Pop N Wood

Shoot just noticed the half dozen other posts following the one I quoted. Great minds I guess.

The gearing issues are interesting.

Funny you mention headwinds. Came across an article once titled "Riding the Mountains of Nebraska". Being from Nebraska originally I was confused, don't remember mountains. Turns out the writer was comparing the incessant winds to riding a sustained mountain grade.

They got that right. Rode the Cowboy trail a month later and experienced biblical level winds. There weren't many trees to hide behind either.

KPREN

What you are showing with your graph is not sustainable. 108 rpm is not sustainable by most people, maybe you but not me. I can sustain 90rpm for a while. Your battery has already sag down to 47.2 volts and will likely cut out by 3-5 miles of use then power must be reduced considerably because the battery cannot keep up. What I was showing is what is reasonably sustainable but not even really practically sustainable. Remember what the goal of the original poster is to go 25-28 mph on a commute at low cost. Go out and actually try to match your graph with your bike. See if you can reach this. I doubt it. I doubt you can reach 32 mph. You are likely to be putting in less than 100 watts from yourself if you can reach this rpm.
You will notice that my graphs are not at 100% power because I cannot sustain the needed rpm to reach that output. The throttle setting I am using reflects what I can put in through the PAS. I only sag 1 volt because my battery bank is large.

The point I am really trying to make is that you might momentarily or even for short periods of time peak above 750 watts motor output but for all practical purposes, you are really legal the way things are written in the regulations for Class 3 e bikes as long as you use PAS and not actual throttle. As you can see, in the USA, the regulations were written to exclude throttle above 20 mph for a reason. As per your graph, actual throttle might get you to the 32 mph mark for a few miles. PAS limits real motor output even on the most powerful Bafang mid drive through rpm. I can make a damned good case in court for being within the regulations with a BBSHD at 52 volts and under. The regulations are written intentionally vague. Why write them that way? For bike manufactures to avoid liability and as a bonus, every Bafang owner thinks they are busting the regulations so they will keep their nose clean to avoid getting busted.
You want to bust the regulations, you better think about a big direct drive rear hub motor and 72+ volts from a big battery. You will also find out that gasoline will match your supped up rig with lower overall operational costs, up front costs and trash your e bike in range and recharge time.
The way I have my bike set up now, it will operate comfortably in the 17-20 mph range for a long distance days ride. This is not easily attainable.

Pop N Wood

I hadn't noticed the 108 RPM cadence. I've never measured cadence so have no idea what I can sustain.

I do know for a fact I've ridden the bike at 38 mph. Not sure how long, usually several blocks on the home stretch, with me pedaling for all I'm worth. Battery had zero issues, cut out is 43 V. Luna makes big claims on their wolf batteries

A sustainable speed with this bike is well under 30 mph. Like most people I generally don't ride that fast. But from what you and this tool are saying is that puts this bike under 750 watts motor output

So all of this beg the question what "power" does one talk about? You talk motor output, which almost certainly leads to a lot of miscommunication with other. Max battery volts time controller current limit seems to be the norm.

"Legal" is a great big don't care. All of these systems can be neutered via software. Almost no way to verify one way or the other and in the end, who is even cares enough to bother checking?

gsa103

Cadence is irrelevant on the BBS motors. The motor will continue to put out power at 120rpm and higher. The PAS will continue to supply power even if you're only pedalling at 60 rpm and the motor is spinning at 120rpm. You are contributing 0W to the drivetrain since the crank is just free spinning, but you can keep it active. I've definitely had my BBS02 up to 35mph (using throttle), it was pulling about 1000W from the battery, and would've let me do it for awhile.

In general, I also agree with the other posters. Above 25mph is just sketchy on a rigid bicycle, roads & trails are perfect. If I regularly wanted to ride at 30mph, that's definitely quality full suspension, big brakes and good tires.
Also, drivers definitely mis-judge your speed once you get up above 20mph, so you need to be extra vigilant and it puts more strain on the brakes.
I've downgraded my BBS02 to where I'm normally using ~250W for commuting at about 23mph.

KPREN

I highlighted your last sentence because this is pretty much what it all means with a Bafang mid drive 52 volts and under.

None of the bikes that I have built have ever attained more than 33 mph. I have built 10 bikes, none of these bikes was a full on road bike but some were very efficient. Mine is the only bike I have built with a BBSHD. The rest were all BBSO2's. 8 were 48 volt and two are 52 volt. Age of the riders might have something to do with that. The youngest is 55 years old but north of 300 lb. The oldest is 92. I am near the bottom at 65.. My bike is a tank with me and the bike normally just over 300lb riding weight. I don't get much more than 30 tops out of it on the level and I don't stay there long because of the possibility of motor overheat.
My normal riding speed on a bike path is around 15-16 and 17-21 on the road.
The regulations are written as maximum motor output power in watts. That is measuring the work the motor is doing at any point in time. That means that controllers and software are pretty open at the lower speeds to push a lot of torque and high battery draw because the motors do not reach near maximum until they are at higher rpms. This is why most commercial bikes have temperature sensors and hall sensors.

KPREN

most of you guys think maximum or near maximum when discussing e bikes I am sometimes misunderstood because I think more practical and sustained within a range of acceptable maintenance and range. Just looking at manufacturers numbers and specs on kits and e bikes can lead a person to buying something that will not do what they bought it to do.
The last thing I want to do is use throttle or trace through turns with the pedals producing zero input from me at high speed.

250 battery watts at 23 mph means you have more of a road bike and put a fair amount of power in from yourself. With me pedaling, my battery draw at that speed is around 600 watts on the road. My design criterion were far different from yours.
My criterion were for an all weather, all terrain rugged electric touring e bike with a range in excess of 100 mile off road without charging and the ability to charge it up from dead in under 4 hours. I have that bike but the mileage is far less than yours. I have used as many as 60 watt hours per mile in loose sand, mud and deep snow. At that mileage, range is only around 40 miles with a 52 volt 49 amp hour battery bank. I still have to be cautious on some rides to prevent range anxiety.
My bike is very stable. It was still not to scary at 48mph down a mountain road.

Pop N Wood

When I go 38 mph I'm definitely putting power to the cranks and not ghost pedaling.

interesting, KREN is seemingly the only one on the internet talking output power instead of battery power. When I think about it every motor, gas or otherwise, is rated in output power. Only makes sense. Who knows what they were thinking when the laws were made. BUT since displays all show battery watts that is probably a difficult distinction to make with most people.

Range anxiety, Guess that applies to a fat bike in the snow. Can't say it enters my mind on my street machine. I do think twice about battery level if I want to run someone.

One thing about that simulator, it shows the max torque of the BBSHD as something like 50 n-m, yet the units are rated at 165 n-m. Wonder what gives?

KPREN

I am a very rare bird. I did not know how rare my way of thinking was until recently. Justin at Grin Technologies is another one of those rare thinkers. I found big money in repurposing old machinery to do much more than the original design plus the installation of that machine. Most machine designers ask "What do you want the machine to do?" and then design a machine to do it. I ask, "Who is going to operate this machine, in what environment will the machine operate in, what is the expected up time and who will need to fix it ?" I will also ask "what does the machine need to do and how does this machine integrate with previous and future manufacturing steps".
The design formula is then simple CFM + machine + operational environment + logistics = Q Or Complete F-ing Moron + my machine + how bad is your space and maintenance + how do you get stuff to the machine or away from it = Quality of the output.

Keep in mind , Justin's formulas he has put into the simulator are not what the motor drive manufacturer puts out in a brochure. He is calculating motor torque output from the motor design, the controller type and input parameters. Actual expected torque, not theoretical maximum.

I am currently looking at producing a line of e bikes to fill a niche at the extreme end of touring. Bikes that will operate in extreme environments without regular resupply services. Areas such as the arctic, Patagonia, The deserts and Siberia. Prices would range from $8kUS to well over $20k US. Owners manuals would be written for field maintenance, repair and clearly lay out the design limitations. Theoretical does not cut it. Theoretical designs kill people in harsh environments.
My current bike is more limited than I want. I currently have about $6k in it. I have a bike on the drawing board at about $12k. I need to probe some of the nasty stuff with the current bike to feel safe in the design of the next bike. In the bike world, it is very difficult to get good information on the design limitations and actual usage life cycle of bicycle components. I am still learning fast.

gsa103

[QUOTE=KPREN;21940374
250 battery watts at 23 mph means you have more of a road bike and put a fair amount of power in from yourself. With me pedaling, my battery draw at that speed is around 600 watts on the road. My design criterion were far different from yours.
My criterion were for an all weather, all terrain rugged electric touring e bike with a range in excess of 100 mile off road without charging and the ability to charge it up from dead in under 4 hours. I have that bike but the mileage is far less than yours. I have used as many as 60 watt hours per mile in loose sand, mud and deep snow. At that mileage, range is only around 40 miles with a 52 volt 49 amp hour battery bank. I still have to be cautious on some rides to prevent range anxiety.
My bike is very stable. It was still not to scary at 48mph down a mountain road.[/QUOTE]

My bike is a Giant Toughroad (rigid 29er touring), so probably lighter, but not all that different. My battery draw is based on perfectly flat, no wind, good pavement, and I'm probably adding ~150W. Compared to my road bike the Giant has about 100W more drag at 18mph. Off-road or poor conditions, I'd be going much slower. My statement about speed was largely based road conditions, not necessarily inherent. Typical suburban roads and bike paths have lots of undulations, cracks and potholes that aren't suitable for high speed on a rigid bike. Especially one that I'm riding with only one pannier, so asymmetric loading. Mountain roads are frequently smoother and better suited to high-speed, and would be fine, especially once you shift weight for descending.

As for your bike, that operating environment is much more demanding. Charging from dead in 4 hours isn't a big deal for any healthy Li pack. That's a nominal 0.25C charge rate, which is considered "normal" for most cells. The trick for you is that's about a 700W charger, which is expensive, heavy, and a little scary from a damaged cell perspective.

2old

I tested a Pedego bike on a long off road ride with a group once. It had five levels of PAS (AIR, maybe six). At the highest PAS level the bike put out maximum power as long as you pedaled at any speed. So sure I was contributing to its power output; how much = diddly squat.