4. Requirements
● Ride on deep and light snow without sinking
● Usable in cold environments
● Capable of climbing small hills, 5% gradient
● Stop on ice
● Support a 100 kg rider.
6. Wheel Ideas - Ski
● Large contact area
● Slides well on snow
● Too slippery on ice
● Expensive
● Drags on pavement
● Gets stuck in snowbanks?
● Cannot transfer power
7. Wheel Ideas - Big Wheel
● Easy to change frame
● Good grip on ice
● Simple design
● Rubber must remain soft in the cold
● Snow may freeze in tires if left outside.
8. Wheel Ideas - Double Wheels
● Good grip
● Can use existing tires
● Rubber must remain soft in the cold
● Snow may freeze in tires if left outside.
9. Wheel Ideas - Partial Track
● Good grip and area
● Spreads weight
evenly
Increased power need?
Temperature changes may change tension
10. Wheel Ideas - Full Track
Huge amount of area
to spreads weight
● Increased power needed
● How is it steered?
11. Wheel Ideas - Studded wheels
● Increases grip
without large
change in weight.
● Good grip for
steering and
stopping.
● Difficulty on pavement.
12. Brakes - Wheel Brakes
● Work for traditional
bicycles
● Require friction from the ground
● Designed for wheels
13. Brakes - Ground Brakes
● Takes advantage of
the environment
● Creates additional
stopping force
● Work for toboggans
● May wear out quickly
● Unusable on pavement
14. Brakes - Manual Braking
● Requires no design
work
● Free
● Probably unsafe
● Takes longer to start again
18. Design Specifications
Rider weight 100Kg
Power Used 75 W
Top Speed 14km/h
Smallest Static FOS: 2
Smallest Fatigue FOS: 4.7
Max incline 4.8 deg (8.4%)
Stopping Distance 21m
Total Cost $1000
Rider weight 68Kg
Power Used 75 W
Top Speed 19 km/h
Smallest Static FOS: 2
Smallest Fatigue FOS: 6.4
Max incline 8.6 deg (15.1%)
Stopping Distance 36m
19. Tread Fit Design
w
The driving wheel would have 25 studs
spaced out evenly on the surface to fit inside
of the belt track.
Stud design works on keeping the belt and wheel
together.when the belt studs fit in the wheel studs
this causes friction which adds to the grip.
20. Tread design
The smaller wheel on the back could follow a
pulley design, which fits the belt studs inside.
The belts top teeth are to for grip purposes
between wheels and belt. While the bottom teeth
would cause traction forces to help get control
driving on slippery surfaces.
21. Shigley’s Mechanical Engineering Design book was used
to determine the length of the track,the area in touch with
snow,pressure distribution on the wheel.,etc….
The total length of belt around 4.5 meters, 1.3meters would
be in contact with snow, width of track would be 0.1meters.
Tension in tight side of belt would be 80N, while beam
supporting the big tire to the small tire would have to be
able to take 86N with a radius of 0.04m
22. The bike would be working in cold conditions.
Polyurethane has been chosen as the material
for the belt. Its tensile strength,elongation and
hardness changes over time are very resistant
to weather conditions.
Choosing polyurethane also allows the bike to
be used in sandy areas with high temperatures.
23. There are PU belt manufacturers, from which
the dimensions can be specified and ordered.
Decreasing Prices of PU timing belts
showing a price 7.5$/meter.
To avoid distributing the pressure around the wheels in an unwanted manner Fuji Prescale Films
would be placed in between the wheel and the belt.Where a matlab function would read the different
colours on the film which give pressure readings.
26. Frame Design
- The highest tensile force is 124N at FE
- The highest compressive force is 414 N at FC
(per frame)
Factor of Safety
Tensile Strength: 553 (124N < 68612N)
Column Buckling: 28.5 (414N < 11790N)
Butt Weld Strength: 299 (336MPa < 1.12MPa )
Each frame is a hollow cylinder with 2cm outer and 1.9cm inner radius
27. Frame Suggested Materials
- High Tensile Carbon Steel: Durable and long lasting but it is
relatively heavy
- Titanium: Very flexible, light, and strong as steel but expensive
- Aluminum Alloys: Relatively weak but light
- Chrome Molybdenum: Strong and light steel.
Offers good flexibility while maintaining
its form. Good all-around.
$800 ~ $1400 per 1000kg of Chrome Molybdenum Steel
28. Pedals and Axles Design
Fairly standard Bicycle
pedals.
1.35 to 1.67 gear ratios
30. Pedals and Axles Safety
Typical force of 120N => design factor of 3
Max force of 1000N => design factor of 2
3cm front gear minimum
Fatigue FOS of 4.7 on rear axle
31. Pedals and Axles Costs
● Shafts, pedals and chain are common
● Gears may be custom
● 1kg of steel for the axle $1 + machining
● Chain costs $20
● Gears cost $60?
32. Steering
The coefficient of friction of snow particles is
small compared to concrete therefore designs
were made to increase stability on ice.
● Increase the contact surface area on snow
● Reduce the centre of gravity for the front
steering
33. ● Reducing the centre of is an easy way to
reduce the bulkiness of the design.
34. Reducing Centre of gravity
● Increase the Head angle of a normal
bicycle for the icycle.
● This will increase the stability of the fork
easy steering.
38. Braking
1. Friction
the material of tire is made same with
automotive snow tire.
2. studs pin of the surface. pin material is
stainless steel, 10mm for L, 300 studs.function
to increase the friction, grip on the ground
39. Braking dice
1. Material: stainless steel or ceramic
2. Torque: It can apply torque about
9-10.2Nm
3. Holes: disperse the heat fast
Riding a Bicycle in the snow is very difficult, you often get stuck and have to push your bicycle.
So our problem is to design a Bicycle that can be ridden on both Ice and Snow.
It needs to be able to ride on deep snow without sinking in. It needs to still be usable when it is cold outside. It needs to have enough grip to climb small hills. The wheels need enough grip to stop on icy surfaces and it needs to be strong enough to support a 100kg rider.
The parts of a standard bicycle are the wheels, the brakes, the pedals and gears, the frame and the steering. We will go through some ideas that we considered.
We could replace one of the wheels with a ski. It spreads the weight on snow but cannot transfer power itself.
Big Wheel is a straightforward concept. Like the name suggests, using larger wheels.
Instead of a big wheel, two wheels is also an option. You can use existing tires but the frame will need some changes to accommodate.
Partial track means to replace one of the wheels with a tread that will still rotate but will spread the weight over a large area.
Instead of using a track for just one wheel, replace both the front and back wheels with a single larger track. This particular design was made in the 1940s for a motorcycle.
We can add studs, either metal or by redesigning the tire pattern. Not a lot of weight but they add a lot of grip.
Wheel brakes stop the Icycle by preventing the wheels from rotating. Rim brakes grip the outside of the tire and disk brakes create a torque in the centre of the wheel.
Ground brakes dig into the snow to hold the Icycle from moving.
Manual Braking, that is the user has to stop the Icycle themself.
These are the components that we decided to use for the Icycle. Studded wheel for the front wheel, Two tracks, one for each of a pair of treads as rear wheels. Disk brakes are used to stop all wheels.
And this is what it looks like once the actual parts are assembled
Basically list off the stuff on this slide. If the rider pushes hard, they can manage to climb slopes as much as 4.8 degrees, a 8.4% incline. 3% without increasing power at all. Typically roads do not go above 5% incline so this is sufficient.
Mention that a 68kg (150 lb) rider could reach 19km/h with the same power. They could also ascend a 8.59 degree, 15.1% slope, 2.29 / 4% without increasing power.
We will be using fairly standard bicycle pedals. They have a crank length of 15cm. Because of the larger wheels, the gear ratios need to be lower than a typical bike, 1.35 to 1.67 instead of around 2.
At the back end of the Icycle is where it differs. Instead of linking directly to a wheel, the chain powers a shaft that supplies the power to both rear wheels. This rear shaft is 2.5cm in diameter, 0.25 cm in thickness and 50cm in length.
We considered a typical pedalling force to be 120N, only ⅔ of it actually becoming usable and a temporary force of 1000N for extreme failure cases.
It was designed around an extreme safety factor of 2 and a fatigue safety factor of 3. The smallest that the gears on the front axle can be in this case is 5cm radius before we risk bending the rear axle.
The shafts pedals and the chain are fairly standard components which are commercially available. The gears may have to be designed ourselves because of the unusual ratio but we expect something to be available. We estimate 1.4kg of steel which would cost 7$, another 20$ for the chain and have not determined the cost for the gears.
