Cost-Benefit Comparison: Felt Mountain or eBike?

Mike leroy

Active Member
What benefits justify additional eBike costs? Scroll to the last post for the answer.

Google Sheet for Cost-Benefit Analysis

The aim of this article is to relate an eBike's benefits to technical detail, your physical ability and subjective opinion. A cost-benefit picture is drawn that reflects your situation, that is easy for everyone to interpret. The technical details and personal information is rated on a scale from 1 to 5. The ratings are the data for the cost-benefits picture.

The same technique applied in text format for EasyMotion bikes.

A Google Sheet to associate 50+ major eBike features (i.e., costs) with benefits. Benefits are rated on a scale from 1-5. Associate any bike feature (i.e., costs) with a benefit. The benefits are categories tailored to your situation. The seven benefit categories in this example are based on Bosch research. The features (i.e., costs) are taken directly from bike manufacturer spec sheets.



Google Sheet sorted by Cost(above) or Benefit(below)



The technical features are classified under six benefit categories, according to the relevance for your particular purpose or environment. The benefits score is the average of the ratings that comprise that benefit. Most people refer to this approach as a "software algorithm".
  1. Economy
  2. Elegance
  3. Excitement
  4. Endurance
  5. Enjoyment
  6. Ease
We might refer to the two personas in this article as Ms. Ease and Mr. Endurance, due to the characteristic tradeoff decisions.

The NINEe 20 electric bike and NINE 60 mountain bike look very similar, but the structural differences are significant. Some of reasons are:
  • Additional weight and motor forces
  • Reinforced frame and rims for additional weight and acceleration.
  • Additional braking power due to higher speeds.
  • Stronger drive chain due to motor.
 
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Mike leroy

Active Member



The electric bike and NINE 60 mountain bike look very similar. The structural specifications are very different. The ebike is more similar to the NINE3, which costs $2K more than the NINE 60 shown below.
 
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Mike leroy

Active Member
The eBike is more similar to Nine 3, which costs $2K more than the Nine 60. Specification sheets are the basis for comparison. The Nine 3 is used for the remainder of the comparison.
 
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Mike leroy

Active Member
Discomfort, shortness of breath, sweat and a strong urge to strike the ground with your heels are signs that a hill is too steep for your fitness level.

To know how steep of a hill a person can climb with a particular bicycle, a calculation is made. The relationship between the distance travelled by the wheel and one turn of the pedal is called the "gear display".

"Gear Display" for the Nine 3 mountain bike is measured in meters (1.6m):
"Gear Display" = 24 front teeth / 36 rear teeth x 0.74m (29") x 3.14 = 1.6m

To know if Mr. Endurance or Ms. Ease can pedal a hill of a certain "grade percentage", we find the 1.6m "gear display" in the following table.

The power of Ms. Ease's legs are "100 Watts", located in the first column. Ms. Ease cannot climb hill more than 7.5% grade, which is considered moderate by most people.

The power of Mr. Endurace's legs are "200 Watts", located in the second column. Mr. Endurance can climb hills below 12.5% grade, which are considered steep by most people.

To optimize your bike, match this table to your gears, local environment and leg + motor power!



Note: see calculations to increase torque by 25%, i.e., 2.0m display, by changing chainring.
 
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Mike leroy

Active Member
Cost-Benefit Ratios

The eBike is clear benefit to Ms. Ease. Ms. Ease can climb hills that were beyond her ability.

For Mr. Endurance, the eBike provides benefits when the motor can push 50 pounds of groceries from a store closer to home, but with extremely steep hills. The less expensive mountain bike is a better choice for the store that is further away on a much less steep route.

Another calculation is required to assess whether the motor provides enough power.

I estimate 5Nm torque per grade-percent. So, the 60Nm Bosch drive can handle 60Nm / 5 = 12% grade. Another way to state Mr. Endurance's situation is the need for 90Nm of torque, 18% grade x 5Nm.

The Bosch drive does not help Mr. Endurance up the steep 18% hill. Mr. Endurance chooses the NINE 3 conventional Mountain Bike. A 750W, 48V, 120Nm motor for the NINE 3 kit better achieves his objectives for the very steep 18% grade hill.

Your decision is highly dependent upon personal leg strength. Mr. Endurance six feet tall. His weight varies +- 10 pounds from 175. Mr. Endurance's 2.4 weight-to-height ratio is ideal for hill climbing. Check out the Tour de France champions for the past decade, (i.e., 2.1).
 
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Mike leroy

Active Member
The automobile industry has a long-standing history of using "Star Plots" or "Spider Charts" to visually diagram differences between cars. The Battery University also uses spider charts to explain battery chemistry. Suppose we rate aspects of a bike ride on a scale from 1 to 5. We can also include personal information, i.e., our Heart Rate.

The following Star Plot illustrates a typical ride. All bike considerations are rated a "3", on a scale from 1 to 5. We also score our personal information , i.e., Heart Rate, as a "3", or average.

The following Star Plot tries to convey an under-powered bike because the outcome, Heat, has the highest score of "5". The bike was overheated.

If we scored Heat as too cold, "1", for another bike, then that motor is over-powered. The potential power was never utilized, so we overpaid for the bike.



Now that the concept of star plots has been introduced, we will compare the Felt 3 Mountain and NINEe bikes in a star plot.

To evaluate the bike from a holistic viewpoint, we considered the outside temperature, bike speed, additional weight, steepness, etc.... To make this comparison relevant we will compare:
  1. Economy - eBike rated as 3/5. Mountain bike 5/5.
  2. Elegance - eBike 5/5. Mountain 3/5.
  3. Excitement - both 4/5.
  4. Endurance - eBike 5/5. Mountain 3/5
  5. Enjoyment- eBike 5/5. Mountain 4/5.
  6. Ease - EBike - 5/5. Mountain bike 2/5.
The Star Plot for the NINEe electric bike tradeoff decisions made by Ms. Ease:



The Star Plot for the NINE 3 mountain bike tradeoff decisions made by Mr. Endurance:

 
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Mike leroy

Active Member
The eBike is well suited for a particular type of person. Both bikes scored 5 of 5 in the "Results" part of the star plot graph. The star plot is a visual aid to comparing vehicles. Star plots should remove a great deal of the effort required to find the most appropriate bike for a particular person or purpose.

The tradeoff decisions made by Ms. Ease and Mr. Endurance illustrate the benefits that appeal to different types of people.

Mr. Endurance
protects his bike from overheating by adding a thermometer. Electric motors operate most efficiently at 140F. Because Mr. Endurance carries 50 pounds of food up an 18% grade hill, he runs the risk of overheating the electrical system on hot days. Products like CycleAnalyst display temperature.

Ms. Ease uses an FLIR lens on her cellphone to get temperature readings.
See Cellphone Camera Reveals eBike "just right for you" post.
 
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Ann M.

Well-Known Member
An elegant analysis of the value of ebikes based on different people, @Mike leroy . Don't forget to include that the use of an ebike vs. a regular bike, no matter how steep or flat the terrain, allows the rider to have more energy and time to direct to other purposes after riding, thus improving the overall quality/efficiency of life.
 

Mike leroy

Active Member
Compare Felt compulsion full suspension mountain bike with Felt DUALe electric bike.

To judge a bike we relate conceptual benefits to the corresponding technical detail. The conceptual benefits are:
  1. Economy
  2. Elegance
  3. Excitement
  4. Endurance
  5. Enjoyment
  6. Ease
The previous comparison contrasted Ms. Ease with Mr. Endurance. The approach taken in this example is solely for one person, rather than two different types of people. We introduce a new persona, Mr. Excitement. Mr. Excitement like jumping his bike, so he needs to relieve the motor/pedals/spindle of some of the pressure. The rear suspension absorbs some of the landing impact, so the spindle is less stressed.

The two bikes are:



The DUALe electric bike:
 
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Mike leroy

Active Member
How does Mr. Excitement relate conceptual benefits to the corresponding technical detail? The six benefits are categories that he elaborates upon.
  1. Economy
    • Power Consumption Bosch rated 5, mountain bike rated 3. More power requires two batteries for same time period.
    • Battery replacement cost Bosch rated 2, NTS Works 48V rated 5.
    • Your personal rating (scale 1-5), relative to total cost and budget.
  2. Elegance - measured in performance, rather than fashion.
    • Fork - eBike 4, Mountain 5
    • Wheelset - eBike 4, Mountain 5
    • Your personal rating from demo rides.
  3. Excitement - how much fun, access to remote places, etc...
    • Torque Acceleration - Bosch 3, 8Fun 5.
    • Steepness - Bosch 12% grade rated 3, 8Fun 20% grade rated 5
    • Your personal rating from demo rides.
  4. Endurance - how much longer he can play.
    • Battery Heat - 36V Bosch rated 3, 48V NTS Works rated 5
    • Throttle - Bosch 0, 8Fun 5.
    • Your fitness level rating - Shortness of breath, sweat and a strong urge to strike the ground with your heels are signs that a hill is too steep for your fitness level.
  5. Enjoyment - new types of thrills
    • Speed - Bosch 3. 8Fun 5.
    • Jumping - Bosch 3. Mountain 5. Suspension.
    • Contentment - Your personal rating from demo rides.
  6. Ease - access steeper grades that were not previously climbable
    • Gear switching torque sensor - Bosch 5, 8Fun 0.
    • Drivetrain - EBike rated 4, mountain bike rated 5
    • Discomfort - Your personal rating from demo rides.
    • "Gear Display" mountain = 1.6meters
    • Your leg power (100, 200 or 300 Watt category)
    • Your max steepness grade for mountain bike 12.5% (Mr. Endurance 200W)


HPC gear display (25% more torque)
Custom Single Speed 38T sprocket for nearly 25% more torque and higher efficiency.
38 front teeth / 42 rear teeth x (0.7m) x 3.14 = 2m

Felt gear display calculations

  • Chainwheel
    RaceFace NW 30T 1x11-speed
  • Freewheel:
    SRAM X1 11-speed 10-42
  • Tires: 27.5" x 2.35" (0.7 meters)
  • 30 front teeth / 42 rear teeth x (0.7m) x 3.14 = 1.6m
 
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EddieJ

Well-Known Member
I'd sooner just simplify things.....

I have the benefit of both a KTM e-mtb and a KTM Ultra 1964 hardtail, and since the Bosch Performance line motor is proving to be both unreliable and extortionately hard on bike components, I'm now thinking that pedal only or hub drive is the way to go. The performance Line motor only gives a range of about 20 miles when used off road in eco mode for duration, I weigh 75kg so not exactly heavy. The pedal mtb weighs 11 kg compared with approx 21kg for the e-mtb, and that range of 20 miles is relatively easy for me to pedal with my level of fitness. The 8kg weight saving of the pedal mtb more than makes up for not having a battery and motor. The pedal mtb is faster everywhere other than on hills, floats over ground, and hops over holes and rough terrain, and most importantly of all, is kind to components in relation to wear and tear.

Taking the e-mtb. and leaving the Bosch reliability out of things, the bike has covered 630 miles from new, is three months old, and already requires a new front sprocket, new rear cassette, new jockey wheels, new chain, new headset bearings, and the tyres are wearing fast. These components would need to be changed four times a year with my riding requirements.

The pedal mtb has covered a similar mileage and requires nothing.

Had the motor been constructed using a conventional sized front sprocket, then wear and tear would be reduced, but a rear hub drive motor would suffer far less.
 

Mike leroy

Active Member
I'd sooner just simplify things.....

I have the benefit of both a KTM e-mtb and a KTM Ultra 1964 hardtail, and since the Bosch Performance line motor is proving to be both unreliable and extortionately hard on bike components, I'm now thinking that pedal only or hub drive is the way to go. The performance Line motor only gives a range of about 20 miles when used off road in eco mode for duration, I weigh 75kg so not exactly heavy. The pedal mtb weighs 11 kg compared with approx 21kg for the e-mtb, and that range of 20 miles is relatively easy for me to pedal with my level of fitness. The 8kg weight saving of the pedal mtb more than makes up for not having a battery and motor. The pedal mtb is faster everywhere other than on hills, floats over ground, and hops over holes and rough terrain, and most importantly of all, is kind to components in relation to wear and tear.

Taking the e-mtb. and leaving the Bosch reliability out of things, the bike has covered 630 miles from new, is three months old, and already requires a new front sprocket, new rear cassette, new jockey wheels, new chain, new headset bearings, and the tyres are wearing fast. These components would need to be changed four times a year with my riding requirements.

The pedal mtb has covered a similar mileage and requires nothing.

Had the motor been constructed using a conventional sized front sprocket, then wear and tear would be reduced, but a rear hub drive motor would suffer far less.
I do not know if a planetary chainwheel can be used to replace the broken sprocket. Something like this idea may make your broken bike a little more useable?
 

EddieJ

Well-Known Member
Thanks Mike.

If nothing else, that will make for some very interesting research. :)

The current sprocket size has 15 teeth, which is the equivalent to a conventional sprocket size of 37 teeth. Personally I feel that Bosch have screwed up big time with this arrangement. It places too much strain onto too smaller contact area, and the load/stress isn't spread across a great enough sprocket area, which means that the sprocket is having to do proportionally too much work, and wear is exaggerated/increased.

15 teeth is also the smallest available, and the gearing is completely wrong for off road use. A disproportionately high level of riding time, is spent in the first two gears when riding off road. The wear on those first two sprockets of the rear cassette is very noticeable, and also in an unacceptable short period of time. It also places even more strain on the chain, as it isn't running a particularly straight and true line.
 

Lenny

Well-Known Member
Thanks Mike.

If nothing else, that will make for some very interesting research. :)

The current sprocket size has 15 teeth, which is the equivalent to a conventional sprocket size of 37 teeth. Personally I feel that Bosch have screwed up big time with this arrangement. It places too much strain onto too smaller contact area, and the load/stress isn't spread across a great enough sprocket area, which means that the sprocket is having to do proportionally too much work, and wear is exaggerated/increased.

15 teeth is also the smallest available, and the gearing is completely wrong for off road use. A disproportionately high level of riding time, is spent in the first two gears when riding off road. The wear on those first two sprockets of the rear cassette is very noticeable, and also in an unacceptable short period of time. It also places even more strain on the chain, as it isn't running a particularly straight and true line.
Could it be because it was winter and the bike was subjected to harsh, chalky off-road conditions?
I remember you were really excited about this bike and sold off your Neo Xtrem. Very small % of ebiker demography use the bike the way you do.
 

Mike leroy

Active Member
Thanks Mike.

If nothing else, that will make for some very interesting research. :)

The current sprocket size has 15 teeth, which is the equivalent to a conventional sprocket size of 37 teeth. Personally I feel that Bosch have screwed up big time with this arrangement. It places too much strain onto too smaller contact area, and the load/stress isn't spread across a great enough sprocket area, which means that the sprocket is having to do proportionally too much work, and wear is exaggerated/increased.

15 teeth is also the smallest available, and the gearing is completely wrong for off road use. A disproportionately high level of riding time, is spent in the first two gears when riding off road. The wear on those first two sprockets of the rear cassette is very noticeable, and also in an unacceptable short period of time. It also places even more strain on the chain, as it isn't running a particularly straight and true line.
Eddie,
I have been on a crusade to get the Yamaha motor in the USA. One of the major reasons is the sproxket. Yamaha has a conventional chainring. The first impression bosch left on me was that it is a toy.

Haibike is discontinuing bosch next year, in favor of yamaha.

I never bought into the bosch, for several other reasons, I.e., 350W and 60Nm. The replacement battery is expensive. why? The full suspension frames all look weird to me. The shocks seem to be designed around the motor or battery. I want a 48V battery. Why use such an expensive torque converter? I do not like the oval bottom bracket. Why not something more conventional?

Why is the battery as unstealthy as a brick? If the bottom bracket is oval, why not tie the battery into a graceful arc? In case you do not know, I prefer nobody notices a motor on MY bicycle! Ok? I fail to see the elegance. Is that the best $4000 can buy?

My primary road is an 18% grade. Gearing is everything. I would void the bosch warranty, if I modified the sprocket. I need a 400%+ gear range. The bosch is designed for euro cities.

I finally figured out how to get 50 pounds of groceries up an 18% grade -- "run assist" mode. I am not kidding. Seriously, like walk assist, only I run uphill, as if the bike were a dog on a leach. Not terribly weird, but it would work.
 
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Mike leroy

Active Member
Could it be because it was winter and the bike was subjected to harsh, chalky off-road conditions?
I remember you were really excited about this bike and sold off your Neo Xtrem. Very small % of ebiker demography use the bike the way you do.
I have read the bosch specs. I cannot recall the exact temperature range, but I was surprised by the impressive specs.

From another angle, what about all the fat bikes designed for snow? It must be able to tolerate very cold, high altitude Alp wearher.
 

Lenny

Well-Known Member
I have read the bosch specs. I cannot recall the exact temperature range, but I was surprised by the impressive specs.

From another angle, what about all the fat bikes designed for snow? It must be able to tolerate very cold, high altitude Alp wearher.
M1 Sporttechnik Spitzing should be good choice for your 18% grade
48V battery,
120Nm Torque
Conventional chanring
880Wh battery etc.
 

Mike leroy

Active Member
M1 Sporttechnik Spitzing should be good choice for your 18% grade
48V battery,
120Nm Torque
Conventional chanring
880Wh battery etc.
Thanks for the suggestion. I am very concerned about the motor history. The project was originally called "Clean Mobile", or something like that. The company went bankrupt. I has been revived. It might actually be a good motor. I am inclined to wait one year. I feel battery tech will explode with apple eCar and Tesla research plant in Nevada.

I am a runner. I love running. I run 2 miles to the store and carry 30+ pounds of food back. My only reason for the bike is grocery shopping. I love the eBike concept. I want to replace my gas car with electric power. I think more viable options will appear. I am willing to spend several thousand dollars for a reliable lifestyle change. I will be dependent upon it, so I must not have no doubts about it.
 

EddieJ

Well-Known Member
Crazy Lenny, I can't deny that my riding conditions don't contribute to the wear rate, and I do really love the bike, just not the Bosch system.

In my opinion, Mike is correct about the motor being only suitable for European shopping bikes, the gearing is just completely wrong. Looking at the German pedelec forum, owners are fitting a 42 tooth extra rear sprocket to the rear cassette, in an attempt to compensate for poor design. I wonder if companies such as Bosch actually even bother to test their products. Of course they will say that they, but with who riding the bikes. I guess some pro, or ex pro rider who wouldn't even need assist modes. Why don't they use 'real' end users.

I have grown accustomed to the brick shape battery, but totally agree about battery integration. That was why I first bought the BH. Sadly look at how that turned out. :(

One aspect of the Bosch battery design that you probably won't be aware of, and there is no excuse for, and that is the amazingly poor mounting system. What kind of design team thinks that mounting a battery in such a way that water and mud collect around connectors is a good idea! Evidently pretty dim ones. Another un mentioned aspect, is that many riders suffer from issues relating to the battery lock, You can just never get the damn thing to work.

battery one..JPG
 
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Mike leroy

Active Member
Crazy Lenny, I can't deny that my riding conditions don't contribute to the wear rate, and I do really love the bike, just not the Bosch system.

In my opinion, Mike is correct about the motor being only suitable for European shopping bikes, the gearing is just completely wrong. Looking at the German pedelec forum, owners are fitting a 42 tooth extra rear sprocket to the rear cassette, in an attempt to compensate for poor design. I wonder if companies such as Bosch actually even bother to test their products. Of course they will say that they, but with who riding the bikes. I guess some pro, or ex pro rider who wouldn't even need assist modes. Why don't they use 'real' end users.

I have grown accustomed to the brick shape battery, but totally agree about battery integration. That was why I first bought the BH. Sadly look at how that turned out. :(

One aspect of the Bosch battery design that you probably won't be aware of, and there is no excuse for, and that is the amazingly poor mounting system. What kind of design team thinks that mounting a battery in such a way that water and mud collect around connectors is a good idea! Evidently pretty dim ones.

View attachment 2443
I am going to repeat this type of comparison. I will compare the Volton 350W mid-drive, Sondors rear hub and SSR Sand Viper front hub. Court gave #1 ratings to the Volton and SSR, which cost $2,250 and $1,400 respectively.

The Volton has an elegant battery and frame design, which I find very aesthetically pleasing. I think Volton could easily overcome Court's review "Cons" by allowing users to configure a limited set of options, e.g., battery voltage, motor wattage, shocks and brakes. Just build from the basic frame design. I am willing to wait a few months for Volton to accumulate enough orders to produce a batch of bikes.