How to transform the USA bicycle according to the Honda Super Cub model: eBike as revolutionary USA short distance transportation

BikeMike

Active Member
Not to hijack your thread, but I'm posting this because I thought it was relevant.
Honda has been developing the Super Cub EV and the rumor says it is almost production ready.

I have seen a lot of Chinese electric scooters online and in stores, but this time because it's a Honda, I bet it is going to be robust and reliable.
Not to mention the warranty, customer service and distribution network. Also comes with a name "Honda", and you know how important that is when it comes to business.




Here's a gas to EV conversion kit: https://electrek.co/2018/08/08/iconic-honda-super-cub-electric/
 

BikeMike

Active Member
I am beginning to wonder how inefficient external, OEM motor and batteries systems are on aluminum bikes. Aerodynamic inefficiency from a bulging motor and battery is obvious. Yesterday's fierce sirocco winds (SW 20 to 28mph, gusting to 39mph) in the Platte River Canyon area made me acutely and painfully aware of aerodynamic inefficiencies. Nothing worse than climbing out of a steep ravine, only to get blasted by intense winds for the next couple of miles.

The NW winter winds tend to fall in the 15 to 25mph range, but the temperatures are often 25F to 45F.

Please note how the trees in the center of the picture are obscured by dust, behind the lake. The dust cloud looks like the clouds in the clear blue sky.


The more subtle and rarely discussed inefficiency is loss of power through the frame and due to weight. For some unknown reason, I could feel the difference in power from pedaling on the two sides of my conventional carbon road bike. Perhaps the wind depleted my energy or strength, or my crawling speed make the differences apparent? I usually ride that path at least twice per week, year round.

Anyhow, i wonder how efficient aluminum frames are with a motor. I am sure some types of carbon frames are less efficient than some aluminum frames. I prefer to invest money in the frame, rather than the electrical system.

I think the point of this video is that frame flex is a matter or perception, not physical energy loss. When you feel the frame flex, you do not actually lose energy. So, it all comes down to strength to weight ratio. For a given power level, what is the minimum weight? The key is knowing how much power you need.


The point is:
  • How much motor and battery power is lost through eBike design inefficiency?
    • if the bottom bracket area needs to be reinforced with 40% more layers of carbon fiber, what does that mean for flex through Aluminum chain stays?
  • What is the minimum power needed for 15mph speed in areas with a maximum of 7.5% grade?
    • My guess is 50Nm.
 
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BikeMike

Active Member
I still do not know what to make of the Fazua bottom bracket. The maximum torque load is 60Nm.

Some gears are attached to the axle that connect to the motor power. A clutch detaches the motor at 15mph.

(Link Removed - No Longer Exists)

In order to get the best possible support from our engine, your pedaling frequency should be between 65 and 85 crank revolutions / minute.

My natural cadence is a very consistent 95 RPM. Why such a limited cadence from 65 to 85? Reduction plays a role, but why?

IMG_0695.JPG


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BikeMike

Active Member
Orbea Gain battery has a rather high minimum temperature restriction of 50F (10C). The Bosch battery has the same restriction.

Does this mean the warranty is void for cold temperatures? Seems more like a warranty disclaimer, because li-ion battery packs generally function below freezing. 50F seems like an arbitrary temperature limit. If running below 50F were a hazardous condition, i believe you would see a prominent warning, like tire pressure limits on tire sidewalls.

Also see the last set of icons. Keep out of freezing temperatures, hail and thunderstorms. I believe these restrictions refer to the hub and power cable connection, because the battery is enclosed in the downtube. The external power connection to a hub motor is a fundamental disadvantage, compared to an internally routed power connection in a mid-motor configuration.

Colder temperatures cause more electrical resistance, which can result in an under voltage. Undervoltage will cause the controller to turn off power to the motor. Perhaps, hub motors draw higher amounts of current under peak demands, like climbing, which makes hub motors more sensitive to electrical resistance. Anyhow, why such warnings are given is not apparent to me.

(Link Removed - No Longer Exists)

IMG_0696.PNG
 
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BikeMike

Active Member
Orbea Gain carbon version is 14% lighter than the alloy eBike. Another way to interpret the weight reduction is a 14% improvement in power to weight ratio. Orbea allows the user to configure power levels via a power meter in the hub motor.

https://www.cyclingweekly.com/news/...e-bike-gets-carbon-frame-11-3kg-weight-384423

I subscribe to Orbea's efficiency-and-sufficiency eBike philosophy, because aerodynamic drag from natural or apparent wind is my major concern. An eBike provides a substantial benefit for foul-weather (i.e., winds over 15mph and/or temperatures below 45F or over 75F).

Orbea's efficiency-and-sufficiency eBike philosophy.

  • And yet it [bicycles] continues to have limited appeal in the modern world although the benefits are outstanding. Reasons for this could be:
    • hills
    • bad weather (natural wind over 15mph, or temperatures below 45F or above 75F)
    • risk
    • inconvenient sweat and fatigue
    • not being able to push the body as hard as before
    • [Aerodynamic drag from natural or apparent wind over 15mph]
  • More is not necessarily better. The most important aspect of an e-bike is not the power of the motor, rather
    • how much energy we let through from the battery to the motor,
    • how we let it through and when.
    • This is the job of the motor controller, which is ultimately what makes your e-bike give you the level of assistance you need according to different use situations you encounter on your bike.
  • At one time or another you may have tried e-bikes with a very powerful motor whose controller is limited to suddenly giving you more or less energy according to the selected level of assistance (25% energy at level 1, 50% at level 2, etc.).
  • This logic of a single motor map can cause your bike to behave somewhat unpredictably, and as a result, you don't feel safe or natural - like the bike is doing all the work.
    • In short, the bicycle gives you a feeling of insecurity instead of the sensation of freedom we mentioned earlier.
    • That’s why efficiency, or better yet, a sufficient distribution of energy, is so important.
  • Sufficient power is a special development for ebike users who have a more sporting concept of riding.
    • They’re not looking for a means of transportation that requires very little effort on their urban commute or heavy, 500W batteries with which to conquer their adventures.
  • They’re looking for a bicycle with characteristics similar to those of a mechanical bike:
    • a bike with a geometry to optimize pedaling efficiency that has good levels of rigidity and lightness similar to those of traditional bikes.
    • They appreciate a motor that doses out power gently along the route in order to improve the experience, with added support to keep going on those long days of pedaling.
 
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BikeMike

Active Member
Fauza Evation operating temperatures are -20C to +60C. The power levels are: 125W, 250W and 400W.

The heavy Bosch Active Line motor(2.9 kg) power-to-weight ratio is very poor, when compared to the combined Fauza motor AND battery 2.5kg weight. Something is very wrong with this picture, when the Fauza maximum power level is 150W higher. What? The Fazua middle power level equals the Bosch highest level. What?

TURBO: 250W
SPORT: 170w
TOUR: 100w
ECO: 40w

When an object's velocity is held constant at one meter per second against a constant opposing force of one newton, the rate at which work is done is 1 watt.

One mps = 2.2mph
 
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BikeMike

Active Member
Bianchi has a Fazua powered bike named: E-DOARDO. This bike appeals to me more because it is fitness orientated. A light is built in. €3,000. Only seems available in Italy.

Bianchi is sold through Backcountry.com, so Beeline.com can deliver and service your bike at home.

https://germignagasport.com/en/elec...e-disc-10sp-2018-electric-bike-sale-1586.html

The E-SPORT range is ideal for fitness and tourism, and for exploring new cities and places. Routes that once seemed too long and too difficult are now the ideal rides for you. The Bianchi E-SPORT range gives the extra power needed to your rides, whether you’re alone or with family and friends, while you explore new places, enjoy your vacation or free time, and get in better shape without focusing too much on your personal performance.

MODEL IN THIS CATEGORY: E-DOARDO, MANHATTAN


THE MOST NATURAL WAY TO RIDE
THANKS TO A REVOLUTIONARY POWER-ASSISTANCE SYSTEM

The innovative Bianchi E-doardo has a completely integrated and light system that makes you feel like you are riding a traditional bike, eliminating the friction sensation during use.
E-doardo is two bikes in one: it can be used as an e-bike or as a traditional bike by taking out the motor.
It’s a multi-purpose e-bike for the city or for extended touring. It’s special for its integrated designed, attractivness and value.


(Link Removed - No Longer Exists)

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Timpo

Well-Known Member
Yamaha's solution for a more natural riding experience: an incline sensor (altimeter or barometer?).

https://global.yamaha-motor.com/business/e-bike-systems/products/pw-te/index.html

I don't think they use barometer or altimeter do determine the slope.

The Yamaha YZF-R1 for example, has wheelie control, which is equipped with gyro sensor that detects the pitch, yaw and roll of the bike.
It also has lean angle sensitive traction control and ABS. The six axis inertia movement measuring unit can calculate the state of bike 125 times per second.

If you Google it, the info on the YZF-R1 is everywhere, I'm pretty sure it was derived from Moto GP technology.

 

BikeMike

Active Member
I don't think they use barometer or altimeter do determine the slope.

The Yamaha YZF-R1 for example, has wheelie control, which is equipped with gyro sensor that detects the pitch, yaw and roll of the bike.
It also has lean angle sensitive traction control and ABS. The six axis inertia movement measuring unit can calculate the state of bike 125 times per second.

If you Google it, the info on the YZF-R1 is everywhere, I'm pretty sure it was derived from Moto GP technology.


Amazing technology!
 

BikeMike

Active Member
More Pinarello Nytro details. https://www.bicycleretailer.com/sites/default/files/downloads/article/WP_PINARELLO-NYTRO.pdf

Pinarello’s asymmetry concept is even more enhance in the new Nytro. We must consider that in a e-bike the frame undergoes higher stresses due to the combined action of the rider’s legs plus the electric motor.

The power transmitted to the frame can easily reach values around 550W (where 400W are just coming from the electric motor). In order to assure a more responsive to the stresses and provides a more balanced and symmetrical behavior the frame was designed with the following features:

- Seat tube right half section considerably wider then the left section
- Top tube right side wider as the left side.
 

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BikeMike

Active Member
A quick power-to-weight comparison of a Trek Super Commuter+ 8 and Pinarello Nytro is very telling. I picked the Trek merely because I am familiar with the bike. It may not be the most equivalent bike for comparison sake.

https://electricbikereview.com/trek/super-commuter-plus-8s/

2017 - 570 peak watts / 23.7 kg = 24.0 w/kg, 170W greater peak power.

PInarello Nytro 400W / 13kg = 30.8 w/kg or 22% higher power-to-weight, 10.7 kg or 55% lighter.

So, do you need the additional 170W?

I do not have a watt meter. The only data point that i have is an unreliable 800W from a store display test, which I disbelieve. I do not need the additional 170W. I certainly can benefit by dropping 10.7 kg in bike weight.

The choice is overwhelmingly simple in my case, because aerodynamic drag is not even factored into the decision. I would not be surprised if most of those additional 170W were lost to drag above 25mph.

https://www.cyclingweekly.com/news/...ro-become-more-significant-than-weight-316952

Aerodynamics is all-important over the cut-off speed. The Nytro only assists up to 15mph, so aerodynamics should dominate decision making. The Trek SuperCommuter+ 8 is a 28mph bike. The Nytro will crush the Trek over 28mph. I hit 35mph a few times per day on my normal route.

The perception of an eBike is very dependent upon your conceptualization of the experience you expect from the bike. Comparing a 28mph eBike on the flats is irrelevant to me. My average flat speed is 22 to 25mph. The worst case scenario for a Nytro design is 15mph uphill in heavy wind. I really do not care about uphill speed. The exciting part to me is downhill speed. Downhill speed is entirely dependent upon bike aerodynamic design, for my purposes.

So, my conceptualization of an eBike is the conventional bike design, especially wrt aerodynamics. My low-end conceptualization speed is under 15mph due to wind. My upper-end conceptualization speed is over 30mph, due to wind resistance. The motor power and battery capacity plays a small role in my perception of an eBike, because the speeds between 15mph and 30mph are merely a means to an end. The effects from wind over 15mph are my primary concern in my mental model of an eBike.

You can accurately state your power requirements when you specify the length of time spent at your lower and upper power levels. My lower and upper power levels are one and the same. My power requirement is minimalistic. Therefore, weight and aerodynamic design dominate my buying decisions.

I subscribe to Orbea's efficient and sufficient philosophy. See post #24 for complete detail. In concrete terms, a 200W motor and 200Wh battery are sufficient. The efficiency derives from weight under 13kg and aerodynamic design. The lower your top-end speed requirements are, the lower your aerodynamic needs are. Lower aerodynamic efficiency mean lower bike cost. So, a person with a 20mph top-end speed has no significant aerodynamic concerns. The longer your power needs extend past one hour riding at 15mph, the greater your battery capacity needs are. Battery power is the most significant factor for an eBike's electrical system cost.

If you grasp the tradeoff principles elaborated in this post, you can optimize your eBike buying decision. You have no reason to fear buyer's remorse for spending less than $1,500 or more than $5,000 for an eBike, because you have found value that addresses your needs.
 
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BikeMike

Active Member
https://www.ispo.com/en/trends/e-bikes-these-are-e-mtb-trends-2018/2019

Digitalization and networking are, of course, also becoming an increasingly important topic for the E-MTB. For E-MTB's there are many smart smart smartphone apps with interface to the supplied display. Bike-Crowd from the IT service provider Double-Slash from Friedrichshafen, for example, is developing a route planner that also takes into account current weather data such as wind direction uAnd of course, uphill, downhill and driving style are taken into account.
Thus, the range of the E-MTB can be calculated depending on the battery size. The navigation device should only be a puzzle piece of a large platform, via which dealers are networked with manufacturers. A software update should then also be possible there or emergency help should be organised. Let's start with the beta phase at the end of the year.
 

BikeMike

Active Member
Aerodynamics dominate bike dynamics starting at 15mph. The rational approach to eBike design would optimize motor and battery weight for a 15mph speed cutoff, rather than legal limits of 20 or 28mph, which are arbitrary. Costs can also be significantly reduced.

efficiency-and-sufficiency.png

My usual route travels through a CO State Park for several miles. The park speed limit is 15mph, which also applies for a few miles of bike path travel connected to the park.

https://www.cyclingweekly.com/news/...ro-become-more-significant-than-weight-316952

Apply Orbea's efficiency-and-sufficiency eBike philosophy to 15mph cutoff speed:

  • ... And yet it [bicycles] continues to have limited appeal in the modern world although the benefits are outstanding. Reasons for this could be:
    • hills
    • bad weather (natural wind over 15mph, or temperatures below 45F or above 75F)
    • risk
    • inconvenient sweat and fatigue
    • not being able to push the body as hard as before
    • [Aerodynamic drag from natural or apparent wind over 15mph]
  • More is not necessarily better. The most important aspect of an e-bike is not the power of the motor, rather
    • how much energy we let through from the battery to the motor
    • how we let it through and when.
    • This is the job of the motor controller, which is ultimately what makes your e-bike give you the level of assistance you need according to different use situations you encounter on your bike.
  • At one time or another you may have tried e-bikes with a very powerful motor whose controller is limited to suddenly giving you more or less energy according to the selected level of assistance (25% energy at level 1, 50% at level 2, etc.).
  • This logic of a single motor map can cause your bike to behave somewhat unpredictably, and as a result, you don't feel safe or natural - like the bike is doing all the work.
    • In short, the bicycle gives you a feeling of insecurity instead of the sensation of freedom we mentioned earlier.
    • That’s why efficiency, or better yet, a sufficient distribution of energy, is so important.
  • Sufficient power is a special development for ebike users who have a more sporting concept of riding.
    • They’re not looking for a means of transportation that requires very little effort on their urban commute or heavy, 500W batteries with which to conquer their adventures.
  • They’re looking for a bicycle with characteristics similar to those of a mechanical bike:
    • a bike with a geometry to optimize pedaling efficiency that has good levels of rigidity and lightness [and aerodynamics] similar to those of traditional bikes.
    • They appreciate a motor that doses out power gently along the route in order to improve the experience, with added support to keep going on those long days of pedaling.
 

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BikeMike

Active Member
Let's revise the original evaluation system from post #2. We use a rating scale from -3 to +3, to discuss the merits of certain eBike features, according to the Orbea efficiency-and-sufficiency philosophy, with a 15mph cutoff.

You might want to score eBikes with 15, 20 and 28 mph cutoffs to determine the most desirable tradeoffs for your needs.

  • -3 :oops: Worst
  • -2 :rolleyes: Worse
  • -1 :( Bad

  • 0 :confused: Ambivalent or Ambiguous

  • +1 :) Good
  • +2 :D Better
  • +3 :p Best

  1. :p Efficient Bike Design (Drivetrain and Aerodynamics)
    1. :p No Resistance From Electrical System
      1. Desired: +3
      2. I want to reach conventional bike speeds, without hitting a speed wall induced by motor gearing
    2. :p Weight, Shape and Gearing of Motor for Acceleration (2.3 kg)
      1. Desired: +3
    3. :p Weight and Aerodynamic Shape of Battery (2 kg)
      1. Desired: +3
    4. :p Electrical System designed for carbon frames
      1. Small size that minimizes frame width
      2. Aluminum is 50% heavier
      3. Aluminum has 20% lower power-to-weight ratio
      4. Carbon flex to absorb shocks via seat post and stays
      5. Carbon is stiffer for better power transfer from bottom bracket to rear axle
      6. Desirability: +3
    5. :p Gear Ratio
      1. Desired: +3
        1. Need 400% on a double chain ring
    6. :p Aerodynamics
      1. Desired: +3
      2. Need dropbars to reach 35mph easily.
      3. Motor and battery cannot introduce drag.
    7. :p Highest Achievable Speed
      1. 35 to 40 mph
  2. :p Sufficient Motor Power
    1. :p Power Cutoff
      1. :p 15 mph
      2. 20 mph
      3. 28 mph
    2. :D Distance
      1. Desired: +2
      2. One hour (200 watt-hours) at full power (200W) = 15 miles in worst case
        1. In reality, the range will probably be 60 to 90 miles, because full power is brief.
    3. :p Wind
      1. Aerodynamic drag begins at 15mph ("Apparent Wind")
      2. Natural wind over 15mph is a burden
    4. :p Acceleration from 0 to 15 mph
      1. Desired: +3
      2. Mostly for crossing big intersections in the middle gear on the first chainring.
      3. Two or more speed sensors for accurate and sensitive acceleration measurements (or accelerometer)
    5. :p Miserly Battery Consumption
      1. Desired: +3
      2. I only want the motor to deliver power assist at critical moments.
      3. I want the motor to disappear on the flats and downhill sections, so I can travel long distances.
      4. I want strong assist at the critical moments.
      5. For the most part, I want the electrical system to blend in with the bike and disappear as part of the cycling experience.
    6. :D Cold Temperature Range
      1. Desired: +2
      2. My biggest fear is an undervoltage that shuts down the engine from electrical resistance at cold temperatures.
    7. :rolleyes: Cost
      1. Desired: -2
      2. I do not expect low cost or want to sacrifice quality.
      3. Reliability is important.
    8. :p Removeable Battery
      1. Desired: +3
      2. Need to bring battery inside for charging.
  3. Other
    1. :p 12v Front and Rear light system
      1. Desired: +3
      2. I ride through at least five tunnels and/or bridge underpasses. The C470 tunnel is 425 feet long. I cannot see mud or ice at the other end of the tunnel. I need a very powerful light with high and low beams. I want a rear light to alert other riders in the tunnel of my presence.
    2. :D Traction
      1. Desired: +2
      2. Wet or muddy conditions require wider tires. Also power assistance needs to be applied in a gradual manner to avoid sliding out. Inner rim width is main influence on contact patch shape.
    3. :D Braking Power
      1. Desired: +2
      2. Wet conditions need larger hydraulic disc brakes (180mm)
    4. :D Nible Steering
      1. Desired: +2
    5. :D Tubeless Tires
      1. Desired: +3
      2. Flat tires in cold weather is a total drag
    6. :D Aesthetics
      1. Desired: +2
      2. A bike should look beautiful, not like some car parts were glommed onto the frame.
    7. :) Boost Axle
      1. Desired: +1
      2. A good rider can put out 800 watts. The total acceleration force may be very high.
      3. Need strong rims.
    8. :DDisplay motor and human power in watts.
    9. :p Configuring Power/Torque Curve from cell phone in a user friendly way
      1. Desired +2
      2. I want a UI to specify parameter values for when and how much power assistance should be applied
    10. :p Bluetooth Motor and Battery Management System
      1. Desired: +3
      2. Need to know when to avoid using due to weather conditions.
        1. Need health status of every battery cell.
        2. Need to update firmware via internet.
        3. Need to run diagnostics against battery to know how risky a cold weather ride is.
 
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BikeMike

Active Member
Applying Orbea's Efficiency-and-Sufficiency eBike philosophy to market segments

An overly simplified market segmentation scheme to communicate basic market needs.

Fast Commuters - 350W motor, 500 watt-hour battery pack, 55 pound eBike (e.g., Trek Super Commuter+ 8)
  • Legal classification - Class 3
Leisure - 250W motor, 400 watt-hour battery pack, 50 pound eBike
  • Legal classification - Class 1
Performance Conscious - 200W motor, 200 watt-hour battery pack, 30 pound eBike (e.g., Pinarello Nytro)
  • Legal classification - Class 1 (allowed on CO bike paths)


Screen Shot 2018-08-30 at 9.01.55 AM.png


  • ... And yet it [bicycles] continues to have limited appeal in the modern world although the benefits are outstanding. Reasons for this could be:
    • hills
    • bad weather (natural wind over 15mph, or temperatures below 45F or above 75F)
    • risk
    • inconvenient sweat and fatigue
    • not being able to push the body as hard as before
    • [Aerodynamic drag from natural or apparent wind over 15mph]
  • More is not necessarily better. The most important aspect of an e-bike is not the power of the motor, rather
    • how much energy we let through from the battery to the motor
    • how we let it through and when.
    • This is the job of the motor controller, which is ultimately what makes your e-bike give you the level of assistance you need according to different use situations you encounter on your bike.
  • At one time or another you may have tried e-bikes with a very powerful motor whose controller is limited to suddenly giving you more or less energy according to the selected level of assistance (25% energy at level 1, 50% at level 2, etc.).
  • This logic of a single motor map can cause your bike to behave somewhat unpredictably, and as a result, you don't feel safe or natural - like the bike is doing all the work.
    • In short, the bicycle gives you a feeling of insecurity instead of the sensation of freedom we mentioned earlier.
    • That’s why efficiency, or better yet, a sufficient distribution of energy, is so important.
  • Sufficient power is a special development for ebike users who have a more sporting concept of riding.
    • They’re not looking for a means of transportation that requires very little effort on their urban commute or heavy, 500W batteries with which to conquer their adventures.
  • They’re looking for a bicycle with characteristics similar to those of a mechanical bike:
    • a bike with a geometry to optimize pedaling efficiency that has good levels of rigidity and lightness [and aerodynamics] similar to those of traditional bikes.
    • They appreciate a motor that doses out power gently along the route in order to improve the experience, with added support to keep going on those long days of pedaling.
569
 
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lkcl

New Member
History has a peculiar habit of repeating itself. The time seems right for another iteration of the Honda Super Cub transformational experience.
The original Honda Super Cub was a gas-powered scooter, in my opinion. A step-thru ebike can be considered an electric scooter, in some cases.

we absolutely love the honda cub. 100 million and climbing manufactured worldwide since the 1950s, with 40 million of those made *in the last 10 years*. we saw the Honda EV concept: the problem is that unfortunately, as all of the traditional gasoline bike manufacturers are finding, its sale actually threatens Honda dealers who make most of their money not from sales of the actual bike, they make it on maintenance.

e-bikes are a lot less maintenance, particularly as regen recovers energy during braking, so the brake pads don't end up as toxic dust at the side of the road.

realistically, then, to keep the iconic Honda Cub on the road and make it clean and eco-friendly as well, we need an upgrade kit, so that's what we're doing.

these are a mid-mount kit that literally bolts in place of the existing motor, after taking out the clutch, gearbox, exhaust and fuel tank. unlike the shanghai motors kit, which is a wheel hub design that adversely affects handling, weight distribution, and won't get you up steep hills, you don't replace the swing-arm or back wheel. you keep the brakes, you keep the lights and indicators, you keep the stock suspension, tires, wheels, everything.

BikeMike: we've been following GoGoRu and other companies doing battery-swap stations: we'll be using Grin Technologies "LiGo" packs, which you can upgrade, swap, put in parallel to get better range, split so that you can charge some packs whilst riding the bike on others, and so on.

it's not just for convenience: normal e-bike monolithic battery packs, you want to "upgrade" you have to *throw out* an existing pack, which is just highly irresponsible. for anyone who's tried opening an e-bike pack, you'll know that splitting the cells apart is just not a safe option.

lots going on, here: we'll be writing updates on the campaign as it progresses, and keeping an eye on things here. looking forward to peoples' reactions.
 
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Ken M

Well-Known Member
Before getting injured I rode an ebike for commuting in the Denver area for over 6,000 miles in just over a year. I do not agree with the idea that a super light low power ebike is the best commuting solution. For anybody commuting to work, time is money, so average speed plays a huge role in the value of a transportation device. A few $100 for a larger battery and more powerful motor will be paid back quickly via the higher average commuting speeds possible.

I had several ebikes and I found my fastest commute times were on a 750W hub motor ebike that I could sustain about 22mph with reasonable pedaling effort and typically maintain 15mph or higher up most hills (albeit with more effort). I found that both my Yamaha and Bosch mid drive ebikes with assists that cut out at 20mph increased my commute times because of slower hill climbs (albeit with less effort because that's where mid drives shine best) and slower average cruising speeds.

I think we need effective human scale transportation more than we need to set most ebike assist speeds at 20mph. I understand the Class 3 pedelec higher limit but most of those bikes are under-powered to sustain that speed in reality. All I can think of when a 200W motor (even a mid-drive with gear reduction to help torque) and a 200wh battery is a mamby pamby neighborhood ebike. I want a 1000W mid drive with over 120nm and a 1kwh battery that I can occasionally cruise at 30mph+ on and realistically sustain over 20mph up even the steepest hills in most cities. Now that effective transportation - going 15mph to work on a weak bike will not get people out of cars. I understand this is subjective but will be interesting to see how the responses go from here.
 

lkcl

New Member
I want a 1000W mid drive with over 120nm and a 1kwh battery that I can occasionally cruise at 30mph+ on and realistically sustain over 20mph up even the steepest hills in most cities.

that's actually a nice combination. i've a software engineering background: one of my first jobs was to write a Vehicle Simulator for Detroit Diesel (hey cool it's being sold online, now, wow! (Link Removed - No Longer Exists)), so i know the math (you can see a recreation of that work, including rolling and wind resistance, below, if you want to try it out)

based on those numbers, let's go through it (ignore efficiency and losses for now), see if the targets are achievable.

120nm is a tall ask for a 1000W motor unless you have a secondary belt-reduction drive similar to the one on the Sur-Ron. if you make sure to use an Axial Flux motor it should be easily doable. https://www.designnews.com/content/new-generation-axial-flux-ev-motors/186519862158706

from figures for the Sur-Ron Motor, 3kW nominal gets you around 25Nm of torque, so let's assume (reasonably) that 1kW would give 8Nm sustained. primary and secondary gearing (belt drive followed by chain drive) would need to be 15:1 to give the 120Nm you're looking for.

now with the gearing known, let's do the motor speed needed to sustain 30mph. 30mph is 12.3 metres per second (i've done vehicle simulations), a 26in diameter wheel is a 33cm radius, multiply by pi and you're looking at around 1 metre of travel per revolution. therefore to get 30mph you have 12 revolutions per second. 12 times 60 is 720 RPM (at the wheel). therefore, multiply that by 15 to get the motor RPM (because the 15:1 gearing is for the torque you wanted): and that's going to be a SCREAMING DEMON at 10,800 RPM to achieve 30mph.

you'll scare kids, go deaf, and unwork the earwax from grannies half a mile away at those RPMs :)

if it was 2kW you could back that down to a more reasonable 5,000 RPM. even 1500W would still be 7200 RPM, which is a little high but doable.

about the hill climbing ability: that's a little more complex as it involves the vehicle weight. rough numbers: the Sur-Ron can do a 45 degree slope at 20mph and the bike itself weighs 50kg. gearing is around a 5:1 reduction and it's 26in diameter MTB wheels. i do have a vehicle simulator online that you can put numbers in to, it has a gradient parameter. i designed it for cars, it *should* cope with ebike numbers as well, feel free to try it out http://lkcl.net/ev/vehicle_simulator/output/Simulator.html
 
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