Les Increvables, groupe cycliste de Brossard
Bike ajustment chart
Content table
Recording road bike position 2
Procedure 2
A: Saddle Height 3
C: Saddle to Handlebar Reach 5
D: Saddle Angle or Tilt 5
E: Saddle fore-aft 6
Record saddle brand and model. 6
G: Stem Length 6
H: Stem Angle 6
M: Brake Level Position 8
[pic] 11
Chart Measurements 15
Cycling Shoes 16
Recording road bike position
This article will describe the use of the Road Positioning Chart for competitive road bicycles. A similar article for MTB bikes is at MTB Bike Positioning. The chart is intended primarily for the mechanic to quantify and record the various aspects of a cyclist positioning adjustments. It can also be useful for a cyclist to track and record changes to his/her position. For example, if saddle height is raised, the new height and date of change can be noted. This will allow the cyclist to track changes in performance. Additionally, if the bicycle is lost or somehow destroyed, this chart will help in quickly setting up the new bike to closely match the original positioning.
The Road Positioning Chart can be downloaded as an Adobe® PDF file. The Adobe® Reader program is required to view and print this file. See Adobe® if you do not have this program.
Procedure
Useful tools for measuring rider position:
• Positioning Chart, plus pen or pencil
• Metric tape measure
• Angle finder
• Plumb bob
• Straight edge
• Measureing caliper
Begin with the bicycle on level ground. If possible mount bike on trainer and level bike by checking that both wheel axles are the same distance from the ground.
There is often more than one method for measuring a component or position. It is important that the user be consistent and that the method of measuring is noted. Record all units of measurement. For example, record "50cm" for fifty centimeters, and "50mm" for fifty millimeters. Complete the chart and makes notes with the assumption that someone else will need to set up a bike from only this chart.
Begin by recording customer/rider information, such as name, address, etc. Also record bike make, model, year of production, and serial number. Also record bike's color scheme and any unique or obvious physical characteristics that might distinguish this bike. Assume this will be used in a police report of a stolen bike. It is also recommended that the traveling rider carry a recent photo of the bicycle.
|A: Saddle Height |
|Record saddle height and note method of measurement. A simple method is to place a straight edge on top of the saddle and|
|record height from the bottom bracket center to the lower edge of straight edge. Measure along the seat tube. |
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|B: Saddle Height Over Bars |
|[pic] [pic] |
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|Record handlebar-over-saddle height difference. A simple method is to measure perpendicularly from saddle to ground, and |
|then bar to ground, and take the difference between these two measurements. Use a straight edge on top of the bars, and |
|measure to lower edge of the straight edge. |
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|Another option is to use a long straight edge and the level finder. Use level finder to hold straight edge horizontal |
|from saddle. Measure from lower edge of straight edge to top of handlebars. |
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|A related option is to measure from the front axle to the top of the bars. This is a useful measurement when tracking |
|changes in position on the same bike. However, this number is also related to stem length, fork rake and wheel base, |
|making it less useful when setting up a duplicate position on a different frame. |
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|C: Saddle to Handlebar Reach |
|Measure from saddle tip to the center of the bars at the stem. This gives a reference for bar reach. |
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|D: Saddle Angle or Tilt |
|Using a straight edge on top of saddle, measure saddle angle from horizontal. If the front end of the saddle is raised, |
|record this upward sloping saddles as a positive number (+). Record downward sloping saddles with a negative number (-). |
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|E: Saddle fore-aft |
|Drop a plum bob line from the saddle tip and measure distance from line to center of bottom bracket. It is easiest to |
|tape line to saddle so it hangs from saddle end and extends freely toward the ground. |
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|F: Saddle Brand and model |
|Record saddle brand and model. |
|G: Stem Length |
|Measure center of the stem binder bolt to the center of the bars. |
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|H: Stem Angle |
|Record the stem angle from horizontal. Especially on shorter stems, hold angle finder so it is parallel to stem angle. In|
|the stem is downward sloping, record as a negative number ( - ). It stem is upward sloping, record as a positive number (|
|+ ). |
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|NOTE: Some stem manufacturers specify stem angle using the steering column as a reference. If this angle is known, record|
|this as well. It is possible to measure the manufacturers angle by taking the stem angle and the quill (steering column) |
|angle. Stem angles sloping upward are recorded as positive numbers, while stem angles sloping downward should be recorded|
|as negative numbers. For example, a bike is measured and the angle from vertical is 18-degrees. (This means the headtube |
|angle as the bike sits is 72-degrees.) The angle from horizontal is 25-degrees. The manufacturer's angle is then 90 - 18 |
|+ 25 = 97 degrees. In the right image below, assume the stem sloped downward 6 degrees instead. The manufacturer's angle |
|is then 90 - 18 + (-6), or 66 degrees. |
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|Manufacturer's angle = 90 - Angle from Vertical + Angle from Horizontal |
|I: Handlebar brand and model |
|Handlebars vary in shape and design. Record the brand and model. |
|J: Handlebar Width |
|Measure width from center to center at the lower section of the drops. Some manufacturers specify width as an outside to |
|outside dimension. However, when a bar is wrapped with thick tape, this makes an accurate measurement more difficult. |
|Record method of measurement. For example, "46cm center-to-center". It is use to know bar width when bike is crashed. The|
|width after the crash can be compared to the width before the crash. Replace bar if this measurement is different. |
|K: Handlebar Tilt or angle |
|Measure drop type bar angle off of lower section of drops using level angle finder. Record any positive or negative |
|angles to be consistent with the system use on the stem. In other words, if the lower section is pointing downward, or |
|more toward the rear axle, record this as a positive number. If the lower section is sloping upward, toward the rider, |
|record this as a negative number. |
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|L: Handlebar Clip-on Bars or Aero Bars |
|Measure angle of aero-type extensions from horizontal. If the bar extension is adjustable in reach, also record reach |
|from bar center to end of extension. |
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|M: Brake Level Position |
|Record position of brake levers on handlebars. Place straight edge on lower drops and measure tip of lever as above (+) |
|or below (-) this line. |
|N: Crank Length |
|Record crank length. Cranks are measured from the center of the pedal mount to the center of the spindle square. Arm |
|length in millimeters is typically labeled on the back of the crank. |
|O: Chainring Sizes |
|Record the preferred large and small chainring sizes. |
|P: Pedals |
|Record the pedal make and model. Changing pedal types may affect the saddle height. |
|Q: Shoes |
|Record shoe size, make, and model. It is also useful to record user preference of either a fixed or floating type of |
|cleat. The cleat position on the sole may also be recorded. |
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|Rotation: Engage shoes on pedals, without rider. Hold shoe parallel to crank. Measure distance from crank bolt to center |
|of shoe sole. If the pedal has adjustable float, hold sole in middle of float range. If cleat has float, hold sole toward|
|crank. |
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|Fore-Aft: Record cleat fore-aft position on sole by measuring from tip of sole to cleat |
| |[pic] |
| |Easily the most important aspect of selecting a new bike is achieving the right fit. Forget the in’s and out’s of titanium vs. |
| |steel vs. aluminum, ignore the road tests and race wins. One thing matters more than anything else when you select your new |
| |bike—that it fits you! |
| |When a cyclist fits her bike well, she rides more comfortably and efficiently. She rides with more power, and yet the effort |
| |comes easier to her. Her body is relaxed, her bike handling skills almost second nature. |
| |True, setting up your ideal position on a bike takes some time, and can be difficult. Why? We cyclists hear conflicting advice, |
| |and conflicting formulas, on sizing and positioning. Variances in body sizes and proportions, in levels of fitness and |
| |flexibility, in technique and style, all affect a cyclist’s best position on the bike. |
| |Where do you learn how to fit yourself correctly on the bike? We’ve found useful sizing and positioning information in books by |
| |coaches and racers (Eddie Borysewicz’s, Greg LeMond’s, Davis Phinney and Connie Carpenter’s). About once a year the major |
| |cycling magazines publish articles on sizing and bike fit, which are also often available at their websites. Commercial sizing |
| |systems such as the Fit Kit, BioRacer and Serotta’s Size-Cycle can be very helpful. |
| |Truthfully, though, the best resource you have is your own experience, especially when teamed with feedback from a coach or |
| |knowledgeable cycling friend, or video or mirror analysis. Drawing on your expertise, and ours, together we can set you up on a |
| |bike that feels like a natural extension of your body, and invites you out to ride for hours at a time! |
| |[pic] |
| |See our Bike Sizing Worksheet [pic]» |
| |Your Inseam and Frame Size |
| |We'll talk primarily about fitting a road bike, and make notes about fitting a mountain bike where appropriate. |
| |The best frame size for a cyclist is as small vertically as possible, with enough length horizontally to allow a stretched out, |
| |relaxed upper body. This frame will be lighter and stiffer than a larger one, and will handle better and be more comfortable |
| |than a smaller one. |
| |[pic]Determine Your Proper Frame Size |
| |To determine your proper frame size, you’ll first need to get an accurate inseam measurement . Stand with your back against a |
| |wall, your bare feet 6" apart on a hard floor, looking straight ahead. Place a book or carpenter’s square between your legs with|
| |one edge against the wall, and pull it up firmly into your crotch, simulating the pressure of your saddle while riding. Have a |
| |helper measure from the top edge of the book to the floor, in centimeters. (You can convert inches to centimeters by multiplying|
| |inches by 2.54.) Repeat two or three times, for consistency, and average the results to get your inseam length. |
| |Bike Sizing Worksheet [pic]» |
| |[pic]Frame Size |
| |Frame size refers to the length of the frame’s seat tube. Pro frames are measured along the seat tube in one of two ways, |
| |center-to-top (C-T) or center-to-center (C-C). C-T measures the distance from the center of the bottom bracket to the top of the|
| |top tube or seat lug (See image bellow). C-C measures from the center of the bottom bracket to the center of the top tube. Since|
| |C-T measures to a point higher on the frame, a frame measuring 55cm C-T would also measure roughly 53.5–54cm C-C, a difference |
| |of 1–1.5cm. |
| |To size your C-T road frame, we use a guideline of .67 x inseam length. For example, if you have an 85cm inseam, your C-T frame |
| |size would be .67 x 85cm, or 57cm. |
| |LeMond’s formula, from his former coach, Cyrille Guimard, establishes C-C size by the formula .65 x inseam length, which yields |
| |virtually the same frame size when you add the 1–1.5cm difference between C-C and C-T. |
| |Larger riders (6'0" and up) may find that this formula puts them on a too small, and uncomfortable, road frame. A taller cyclist|
| |who wants a more comfortable frame may be better off selecting a frame 27–28cm less than inseam length, C-T. |
| |For a mountain bike, we start by recommending a frame in the range of 10–12cm smaller than you take in a road frame. For |
| |example, if you ride a 55cm C-T road frame, look for a 43–45cm (17–18") C-T mountain frame. |
| |[pic] | |
| |Click for larger view. | |
| |Frame Dimensions | |
| |[pic] | |
| |A1 Seat Tube Length (C—T) | |
| |A2 Seat Tube Length (C—C) | |
| |B Top Tube length (C—C) | |
| |C Stem Length (C—C) | |
| | | |
| |In many ways, though, it is more important to fit a mountain frame by the top tube length needed, rather than by the seat tube | |
| |length. For instance, you might be able to get to the proper frame clearance, saddle height and neutral knee position (see | |
| |below) on either a 17" frame or a 19" frame. Yet the 19" frame will likely have a top tube 1" longer than the 17" frame, which | |
| |changes your stem length accordingly. Or, one manufacturer’s 17" frame may give you a 22" top tube, while the next one’s 17" | |
| |gives you a 22.8". More on this below… just make sure that you’ll be able to work out your top tube and stem length for a given| |
| |frame. | |
| | | |
| |Bike Sizing Worksheet [pic]» | |
| |[pic]Saddle Height |
| |With the right frame size, you’ll be able to set your correct saddle height, which will be within a centimeter of .883 x inseam |
| |length, measured from the center 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. |
| |LeMond recommends that you then shorten this length by 3mm when using clipless 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. |
| | |
| |Bike Sizing Worksheet [pic]» |
| |[pic]Neutral Knee Position |
| |Next, 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. |
| |Then, as you continue to look ahead, slowly stop pedaling, 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’ll 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. |
| |The neutral knee position serves as a good starting point for most cyclists, though many adjust it from here: long distance |
| |(stage) 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. |
| | |
| |Bike Sizing Worksheet [pic]» |
| |[pic]Top Tube and Stem Length |
| |Next, dial in the correct "reach" to the bar, or horizontal fit. 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 improve. As Phinney notes, though it may |
| |be difficult to achieve a truly flat back, we cyclists should all strive to be “longer” across the top of the bike. |
| |Unfortunately, there is no formula for sizing the top tube and stem that works as well as the inseam method. One indicator comes|
| |from glancing down at the front hub while riding in the drops; your view of the the front hub should be obstructed by the |
| |handlebar. LeMond recommends that your elbows, bent at 65–70° with your hands in the drops, should be within an inch or two of |
| |your knees at the top of your stroke. |
| |Measure your current bike’s top tube and stem. Then, decide how you’d like to alter that fit; add the top tube length to the |
| |stem length to get your overall top dimension. The very reason we stock stems in 1cm increments, from 7cm to 14cm, is just to |
| |let you dial in your best top tube and stem length. |
| | |
| |Bike Sizing Worksheet [pic]» |
| |[pic]Handlebar Size |
| |Road handlebars come in several widths and bends. Most cyclists select a bar that is just as wide as their shoulders, measured |
| |as the distance between the shoulder joints. A wider bar opens the chest for better breathing and more leverage, but is less |
| |aerodynamic. You’ll need to find your own balance between the two. |
| | |
| |Bike Sizing Worksheet [pic]» |
| |[pic]Crank Length, Gearing |
| |Choosing the right crank arm length, like the rest of this, comes down to your size and riding style. Longer cranks give you |
| |more leverage, helpful if you like to push big gears at a low cadence (climbing, time trialing, etc.). On the other hand, if you|
| |like to spin at a high cadence, you’ll do better with standard cranks. As a starting point, we often recommend 170mm cranks on |
| |54cm C-T road frames and smaller, 170–172.5mm cranks on 55–61cm frames, and 172.5–175mm cranks on 62cm frames and larger. |
| |Mountain bikes generally get cranks 2.5–5mm longer than road bikes; that is, you might want a 175mm crank on your mountain bike |
| |if you’re set up with a 172.5 on your road bike. |
| |We offer a wide range of gearing options for chainrings and cassettes. Depending on your strength and terrain, you’re welcome to|
| |specify the close-ratio gearing generally used for racing, or wider ratios for hilly terrain or more recreational riding. |
| | |
| |Bike Sizing Worksheet [pic]» |
| |A Final Note |
| |One of the objections your local shop may have to your purchasing a bike through the mail is that it cannot be fitted correctly.|
| |For the resourceful cyclist, the opposite is true. The retail shop often offers a cursory fit that involves the customer |
| |standing over the top tube of a few bikes on the floor; frames 5cm (2 inches) apart rather than 1–2cm apart in sizing; no stem |
| |sizing, no bar sizing, no crank sizing, no wheelbuilding options. Compare that with the program we have for you. The Colorado |
| |Cyclist offers quality and variety in professional road and mountain bikes, at significant savings—as well as a great fit! |
| |Bike Sizing Worksheet [pic]» |
Chart Measurements
|Click on a letter to return to the Bike Fit page |
|[pic] |
|Enter your inseam measurement: |
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|__________cm inseam |
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|[pic] |
|Calculate your frame size (C-T): |
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|Road: _____cm inseam * .67* = _____cm |
|Mountain: (____cm inseam * .67*) |
|-(10-12cm)=____-____cm |
|*See notes for riders 6'0" and taller, |
|and for mountain bike top tube length. |
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|[pic] |
|Calculate your saddle height: |
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|____cm inseam * .883 = |
|____cm saddle height |
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|[pic] |
|Establish "neutral knee:" |
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|Move saddle fore or aft? |
|Recheck saddle height |
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|[pic] |
|Enter your TT and stem lengths: |
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|Top tube = _____cm |
|Stem = _____cm |
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|[pic] |
|Enter your handlebar size: |
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|Bar width = _____cm |
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|[pic] |
|Enter your crank length, gearing: |
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|Crank length = _____mm |
|Chain rings = ____ * ____ |
|Cassette = ____ * ____ |
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|Note: |
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|Wheelbuilding: |
|# Spokes ____F/____R |
|Spoke Gauge ____F/____R |
|Nipples ____F/____R |
|Conversions: |
|____inches * 2.54 = ____cm |
|____cm * .394 = ____inches |
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|Cycling Shoes |
|US |
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