Electric Bicycle Road Racing Theory
...okay, that gets me caught up with the old stuff.
Will post more later. :)
Arguments Contrasting 1000 Watts vs One Stone
Argument For 1000 Watts -
1. There are controllers that claim to be 1000 Watts.
2. Traditions have mostly supported power as a metric.
3. With electric and proper metering onboard you can precisely limit to 1000 Watts.
Arguments For One Stone -
1. The force of gravity is an easy concept to understand.
2. Measurements can be done at the track and they do not rely on electronics.
3. Force limiting also limits motor heating, which preserves machinery.
Rebuttal Against 1000 Watt -
1. Most 1000 Watt controllers seriously over permit power by up to 50%.
2. Traditional metrics were because of gas bikes which are very "organic", electric is more precise.
3. Having to install "restricting chips" to the ebikes would be unwelcomed.
Rebuttal Against One Stone -
1. One Stone turns out to be the same integral power overall, but the extra top end power means they go too fast.
2. Force seems too simplified, many racers like to cheat a little and have an advantage.
3. By eliminating the motor heating problem you don't get the fun of destroying the motors anymore.
Note: "One Stone" is 14 lbs of Force. See the Force Dyno thread to read about Force as a different metric.
safe, i appreciate your ideas, most of which make good sense.
Glad to be of help.
Maybe if you are young, ambitious, and hard working you could turn some of these ideas into reality.
I'm too old now to have the drive to do it and these are tough times to even try:
I didn't see anything about gears in the rules.
I build shifting motorized gas bicycles and recently started building some electric shifters and as we all know gears change everything.
The "problem" with any type of motorized bicycle sport is at what point do the pedals become useless.
Gears increase torque which increases the net Force of acceleration.
What is desired (it took years for me to realize) is "Constant Force Racing".
Check out the "Force Dyno" thread for more.
My present ebike build is "tuned" to 25 lbs of Force.
...I'm still experimenting with the amount of Force, but 25 lbs seems a good balance between needing to pedal at low speed and being able to pull hard at high speed. (as well as having a little surplus for hill climbing)
Simple math... 25 lbs of Force / 250 lbs bike plus rider = Acceleration equal to 1/10 the Force of Gravity. (constant)
This thread was started years ago in the "primitive days" of the thought process.
Force is a better metric than Power.
People that turn their bicycles into motorcycles are a dime a dozen.
I've completely rejected the concept of adding more and more power on a bicycle.
The question going forward is:
"How much Force is ideal?"
Top level dragsters accelerate at near the Force of Gravity (1g)
Just thinking. Pedal force on an e bike is unlike like the pedal force in a dragster, simply because the application of force is directed with a different intention. So, you might have to investigate pedal force and balance more from a regular bicycle to get an idea of the force you are trying to quantify. The optimum force would still allow you to maintain balance, which is another use of the 'force'.
Yeah... hmmmm... I think you've mangled the concept.
"Constant Force Racing" means that as measured on a dyno the final output to the road increases linearly at a constant rate.
Power = Force * Velocity
...so as velocity increases the power increases with it. (force is held constant)
Power is what you call a "derived quantity", it can't exist without a velocity attached to it.
Power can also be expressed as torque:
Power = Torque * Rotation
...so for something like pedal power you would have to convert units of muscle applied to the pedals and get it into units of torque and then find the pedal speed and compute overall power.
The easiest Force is gravity... it produces a constant acceleration on everything.
Basically the idea is that while dragsters can accelerate at near the rate of gravity, this ebike sport should be kept down to about 1/10 th of gravity to preserve the "cycling feel".
The trick here is to give just enough acceleration to make the ebike increase speed while ramping up the power so that you maintain that same acceleration at higher speed.
My testing suggests that 25 lbs of "acceleration" (Force) should be about right. It's not too much (making you not pedal) but at higher speed it's plenty of power.
...this is of 23 lbs of Force. (I plan to bump it up slightly to 25 lbs, but I'm still testing)
Go to "The Force Dyno" thread for more:
Power is what you call a "derived quantity", it can't exist without a velocity attached to it.
what then is the velocity of a 100 Watt light bulb?
The "watt" is a "derived quantity" too.
It's the Voltage (V) times the equivalent of velocity for electrons which is Current (I).
So Power is always a combination of two things where one is a "vector like" entity like Force, Torque or Voltage and the other is a velocity like entity like Velocity, Rotation or Current.
Don't worry... a lot of people that should know better get this wrong. :)
For the first few years of my "studies" on this I was satisfied with the derived "Power" unit. But then as I came to understand the problem deeper I moved to the perspective that by extracting Force from the Power equation it would be a better match for the needs of an Electric Bicycle Road Racing sport.
The reason I "changed" my mind is that I realized Force is a better metric than Power. (for this type of sport)
Was out riding my regular bike today and ran into a regular bicycle race.
Do we really need motors after all?
...seems like people have plenty of fun racing regular (road) bikes and this whole electric bike "concept" just doesn't seem necessary. I know we "can" go through a lot of work to create a sport that uses electric power, but human power is pretty good just as it is.
I rode for 30 miles today (and I'm 52) and it was no big deal. The distances you can cover on regular bicycles is pretty amazing.
Unless you are somehow physically impaired (way out of shape or injured somehow) it's hard to see the need for the added complexity and costs that electric brings. Even in truly uncomfortable climates (like Kansas City in summer) it's still possible to ride respectable distances if you are in decent shape.
The only argument for ebike racing has to be the extra speed on the top end and being able to run wider tires with better traction that would otherwise be impossible because of the extra rolling resistance.
Anyways... the world will survive (or not) as it is... one pedal at a time.
...and here you go, finally making absolute sense about Human Powered Vehicles. Yeah electricity is great, even in miniscule amounts (like the amounts needed to fire your muscle groups, or bzzzt your brain)
Good for you Safe.
As for the amount needed to run this computer and the connection thereof, well, that's another posting.
Don't get me wrong... I still can see ebike racing as something that could be entertaining for people.
I just have to admit that the interest seems to have evaporated recently.
We can possibly blame the political experience we went through in 2008 where all sorts of people got into "Green Technologies" because it was fashionable and this sort of distorted the collective ego towards something that was too focused on "being cool". This drove the online dialog to where it is today.
Disputes arose over what defined an ebike as more and more powerful ebikes really made it difficult for any agreement to occur. I know one guy (liveforphysics on endlesssphere) probably destroyed the sport all on his own because he placed himself as the "cool guy" and many were seduced by his evil logic. (by the time he was done his ebike was using a motorcycle front end and had a motor producing 10-20 hp)
It's hard to say.
In the best of worlds any new undertaking is difficult and sometimes the times you live in can simply be the wrong time. I know that when I was inventing and trying to sell Gravity Bikes back in the 1980's that it went nowhere. But then 20 years later it was part of the X Games. (I'm not saying Gravity Bikes became big, but they did resurface)
So you never know, people might have read these ideas and become inspired by them and maybe one day after I am dead and gone they will race true electric bicycles on go kart tracks in the way I see it. (or something close)
One does not care in his own time what history has to say.
(I think that's a George Bush quote)
Also, motorized bicycle racing (gasoline) seems to be doing fine in Southern California. They have the right idea and have low powered classes for beginners. So the use of go kart tracks as race tracks for this sort of thing is still around.
I finally have a workshop setup now here in Wisconsin so I can get back into the hobby.
After testing the FORCE based controller (Kelly) I'm thinking I'm going to go back and fool around with the "old school" 1000 watt chinese controller.
The constant FORCE (constant current) idea is great, but the constant POWER approach is good too.
With the low gearing (30 mph) I shouldn't have to worry about overheating with a one speed.
Constant POWER is able to deal with hills better and actually runs more efficiently at full speed because your current goes down as speed goes up. As a "suburban scooter" it's more practical.
Lot's of people here in Wisconsin ride these 50cc scooters which are perfectly legal and go 30-40 mph, so I'm realizing that speed is no big deal here. Like Missouri, it's likely legal issues will not crop up because it's an ebike.
Just a quick update:
Wisconsin is an amazing place in summer.
Unfortunately I've had so much fun doing other things that the ebike has just been sitting the whole time. Winter is coming and I'm a pretty mobile person these days so I'm headed back to the deserts (or mountains) of Nevada.
I actually got a new chinese controller and installed it ($30) only to discover that the problem was a failing throttle all along.
The ebike is back in storage. No plans to bring it out any time soon.
I still follow the ebike world to see what is going on.
These low cost mid drive motors really seem to be catching on. If they proliferate to the degree I expect then it's possible a realistic foundation for future ebike racing could form.
Since most chains break at power levels grossly above human level it gives yet another encouragement to keep things down in the legal power range.
Racing at 750 watts through a mid drive would be good. From my experience (10,000 miles) on an ebike with gears using roughly 750 watts it's enough power and flexibility to deal with what you need. In a tight tuck on an aerodynamic ebike you can easily go 40 mph.
This is probably how things will go.
These mid drives have double freewheels... so it's everything you would want.
After the "disaster" of excessively overpowered ebikes it does appear that hope returns to the sport. :)
Maybe we return to the beginning:
It would involve removing the bike stand mount, but the advantage of going mid drive would be that I can return to standard bicycle components like a derailler. While the motor and #219 chain and sprocket work okay now I'd rather have an abundance of gear ratios to choose from rather than a single speed. Multispeed gearing would allow me to go anywhere. (uphill, flat, downhill)
Maybe one day... just for the fun of it.
I ride a regular bike two hours a day as it is, but I'm not a risky guy anymore as far as speed so my "racing" desire has faded with age.
What make is the mid drive mounted on the Townie? Is that a freewheeled motor as well?
I think it's a Bafang.
You should look here though:
It appears that (at Eurobike) there is a flood of mid motor designs.
If you know the history on this, it's very hard to create the double freewheel as a DIY builder because it requires some serious machine work. If the technology finally gets stabilized and high quality mid drives flood the market I'd guess this is where it will go.
The nice thing about double freewheel mid drive is the motor doesn't force you into undesired situations.
It's very positive to see this coming out now.
Thr Germans and Austrians seem the best equipped to be leaders here because they know how to manufacture quality components and (in Austria) they have the mountains for the mountain bikes. I can easily imagine the mountain ebikes as being a huge success for those conditions.
The Bafang is Chinese and probably cheap, but functional. You get what you pay for sometimes.
When people get serious about efficiency the quality will go up along with the price.
Thanks for the MB Action page on Eurobikes. I agree, this will help simplify mid motor design, which will help simplify using mountain bike gearing. Definitely worth studying up.