correctly just looking at the shoe in the pedal. The foot needs to be “level” on the pedal, with the outside edge of the foot being tilted neither downward nor upward. One would hope that the pedal, cleat, and shoe conspire to hold the foot properly level – but don’t count on it. The foot being held with the outside edge tilted downward – compounded with a flexible crank arm that allows the pedal to tilt even more downward under load – is a prime cause of knee problems. The downward tilt tends to cause the knees to move outward, and the stresses and misalignments that result cause ligament damage. You need to make sure that your feet sit properly on the pedals. The common way to accomplish an adjustment here is to insert a “wedge” between the cleat and the bottom of the shoe. Such wedges can be purchased, but really it’s almost easier just to make something. Slip a layer of plastic from a milk bottle in between the cleat and the shoe at the outer bolt only, or some such. If the tilt you’re trying to correct is caused by the crank flexing under load, it is highly recommended that you purchase a stiffer crank. Using wedges is better than nothing, but really it’s the wrong solution to the problem. You all end up with too much tilt the other way when pedalling gently, which will just cause its own problems. In general the seat tube angle should be selected based on the type of riding expected. Those who plan to race will want an aerodynamic position that allows them to apply maximum force to he pedals without having to tire themselves yanking the handlebars, so they want the seat forward and the handlebars forward and down. It also takes weight off the seat, allowing the use of a puny little seat to save weight at the top of the bike where it counts most. One other reason for varying seat tube angle is for riders that have unusual proportions I their legs and feet. If their upper leg is unusually short compared to their lower leg, for example, that might call for a slightly steeper seat tube angle. If their feet are unusually long for their leg length, that might call for a slightly shallower seat tube angle. With the right frame size, you all be able to set your correct saddle height, which will be within a centimeter of .883 x inseam length, measured from the centre of the bottom bracket to the low point of the top of your saddle. This allows full leg extension, with a slight bend in the leg at the bottom of the pedal stroke. A recommendation that you then shorten this length by 3mm when using clip-less pedals. Also, you might consider a slightly taller saddle height if you ride with your toes down and your heel raised. Most importantly, make any changes in saddle height gradually, and give your body time to adapt to the new position. To state the obvious: one guy’s butt is not the same as another’s. Just because Lance Armstrong uses such-and-such type seat doesn't meant it all feel comfortable under your butt. If you find a seat that works for you, stick with it. The more modern seat design is a flexible plastic shell covered with cushioning and thin leather or vinyl. The cushioning used to be foam, but lately it can be gel or some such. Either way, a key part of this seat’s operation is the flexibility of the shell. Good ones have a really flexible shell while cheap ones use a hard shell. You all definitely know the difference after a hundred kilometer race! Some of these type seats have interesting shapes. A slot down the centre, right on the points where the pelvis bone hit. This is where the seat is cushioned thickest. The advantage of this seat is that you can often sit comfortably on it in several different positions: out on the nose, slid to the back, right in the middle, etc.
Put your bike in a stationary trainer, raising the front wheel to level the bike. Check your position with a video camera or mirrors in front and to the side, or with the help of a friend. 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. Warm up by riding easily for 8–10 minutes. The neutral knee position serves as a good starting point for most cyclists, though many adjust it from here: long distance racers and mountain bikers often move the saddle back by 1cm or more, for power, and sprinters may move it forward, “getting on top of the gear” for quick acceleration. One more note on frame size and geometry: if you cannot move the saddle back far enough to get your knee to the neutral position, you should look for a frame with a more relaxed seat tube angle, or consider a slightly larger frame; if you have trouble moving the saddle forward enough, look for a steeper seat tube angle on your next frame, or consider a smaller frame. For most frames, a seat tube angle shallower by 1° moves the seat lug 1cm back, relative to the bottom bracket. Finally, recheck your saddle height. If you’ve moved your saddle forward or back, you’ve effectively shortened or lengthened your saddle height, and will need to readjust it. |
Then, as you continue to look ahead, slowly stop pedalling, and bring the cranks to rest at horizontal, parallel to the ground. Check the position of your forward knee relative to the pedal spindle —for a "neutral knee position," you’all be able to drop a plumb line from just below the front of the forward kneecap, and have it bisect the pedal spindle and ball of your foot below. Remember to not raise or drop your heel or hip as you check this. Then, move the saddle fore or aft, as needed, to achieve this neutral position.