Scooters

FYI, according to the US Department of Transportation, the number of fatalities per vehicle mile traveled was 37 times higher for motorcycles than for cars.

motorcycle, motorbike, conventional motorcycle - feet on pegs, manual transmission

scooter, motor scooter - step-through design, with flat floorboard for feet, CVT automatic

kick scooter - standup design

moped - motor plus pedals

hard tail - a bike with no rear suspension, also called rigid. Used in some Harley and Indian touring bikes.

sport motorcycle - Dropped handlebars, rear-set pegs, to allow the rider to tuck in for aerodynamic position.

cafe racer - a genre of sport motorcycles that originated among British motorcycle enthusiasts of the early 1960s in London. Standard production bikes that were modified by their owners and optimized for speed and handling for quick rides over short distances (from cafe to cafe). photos

German company
Carbon fiber frame, as of 2019, 35,000 EUR

Swedish company founded 2016
Osa model as of 2022 $11000 USD

Note kilometer to mile conversion rates.
1 km = .6 mi
1 mi = 1.6 km
50 mi = 80 km
60 mi = 96 km
100 mi = 161 km

Top speed: 60 mph (100 kph)
Cruising speed:
Range: 300 mi
IP Rating: IP65 (protection against dust and moisture)
Acceleration 0 to 30 mph (0 to 48 kph: 3 seconds
Acceleration 30 to 60 mph (48 to 96 kph): 5 seconds

Top speed

60 mi = 96 km

Cruising speed

very fast production motorcycles can go over 300 kph (186 mph)

a 125 cc motorcycle tops out between 80 and 120 kph (50 and 75 mph)

0 to 60 mph

the fastest drag-racing bikes can reach 60 mph in less than 1 second

125 to 150 cc engines 0 - 60 mph: 10 to 15 seconds 0-30 mph, 30-60 mph

An internal combustion engine has an rpm sweet spot.

An electric motor has a constant torque at all rpm's.

braking, regenerative braking

free wheeling

range, gas tank vs batteries

braking modes

traction: acceleration, braking, steering

controller, free-wheeling, avoid accidental wheelie, avoid accidental nose over stopping detect airborne or mud spinning situation

The mid-motor

requires drive train from motor to wheel, usually a chain drive, no drive train

sprocket ratio of 3:1 means the motor must run at higher rpm

weight distribution, rear vs center, center vs wheels

Ingress Protection standard
a two-digit number, each digit between 0 and 9
first digit: protection against solid foreign bodies
second digit: protection against water and moisture

A typical motorcycle will be rated IP65.

Essence:

• Battery specs
• Motor specs
• Wheel size

max rpm * outside tire diameter = gives max speed

how to measure torque

Regenerative braking? How implemented?

Comparison to petrol bikes 50, 110, 125 cc

1 hp = 746 W = .746 kW 1 hp = 15 cc (14 to 17 cc) 1 hp = 32 cc

1000 cc = 200 hp 1000 cc = 60 hp

Torque and speed (single vs dual motors)

Acceleration, max speed

watts, volts, amps

amp hours

Range

• Frame with rear Suspension
• Front fork with suspension
• Kick stand
• Wheels
• Brakes
• Splatter guards
• Seat
• Foot pegs
• Handlebars
• turn signals, brake lights

• physical UI
  • Throttle
  • Brakes
  • Mirrors
  • turn signals

• electronic UI
  • bluetooth
  • usb plugin for charging
  • smartphone holder
  • android app
    • power on, power off
    • replicate dashboard display

• Cladding
• Storage compartments

• Battery
• Motors
• Speed controllers

Compatible with a 125 cc petrol scooter.

• power: 12 hp, 9kw (746W = 1 hp)
• acceleration: 0 to 60 kph in 7 seconds
• max speed: 100 kph
• range: 400 km (10 liter tank and 40 km per liter at 80 kph = 400 km in 5 hours)
• tire size: 100/90-19 (100 mm width, 90% sidewall height = 90 mm, 19 inch rim diameter)
• suspension: front and rear
• kerb weight: 150 kg
• max load weight: 150 kg
• passengers: driver plus one
• price new: 3000 USD
• ground clearance: 150-170 mm
• saddle height: 760-780 mm
• handlebar height: 1160 mm
• torque: 10 Nm
• wheelbase: 1250-1280 mm

Safety first.

• Keep all tried and true design features of today's 125 cc petrol scooter.
• form factor - conform to other motorist's expectations
• UI - throttle, brakes, dashboard - require no additional learning to drive
• acceleration - for superior maneuverability in traffic
• brake lights, turn signals
• mirrors
• wheel size - for traction and stability on today's roads

Minimalist design. No cladding. No storage compartments. No luggage rack.

Frame design decisions.

• battery down low, to lower center of gravity, for stability of the ride
• step-through design, with battery below the feet
  • ? ground clearance
  • heavy steel bottom
  • battery pack size, height
• upright driver position - handlebars higher than the seat
• two-person saddle
  • the bicycle post seat is rejected as uncomfortable

Dual hub motors.

• dual motors has favorable cost-performance ratio over a single motor
• a drive chain would apply only on the rear
• eliminate cost, engineering, wear of a drive chain.
• accept the additional wear on the rear motor due to road vibration

Must connect:

• rear wheel with suspension and brakes
  • modern bikes use a double-sided swingarm, a single shock, and a linkage
• battery
• foot pegs
• seat
• front fork which must support:
  • wheel with suspension and brakes
  • steering
  • handlebars, with dashboard, throttle, brake handles, light switches
  • head lamp, turn signals, brakelights

Material:

• steel
• aluminum
• carbon fiber
• magnesium
• titanium
• composite

Sensors

• speedometer
• tachometer
• battery gauge
• braking sensors
• roll

bluetooth radio

Processor

• connection to smartphone app
• broadcast sensor data
• receive and execute commands

Placement

• mid motor with belt drive to rear wheel
• hub motor on front wheel
• hub motor rear wheel
• dual hub motors, front and rear

Why use dual motors?

• redundancy
• traction
• power
  • at low power, single motor is more efficient
  • at high power, dual motors can be more efficient

electronic free wheeling vs regenerative braking

Using only one of two motors makes no sense, because the idle motor drags. Always share the load between multiple motors. If motors are unequal, split based on power ratio.

One throttle, two controllers.

Use Y cable to split throttle signal.

Multi-motor drive systems, from Grin Technologies https://www.youtube.com/watch?v=Ub4EP2_mAds&t=165s

Motor Simulator, from Grin Tech, interactive simulation. https://ebikes.ca/tools/simulator.html

leave 25-28 mm for disk calipers

EV-Propulsion, http://ev-propulsion.com/motorcycle-hub-motors.html
mostly sells parts for electric cars
But they also seem to sell the EnerTrak hub motor for motorcycles.

EnerTrak, https://www.enertrac.net/index.php
1295 USD motorcycle hub motor

https://www.made-in-china.com/products-search/hot-china-products/Disc_Brake_Hub_Motor.html

QS Motor http://www.qs-motor.com/product/qs205-2000w-spoke-hub-motor-v3-for-electric-motorcycle/

1. Procure batteries, wheels with hub motors, speed controllers, throttle
2. Design and build a test frame to hold the wheels and put a load on them.
3. Design and build electronics
4. Design and program Android app
5. Get all the above working
6. Design frame
7. Fabricate frame (outsourced)
8. Procure remaining components - salvage a wrecked bike?
9. Assembly (outsourced)
10. Government registration

look for a wrecked Vespa or Filano or other step-through 125cc scooter

SONDORS Metacycle: First affordable 80 MPH electric motorcycle? 5000 usd Battery weight low https://youtu.be/6BG8fFma6nM

10 scooters https://youtu.be/5XVdOe6YvJo

9 Scooters - 450X by an Indian company Ather Mobility; - SEAT MÓ eScooter 125; - NQi model lineup by the NIU brand; - Yadea G5 and V7; - recent additions to Gogoro smartscooter lineup; - TVS iQube - Bgauss B8-WOW E-Scooter from Italy. https://youtu.be/WImNcD2vLc8

For each motor Define requirements for:

 battery: volts, amps, watts
 Wheel: dimensions, spokes
 Frame: axle width, clearance
 Controller: comes with?
 Speedometer:  comes with?
 

Controller Throttle Dash display

Define desired specs for motor Torque, power, rpm, volts

V volts voltage force, hp pressure I amps A current load flow rate R ohms (omega) resistance pipe size P W power watts

V * I = P

V = I * R ohm's law

hp horsepower T torque

sproket teeth front/rear = 3.0

tire size, rimsize, rpm, top speed

max eff at 75%

temperature, cooling

Chain Drive Factors

• cleaning
• lubrication
• tensioning

A hard-tail bike has no rear suspension, and the center-to-center distance between sprockets is fixed. Most riders tension the chain with 13 mm slack.

On soft-tail bikes, the sprocket distance varies as the swing arm travels up and down. The greatest distance occurs when the swing arm is level with the front sprocket. The chain should be tensioned with 13 mm slack when the swing arm is at that level position.

What is the difference in sprocket distance due to swing arm travel? Consider the following example.

In this diagram:

• Point A is the pivot bolt.
• Point B is the center of the rear sprocket.
• Line AB represents the swing arm at level position, with a length of 500 mm.
• Line AC represents the swing arm with 100 mm of travel upwards.
• Point D is the center of the front sprocket, 100 mm in front of the pivot bolt.
• Line DB represents the longest distance between sprockets at 600 mm.
• Line segment DC represents the shorter distance between sprockets at 598.3 mm.

In this example, the difference in sprocket distance between level and upward positions is 1.72 mm. (600 - 598.3 mm)

This means that if a rider were to tension his chain with the swing arm at the upward travel position, he would position the rear sprocket 1.72 mm too far to the rear, thus making the chain too tight at the level position.