Cost-Benefit Comparison: Electric Bicycle vs. Electric Motorcycle

Mike leroy

Active Member
This article provides background information about electric bicycles that exceed 35mph -- without pedaling. The HPC Revolution is compared against the ZERO FX motorcycle. Electric bicycles are encroaching into electric motorcycle territory due to NMC battery chemistry in lithium-ion batteries.
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Some benefits of NMC over conventional li-ion batteries follow. For a technical comparison, compare the graph of the Sanyo batteries in the previous link.
  • About half the weight
  • Much further range (i.e., battery distance)
  • Chemicals are much less expensive
  • Should last about twice as long as traditional li-ion batteries.

In my personal situation, competing with car traffic is the most significant issue when considering a bike for road use. A fast bicycle levels the road against cars in ways that traditional eBikes are incapable of.

In my opinion, high performance bikes need to be designed around the battery -- above and beyond -- all other considerations. Powerful and customizable batteries enable new motor capabilities. Fast eBikes need double the voltage (i.e., 76V) of conventional batteries. Most home electrical outlets are 110V! The bicycle frame and stealth design are heavily influenced by battery size and weight characterisics.

How useful is a 60mph bike with a 20 mile range and six hour charge time? Batteries are currently the weak link in any eBike system. Batteries deserve most attention and not dismissed like an ugly ducking.

Lithium-ion batteries become unusable after a few years of recharging. Battery and replacement cost is a significant, if not the most expensive, part of the total eBike cost.

Powerful battery packs typically have individual Battery Management System (BMS) chips for every battery cell (i.e., 48), rather than one BMS chip for the entire pack, as typically found today. Battery packs suffer from the weakest link principle. In other words, one rotten apple spoils the bunch. Individual cell BMS chips are a huge advantage. Companies like Polaris, that manufacture many vehicles, i.e., cars, motorcycles and eBikes, utilize individual cell BMS chips to optimize performance and prevent disaster.

Ragone Charts are the most common way to compare battery performance. Think of a Ragone Chart as comparing a sprinter's speed (vertical axis) against a distance runner's endurance (horizontal axis). Ragone Charts indicate how long an electric battery can operate at the peak output. If you ride at high speeds, then voltage is more important than amperage. To carry a heavy load up a steep hill, great torque or high amperage is required.

Ragone charts help you match your riding style to the appropriate battery chemistry. NMC is unique lithium-ion technology because only NMC can target either specific energy (capacity) or specific power.

Replacing the chainring with a Schlumpf gear box is worth considering when 35mph speeds are attainable. The gear drive is similar to a motorcycle gear box. Increase hill climbing or speed gear ratios by 2.5 times. Some compensating gear ratios are needed to accommodate the 80 pound weight. Consider reducing chain twist under high loads by using a cassette with a minimal number of gears, e.g., 7 or 8. Consider replacing the chain at frequent intervals, e.g., every 1,500 to 3,000 miles. Chain change, as opposed to oil change.

Also consider the Grace One.15 Pinion P1.8 gearbox approach, rather than a rear dérailleur. I prefer the Pinion, which is designed by ex-Porsche engineers. Grace utilizes the Gates Carbon Belt, rather than a metal chain. Durability, cost and safety are serious considerations.

Although this bike is ten times more powerful than a typical eBike, it also is twice as heavy. Synchronizing gear ratios to PAS profiles will optimize energy consumption and ease physical exertion.

The most effective way to increase your battery range is to set your Power Assist Levels (PAS) as low as possible. Also, conserve your battery by restricting high loads to uphill only. Optimize gear ratios to achieve pedal and battery efficiency. I suppose battery range can be doubled with careful energy economy.



HPC Revolution Sport is an off-road bicycle. The web page indicates that all models can be made street legal with the Cycle Analyst. In which case, I would simply set power to 1kW when I need to comply with motor vehicle laws. If the 3.5kW is the antidote for suburban car traffic, then I would register the eBike with DMV as a motorcycle.
  1. 3.5kW hub motor
  2. 80 pounds or 44W per pound (typical 350W / 40 lbs = 9W per lb.) ~ 5x power-weight ratio.
  3. 50+ mile range at 20mph
  4. Capable of speeds over 45mph
  5. 78V electrical system (double conventional eBikes)
  6. 12.5 AH, UN 38.3 Certified Battery available in different capacities
  7. ? Nm torque
  8. $7000
A street legal conversion kit using the HPC Revolution components for $3200, is the 32 pound, full-blown HPC Striker.

HPC is the only electric bicycle manufacturer, that I know of, offering NMC batteries for their eBikes. Please inform of any other NMC bikes sold today.

HPC Battery Management System(BMS) may not be optimized. Bicycle NMC batteries now sell for a premium. Heavy hub motors necessitates strong rims, e.g., triple-walled rims. The 12.6 pound, gearless, 1 kW HPC motor may need triple-walled rims. AlexRims Supra BH may not be strong enough to support extra weight. Some downhill rims, like Spoon, are triple-walled.

Zero FX has an long history in electric motorcycles. The entry-level ZERO FX ZF2.8 is a:
  1. 28kW motor
  2. 247 pounds ( 113.4W per pound)
  3. 35-mile city range
  4. 70mph sustained speed
  5. 102V
  6. 2.5 kWh battery, 2,500 charge cycles
  7. 95 Nm torque
  8. $13,300
The ZERO FX is 2.5x greater than 3.5kW eBike power-to-weight ratio. However, the 6kW eBike is 77W per pound, or 70% of the motorcycle power-to-weight ratio.
 
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Mike leroy

Active Member
Cost-Benefit considerations are rated on a scale from 1 to 5 to allow different types of information to be directly compared. A math trick to compare apples and oranges. Hundreds of bicycle features are associated with six basic benefits. You can configure benefits to suit your situation. The benefits used in this example are:
  1. Economy
  2. Ease
  3. Enjoyment
  4. Endurance
  5. Excitement
  6. Elegance

To ease comparisons, I created a Google spreadsheet. The idea is rate bike features on a scale from 1 to 5, rather than confusing, technical jargon. The values in the spreadsheet are rules of thumb, rather than absolute values. Customize the rules for your situation to compare different bikes.

(Link Removed - No Longer Exists)

The information is diagrammed in the following pictures. The primary difference between the bicycle and motorcycle is Risk. The ZERO FX is established technology that meets US DOT standards. EBikes are much less proven technology.

The roadworthiness of the eBike drivetrain is my greatest concern. Adding power to the drivetrain increases risk. The derailleur is exposed to road debris. At 35+ mph, a large stone could ruin the derailleur or your life. The chain is subject to higher stress with external gears due to twisting from the chainring.

The next step in the analysis is to compare different eBikes drivetrains over a standardized course.

A related comparison is the Honda FSX150 Scooter vs. Grace One.15.

HPC Revolution:
HPCRevolution.png

ZERO FX:

StarPlotZeroFX.png
 
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Mike leroy

Active Member
Assessing power-to-weight alternatives. The Grace One.15 is a more relevant comparison at this point, than the ZERO FX. The Polaris Aapex is another contender, however the Aapex is significantly underpowered at 750W. More importantly, the LMO chemistry is old technology.

The 2kW Grace and 2kW HPC XC (62 lbs, $3900) are compared in the remainder of this posting.

one15-01.jpg

The Grace One.15 is scheduled for Sept. 2015. Check out these specs:
gearbox: Pinion P1.9 (crank only, no cassette needed)
Weight ca. 31 kg (68 pounds)
Battery 15,6 Ah / 718 Wh (Range Extender: 23,4 Ah / 1076 Wh)
Torque 55 Nm
Support Levels 3 Modi Eco, City, Sport
Controller Electrical System by Eltronic AG
Fork Grace Rigid Fork, Rock Shox Domain RC
Shifting system Pinion P1.9
Engine 2000 W Ultra Motor
Drive Gates Carbon Drive
Braking system Magura MT 4
Tires Schwalbe Crazy Bob 26″
Front light Grace developed Light System/front light LUMOTEC IQ Cyo E
Back light LED Backlight
Options carrier set
Range max. 60 km* (Range extender: 90 km*)
Recommended sales price 4.999 € (~ $5300)


Considering the Amtrak excursions or Mt. Shasta 100 mile ride, as a standard comparison basis.
 
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Mike leroy

Active Member
Star Plot Diagram for Grace One.15 appears below. The notable features make arrow shapes, i.e., Cost, Bias, Elegance, Risk, Economy and Endurance. Grace is one the most established international eBike manufacturers, which presents a low risk level. The Pinion gear box is safely protected in the bottom bracket. The Gates Carbon belt should handle high stress levels better than a metal chain attached to a gear cassette.

German eBike excel at design, which creates a strong Bias in my mind. The Grace, like the name indicates, is very aesthetically pleasing. I just love the elegant lines. I have to pinch myself by paying attention to the high emotional Bias rating.

Grace OEM the Indian Ultra motor. The performance specifications disappoint me. The battery chemistry is unpublished. The Economy rating reflects the low performance levels.

StarPlotGrace15.png

Star Plot for HPC XC follows. The XC pattern is more rounded which results in a higher benefit score and Cost-Benefit ratio. Is the $1400 cost savings worth the higher risk? I believe so. Check out the Grace One (only 1.3kW) video where you can see US DOT standards being demonstrated.

Both bikes are good decisions. Which bike you prefer will be highly influenced by personal circumstances. The HPC costs less and provides a different type of value.


StarPlotHPC_XT.png
 
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Mike leroy

Active Member
know the law. You can only use an eBike in bike lanes with a Class 1 bike. The types of bikes described here require riders to register the bike with DMV. Also, a scooter M2 or a motorcycle M1 license is required. I live in California, so I only know CA law.

Grace One video is an example of an eBike built to US DOT legal standards. Grace One is a "moped" in CA. Between 1000- 1500 watts and 20-30mph power cut-off.

The trick to bending the law is to use software to set the output power limit. I do not know if this would hold up in court, if you got into an accident. You could buy a Cycle Analyst that allows you to set the output watts. For example, I want to ride the fire road in my park. The watts can be set to under 1001 watts from the software. However, to get up the hill at 35mph, i reset the software output watts above 2kW. I still need a license and insurance for the road with this software override.

Is 74 pounds too heavy for you to lift or push? If I take the bike into my park fire road, then I must push it. Walk-assist mode is essential.

The advantage of registering an eBike with DMV is you have full legal rights to the road, like a scooter or motorcycle. Driving in the car lane is safer than riding in the bike lane because drivers see you in the rear view mirror.

If you know you would rather drive in a car lane, then start at 1300 watts. I doubt you need much more than 2kW. Above 25mph, wind resistence causes the battery to drain very fast. The upper limit is actually the battery, not the motor. So, you need to start with the battery, not the motor.

In the reviews, look for
  • Electric Bike Class : Moped or Motorcycle (Class 4) - Learn More about Ebike Classes
 

Mike leroy

Active Member
The One.15 is Legally considered a motorcycle in CA. It also has a gearbox designed by Porsche engineers, rather than bicycle derailleur. The frame bottom bracket is square for a gearbox, not a chainring. the drivetrain uses a carbon belt, not a metal chain. The frame has monster sized tubes to accommodate a huge battery.

One thing is for damn sure. When you start DRIVING a bike on american roads like the German Autobahn, you better have a motorcycle license. You will get pulled over by cops without a license plate.


 

Cory151

Active Member
Great job. I would love to know more about the Grace.15, seems like an amazing bike. Ive not seen any grace stuff at the local shops.
Whats the top MPH on the Grace.15 anybody road pre release version?
 

Mike leroy

Active Member