Why do ebikes need gears?

[tomjasz]

My last and final build was a single speed. It will be ridden in a city with no hills or slopes to navigate. 42T x 22T. MAC 10T 36V

 

[K PierreR]

I think it's certainly going to be an interesting evolution through the middle ground. We are definitely reaching the limit of the current technology for conventional/traditional bicycle components, and you're right the tolerance for true monsters on the city trails and sidewalks isn't/won't be there, which suggests a couple of routes we can go. One of them involves simplifying the current drivetrain, so we can improve chain lines/beef up remaining components, maybe reduce overall weight, etc. I think the idea of doing this on cargo bikes and certain ebike models makes sense, and would better address the interim needs of the 'heavy-bicycle' community. It does also suggest migrating outside of the current conventional bicycle definition, so there is obviously going to be room for interpretation and redefinition. I could actually see using my mid drive with only 6 wider-range gears instead of the current 9, as I'm really only using the extra gears to reduce cassette wear right now and have my 5 favorites for 99% of my riding. There is also a potential ease of use benefit to fewer gears and simpler systems, especially with the older riding demographic, so I could see that being in our future. Time will tell, but I'm not a gambling man...

There is really no grey areas in the e bike definitions. The ultimate restraint is power, not speed. There is legal and illegal.

I NEED all 11 gears on my e bike from my 11X46 tooth cassette. Cuz it's a bicycle, not a motorcycle. Need of course, is subjective.

 

[theemartymac]

There is really no grey areas in the e bike definitions. The ultimate restraint is power, not speed. There is legal and illegal.

I NEED all 11 gears on my e bike from my 11X46 tooth cassette. Cuz it's a bicycle, not a motorcycle. Need of course, is subjective.

But ask 6 manufacturers how they define their power ratings, and you'll get 16 answers... ;-)

 

[K PierreR]

But ask 6 manufacturers how they define their power ratings, and you'll get 16 answers... ;-)

That is marketing, not definition.

 

[m@Robertson]

I don't understand the need for speed on a bicycle though. For me, once you move into the 30-50MPH range on flats and uphill you are looking for a motorcycle or scooter. Either allow enough time for your commute, use multi-modal transportation, or buy, register, and insure a motorcycle.

Well, speed is a factor of convenience just like it is for any mode of transportation. "allow enough time for your commute" by going slow? How would that be accepted if you applied it to automobiles and limited them to 30 mph? The reality is that convenience transcends the mode at which you travel from place to place.

If you hold to the goal of having ebikes be a viable replacement for automobiles and their congestion (regardless of ICE or BEV), I think you have to accept speed as part of their utility.

 

[RunForTheHills]

Well, speed is a factor of convenience just like it is for any mode of transportation. "allow enough time for your commute" by going slow? How would that be accepted if you applied it to automobiles and limited them to 30 mph? The reality is that convenience transcends the mode at which you travel from place to place.

If you hold to the goal of having ebikes be a viable replacement for automobiles and their congestion (regardless of ICE or BEV), I think you have to accept speed as part of their utility.

I would argue that if you need to go faster than 30MPH on your commute (average, not downhill bursts), you need to accept the trade off of complying with vehicle safety codes, registering your vehicle as a motorcycle, and paying for insurance. You can still buy an eMotorcycle, but wouldn't be able to use the MUPs and bike lanes with it. There are many places that automobiles are limited to 30MPH, but that wasn't my point. In most places, automobiles and motorcycles have to comply with vehicle safety codes and be registered and insured. A bicycle doesn't, but it is still relatively safe due to the low speed of travel.

 

[Gionnirocket]

I think ya'all be complicating a simple answer.
An eBike still needs to be a Bike
Powered by a human.
The gears make that easier.

And that's all I have to say about that.

 

[m@Robertson]

I would argue that if you need to go faster than 30MPH on your commute (average, not downhill bursts), you need to accept the trade off of complying with vehicle safety codes, registering your vehicle as a motorcycle, and paying for insurance. You can still buy an eMotorcycle, but wouldn't be able to use the MUPs and bike lanes with it. There are many places that automobiles are limited to 30MPH, but that wasn't my point. In most places, automobiles and motorcycles have to comply with vehicle safety codes and be registered and insured. A bicycle doesn't, but it is still relatively safe due to the low speed of travel.

Well, your position presupposes I am doing something illegal. In California where I live, there is a 28 mph assist limit. Its commonly misunderstood as a speed limit but its not. I gear the bike higher so I can push it beyond its electrical limits, which I do for a workout. 100% legal use of the bike as a bike on public roads.

 

[RunForTheHills]

Well, your position presupposes I am doing something illegal. In California where I live, there is a 28 mph assist limit. Its commonly misunderstood as a speed limit but its not. I gear the bike higher so I can push it beyond its electrical limits, which I do for a workout. 100% legal use of the bike as a bike on public roads.

No, I wasn't assuming you are doing something illegal. I was using "you" in a generic sense, not you in particular. I was just defending my position on why I don't think an ebike needs to be able to go faster than 30MPH (okay, under motor power). 30 was a round number and I am also good with 28MPH. I live in California and I am familiar with the current ebike laws here. At some point you have to draw the line between an electric bicycle and a motorcycle.

 

[Mr. Coffee]

If you hold to the goal of having ebikes be a viable replacement for automobiles and their congestion (regardless of ICE or BEV), I think you have to accept speed as part of their utility.

I'd argue that things like safe infrastructure for bicycles and weather are larger barriers to bicycles as car replacements than speed. Nearly 60% of vehicle trips in the USA are less than six miles. At those distances the difference between 20mph and 30mph are pretty trivial.

 

[m@Robertson]

No, I wasn't assuming you are doing something illegal. I was using "you" in a generic sense, not you in particular. I was just defending my position on why I don't think an ebike needs to be able to go faster than 30MPH (okay, under motor power). 30 was a round number and I am also good with 28MPH. I live in California and I am familiar with the current ebike laws here. At some point you have to draw the line between an electric bicycle and a motorcycle.

I certainly don't disagree with that. I think from a safety perspective, a 28 mph assist limit is fine. Up past 35 you quickly reach a point where even top drawer components are no longer up to snuff vs. say a pothole (for example, analog downhill bikes have wheels made to be smashed on repeatedly at higher speeds than I can achieve, along with suspension to help do the job). So there's not much upward room past the limits already in place. I'm not a fan of the Stealth Bomber style of bikes with vestigial pedals.

I'd argue that things like safe infrastructure for bicycles and weather are larger barriers to bicycles as car replacements than speed. Nearly 60% of vehicle trips in the USA are less than six miles. At those distances the difference between 20mph and 30mph are pretty trivial.

There may be larger barriers, sure. But they are all barriers and its still a benefit to get a little headroom on any of them.

But you can't design a piece of transportation you rely on 100% of the time for only 60% of your use. Bicycles taking over from cars... how' that gone so far in society? Poorly. To do better, we have to broaden our definitions and do more to satisfy people's needs. The 'e' in ebike is the first thing that has made a meaningful dent in that fight, and it has done so for a lot more reasons than sweat reduction.

With that said, Living in some places, even a 15 mph speed is too much. But that just points to the fact there cannot be a single yardstick in use.

 

[AHicks]

That again depends on where and how far you intend to ride.

If you have a more powerful bike, obviously for a given battery size you will have less range. So if you are on a super long climb (or even poor road conditions) you are probably forced to run at a lower assist level just to make the trip at all, which brings you back to having lower gears. So unless you pack around a ridiculously large battery that bigger motor does you less good than you'd otherwise think.

Also there are pretty brutal practical limits on how big a battery you can put on a bicycle.

Terrain makes an enormous difference. I can easily run at 10wh/mi (or even less) in gentle terrain and good road surfaces. Change that to steep, rough roads and it is more like 100wh/mi.

Not so obvious from where I'm sitting. Something you would see easily when you've ridden the bigger ones. The big motor has more power available, no doubt. And granted, if I turn the wick up high enough to go blowing by somebody, the big motor is using more power. If we were riding side by side though, on similar bikes, that wouldn't be the case at all. We would be using pretty much the same amount of power.

Further comparison is going to need to focus on the potential for a big mid drive, or big gear drive. WAY different bikes, though available power not that different.

And getting back to gears, neither are very fussy (mid or geared hub). It's more about the cruise speed than anything else, until you get to a big hill. Then you can drop a gear or 2, or increase your PAS level if necessary.

As far as distance riding, my butt is only good for 20 miles, so I'm not able to speak with any experience there at all, other than to share that the batteries on both bikes will go twice as far as my butt between charges...

 

[K PierreR]

That again depends on where and how far you intend to ride.

If you have a more powerful bike, obviously for a given battery size you will have less range. So if you are on a super long climb (or even poor road conditions) you are probably forced to run at a lower assist level just to make the trip at all, which brings you back to having lower gears. So unless you pack around a ridiculously large battery that bigger motor does you less good than you'd otherwise think.

Also there are pretty brutal practical limits on how big a battery you can put on a bicycle.

Terrain makes an enormous difference. I can easily run at 10wh/mi (or even less) in gentle terrain and good road surfaces. Change that to steep, rough roads and it is more like 100wh/mi.

Like me, you have obviously tried and found out that the problem with an e bike is that it's a gd bicycle. Not a motorcycle and the regs are written near the max already. These guys who think they are going to convert a threaded headset comfort bike with a big motor and cruise at 25-28 mph for a long commute are in for a rude awakening.

I sure found out when I tried to beat the low speeds and short ranges for something more capable. During my trials, I wanted to throw every one of those SOB's that call an e bike a motorcycle out in traffic on a powerful e bike at rush hour and tell them they cannot use the bike paths. Let them find out an e bike is a bicycle with some assist.

It was a struggle to hang 2,540 watt hours worth of batteries on my bike and have something that was quite stable, handled like a good bike and retained some ability to carry a load. If I want to carry much, I need to pull a trailer The result is sure as hell not sheath, light or small. No one mistakes my bike for being a normal bike. Most people ask me how far I am going. Everyone seems to sense its purpose.

I have not had issues with the authorities at all. It looks off road heavy duty slow. Range is all over the place from 60-300 miles. I don't see under 10 Watt hours per mile any more. I have learned a whole lot about the e bike category and have some ideas for my next build. I have to think out of the box because there really isn't much out there to pattern after.
.

 

[AHicks]

What I'd like to know is why everyone assumes anyone riding with a big motor is going to be interested in speed? NOT SO!
Speaking for myself, I stop pedaling at 14 or 15mph tops. If the bike goes any faster it's because it's rolling down a big hill. The reason I like big power becomes clear when we get to the next hill - which is going UP!

 

[Mr. Coffee]

If we were riding side by side though, on similar bikes, that wouldn't be the case at all. We would be using pretty much the same amount of power.

No.

First off, a bigger motor is going to be heavier. So all other things being equal you'll need to use more power just to have the poor bike get out of its own way. That is a small factor but many small factors add up.

Second, a bigger motor implies a beefier bike all around, and because the bike is heavier it needs bigger brakes too. These things tend to snowball. With a skinny 250w motor you can get away with an e-bike around 40lbs. With a much bigger motor you'll easily double that.

Finally, for small motors generally the peak efficiency of the motor is around 75% of rated power. So a 1000w motor running at 20% of its rated power is likely to be a hell of a lot less efficient than a 250w motor running at 80%, even though both are theoretically running at 200w.

 

[Art Deco]

Yes the speed problem with ebikes is up hills, heavy loads, and into headwinds, not the flats and downhills. Even the worst car can climb a hill at the same speed it decends one. I don't care about 20mph, 25mph, or 30mph top speed, but climbing at a quarter (or less) of that speed with traffic piled up behind me is not going to work for replacing a car.

 

[indianajo]

First off, a bigger motor is going to be heavier. So all other things being equal you'll need to use more power just to have the poor bike get out of its own way. That is a small factor but many small factors add up.
Second, a bigger motor implies a beefier bike all around, and because the bike is heavier it needs bigger brakes too. These things tend to snowball. With a skinny 250w motor you can get away with an e-bike around 40lbs. With a much bigger motor you'll easily double that.
Finally, for small motors generally the peak efficiency of the motor is around 75% of rated power. So a 1000w motor running at 20% of its rated power is likely to be a hell of a lot less efficient than a 250w motor running at 80%, even though both are theoretically running at 200w.

My bike as loaded for most required repairs + load carrying gear + 40 oz water weight 94 lb. The motor + battery weighs 10. I have no trouble pedaling it unpowered up 15% grades, and pant a bit with 80 lb cargo. The 160 mm cable pull disks have no trouble stopping it from 35 mph downhill, either.
What really slows me down is the wind!. > 12 mph all week. Usually changes at 2 pm to be against me both ways when I go shopping. There were gusts to 38 mph Derby day. ********* global warming. Didn't used to be this way. I pedaled unpowered to from my summer camp 10 years without electricity. Not any more. I can when the wind is <10 mph. Or behind me. Not too often anymore.
Americans that spend $$$$ to shave pounds off their bike strike me as weird. The lycra crowd that pass me are not exactly svelt. It is a lot cheaper to shave pounds off the body. I dropped 55 lb pedaling, mostly a steel frame MTB weighing 80 lb with steel baskets. This aluminum stretch cargo bike with more cargo space would weigh the same without the motor battery water or tools.

 

[Cyklefanatic]

Well this post got way off topic pretty fast. But from some of the on topic posts I have learned that if a bike has a transmission because the rider needs it then you might as well have it do double duty and connect the motor through it too. But I am thinking that as electric cars mature we might see some two and three speed electric cars for the weight savings, better performance over a greater speed range and reduction in battery power per kilometre. Maybe the ebike formula is the future for cars!

 

[Gionnirocket]

Well this post got way off topic pretty fast. But from some of the on topic posts I have learned that if a bike has a transmission because the rider needs it then you might as well have it do double duty and connect the motor through it too. But I am thinking that as electric cars mature we might see some two and three speed electric cars for the weight savings, better performance over a greater speed range and reduction in battery power per kilometre. Maybe the ebike formula is the future for cars!

Your first reply, and the simplest was the best answer
Ouch!
Just twisted my arm

 

[AHicks]

No.

First off, a bigger motor is going to be heavier. So all other things being equal you'll need to use more power just to have the poor bike get out of its own way. That is a small factor but many small factors add up.

Second, a bigger motor implies a beefier bike all around, and because the bike is heavier it needs bigger brakes too. These things tend to snowball. With a skinny 250w motor you can get away with an e-bike around 40lbs. With a much bigger motor you'll easily double that.

Finally, for small motors generally the peak efficiency of the motor is around 75% of rated power. So a 1000w motor running at 20% of its rated power is likely to be a hell of a lot less efficient than a 250w motor running at 80%, even though both are theoretically running at 200w.

You're splitting hairs and guessing/assuming, and we're way off topic. I'm done.