Cost-Benefit Comparison: instant switch from a legal 20mph "bicycle" to 40+ mph motorcycle

[Mike leroy]

Which motor best suits your riding style? Is it possible that a simple switch can convert the same bike from a legal 20mph "bicycle" to a 40+ mph motorcycle? Yes. Four Crystalyte rear hub motors are compared to illustrate the relationship between power(W), speed(mph), torque(Nm), volts(V) and amps(A). Three 8Fun BBS02 center-mounted motor are also compared in the same manner.

The conclusion is the most flexible solution is a 27Amp, 72Volt, 1944Watt controller, compatible with two 13 Amp-hour, 37V battery packs. Certainly, a 72V, 27A, 1944W system is fun for off-road use. Switching the 72V series connection between two 37V volt battery packs to a parallel connection would convert the battery packs from a 72V, 13 Amp-hour into a 37V, 26 Amp-hour power supply. A flexible switch allows a fun, powerful off-road to be instantly converted to a CA legal bicycle. The 37V, 1000W controller switch permits access in CA to bicycle paths as "motorized bicycle".

Unfortunately, the 8Fun BBS02 controller is currently limited to 60V. I encourage bicycle manufacturers to develop a flexible 36-72V switchable controller, as displayed in the following diagram. The idea cannot be patented, because by virtue of appearing here, "prior art" has been established.

The following graph illustrates the conceptual relationships. Torque, an indication of hill-climbing power, is presented in Newton-meters(Nm), rather than foot-pounds. The solid color dots chart torque against speed. The dotted circles illustrate the amp to volt ratios.

​

The dotted line in previous graph represents my idealized watt ratio. Each watt has three parts amps and four parts volts. Amps are correlated with hill-climbing power. Volts loosely relates to speed and acceleration. Think of the ratio as a cup of coffee. How much cream and sugar suits your taste?

In other words, a 36 volt, 9 amp, 350 watt EuroMotor just ain't my cup of tea -- about half my desired amp ratio. My favorite motor in the following graph is the 4200 watt 5403, but unfortunately is too heavy. My ideal choice is a 27 amp, 36 volt BBS02, which is three times EuroMotor amperage.

The 8Fun BBS02 center-mounted motor is contrasted with hub motors in the following picture. The optimal amp-to-volt ratio for the BBS02 is 0.53.

​

My pedal strategy is to exploit motor power to overcome sub-20mph speeds. I will use a 50 tooth chainring to achieve high, leg-powered speeds over 20mph without motor assistance. I am primarily concerned with accelerating past inattentive car traffic and easing steep hill climbs. My goal is an average 25mph speed in a three mile radius. The most frequent trips are transportation related, e.g., grocery shopping, train connections, etc....

​

Motor weight, or torque-to-weight ratio, is the reason I chose a center-mounted motor over hub motors. The Crystalyte 5403 weighs 30 kg, or 7.5 times the BBS02, for the same 120Nm torque. The higher weight comes from more powerful, thicker magnets and copper wire in the hub motor. The center-mounted BBS02 relies on gears to run at the most efficient RPM, rather than stronger magnets.

The 5403 also uses the more expensive 72V battery pack to achieve higher power, which costs $1200 more for the 26 amp-hour pack.

In California, 1000 watts is the legal limit for "motorized bicycles". Since the motor is restricted to 1000 watts of electrical power, my goal is to find the motor that generates the greatest torque for 1000 watts. In CA, 1001 to 1500 (2 HP) is a M2 scooter, which is prohibited from bicycle paths.

The constraints I choose to accept are a maximum 54 volts and 27 amps. Therefore, optimizing the bike gearing is crucial for a satisfactory outcome. Configure the highest gear ratio possible with Rohloff Integrated Gear Hub (IGH) to pedal the largest chainring my legs can tolerate.

• Conceptually the Gates Carbon Drive front/rear sprockets are like a BMX no-gear bike.
• The IGH provides gearing. The front/rear on a BMX is approximately 27:9, or 3:1. The Gates 55:19 is closest at 2.8:1 . Use this chart and calculations for the previous PDF doc to customize for your situation.
• I probably need about a 1.6m display, so a 50:20 (2.5:1) is probably the closest match for my fitness level.

​

Some of the reasons I chose the following frame are:

1. Split frame for belt and chain compatibility. Frame weighs only weighs 19 pounds.
2. The battery tank capacity is enormous, 26 Amp-hours! 52V, 26Ah NMC battery pack only weighs 16 pounds, but costs $1900.
3. The swingarm suspension for safe driving at 45+ mph downhill coasting speeds in two-lane traffic. My neighborhood also has 15mph speed bumps on hills with 30mph downhill coasting speeds. I will also take dirt paths that cut across residential streets. About ten concrete curbs meet the dirt paths at the street intersections. The ride is jarring. The 40mph downhill, potholed, tree-rooted, backroads are in a state of disrepair. My favorite backroad is one that I take, every chance I get.
4. Either a mid-drive or rear hub motor up to 6000 Watts can be installed. The bottom bracket is a generic standard, rather than a proprietary brand.
5. Must weight under 50 pounds to meet Amtrak regulations. Weight without front wheel and battery pack.
6. In California, 1000 watts is the legal limit for "motorized bicycles". Since the motor is restricted to 1000 watts of electrical power, my goal is to find the motor that generates the greatest torque for 1000 watts. The 750w BBS02 generates 115Nm of torque.
7. Has a throttle. Controller has adjustable 20mph cut-off. I also want the flexibility to upgrade to 45+ mph rear hub, if the side roads do not work out.
8. All wires routed internally.
9. U.S. DOT VIN number to register in CA as legal motorcycle, should I choose that option.
10. A mail-order and service bike, so components must be the most reliable.
11. Configure the highest gear ratio possible with Rohloff IGH to pedal the largest chainring my legs can tolerate. My strategy is to rely on motor to power me through sub 20mph speeds. I will use a 50 tooth chainring to achieve speeds over 20mph without motor power.
    • Conceptually the Gates Carbon Drive front/rear sprockets are like a BMX no-gear bike.
    • The IGH provides gearing. The front/rear on a BMX is approximately 27:9, or 3:1. The Gates 55:19 is closest at 2.8:1 . Use this chart and calculations for the previous PDF doc to customize for your situation.
    • I probably need about a 1.6m display, so a 50:20 (2.5:1) is probably the closest match for my fitness level.

 

[Mike leroy]

Conclusion​

My goal is to optimize sub-20mph pedaling. The 1500W, 27A, 54V controller can be downgraded to meet the CA 1000W limit. The amp-to-volt ratio would increase to 0.73, which I consider the ideal ratio. BBS02 Pedal Assist System (PAS) settings can be configured downwards from 1500W to 1000W to suit your riding style. Select different PAS levels from the controller display while riding to access higher (1400W) or lower power levels. I am not sure what the top-speed is, but be careful in public because you are likely breaking the law.

You might gain ~7Nm per amp, which might equate to a one percent hill grade. So, the torque increase from 20 to 27 amps would make a big difference in my neighborhood. One hill is a 12% grade. Seven extra amps might enable me to climb the steepest hill, an 18% grade. That is a substantial difference, provided the 36V, 20A struggles on the 18% grade at wobble speed (9mph).

The bike share lane in the rolling hills has a 25mph speed limit. The hills are about a 5% grade. The extra torque might be a substantial help to maintain 25mph pedal speeds. If the additional seven amps maintains a 20mph minimum speed, keeping up with traffic would be much easier and safer.

All I can say is some drivers think they own the road. Some ugly, obese driver in a monster, gas-guzzling, white Cadillac Escalade cut me off in the crosswalk, when I was walking yesterday. He was more concerned about oncoming traffic around the bend, than pedestrians. I looked the guy in the eye as he was talking on his phone, while I backed up to the curb. He beeped his horn at me, as he speed past me on the curb. I wished he had gotten out of his car, especially with a weapon.

I believe power overkill begins around 2500 watts. So, buy all the available power you can compress under 1001 watts. At least you have the option to upgrade to a CA M2 class scooter or CA M1 motorcycle. The 27 amp controller is more important than both the 54 volt battery pack and 1400 watt motor! The controller is the limiting constraint.

The most flexible solution is a 27A, 72V, 1944W controller, compatible with a 36V battery pack. Certainly a 72V would be fun for off-road use. Switching the 36 volt battery pack connection from series to parallel would allow legal bicycle path access. Neither I, nor HPC knows of such a system for BBS02, as 60V is the highest controller available.

Since I will by the 52V system, I have the option to double the voltage for a rear 104V hub motor. With a 40A or 55A controller, that would result in a 45-60mph, 4500- 6000W motorcycle .

Zany fact: Keith Richards played bicycle spokes on the Steel Wheels "Continental Drift" song.

 

[Mike leroy]

I research and write articles in fits-and-starts, as my spare time permits. Writing an article usually takes one full week. So, check back regularly.

 

[noob]

I don't know anything about designing my own e-bike; that's why I'm here looking at expensive builds that don't do exactly what I'd like, but if I could I'd consider one of these: http://www.lightningrodev.com/kits/index.html with the recommended Lyen controller and Cycle Analyst. The kit doesn't look too difficult to set up, but what do I know?

It seems to anger some people that these motors aren't "legal". I'd use one legally, as I need the torque to pull 240 lbs of me with the additional weight of groceries, laundry, etc. up a grade. This is why I've never considered an e-bike before, and I'm not convinced that there's anything currently available that can suit my needs, but my disgust at the prices of used cars and motorcycles on Craigslist, the cost and bother of buying new from a dealer, and a doctor's order to lose weight are all reasons why I'll probably spring for a Kalkhoff instead, although I'm pretty worried that I'll quickly burn up a little 250W motor and flush ~$4,000 down the toilet.

 

[Mike leroy]

I don't know anything about designing my own e-bike; that's why I'm here looking at expensive builds that don't do exactly what I'd like, but if I could I'd consider one of these: http://www.lightningrodev.com/kits/index.html with the recommended Lyen controller and Cycle Analyst. The kit doesn't look too difficult to set up, but what do I know?

It seems to anger some people that these motors aren't "legal". I'd use one legally, as I need the torque to pull 240 lbs of me with the additional weight of groceries, laundry, etc. up a grade. This is why I've never considered an e-bike before, and I'm not convinced that there's anything currently available that can suit my needs, but my disgust at the prices of used cars and motorcycles on Craigslist, the cost and bother of buying new from a dealer, and a doctor's order to lose weight are all reasons why I'll probably spring for a Kalkhoff instead, although I'm pretty worried that I'll quickly burn up a little 250W motor and flush ~$4,000 down the toilet.

I am elaborating on this concept in a new post that is focused on a particular motor that will exceed your needs. In CA, they can be made legal, as I describe in this post. The HPC Revolution has a U.S. DOT Vehicle Identification Number (VIN). Personally, I only consider bikes with a VIN.

Your first decision is a full suspension, hardtail or cargo bike. Full suspension only supports 40 pounds with a seat rack. My approach is to use a fanny or backpack. Unless I find a better seat post solution, I will forego a rack.

My guess is you actually seek a cargo bike.

I weigh 182 pounds and am six feet tall. My total weight with groceries is about 220 pounds. I estimate 5Nm of torque for each percent grade. My hills are very steep 10% to 18%. I travel about one mile on 12% grade. I only consider bikes with at least 90Nm torque, which rules out the Kahlkoff . I hold no illusion that 1000W is an absolute minimum for my situation.

Every week I carry at least 30 pounds of food from the store -- your best solution! The trick is to use a high quality fanny pack and a backpack. I use an expensive MountainSmith fanny pack for dense groceries. I use a cheap backpack for light, bulky paper goods. REI carries MountainSmith. I stuff the backpack into the fanny pack on the way to the store.

I split the meniscus in my knee in half in a sparring accident. The doctor told me surgery is useless. I need exercise to strengthen my knee. I started by carrying groceries.

I have been considering this for over 18 months, sharing your reservations. I have considered every high-end bike evaluated by @Court, the site admin.

My biggest concern is my neighborhood banning eBikes. I have talked with town council members about bike safety, as a 14 mile stretch of road resulting in several bicycle deaths. If I register an electric bike as a "motorized cycle", I have full legal access to the road, like any other motorcycle.

Today, Sunday at noon, I took a one block random sample as I walked: 12 bikes, 6 cars and 3 motorcycles.

http://almanacnews.com/news/2013/11/22/the-troubled-beauty-of-skyline-boulevard

According to California Highway Patrol accident records, between 2003 and 2012, there have been 205 accidents on Skyline Boulevard between Page Mill Road in Palo Alto and the northern edge of Woodside (roughly mileposts 3 and 17). About half those accidents have involved two-wheeled vehicles: bicycles in 18 of them and motorcycles in 92, with fatal injuries killing two bicyclists and eight motorcyclists.

With the odds permanently stacked against the bicycle in a collision, the best course is not to have one. Flashing daytime lights are a must, she says, a small investment with big safety returns in that the lights give motorists a clue.

 

[Bike_On]

Which motor best suits your riding style? Is it possible that a simple switch can convert the same bike from a legal 20mph "bicycle" to a 40+ mph motorcycle? Yes. Four Crystalyte rear hub motors are compared to illustrate the relationship between power(W), speed(mph), torque(Nm), volts(V) and amps(A). Three 8Fun BBS02 center-mounted motor are also compared in the same manner.

The conclusion is the most flexible solution is a 27Amp, 72Volt, 1944Watt controller, compatible with two 13 Amp-hour, 37V battery packs. Certainly, a 72V, 27A, 1944W system is fun for off-road use. Switching the 72V series connection between two 37V volt battery packs to a parallel connection would convert the battery packs from a 72V, 13 Amp-hour into a 37V, 26 Amp-hour power supply. A flexible switch allows a fun, powerful off-road to be instantly converted to a CA legal bicycle. The 37V, 1000W controller switch permits access in CA to bicycle paths as "motorized bicycle".

Unfortunately, the 8Fun BBS02 controller is currently limited to 60V. I encourage bicycle manufacturers to develop a flexible 36-72V switchable controller, as displayed in the following diagram. The idea cannot be patented, because by virtue of appearing here, "prior art" has been established.

View attachment 2949​

The following graph illustrates the conceptual relationships. Torque, an indication of hill-climbing power, is presented in Newton-meters(Nm), rather than foot-pounds. The solid color dots chart torque against speed. The dotted circles illustrate the amp to volt ratios.

View attachment 2934​

The dotted line in previous graph represents my idealized watt ratio. Each watt has three parts amps and four parts volts. Amps are correlated with hill-climbing power. Volts loosely relates to speed and acceleration. Think of the ratio as a cup of coffee. How much cream and sugar suits your taste?

In other words, a 36 volt, 9 amp, 350 watt EuroMotor just ain't my cup of tea -- about half my desired amp ratio. My favorite motor in the following graph is the 4200 watt 5403, but unfortunately is too heavy. My ideal choice is a 27 amp, 36 volt BBS02, which is three times EuroMotor amperage.

The 8Fun BBS02 center-mounted motor is contrasted with hub motors in the following picture. The optimal amp-to-volt ratio for the BBS02 is 0.53.

View attachment 2937​

My pedal strategy is to exploit motor power to overcome sub-20mph speeds. I will use a 50 tooth chainring to achieve high, leg-powered speeds over 20mph without motor assistance. I am primarily concerned with accelerating past inattentive car traffic and easing steep hill climbs. My goal is an average 25mph speed in a three mile radius. The most frequent trips are transportation related, e.g., grocery shopping, train connections, etc....

View attachment 2933​

Motor weight, or torque-to-weight ratio, is the reason I chose a center-mounted motor over hub motors. The Crystalyte 5403 weighs 30 kg, or 7.5 times the BBS02, for the same 120Nm torque. The higher weight comes from more powerful, thicker magnets and copper wire in the hub motor. The center-mounted BBS02 relies on gears to run at the most efficient RPM, rather than stronger magnets.

The 5403 also uses the more expensive 72V battery pack to achieve higher power, which costs $1200 more for the 26 amp-hour pack.

In California, 1000 watts is the legal limit for "motorized bicycles". Since the motor is restricted to 1000 watts of electrical power, my goal is to find the motor that generates the greatest torque for 1000 watts. In CA, 1001 to 1500 (2 HP) is a M2 scooter, which is prohibited from bicycle paths.

The constraints I choose to accept are a maximum 54 volts and 27 amps. Therefore, optimizing the bike gearing is crucial for a satisfactory outcome. Configure the highest gear ratio possible with Rohloff Integrated Gear Hub (IGH) to pedal the largest chainring my legs can tolerate.

• Conceptually the Gates Carbon Drive front/rear sprockets are like a BMX no-gear bike.
• The IGH provides gearing. The front/rear on a BMX is approximately 27:9, or 3:1. The Gates 55:19 is closest at 2.8:1 . Use this chart and calculations for the previous PDF doc to customize for your situation.
• I probably need about a 1.6m display, so a 50:20 (2.5:1) is probably the closest match for my fitness level.

View attachment 2917​

Some of the reasons I chose the following frame are:

1. Split frame for belt and chain compatibility. Frame weighs only weighs 19 pounds.
2. The battery tank capacity is enormous, 26 Amp-hours! 52V, 26Ah NMC battery pack only weighs 16 pounds, but costs $1900.
3. The swingarm suspension for safe driving at 45+ mph downhill coasting speeds in two-lane traffic. My neighborhood also has 15mph speed bumps on hills with 30mph downhill coasting speeds. I will also take dirt paths that cut across residential streets. About ten concrete curbs meet the dirt paths at the street intersections. The ride is jarring. The 40mph downhill, potholed, tree-rooted, backroads are in a state of disrepair. My favorite backroad is one that I take, every chance I get.
4. Either a mid-drive or rear hub motor up to 6000 Watts can be installed. The bottom bracket is a generic standard, rather than a proprietary brand.
5. Must weight under 50 pounds to meet Amtrak regulations. Weight without front wheel and battery pack.
6. In California, 1000 watts is the legal limit for "motorized bicycles". Since the motor is restricted to 1000 watts of electrical power, my goal is to find the motor that generates the greatest torque for 1000 watts. The 750w BBS02 generates 115Nm of torque.
7. Has a throttle. Controller has adjustable 20mph cut-off. I also want the flexibility to upgrade to 45+ mph rear hub, if the side roads do not work out.
8. All wires routed internally.
9. U.S. DOT VIN number to register in CA as legal motorcycle, should I choose that option.
10. A mail-order and service bike, so components must be the most reliable.
11. Configure the highest gear ratio possible with Rohloff IGH to pedal the largest chainring my legs can tolerate. My strategy is to rely on motor to power me through sub 20mph speeds. I will use a 50 tooth chainring to achieve speeds over 20mph without motor power.
    • Conceptually the Gates Carbon Drive front/rear sprockets are like a BMX no-gear bike.
    • The IGH provides gearing. The front/rear on a BMX is approximately 27:9, or 3:1. The Gates 55:19 is closest at 2.8:1 . Use this chart and calculations for the previous PDF doc to customize for your situation.
    • I probably need about a 1.6m display, so a 50:20 (2.5:1) is probably the closest match for my fitness level.

Hey Leroy,

I don't know if you still follow the forum. You had some interesting graphs/plots. I like how you discuss the optimization.

You should check out my performance spreadsheet in the compare section.

Best weight/torque: Optibike motors, New Bionx Dd hub.

 

[Mike Smith]

I think one of Mike Leroy's Mountain Lion friends had him for dinner, lol.

"Oh, Pauley, wont see him no more".

 

[MLB]

I am elaborating on this concept in a new post that is focused on a particular motor that will exceed your needs. In CA, they can be made legal, as I describe in this post. The HPC Revolution has a U.S. DOT Vehicle Identification Number (VIN). Personally, I only consider bikes with a VIN.

Your first decision is a full suspension, hardtail or cargo bike. Full suspension only supports 40 pounds with a seat rack. My approach is to use a fanny or backpack. Unless I find a better seat post solution, I will forego a rack.

My guess is you actually seek a cargo bike.

I weigh 182 pounds and am six feet tall. My total weight with groceries is about 220 pounds. I estimate 5Nm of torque for each percent grade. My hills are very steep 10% to 18%. I travel about one mile on 12% grade. I only consider bikes with at least 90Nm torque, which rules out the Kahlkoff . I hold no illusion that 1000W is an absolute minimum for my situation.

Every week I carry at least 30 pounds of food from the store -- your best solution! The trick is to use a high quality fanny pack and a backpack. I use an expensive MountainSmith fanny pack for dense groceries. I use a cheap backpack for light, bulky paper goods. REI carries MountainSmith. I stuff the backpack into the fanny pack on the way to the store.

I split the meniscus in my knee in half in a sparring accident. The doctor told me surgery is useless. I need exercise to strengthen my knee. I started by carrying groceries.

I have been considering this for over 18 months, sharing your reservations. I have considered every high-end bike evaluated by @Court, the site admin.

My biggest concern is my neighborhood banning eBikes. I have talked with town council members about bike safety, as a 14 mile stretch of road resulting in several bicycle deaths. If I register an electric bike as a "motorized cycle", I have full legal access to the road, like any other motorcycle.

Today, Sunday at noon, I took a one block random sample as I walked: 12 bikes, 6 cars and 3 motorcycles.

http://almanacnews.com/news/2013/11/22/the-troubled-beauty-of-skyline-boulevard

According to California Highway Patrol accident records, between 2003 and 2012, there have been 205 accidents on Skyline Boulevard between Page Mill Road in Palo Alto and the northern edge of Woodside (roughly mileposts 3 and 17). About half those accidents have involved two-wheeled vehicles: bicycles in 18 of them and motorcycles in 92, with fatal injuries killing two bicyclists and eight motorcyclists.

With the odds permanently stacked against the bicycle in a collision, the best course is not to have one. Flashing daytime lights are a must, she says, a small investment with big safety returns in that the lights give motorists a clue.

Yes, lights are very important.
But not nearly as concerning as going 30-40mph on bikes.
On bike tires.
Usually without safety (crash) gear like a smart motorcyclists wear. (Pads, sliding material-leather, etc)
I fear a lot of people are going to get hurt and some killed as E bikes get faster and faster and clueless and unskilled riders get on them. (and plenty that should know better)
I see and hear a lot of regulation being discussed thanks to idiots going 25mph on MUV paths and similar.
Use your BRAIN out there!