Electric Bicycle Road Racing Theory (Original)

safe

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Electric Bicycle Road Racing Theory

The idea of this thread is to start with some basic principles and realities and build the sport of EBRR up from the roots. Along the way I will attempt to recreate existing arguments about electric bicycles that seem to recur regularly. This is to be made as a sort of college course... even though it's not really going to be taught anywhere. (well, you never know, I can remember some college courses at about this same level)

Physics

We begin with a review of bicycle physics.

An ordinary human being can (at best) produce 400 watts of power over a sustained period by pedaling. For short durations it's possible for peak athletes to achieve 750 watts of power going out the rear wheel. At about 30 mph the primary losses are due to air resistance, so it's very difficult to go faster than 30 mph by pedal power alone in an upright bicycle.

The electric bicycle was created as a "bicycle" replacement or enhancement. In order to retain a definition of "bicycle" we need to accept that motor power cannot significantly exceed human power. This sets a realistic upper limit of 750 watts (1 hp) as the boundry.

The first major point is that even BEFORE we look at the laws pertaining to electric bicycles we are already more or less bound to a limit of 750 watts simply because it what makes us within the definition of a "bicycle". Going significantly above this level and you are into motorcycle or moped territory.

Present Laws

Europe - 250 watts output
Canada - 500 watts output
USA - 750 watts output

The USA is allowing the logical maximum for a "bicycle" while the other nations seem to cut the limit down to something less than is within the accepted understanding of a "bicycle". This is unfortunate, but what we have to work with.

Since we are discussing "pure forms" in the abstract and we see that in the most pure sense 750 watts is the logical limit for an ebike we simply state that 750 watts is the "proper" level to establish as a worldwide standard for Electric Bicycle Road Racing. Since racing would be done on Go Kart tracks and these are not regulated by street laws there is no reason not to set the level worldwide as 750 watts. (that way in the future if you have the World Cup equivalent of EBRR then everyone is using the same limits)

So the "bottom line" is that laws exist and some are compatible with racing while others are not. In the USA it should be easier to produce machines that can be used on the street as well as the track, but in much of the world these machines would be sold as "off road only".

Motor Input verses Output

We know that at tax time we report our income and then deduct certain things before we actually calculate our taxes. Motor Input verses Output works the same way. Laws are written to limit the "Output" of a motor, but make no reference to what "Input" was required to get there.

A typical motor is about 75% efficient. This means that if you start with 1000 watts of Input power that you will get approximately 750 watts of real Output at the rear wheel.

Given the physics involved and also that fact that it's nearly impossible to limit Output directly (it's always something that is arrived at "after losses") the logical way to organize racing is around an Input side restriction.

So if we want approximately 750 watts Output, then we limit the Input to 1000 watts and we simply allow that through the process of motor losses we arrive at the desired result.

This is a critical insight, because if it's possible to electronically calibrate the precise amount of power going INTO the motor we can have a class of racing that is fair. With a simple meter on the Input it's possible to define a class of racing very tightly.

1000 watts of Input is the logical definition of EBRR.

Other Arguments

It's always important to review each and every other argument for how to organize racing classes.

Unlimited Power

The most natural urge is to want to allow Electric Bicycle Road Racing to use as much power in the motors as the designer can achieve. On the surface this even seems like a good idea until you start to anticipate where the designs will naturally progress. If you can increase motor power on an unlimited basis you will also need to increase battery capacity to feed this higher power level. More battery means more weight and that means a stronger frame and possibly suspension to make it usable. At some point the machine resembles a motorcycle only it retains "faux pedals" to satisfy the bicycle definition. An acronym PINO (Pedals In Name Only - "Pee No") describes this type of machine.

The next logical step is to limit the overall weight of such an overpowered machine so that a limited battery weight places a self induced restriction on effective power usage. Let's say the bike is limited to 100 lbs overall. You now have a situation where a 150 lb racer has a 50 lb advantage over a 200 lb racer because the bikes are limited to a fixed amount of weight.

In order to still try to salvage this approach you have to figure out some sort of indexed relationship of power, body weight, and bike weight to equalize things. It simply gets too complicated and no one will perceive it as being fair.

With a 1000 watt power restriction the rider's pedal strength will tend to match their weight (if they are athletes) so the heavier rider can compensate by being stronger. This nullifies weight differences during accelleration. (though when it comes to top speed aerodynamics the smaller rider probably glides better)

Battery Capacity Limits

Another approach to equalizing the racing is to set a limit on the battery capacity without regard to it's physical weight. This allows all the bikes an equal overall quantity of power but alters the way people will operate their machines in a race. Rather than an all out sprint where the racer applies full throttle whenever they can the Battery Capacity Limited racing will favor those with a smoother riding approach so that less energy is wasted getting around the track. While we can applaud the ideal of increased efficiency, if the effect is to take the passion from the racing experience the psychological negatives tend to make this less attractive. However, there are special cases where this could make sense. (fragile streamliner recumbents for instance)

To date these are the main alternative approaches to ebike racing.

Public Perceptions

There are several broad categories of people that have fairly clearly defined perceptions and opinions about ebikes.

The Cyclist

The pure cyclist simply will not allow a single thought towards electric bikes because it's a violation of everything that the cyclist holds dear.

The Senior Citizen

Many Senior Citizens view the electric bike as a "mobility device" for those who are by now too frail to get around under their own power. In this view the electric bike is a sort of wheelchair. This person will guard the low speed image of ebikes and oppose anything that gives a racing perception.

The Outlaw

The outlaw is someone that knows the laws on the street, but just completely disregards them in favor of whatever power they can achieve by their own bike modifications. When presented complicated issues about how high powered ebikes fit into the larger scheme of things their response is "I do whatever I can get away with." This person might race, but possibly in some other racing category. To the outlaw having a 1 hp power limit seems confining.

The Parent

If you are shopping at WalMart for childrens toys you will come to realize that within the store bicycles are classified as "toys". They sell some electric "toys" such as scooters, pocket bikes and even ebikes. The parental perspective is that ebikes are more or less silly toys that you get your child for xmas, but that they will grow out of them quickly so you shouldn't pay too much or worry too much about quality. The parent will be a little worried about something that appears too fast, so the 1 hp power limitation will provide some comfort to help them decide to purchase an EBRR bike for their child.

...the target demographic for Electric Bicycle Road Racing begins at about the age of twelve and fades out at about thirty much the same as in BMX. (this isn't to say that some older folks might not like it too)

The Passion

What will make Electric Bicycle Road Racing unique?

Cycling already provides numerous excellent racing styles that demand athletic performance of their racers. Motorcycle road racing already gives the rider skill thrills of riding at the edge of traction.

Part of the reason that newer sports like Mixed Martial Arts have taken hold is that they took the best of several other sports and blended them into something that brings out the best of all of them. That same mindset needs to be used in EBRR in that the top level racers need to have mastered all elements of the sport to succeed. There can be no room for the out of shape racer if EBRR is to be considered a real sport.

Walk Through A Race

Let's walk through a typical race...

At the start riders are lined up in rows of two (ideally) based on heat races or best lap times which were decided in advance. The faster riders are placed at the front. To get a fast start the rider needs to stand up and pedal explosively off the line because below 30 mph aerodynamic effects are small. Once the rider gets up to about 25-30 mph it makes sense to drop down onto the seat and tuck behind the fairing to increase top speed to near 40 mph. This is taking place on a Go Kart track that isn't going to allow top speeds for very long, so just as you are hitting your top speed you quickly need to brake for the upcoming corner. In the corner you ride the very edge of traction and both tires may drift a little. Depending on how much speed you lost in the corner you would either stay in the tuck and use all motor power or you might stand up again and get another burst of pedal power.

Different Go Kart tracks are going to stress different racing styles as the tighter tracks will reward more frequent bursts of acceleration coming out of the turns while other faster tracks will reward more time in a tuck for faster top end speed.

Drafting will be a big factor in this sport as it is in Cycling because at 40 mph the aerodynamic wake is much larger than at the 30 mph level that most Cyclists are used to. This means that the rider in second place on a straight away will almost always have passing power coming into the next turn. This means that the racing will be very intense with a lot of chances for passing.

At this point it's important to bring up the notion of "fair play".

You simply cannot allow dirty tactics into a sport like this because it's simply too easy to disrupt another rider and cause a crash. While in many cases the dirty rider goes down with the innocent anyway the sport suffers if there is no authority to penalize foul play. Riders should be stripped of any win if they intentionally cause another rider to crash and if they repeat that behavior that rider should be banned from the sport.

Penalties

What about doping?

I don't think that doping would be a big issue in this sport. Even if some guy is using steroids it will only benefit in the acceleration portion of the sport and that is not so dominant as to make for instant success. While there might be problems down the road with doping it doesn't seem important for now.

Electrical Cheating?

There will be an absolute need for precise power limiting circuitry to ensure that no one exceeds the 1000 watt input limit. Anyone caught tampering with the circuit (which needs to be supplied by the racing organization) would get an instant penalty of some sort. For the early days of the sport there will be the need to accept less precise limiting techniques (like just using known 1000 watt controllers) but over time that will need to be made more strict to ensure fairness.

Distance and Duration

The length of the race needs to be compatible with the amount of battery that is used. We calculate battery size:

Power input restricted to 1000 watts per second = 1000 watt / hour (Wh)

So if the race lasted a full hour at full throttle you would need a battery that was something like 48 volts and 21 Ah. In order to lower the battery requirement it would be preferred to shorten the race to about half an hour which would drop the battery required to:

1000Wh / 2 = 500Wh

...and this can be achieved with a 48 volt and 11 Ah battery.

Lead Acid (SLA) ~ 50 lbs (Peukert's Effect requires 20Ah)

NiCads ~ 30 lbs

NiMh ~ 20 lbs

LiFePO4 ~ 15 lbs

Assuming:

Rider ~ 175 lbs

Bike ~ 55 lbs

SLA = 50 / ( 55 + 175 ) = 22%

LiFePO4 = 15 / ( 55 + 175 ) = 7%

As long as the race duration is kept low the battery is reduced in it's influence on the race outcome. However, just like with being overweight the more athletic rider and the lower weight battery will have an advantage. As with Cycling the quest for lighter and lighter machines will guide technological progress in the sport, but the shorter distance will tend to place a cap on battery costs. The sport needs high technology, but should not only be about technology.

How far is half an hour?

We assume that the average speed is about 30 mph. Half of 30 miles is 15 miles so we calculate that the maximum distance should be LESS than 15 miles.

A realistic track length would be 10-15 miles.

A realistic race duration would be 20-30 minutes.

Commentary

Very often people on forums will read the title of the thread and then skip directly to the end and post whatever popped into their head. I call this the "First Thought" response.

First Thought

The problem with a "First Thought" response is that since the person isn't really responding to the issues presented there is a tendency for the discussion to wander. The "First Thought" response usually has more to do with whatever prejudices the person carries into the thread to begin with.

Deep Thought

The "Deep Thought" about a topic can take months or even years to develop and for peers to be able to communicate on the same level there needs to be some focus on getting everyone onto the same page in the discussion.

How Do I Respond?

The best way to avoid a "First Thought" and an avenue to get to the "Deep Thought" is to simply isolate a VERY SPECIFIC portion of the text and probe into that area. The first response might begin as just a question about what was meant. It's possible that you suspect an error and want to obtain some reassurance of how things were presented.

So the rule here is to identify a sentence or at most a paragraph and direct responses towards that. A "First Thought" that simply wipes the slate clean is not going to be productive.

The thread is now open for discussion...
 
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safe

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Interesting... I went to a lot of work to make individual posts so that people could quote specific sections. Oh well. Still, if people want to comment please slice out just the sentence or paragraph you are quoting.

------------------------

Discussion...

Today in the Tour De France the Time Trials leader that had been wearing the Yellow jersey had mentioned before the days ride (through a mountain stage) that because of his larger body (weight) that he didn't expect to do well... which later turned out to be true.

Seems that heavier riders have more trouble carrying their weight up the hills than the lighter ones even though they have more strength. On the downhills the heavier rider has a slight advantage, but since aerodynamics limit downhill speeds (and safety concerns) the heavier rider never gets "paid back" for his losses.

Thinking about EBRR (Electric Bicycle Road Racing) since the Go Kart tracks tend to be on fairly flat land the heavier riders should not have any significant reason to worry compared to the lighter ones. Time Trials are aften won by cyclists that cannot climb hills very well. It seems like Time Trial racers are the type of racing physique that would do well in EBRR.

So the "bottom line" is that the 1000 watt input restriction rule seems secure in the face of everything learned from the Tour De France.

Being heavy doesn't hurt much on flat land...

(it was impressive that the peloton was riding at 33 mph for stretches today)
 
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darwin

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Buy a bike and put a motor on it and then we will be brothers........no ideas shared unless your an MBer!
 

safe

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I guess I need to state my "history".

First built my original ebike in 2006.

Conceived of EBRR in about 2007.

Am just at about 8000 miles on the first bike.

Top speed was 60 mph downhill.

Top speed on the flat was (once) 50 mph with a stronger motor.

Top speed now on flat due to the 1000 watt restriction is 36 mph.

Currently working on the new bike. (pictured as my avatar)

...so I'm an "old guy" in the sport in that I've been around a long time.

I'm not an "Outlaw" character though, so rivalries and personalities don't interest me much. For me it's all about the sport, the technology and potentially a business venture down the road. I'm not looking to join a sort of MB bikers club.

My hope is to attract the "business demographic" who will be the actual people that determine the course of the sport. The individual riders are sort of a different category of people from the folks that determine what gets built. However, you can't build a product or a sport unless all things come together like rules, laws, riders and business. I'm trying to prepare arguments that might be taken to "corporate headquarters" some day to convince the CEO that an idea is worth pursuing.

So I'm not like most people that post on these types of forums... I have motivations that others don't have. (so I'm probably not a "brother" kind of guy in the sense you suggest) I'd be described as "white collar" and not "blue collar".
 
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safe

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More Observations About The Tour de France

It's an interesting race to watch that's for sure... there is a lot of long term strategic thinking that really makes the sport intriguing.

Crashing On Downhills

Frankly it's hard for me to imagine them going 50-60 mph downhill and then falling off wearing nothing without dying or at least getting more road rash than I've seen. For EBRR I had envisioned racers wearing some kind of special racing gear that was somewhere between motorcycle road racing leathers and something a cyclist would be used to. I guess the logic for Cycling is that crashing without protection of any kind is "okay" as long as the brain is protected... and that rule didn't come into being until recently.

Anyway... those racers take risks on the downhills, but I did notice when the camera's follow them downhill that their turning speeds aren't that great. Skinny little tires don't give all that much traction, though what they do is still impressive.

I wonder what would happen if EBRR became a sport and people had their road racing fairings and all and then a regular bicycle showed up and was able to do well. In some ways the real people that EBRR needs to compete against is the Cyclist, not the motorcycle or the moped.

Within "Outlaw" MB culture there is not supposed to be respect for Cyclists (everyone has their cliques) but I see Cycling as being very impressive. They go really fast considering they are not powered by anything but pedals.

Any type of electric racing needs to reflect on how it relates to other sports. With EBRR there has to be a legitimate advantage over the Cyclist without going so far as to make it purely motorcycling. It's a very delicate balance.
 
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safe

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Elbows To The Head?

"This is a bike race, not a gladiator's arena. Everybody could have ended up on their backs."

http://www.espnstar.com/other-sports/news/detail/item467255/Renshaw-headbutt-mars-Cavendish-win/

In the Tour De France today Mark Renshaw literally "headbutted" another rider and then swerved back and forth in the front of the peloton when it was racing to the finish at above 40 mph.

He got disqualified and sent home.

---------------------------

Electric Bicycle Road Racing (EBRR) has the potential to degenerate into this type of riding very easily because the Go Kart tracks have tight corners that will tend to bunch up the riders. If this type of riding behavior is tolerated it will make the sport more about survival than about speed.

I support the decision to disqualify the guy.

----------------------------

Since this stage had a long gentle downhill and a favorable wind at it's back the peloton was carrying 35 mph to 40 mph for a long time. That's some impressive speed for just bicycles.

Also, they said that Mark Cavendish is capable of 1500 watts (2 hp) on those sprints at the end, so if you coupled a Mark Cavendish level sprinter with the EBRR limit of 750 watts you would have a total of 2250 watts which is 3 hp. That's enough power for people to get some decent speed going on a Go Kart track.
 
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safe

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Long Distance Electric Racing

In a typical stage of the Tour de France the riders are producing roughly 400 watts for five hours.

So if you assume that it took 500 watts of electrical input power into a motor to get 400 watts out and you needed to know how big of a battery would be required then:

500 watts * 1 hour = 500 Wh

500 watts * 5 hour = 2500 Wh

...so you would need:

2500 Wh / 48 volts = 52 Ah

A Thundersky LiFePO4 cell weighs 6.6 lbs and is 12 volts and 20 Ah or a total of 12 * 20 = 240 Wh. Since you would need 2500 Wh worth of battery it would take:

2500 Wh / 240 Wh = 10.4 Thundersky cells

10.4 Thundersky cells * 6.6 = ~70 lbs

Maybe Lipo might be a little better, but the cyclist carries a powerful battery just because he has legs. (the longer a bike race goes the harder it is to beat it with electric power unless you allow for a very heavy battery and then you are essentially riding a motorcycle)
 
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safe

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P.I.N.O. ?

"Pee No" - "Pedals In Name Only"

sbmotoped2.jpg


http://www.motopeds.com

An interesting product and something that might do very well in the Open Class of gas powered motorized bike racing on Go Kart tracks. (if you made a bunch of modifications to it) Weight is about 110 lbs and you can mount larger displacement motors onto it if you want more power. Given the fact that the suspension is built to withstand heavy loads this bike would probably do well. Wheelbase is 54" which is about right for a road racer bike. The suspension might need to be lowered for street racing and the spring rates changed and obviously the seat, handlebars and most everything else needs to be changed too. The frame / motor / pedals would provide a good base though. Probably a good idea to switch the front wheel from 26" down to 24" to match the rear and this would also steepen the steering geometry.

It does stretch the limit of what a "bicycle" is supposed to represent.

But it does have pedals... in name only...
 
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pedalless

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I see you haven't looked far into the seller of this bicycle setup safe
first half of the video is of downhill riding without the motor turned on
rode downhill on pedal power back up with motor. Watch video.

http://www.motopeds.com/video/
 

safe

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True, I did not delve into all their advertising material.

It does seem a great example of a PINO bike.

-------------------------

As far as EBRR it does show the path of "Unlimited Power" and how it could go. They sell 110cc motors that can be installed on that frame and at that point the pedals are really unnecessary. The same kind of mindset applied to electric bicycle road racing will produce similiar results.

I see this as a "shot across the bow" for all those still clinging to the idea that "Unlimited Power" in ebike racing is a good idea. Over time the machines would look more and more like motorcycles.

In a sense this product proves my point.

(even though it's technically not in the electric category, the idea is the same because the pedals become "in name only" at the higher power levels)
 
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