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RACE BIKE DESIGN
SVOČ – FST 2015
Bc. Hana Kolářová
Západočeská univerzita v Plzni,
Sladkovského 38, 323 Plzeň
Czech republic
ABSTRACT
Developing research on the racing bikes topic. Elaboration of design, including systematic requirements
specification and conceptual variant laminate frame, selecting the optimal solution. Determining key features
laminate frame design with the necessary technical calculations.
KEY WORDS
Road cycling, composite bicycle frame
INTRODUCTION
The work focuses on the design of composite road racing bike frame. I carried out a draft frame geometry and
design a 3D model in NX9.0. After that I carried out calculations on computer 3D model and compared the
resulting deformation with the European standard for testing racing bikes. I also optimize the stiffness of the
frame as required by changing the fiber orientation of the composite.
1. DESCRIPTION OF THE ROAD RACE BIKES
TECHNICAL SPECIFICATION
Bike frame sizes:
Most large companies produce 6 frame sizes. Smaller specialist manufacturers offer tailor-made geometry rider.
Figure 1: frame geometry
Factors affecting the performance of cyclists:
• Bike weight
• Weight of the rider
• Frame shape, aerodynamic
Figure 2:aerodynamic test
Specification of components:
The main producers of components are Shimano, Campagnolo and SRAM. The set consists of shifter, rear and
front derailleur, cranks, pedals, wheels,cassette, chain and brakes.
Figure 3: groupset
Analysis of transfers:
Conventional front transducers are 53 and 39 teeth, compact (reduced) are 50 and 34 teeth. Cassette has 9-11
rings. The range of cartridges is 6 variants: 11-23,11-25,11-28,12-23,12-25,12-28.
2. ROAD RACE BIKE FRAME
BIKE FRAME MATERIALS
 Aluminum Alloys:
lower purchase price, less fatigue strength and stiffness of the lower purchase price, less fatigue strength
and rigidity. Even so, some aluminum frames closer to 1150 grams. The modulus of elasticity E =
70GPa
 Composite material consisting of carbon fiber and epoxy:
characterized by a high stiffness and chemical stability. The weight of the frame is between 900 to 1000
grams. Due to the anisotropic properties but is brittle and can crack unexpected shock. E = 200 GPa.
 The main differences:
Carbon is lighter, almost arbitrarily moldable. Carbon has different properties in different directions so
there is a possibility to find optimal riders comfort stiffness. This is reflected in the higher price as their
own material, so high manual intervention in its manufacture and finishing. Dural is significantly
cheaper and, paradoxically, a frame structure is much more demanding. It is mainly the differences in
the production process.
3. ANALYSIS OF THE TYPES OF FRAMES, GEOMETRY
MODEL
USAGE
MANUFACTURING
TECHNOLOGY, SERIES
PRICE
WEIGHT,
MATERIAL
1. SPECIALIZED
TARMAC
RACE/SPORT BIKE
BATCH PRODUCTION,
6 SIZES
40 000 KČ
1050G,
CARBON
STIFF SPORT FRAME
2
2. FOCUS IZALCO
RACE BIKE
BATCH PRODUCTION,
8 SIZES
50 000 KČ
1000G,
CARBON
STIFF RACE FRAME
1
3. CUBE AGREE
SPORT BIKE
BATCH PRODUCTION,
6 SIZES
30 000 KČ
1100G,
CARBON
SPORTIVE FRAME
3
4. CRADDOCK
SPORT BESPOKED BIKE
PIECE PRODUCTION,
BESPOKED GEOMETRY
60 000 KČ
1200G,
CARBON
/
PIECE PRODUCTION,
BESPOKED GEOMETRY
15 000 KČ
1350G,
ALUMINIUM
RACE/SPORTIVE
FRAME
5. DURATEC
CYBORG
SPORT BIKE
PERSONAL FEELING EVALUATION
2
2
According to the riding characteristics and subjective feeling of riding, I choose as an ideal the variant 2.
Own frame design:
Figure 4: frame design
The frame geometry is similar to the previous mentioned option 2 with variations according to the parameters of
the slider (limb length, power, power requirements)
4. COMPARISON THE STIFFNESS OF SELECTED FRAME WITH REGARD TO
THE WEIGHT

The main goal of the analysis is comparing the displacement values obtained from real mechanical tests
(NUD firm bikes). Fair values are compared with the results of FEM analysis. This will be followed
optimization of the frame in terms of the required thickness and composition of the laminate layers.

Due to idealization of the tube joints, we can not be expected in these places accurate stress values.
Furthermore, due to the expected hand-rolling manufacturing by putting individual layers of fabric on
the core, we can not design an accurate model. For this reason, the stress will not be evaluated and the
analysis will focus only on the comparison of deformations.
DESCRIPTION TEST STANDARD 14781: 2005 (E) A PROPOSAL LOAD CONDITION
Standard specifications and subsequent replacement of dynamic loads in an appropriate static load test.
1) 4.8.2. FRAME AND FRONT FORK ASSEMBLY – IMPACT TEST (FALLING MASS)- BRAKING
Rest a striker of mass 22,5 kg on the roller in the fork drop-outs or on the rounded end of the solid bar and
measure the wheel-base. Raise the striker to a height of 212 mm from the rest position of the low-mass roller and
release it to strike the roller or the steel bar at a point in line with the wheel centres and against the direction of
the fork rake or rake of the bar. The striker will bounce and this is normal. When the striker has come to rest on
the roller or solid bar measure the wheel-base again. Deformation shall not exceed 30 mm.
Figure 5: test 4.8.2.
2) 4.8.3 FRAME AND FRONT FORK ASSEMBLY – IMPACT TEST (FALLING FRAME)- JUMP
Mount the frame-fork assembly at its rear axle attachment points so that it is free to rotate
about the rear axle in a vertical plane. Support the front fork on a flat steel anvil so that the frame is in its normal
position of use. Securely fix a mass of 70 kg, to the seat-post as shown in Figure 26 with the centre of gravity at
75 mm along the seat-post axis from the insertion point. Deformation shall not exceed 15 mm.
Figure 6: test 4.8.3.
3) 4.8.4 FRAME – FATIGUE TEST WITH PEDALLING FORCES- TURNING
Mount the frame assembly on a base as shown in figure with the fork or dummy fork secured by its axle to a
rigid mount of height Rw (the radius of the wheel/tyre assembly ± 30 mm), and with the hub free to swivel on the
axle. Secure the rear drop-outs by means of the axle to a stiff, vertical link of the same height as that of the front
rigid mount, the upper connection of the link being free to swivel about the axis of the axle but providing rigidity
in a lateral plane, and the lower end of the link being fitted with a ball-joint. For carbon-fibre frames, the peak
deflections during the test at the points where the test forces are applied shall not increase by more than 20 % of
the initial values.
Figure 7: test 4.8.4.
DETERMINATION OF LOAD IN CASE (1) AND (2)
Replacement dynamic loads in static load test:
 First, we determine the stiffness of the frame in the direction of the load at a load unit force F = 100N,
for each weight variant of the frame
 Then we calculate the load force Fz1 and Fz2 for each variant separately
k1 
k2 
F
 , FZ 1  m  g  2m  g  h  k1
(1)
F
 , FZ 2  2m  g  h  k2
(2)
PROPOSE THE THICKNESS OF THE LAMINATE LAYERS
-combination of fiber orientation +30 a -30 0 .
Figure 8: comparing the weight variants
According to idealized computer model when doing FEM calculation, the results of aluminum and carbon frame
NUD Bikes are closer variant B.
FEM calculations according to the load prescribed standard for variant B
a) A deformation in the x-axis according to the load 4.8.2. braking. Displacement on th front wheel is 4.62 mm.
b) A deformation in the x-axis according to the load 4.8.3. jump. Displacement on th front wheel is 2.38 mm.
c) A deformation in the y-axis according to the load 4.8.4. cornering. Displacement site pedal is 21.6 mm.
Figure 9: Displacement in case a),b),c) from left
5. OPTIMALIZATION THE STIFFNESS ACCORDING TO THE RESULTS OF FEM
ANALYSIS FOR THEIR OWN DESIGNS WITH DIFFERENT FIBER
ORIENTATION
SPECIFICATION OF THE OPERATING CONDITIONS AND THE DESIRED PROPERTIES:
• The frame is designed for racing, with a focus on high stiffness during the sprint and riding out of the
saddle
• We find the stiffness of the head tube and bottom bracket when riding out of the saddle
LOADING CASES
• Based on the operating conditions and the desired properties.
• Because of the load frame in axes x selects the test of braking according to 4.8.2., Then load condition
simulating sprint out of the saddle. When I deal with Sprint, load the head tube and bottom bracket.
a) braking according to 4.8.2.
b) bottom bracket load at the sprint
c) head tube load at Sprint
PROPOSED OPTIONS COMPUTATIONAL MODELS OF FRAMES WITH DIFFERENT FIBER
ORIENTATION
- For The selected variant of the wall thickness of the frame design 3 variants of fiber orientation x
Variant A –combination +30 , -30 0°
Variant B- combination +45 , -45 0°
Variant C- combination +60 , -60 0°
FEM ANALYSIS
The choice of material and mesh remains the same as in the design thickness. Perform calculation according to
the proposed load conditions for all the variants. Sample calculations for variant A (a combination of fiber
orientation of + 30 °, -30 °, 0 °):
Figure 10: Displacement in case a),b),c) from left
• Displacement according to the load condition a) 4.8.2. (braking). A deformation in the x-axis axis in the
location of the front wheel centre is 4.62 mm.
• Displacement according to the load condition b) (bottom bracket load at the sprint) A deformation in the y-axis
of the head tube is 2.2 mm
• Displacement according to the load condition c) (head tube load at the sprint). A deformation in the y-axis of
the head tube is 0.52 mm.
OPTIMAL DESIGN DISTRIBUTION DIFFERENT ANGLES FIBER ORIENTATION
On the basis of the results of calculations proposed as an optimal variant of the distribution of different
orientations required by the use of bicycles for cycle racing, sprint and especially when riding out of the saddle.
In the head tube Used fiber orientation of 45 ° in the region of the center of pedaling fiber orientation of 30 °. In
the rear frame structures, the frame is reinforced by doubling the forks, thus sufficient fibers with an orientation
of 20 ° to increase the stiffness.
Figure 11:Optimál fiber orientation design
Figure 11: Compare fiber orientation variants
There was a dependence on the stiffness of the frame in different orientation of the fibers in different load
directions. Furthermore, by optimizing the stiffness of the frame for the given riding conditions. Combining
various angles of orientation of fibers in different areas of the frame, we get the optimal variant suitable for the
required riding conditions.
Comparison of proposed options to the competition
- Standardised test we verified secure design frame weights for universal use.
- Based on the specific requirements of the rider is further formed an optimum design of the fiber orientation in
different areas of the frame.
- Large bike companies use a universal draft of fiber orientation. Compared with them, establishing a dedicated
frame design related claims riders and ensuring perfect ride bikes for specific riding conditions
CONCLUSIONS AND RECOMMENDATIONS
First I have chosen suitable option frame weight, depending on the tests conducted in accordance with
European standards for testing racing bikes. There was also found dependence of the stiffness of the frame on the
fiber orientation in different load directions. Furthermore, by optimizing the stiffness of the frame for the given
riding conditions. Combining various angles of rotation of fibers in different areas of the frame, we get the
optimal variant suitable for the required riding conditions.
When designing the thickness of the layers, I could also mention the specific weight of the rider and the
specific operating conditions and suggest optimal weight frame corresponding to the parameters of the rider.
This method would require further FEM calculations and mechanical testing to ensure driving safety.
THANKS
I thank especially doc. Ing. Zdeněk Hudec, PhD and Ing. Petr Bernardin for their help and patience in doing my
work.
REFERENCES
A Book Publication:
SOWTER, M., FEATHER, R. : Made in England. Birmingham: Push Projects Limited, 2012
A Research Report:
BOUBELÍK L.,Výpočetní analýza rozložení napětí na rámu jízdního kola při různých zatíženích, ZČU Plzeň,
Fakulta strojní, 2005