safe

Merry Xmas!

safe

safe

Will write more later...

Allen

Wow.
Seriously--wow.

EBikeFL 

+1

Those look like Maxxis Hookworm tires but stretched to fit the wide rims. If they are, I wouldn't want to have the tire lettering visible; that would spoil the whole white/black color combination of the bike.

powell

when you imagine riding position on this ebike, is it comfortable?
good as a proof of concept,
for breaking speed records

safe

They are 3" wide tires I bought years ago and they might be discontinued now. So I will need to find replacements someday.

As for the riding position... yeah, if you are in the tuck too long it's uncomfortable. But it's a "Road Racer" eBike so that goes with the territory.

safe

What Creates eBike Pleasure?

Power?

What is Power?

Power is actually a derived value consisting of a combination of Torque and Rotation. Power can also be expressed as a combination of Force and Velocity. Changing back and forth is just a matter of conversion factors.

So is Pleasure all about Torque?

Yes and No...

The Pleasure Principle

Ultimately we come to realize that it's ACCELERATION that gives pleasure and not Power alone.

We define eBike Pleasure as:

Constant Positive Acceleration or Increasing Positive Acceleration.

We define eBike "dis" - Pleasure as:

Decreasing while still Positive Acceleration.

There is actually another area to consider which is Negative Acceleration (braking) and it also has three different modes:

Constant Negative, Increasing Negative and Decreasing Negative Acceleration.

...but that's another story.


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Looking here at a typical 1000 Watt Mountain Bike we see how the GREEN area represents Acceleration "after losses". Losses fit into different categories like copper loss, iron loss, wind loss and hill loss. You can't really talk about the Pleasure until after you subtract all the losses because they all impact your riding experience. All these losses are specific to the motor, the gearing, the rider and bike weight so it's very hard to talk about anything in isolation.

We see in the GREEN area what is known as the "EV Grin" which is a very strong acceleration beginning at very low speeds (essentially at zero) that "fades out" after 15 mph. Riding this type of powerband gives a pleasurable experience up to 15 mph and then a great sense of disappointment afterwards. The "EV Grin" becomes the "EV Bummer".
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In order to improve the Pleasure it's possible to "shift" Acceleration to a higher point in the powerband. In this example I've also adjusted for a lower Wind loss since the Road Racer concept focuses on improved aerodynamics over a Mountain Bike.
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This extracts only the Acceleration of the two eBikes and shows how the 1000 Watt Mountain Bike "peaks early" and then fades away. For the 20 lbs of Force Road Racer the power comes on slower, but lasts longer which tends to extend the Pleasure.

Which is actually faster?

The truth is that they are probably very similiar. Long ago (2006) when I first started into this hobby it was all about going faster. But it wasn't long before it became clear that it doesn't take much to make something that is absurd... a poorly designed "motorcycle with pedals".

So my goal now is Pleasure... if the "Pleasure Principle" were to expand into actual racetrack action that's great, but for now I'm content that it's something I can enjoy.

My "Road Racer" is fun.
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FMB42

Triple wow.

I must also say that I fully agree with the reality of your "power to pleasure" concept. My 1st build was a 500w geared hub "MTB" that produces low-end torque over HP. My 2nd "unfinished" build is a 750+ watt direct drive hub "board track racer" that's setup for mid/top-end power. Both offer similar top speeds of ~ 17 - 20 mph max. The geared hub bike is good for a range of ~ 25+ miles, while the heavier DD hub machine "runs down" at ~ 18 to 20 miles.

Speed per dollar wise, I'll add that the cost of an ebike power system capable of approaching 35 mph would, imo, require nearly double the cost of a "25mph" system. Approaching 45 mph would more than double that cost once again. But the truth is that I'm not really interested in riding the average "rubber framed" e-bike conversion at much more than ~ 30mph (regardless of how strong the brakes are).

safe

I'm so used to criticism it's really comforting to hear someone actually agree with what I have to say.

Frankly it doesn't seem right for ebikes to go faster than 40 mph as a maximum. I know things have gotten a bit crazy over the years and people have built some monster machines, but my belief has always been that there should be some pedaling involved with ebike riding and the extra power we see sort of erases that need. My "Force Limiting" direction tends to bring the pedals back at the lower speeds.

Most ordinary bicycles have too short of a wheelbase. Mine is 52" and I think the average bicycle is 40" or somewhere in that neighborhood. Just to be able to get into a decent tuck and have legroom to pedal hard you need more space. So the first thing (I believe) that needs to happen is that the wheelbase needs to expand to match the doubling of speed.

I ride my regular bicycle at only 12 - 15 mph most of the time.

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safe

...this sort of gives a visual of the problems confronting the two control techniques.

The 1000 Watt slows down in a linear manner, but the constant Force (20 lbs) ebike holds more speed up to a point and then bogs down. So gearing is much harder (more precise) with the more linear powerband.

I made the mistake of gearing too high at first and on a nearby 4% Grade I would bog down to 20 mph and have no ability to do anything about it. (pedal power stops before 20 mph). So this (above) represents what will be my new gearing. (not tried yet)

My old gearing took me to 40 mph... sloooooowly.

safe

The Steinmetz Equation



Before people get too far into the idea of boosting top end performance you need to be aware of the Steinmetz Equation. For about 100 years designers of transformers and electric motors have used this equation to estimate iron losses.

https://www.digikey.com/us/en/techzon...lications.html

Basically for about every pound of iron you should expect about 10 watts of iron loss assuming your motor switches at a reasonably slow speed like 100 Hz.

However, RC motors tend to spin very fast and also have high internal pole counts which means their "Electrical RPM" can be very high. Add into this that Steinmetz is for A/C currents, not DC and you have to worry that iron loss is worse than expected. When an RC motor switches it tends to swing from positive to negative in a hurry and that magnifies iron losses.



So that's just a caution... know your Steinmetz Equation or at least know what it's trying to tell you... not all electric motors work well at their higher rotation speeds.

FMB42

I've done ~ 40 mph downhill, on good pavement, while riding a "decent for the time" MTB. I found this to be more "eye opening" than doing just over a buck fifty (also downhill on good pavement) while topping-out a Yamaha FJ1100 (had about 17 years of motorcycle experience at the time). The thing was that I could actually stop the Yamaha. However, I had foolishly "over-ridden" the canti brakes on my MTB and, as such, I couldn't stop it (until the road leveled out some). I can also tell you that this was one twitchy MTB ride. Yep, lots of fun.

Sure, my MTB didn't have proper road type tires (PSI was maxed tho). And no, I didn't expect a MTB to handle well while traveling that "fast" on pavement. Yet, I must have routinely reached speeds of 35 while riding the same bike on certain off-road downhill runs (that often had "berms" that helped keep you on "track"). Had some really good, and few not so good, times on those downhill dirt runs. This was, of course, more or less what it was made to do. Nonetheless, I too feel that 40 is about the maximum for safe budget sensible e-bike conversions. Now I'll admit that people can, and do, go quite a bit faster on their e-bike builds. I myself would much prefer doing so while running capable brakes, proper tires, a purpose built frame, and proper weight distribution. The problem for me is that this would cost about as much as a motorcycle that offers far superior performance.

And ya, I too have found that e-bike conversions can be very picky about gearing. Too tall, and you'll over-load/heat the power system. Too "short" and the thing becomes all but useless (you be better off with a regular pedal powered machine). Besides, it must look pretty funny when you're windmilling like crazy on an under-geared e-bike. Luckily I've been flying electric RC fixed and rotary winged aircraft for about 6 years and, as such, realize that it can take a lot of time and considerable trial and error when it comes to configuring electric power systems.

Wheelbase is, indeed, probably one of the biggest safety hurdles with high speed electric conversions imo. The Worksman framed BT racer I'm working on has horizontal rear dropouts that allow for a wheelbase of 42 to just over 44 inches (my other MTBs and road bikes run ~ a 40" to 41" WB). I'm currently @ 43" which gives more than reasonable stability at 20 mph. Note: This single-speed BTR build has really proven to be a challenge in the gearing department (I suspect that I'll be buying more than a few different tooth-count freewheels before I find a usable ratio). The good thing is that I only ride this "BTR" on level hard-packed dirt roads, which should make the final gearing selection easier.

As for your thoughts on pedaling: the average rider on a regular bicycle produces maybe 150 watts over a period of time and what, ~ 250w for a 25 second burst? Well if so, that's some serious power to allow to go to waste imo. Those, like you and me, who subscribe to this belief might do well to consider some of the high powered geared hub-motors, or a "freewheel" type of "mid-drive" power system. IDK, maybe you've incorporated this into your superb build...

safe

Simple Stuff

On the most pragmatic level the only difference between a 1000 Watt configuration and a 20lbs Force configuration is the way you set the parameters in a controller.



So if you had a 40V battery pack and wanted a 1000 Watt configuration you would set:

Max Motor Current = 100%
Max Battery Current = 25%

...assuming the controller limits to 100 amps.

For an "approximate" 20 lbs of Force using the same stuff you would set:

Max Motor Current = 40%
Max Battery Current = 40%

...so it's not "rocket science" to be able to do this.

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safe

FMB42

Well, the nice thing about a constant current "Force Limited" configuration is that you aren't sacrificing top end at all, but you really disable the low end so much that pedaling is a necessity.

It takes a little getting used to... there is no feeling of a "free lunch" with low end torque doing all the work. You literally need to crank about 3-4 hard pedals before you get up to speed and hand off to the motor.

Any more than 3-4 hard pedals and it's no fun anymore.

(this is why the hillclimbing gearing must be able to carry you up without bogging down)

People can generate 750 watts of power for about 3-4 pedals.
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powell

I am glad that you include pedalling as a part of your project.
Every ebike should allow rider to exercise. But gearing should allow for that.
very good points about extended wheel base.

safe

I'm doing things very differently than most people are now. (on ebikes)

When people think of the need to pedal they normally think in terms of having to pedal AFTER the motors acceleration ends and you are getting that feeling of "dis" - Pleasure for not having more power up top.

What I'm doing is forcing all pedaling to be completely done in 3-4 turns of the crank... then AFTER you are at speed the motor continues to pull hard until you reach your maximum speed.

So pedaling is never a "continuous" thing. It's more like BMX where you get sudden surges of pedaling followed by going over jumps, turns, etc...

From the "pure cyclist" perspective this doesn't showcase people with endurance. It's more likely to cause people to use steroids than EPO or a blood transfusion. (think Lance Armstrong)

Creakyknees

Gorgeous bike!

Agree with your thoughts re: pedaling; in designing the motor power profile, take into consideration the power profile and preferences of the intended rider, and, maybe the use profile of the bike (e.g. a cargo hauler or just for fun).

Can't wait to see your next project!

Scaliboy62

Pedaling combined with a shot of juice @ the proper interval makes the E-Biking experience complete for me, it's like a dance. I wouldnt buy an electric scooter without the ability to pedal as well.
I feel the same if not more euphoria as I did when I rode motorbikes in the 1980's going through the gears, technical riding & braking.
What I experience is my adrenaline level stays high & this makes me maintain strong pedaling which = a nice workout & cool cooperative relationship with a silent, gearless in my case 36V 500watt motor that peaks @ over 1000. It keeps me in shape health wise & like a drug I look forward to it every day.
Also a lot of people gripe about 20 MPH limited E-Bikes being too slow I disagree, when I was into boating my most memorable experiences was cruising just a little over planing speed with the motor in a nice groove enjoying the sights, 20 MPH speed limited E-biking is the same type experience, I hit 25 MPH's often but a slow cruise @ 12-14 MPH's with very little shots of power hits the spot as well.. Oh well, my2 cents on this..

safe

At first I advocated the idea of a "one size fits all" mentality with everyone using 1000 Watts. But now I'm suggesting a combination of a linear constant current powerband combined with a table of values that correspond to overall rider + bike weight. That way if people are of vastly different sizes they can "race" together more equally.



For cargo hauling vehicles the non-linear battery limiting "Power" configuration is better.

Linear power is better for top end. (what I call "Force Limiting")

Non-linear is better for slower speed bottom end. (what I call "Power Limiting")

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safe

In the beginning (2006) I had fantastic dreams of making a business out of making these "Road Racers". Over time I came to realize just how hard it is to create something like this where just about everything had to be made from scratch. Throw in the economy going bust and taxes and the "new thinking" of our age and being a businessman just isn't the dream anymore. (also, the people actually racing on Go Kart tracks on motorized bikes are completely power obsessed, so this "human" type racing is very out of style right now)

That said...

It's illegal to "sell" an ebike that goes over 20 mph at the point of sale. But unless you are caught speeding with a modified ebike it's typically okay. (not always). So the concept is to build a great "foundation" with a great frame, fairings and motor that the buyer then modifies to the higher performance level. Sort of the "aftermarket" concept.

What is great about this "Force Limiting" upgrade is you are using the same motor, but just tweeking the powerband to favor top end over bottom end. If you simply add more power you run the risk of overheating... this gets the top end power without requiring a new motor.

I've been testing my ebike and the motor stays very cool even though it's using 1600 watts of power input at peak speed. The motor is basically rated as a 1000 Watt motor.



...I typically do 3-4 hard pedals to get to 20 mph and then the motor takes over after that.

There is no "instant gratification" here, you must "work" to get up to speed.

Maybe I'm just too much of the older generation where we used to talk about being a "work-aholic" because we had the protestant work ethic. This is out of fashion. Effort is "uncool" to the younger generation. (it could change though)

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safe

A Comparison of Range



The Road Racer can pull a higher top speed due to reduced wind resistance.

The Mountain Bike uses the most energy (least Range) because at full throttle and low speed the motor efficiency is poor. (a lower gearing would work better)

The Road Racer (if geared correctly) has a "sweet spot" at top speed because you are approaching the No Load motor speed which has a reduced current. Acceleration is mild here, but motor efficiency is good as long as Iron Loss (remember the Steinmetz Equation) is not a conflicting factor.

Scaliboy62

Great work your very talented, she looks like she's ready for the Bonneville salt Flats. I couldnt handle that riding position for too long even if that means my MTB style E-bike loses efficiency in the wind tunnel over a road racer. But that's Engineering isnt it, it's a give & take in design.

safe

It's designed for suburban roads that have posted speeds of 25 mph and 35 mph "or" Go Kart tracks. (kids would love it)

Would not be much fun to go to the salt flats in order to do 35 mph.

Tucking is "optional" for when you are in the mood. Sitting upright and cruising around town is fun too.

You don't always have to race the ebike.

But a pleasurable powerband is always nice.

Sportbike riders often sit upright:



By my calculations an upright (no tuck) riding position should give me an aerodynamic drag coefficient of about 0.4. A mountain bike is 0.5. In the tuck it's 0.3. So upright I'd still be able to pull about 33 mph, which is only a mile per hour slower. Range gets worse of course and you lose that "sweet spot".

The ebike is actually pretty comfortable when you sit up...
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FMB42

A very professional custom build to say the least. Looks like it's doing 100 mph sitting still. I really can't say enough about the craftsmanship and engineering. I see more than a few top-notch components too. Kelly controllers, for instance, are some to the best around. These controllers are widely used with large robotic devices (in both industrial applications, and prototype design/builds).

Really looking forward to learning more about the battery pack/type/configuration, and just about everything else on this beautiful machine.

About the only time I tucked on my sport bikes (during the 70s and 80s) was when I was at, or near top speed* on good pavement. Control of the machine while tucked is less than that of an up-right position (when it came to handling, 3-4" rise "Beemer" bars had it "all-over" the much lower Clubman style bars in my book).

Anyway, congratulations on your build Safe.


* I do not recommend running at the absolute maximum top speed of your machine for more than a moment or two. I say this because acceleration, or better said, "the ability to accelerate" can often be effectively used to regain control of an "out of control" machine. Always having just a little bit of acceleration on tap can be a real "ace in the hole" when things go "bad" at speed.