Hinault/Genzling Frame Sizing
Method:
In the 1970's and 80's a study of professional
cyclists was undertaken by Frenchman
Claude Genzling to develop a rational frame sizing technique. Genzling
interviewed hundreds of pro road cyclists gaining body measurements
and respective cycle frame dimensions.
This data was combined with photographic
studies of the riders position on
the bike. Working in close collaboration with five time Tour de France
winner Bernard Hinault, Genzling developed
basic relationships between body dimensions
and cycle frame dimensions for "pro-style" road cycling.
In the mid 1980's, I converted Genzling's
graphical frame sizing technique into
the simple analytical sequence given below. So, have some fun, get a
buddy to help you and take the body
measurements, calculate the ratios and plug-n-chug
your way through the equations to arrive at seat tube centerline
length, seat tube angle and top tube
centerline length.
With this done, if you wish to order a custom
Strawberry frame, please fill
out the custom frame order form and I'll get to work. An order
acknowledgement will be sent out upon
receipt of your order providing your custom
frame serial number, description and delivery date. An invoice will
be e-mailed to you upon completion of your
frameset. Shipment will be effected
immediately upon receipt of the balance due.
HINAULT/GENZLING BICYCLE FRAME SIZING
(trigonometric derivations by Strawberry)
TOOLS REQUIRED
A) carpenters square
B) wall
C) stool
D) tape measure
E) 1" diameter dowel
F) table
OBTAINING BODY MEASUREMENTS
A) INSEAM "E": Place square between
legs with the long edge against wall, raise as much as possible, then
measure from top edge of square to floor (cyclist
without shoes).
B) THIGH "F": Sitting erect on stool
press pelvis against wall and hold lower
legs vertically - place square against kneecaps and measure from wall
to square.
C) LOWER LEG "J": Sitting erect on
stool place long edge of square across knees
just behind kneecaps - measure from floor to square.
D) TRUNK "T": Sitting erect on stool
press pelvis against wall - rest square
horizontally on bulge of collarbone - measure from stool to square.
E) ARM "B": In same position as for
trunk measurement, grip dowel vertically
- raise arm to horizontal and perpendicular to wall - measure from
wall to close edge of dowel.
F) FOREARM "A": Hold dowel
perpendicularly to forearm - rest elbow on table
with forearm perpendicular to table - measure from table to close edge
of dowel.
BODY MEASUREMENT RATIOS
A) TRUNK TO INSEAM: T/E (average ratio = 0.76)
If your T/E ratio is greater than the
average, try increasing the top tube length
L.
B) ARM TO INSEAM: B/E (average ratio = 0.87)
If your B/E ratio is smaller than average,
try decreasing the top tube length
L.
C) FOREARM TO INSEAM: A/E (average ratio = 0.40)
If your A/E is larger than average
try increasing saddle/bar length S.
D) THIGH TO LOWER LEG: F/J (man avg. ratio =
1.11, woman avg. ratio=1.14)
If F/J is larger than average try setting saddle
back further.
If your F/J is smaller than average try
increasing saddle height Hs.
CYCLE FRAME DIMENSION FORMULAS:
A) SADDLE HEIGHT: Hs= 0.885E
B) SEAT TUBE CENTERLINE LENGTH: H= 0.65E
C) SEAT TUBE SETBACK: I= 0.734(N/2+R)
D) SEAT TUBE ANGLE: Q= arc cos((N/2+R)/0.885E)
example: E=82cm., R=7cm. (Table 1), N=26cm.
(Measure your saddle),
Q= arc cos (20/0.885(82))=74 degrees
E) TOP TUBE CENTERLINE LENGTH: L=1/tan
t[(Hs-H)sinQ-D]+S-(R+G-M/2)+I
example: E=82cm., Hs=0.885E, Hs=72.57cm.,
H=53.3cm., Q=74 , D=7cm. (from
Table No. 1), t=73 (pick an angle), S=53 (from Table No. 1), R=7cm.
(from Table No. 1), G=10cm. (pick a stem
length), M=2.22cm. (diameter of
English handlebar), I=14.7 (from
formula "C") L=1/tan(73)[(72.57-53.3)sin(74)-7]+53-(7+10-2.22/2)+14.7=55.33cm.
TABLE NO. 1
**E**
Inseam |
**R**
Saddle
setback |
**S**
Saddle to bar |
**D**
Saddle to stem |
75 to 78cm. |
4 to 6cm. |
47 to 51cm. |
5
to 6cm. |
79 to 82cm. |
5 to 7cm. |
50 to 54cm. |
6
to 7cm. |
83 to 86cm. |
6 to 8cm. |
53 to 57cm. |
7
to 8cm. |
87 to 90cm. |
7 to 9cm. |
56 to 60cm. |
8
to 9cm. |
NOMENCLATURE
H SEAT TUBE CENTERLINE LENGTH
L TOP TUBE CENTERLINE LENGTH
h CRANK HANGER CENTERLINE DISTANCE ABOVE GROUND
t HEAD TUBE ANGLE
I SEAT TUBE SETBACK
Av FRONT WHEELBASE
Ar REAR WHEELBASE
M DIAMETER OF HANDLEBAR
f FORK OFFSET
G STEM LENGTH (CENTERLINE OF HANDLEBAR TO CENTERLINE OF BOLT)
c TRAIL (CASTOR)
Q SEAT TUBE ANGLE
Hs SADDLE HEIGHT (CENTERLINE FROM CRANK HANGER TO SADDLE TOP)
R SADDLE SETBACK FROM PLUMB LINE THROUGH CRANK HANGER
N SADDLE LENGTH
S SADDLE NOSE TO HANDLEBAR NEAR EDGE
D HEIGHT DIFFERENCE BETWEEN SADDLE & BAR TOPS
E INSEAM
F THIGH (FEMUR)
J LOWER LEG (TIBIA)
T TRUNK
B ARM
A FOREARM
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Photos: A. Newlands
Last Modified: 3/27/2003 |