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

PERSONAL FEELING EVALUATION

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

/

2

5. DURATEC CYBORG

SPORT BIKE

PIECE PRODUCTION, BESPOKED GEOMETRY

15 000 KČ 1350G, ALUMINIUM

RACE/SPORTIVE FRAME

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

Fk1

, 11 2 khgmgmFZ (1)

Fk2

, 22 2 khgmFZ (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