3.4 Wheels and tires
Exploring MIG-1 and MIG-2, we discovered one problem which name is wobbling. We decided to change bicycle’s rim to motorcycle’s for increasing stiffness on the obstacles. Also we changed type of the wheel structure that is method of controlling wobbling. We use 16” front and rear wheels because they are light. Bike with these wheels is more dynamic, because center of gravity a bit decreased. Thank to this, readability of our bike increased, cornering ability became a little bit better that is important fact for riding on the city’s roads.
Center of Gravity
3.4 Brake system
As for competitions and for city riding there are a lot of obstacles. For undergoing this test successfully, bike must have qualitative brake system. When we were choosing brakes for our bike, we analyzed benefits and limitations of different brakes. For city riding there is need to increase braking power on the front brakes, to improve their stiffness and to reduce general unsprung mass, because smaller stopping time provides bigger speed before the corner, as a result faster lap time, lower force on brake lever leads to better control by driver of braking process, lower unsprung mass improves suspension qualities.
Because of high deceleration and weight distribution to prevent lack of brake power on the front wheel several decisions have been made. New front Hope-TECH 3 V4 brakes were installed, these 4 piston calipers have sufficient piston and pad area to cope with increased braking power.
This system has front floating vented brake discs with 203 mm diameter. Vented brake disc helps to reduce temperature of the braking surface by 15%. It is very important when you ride on the steep descents or other places where you might face with slumping of the power due to overheating.
Caliper V4 is made of solid aluminum. This structure gives increased rigidity for better braking. Increased square of the braking pads improves heat out and extends the life of the brakes.
For rear wheel we chose Shimano Deore BL-M615 brakes with floating 203 mm brake discs.
The Conservation of Energy |
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Mass bike(kg)= |
45 |
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Mass pilot (kg)= |
80 |
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v (m/s)= |
22,22 |
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Kinetic energy (Dj)= |
30858,025 |
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Kinetic energy is converted into thermal energy |
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Mass front brake disc (kg)= |
0,283 |
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Mass rear brake disc (kg)= |
0,405 |
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Specific heat rotor (Dj/kg*°C)= |
470 |
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Temperature rise (°C)= |
250 |
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Thermal energy (Dj)= |
80840 |
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The brake lever |
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M (kg)= |
19,5 |
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L1 (mm)= |
11,35 |
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L2 (mm)= |
49,25 |
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Force input (N)= |
191,1 |
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Force output (N)= |
829,222467 |
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The master cylinder |
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Full stroke (mm)= |
10,5 |
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Piston diameter front (mm)= |
15 |
Piston diameter rear (mm) |
15 |
Area piston (m^2)= |
0,000176709 |
Area pistons (m^2)= |
0,000176709 |
Pressure (Pa)= |
4692587,627 |
Pressure (Pa)= |
4692587,627 |
Front displacement liguid (cm^3)= |
1,575 |
Rear displacement liquid (cm^3)= |
1,575 |
The caliper |
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Pistone diameter front (mm)= |
17 |
Piston diameter rear (mm) |
20 |
Area pistons (m^2)= |
0,000226973 |
Area pistons (m^2)= |
0,00031415 |
One-side force (N)= |
1065,092451 |
One-side force (N)= |
1474,176403 |
Force caliper (N)= |
2130,184902 |
Force caliper (N)= |
2948,352806 |
The brake pads |
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Front |
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Rear |
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Coefficient friction = |
0,4 |
Coefficient friction = |
0,4 |
Friction force (N)= |
852,0739609 |
Friction force (N)= |
1179,341122 |
The rotor |
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Front |
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Rear |
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Torque tire=Torque wheel=Torque rotor |
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Effecctive radius (m)= |
0,09225 |
Effecctive radius (m)= |
0,09225 |
Torque rotor (Nm)= |
78,6038229 |
Torque rotor (Nm)= |
108,7942185 |
The tire |
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Front |
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Rear |
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Effective rolling radius (m)= |
0,2032 |
Effective rolling radius (m)= |
0,2032 |
Force tire (N)= |
386,8298371 |
Force tire (N)= |
535,4046188 |
Total braking force (N)= |
922,2344559 |
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Deceleration of vehicle in motion |
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Deceleration (m/s^2)= |
7,377875647 |
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Stopping distance |
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Stopping distance (m)= |
33,46006517 |
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Static weight distribution |
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Front axle verticale force (N)= |
386,3 |
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Percent front weight (%)= |
37,34375 |
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Wheelbase (m)= |
1,28 |
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Center of gravity front= |
0,802 |
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Rear axle verticale force (N)= |
648,1435146 |
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Percent rear weight (%)= |
62,65625 |
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Center of gravity rear= |
0,478 |
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Total vehicle vertical force (N)= |
1034,443515 |
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Dynamic impacts of vehicles experiencing deceleration |
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Vertical distance from the CG to ground (m)= |
0,827 |
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Weight transferred = |
503,1617007 |
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Front axle dynamic verticale force (N)= |
889,4617007 |
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Rear axle dynamic verticale force (N)= |
144,9818139 |
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Effects of Weight Transfer on Tire Output |
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Coefficient friction tires= |
0,9 |
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Front tire braking force (N)= |
800,5155306 |
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Rear tire braking force (N)= |
130,4836325 |
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Total tire braking force (N)= |
930,9991632 |
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Calculation optium brake balance |
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2,072263864 |
0,201319044 |
static |
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0,9 |
0,9 |
dynamic |
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Required front torque rotor (Nm)= |
83,8736002 |
Required rear torque rotor (Nm)= |
135,8770912 |