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Description
recording road bike position
Document Sample
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
....................................................................... 11
Chart Measurements ................................................................................................. 15
Cycling Shoes ........................................................................................................... 16
jeudi, 10 novembre, 2011 Bike Position
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.
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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.
Receuilli par: Papyvleo 3
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B: Saddle
Height Over
Bars
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.
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.
Receuilli par: Papyvleo 4
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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.
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.
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
(-).
Receuilli par: Papyvleo 5
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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.
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.
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 ( + ).
Receuilli par: Papyvleo 6
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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.
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.
Receuilli par: Papyvleo 7
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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.
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.
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
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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.
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.
Receuilli par: Papyvleo 9
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Fore-Aft: Record cleat fore-aft
position on sole by measuring from
tip of sole to cleat
Receuilli par: Papyvleo 10
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!
See our Bike Sizing Worksheet »
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.
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 »
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
jeudi, 10 novembre, 2011 Bike Position
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.
Frame Dimensions
A1 Seat Tube Length (C—T)
A2 Seat Tube Length (C—C)
B Top Tube length (C—C)
C Stem Length (C—C)
Click for larger view.
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 »
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 »
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.
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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 »
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 »
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 »
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
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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 »
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 »
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Chart Measurements
Click on a letter to return to the Bike Fit page
Enter your inseam measurement:
__________cm inseam
Calculate your frame size (C-T):
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.
Calculate your saddle height:
____cm inseam * .883 =
____cm saddle height
Establish "neutral knee:"
Move saddle fore or aft?
Recheck saddle height
Enter your TT and stem lengths:
Top tube = _____cm
Stem = _____cm
Enter your handlebar size:
Bar width = _____cm
Enter your crank length, gearing:
Crank length = _____mm
Chain rings = ____ * ____
Cassette = ____ * ____
Note:
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 Sidi Carnac* Diadora Time Shimano DMT Pearlizumi
4 36.5 38 36 36 36 36 -
4.5 37 - 37 37 37 37 36
5 38 39 37.5/38 37/38 37/38 37/38 -
5.5 38/38.5 - 38/38.5 38 38 38 37
6 39 39.5 39 39 39 39 38
6.5 39.5/40 40 39.5/40 39/40 39/40 39/40 -
7 40.5 40.5 40/40.5 40 40 40 39
7.5 41 41 41 40/41 40/41 40/41 40
8 41.5 41.5 41.5/42 41 41 41 -
8.5 42/42.5 42 42/42.5 42 42 42 41
9 43 42.5 42.5/43 42/43 42/43 42/43 42
9.5 43.5 43 43.5 43 43 43 -
10 44/44.5 43.5 44 44 44 44 43
10.5 45 44 44/44.5 44/45 44/45 44/45 44
11 45.5 44.5 45.5 45 45 45 -
11.5 46 45 46 46 46 46 45
12 46.5/47 45.5 46.5/47 46/47 46/47 46/47 46
12.5 47.5 46 47/48 47 47 47 -
13 48 - 48/49 48 48 48 47
13.5 - 47 - - - - -
14 49 48 49/50 - - - 48
To convert to US Women's size, deduct 1.5 to 2 sizes.
Example: Women's 7.5 = men's 5.5 or 6
*For Carnac Legend, order 1 size smaller.
Receuilli par: Papyvleo 16
