bicycles and bicycling - introduction
DESCRIPTION
Bicycles and Bicycling - Introduction. History evolution of bicycles Cycling as a sport and as an exercise Reference: Faria and Cavanagh. The physiology and biomechanics of cycling Muscles and movements Physiological demands Design objectives: Distribute rider’s weight appropriately - PowerPoint PPT PresentationTRANSCRIPT
Bicycles and Bicycling - Introduction
History evolution of bicycles Cycling as a sport and as an exercise
- Reference: Faria and Cavanagh. The physiology and biomechanics of cycling
- Muscles and movements- Physiological demands
Design objectives: - Distribute rider’s weight appropriately- Ensure transfer of power from rider to machine - Points of contact must fit the rider:
• handlebars• seat• pedals
Anatomy of Diamond Frame
Important parts: Front triangle (tubes), rear triangle (stays), fork, lugs, bottom bracket, head tube
Types of bicycles: (1) Road bike (10-speed) - touring, racing, and sport; (2) mountain, or all-terrain; and (3) hybrid
Other Frame Types; :Ladie’s Frame
Top tube is sloped considerably
Design Features - Height Height of bottom bracket (bike’s center of
gravity)
- Lower for more stability
- Higher for more pedal clearance Height measurements determine size of
rider Frame size - length of seat tube and top
tube
Design Features - Bike Length Wheelbase length - (Fig 12.6)
- Shorter for quicker response, longer for more stability (varies from 38 to 44 in)
Chainstay length- Shorter chainstays are used on racing bikes for more direct transfer of power
Design Features: Frame Angles
Head tube - steeper for rougher ride, more efficient power transfer; shallower for handling ease and shock absorbing, but less responsive
Rake (amount of bend in fork blades) and trail affect steering stability. More trail equals more stability
Design Features on Different Types of Bicycles
Road bicycles (10-speeds)- Touring, or comfort - long wheelbase, shallow
angles, fair amount of trail (21 speeds)- Racing - short wheelbase, steep angles, little trail
(18 gears)- Sport/triathlon and cross bikes - in between (100
or more miles at high speed) Mountain, or all-terrain
- Fat, knobby tires, upright, sturdy frame, suspension systems
Hybrid - Cross between road and mountain
Bicycles - Frame Materials Important characteristics are elasticity, stiffness, and strength
(esp st/wt ratio) Butted and splined tubing - thicker at ends than in the middle,
with ribs inside Steel - most widely used on cheaper bikes. Reliable,
inexpensive, durable, predictable in handling - but is relatively heavy
Aluminum alloys - light, shock absorbent, comfortable. Newer alloys have improved properties of stiffness and strength (e.g., zirconium on trek bikes (trekbikes.com)
Titanium alloys - stiff, strong, lighter, more shock absorbent - but is expensive hard to weld and hard to machine
Composites - greatest strength/wt & stiffness/wt ratio - but expensive, bonding problems. Used mainly in front fork and stays. May fail catastrophically in other areas of frame.
Frame Materials used by Trek
Schwinn Frame Technology
TrekRacingFrame
Schwinn Suspension Frame
Trek Mountain Suspension Bike
Fisher Suspension Bike
Recumbent Bikes
Tubing design and Construction Methods
•Laser mitering•Butted tubes – varying wall thickness•Splined tubes•Diameter and shape changes
•Lugs no longer used:
Suspension systems
Front, rear, and seat Simple spring Air coil/springing systems
- Travel and stiffness may vary
Bicycle Accessories Drive Train -Crank, chainrings (front
driving cogs), freewheel, derailleurs (indexed and automatic shifting are recent innovations)
Shoes and pedals - clipless or with clips?
Accessories (cont’d) Rims, tires, brakes
Saddles
Stems & handlebars
Accessories (cont’d) Helmets
Gloves, shorts
Websites on Bicycles
How to select a bicycle http://www.primusweb.com/fitnesspartner/library/equipment/equip.htm
Manufacturer’s websites- Trek- Schwinn- Specialized
Assignment for Thursday, 10/21
Go to one of the bicycle manufacturer’s websites (slide 23) and select a bicycle to suit your purposes
Read article on suspension systems and submit 2 questions for clarification or discussion