Is 250w enough power for modest speed up steep hills

Electrically assisted bikes, trikes, etc. that are legal in the UK
Nearholmer
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Re: Is 250w enough power for modest speed up steep hills

Post by Nearholmer »

There is definitely a limit under any given set of conditions, because when the combined losses resulting from the various resistances at play equal the input power that the rider can supply, you will go no faster.

I can’t be bothered to work it all out, but I should imagine that irrespective of the power of the rider, the very fastest speed a bike will reach without motor assistance will be in infinite free fall, but that may not be quite what was meant.
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CJ
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Re: Is 250w enough power for modest speed up steep hills

Post by CJ »

tenbikes wrote: 22 Sep 2022, 8:21pm ^^^ I have no idea of the weight but it is much more than I can lift......logs and wood chippings, loaded in small units to two massive panniers and a trailer.

Off road. Very steep. Distances up to 2km.

Mid drive. 34 front, 46 rear.

Personally I have no issue with power, it is speed that seems to be the issue for people.

It is clear from this thread that policing power output is next to impossible: you need an electronics lab to measure the motor.
Police cannot do this on the beat.
They can check maximum assist speed though, and put a speed gun on bikes which appear to be going excessive speeds.
Sure, we know that that is unlikely too but it is more attainable as a control measure that wattage.

If a bike at 250w passes you at 30mph and one passes you at 15mph but with a wattage of 500w, what will you notice? Speed or power? Which of the two would you prefer to experience?

Cargo bikes like mine should have a generous power allowance but still be speed restricted in the same way as a fast/light road ebike.
I disagree. Once you have more electrical power than typical human power, the machine ceases to be an electrically assisted pedal cycle, and becomes a pedal assisted motor cycle. We already have a word for that: moped.

There is a good argument for a new light touch regulation of speed-limited lightweight electric mopeds, such as the speed pedelecs that are popular in continental Europe, but not here because UK regulates mopeds so strictly that one might as well get a full-blown motorbike. But that is not an argument for this forum. That is for the motorcycling lobby.

I think that cargo e-bikes - including tenbikes' log hauler - should come under the same regulatory regime as this new category of vehicle. They are a significantly heavier vehicle than even a loaded touring bike. Normal bicycle tyres and brakes are not really up to the job and someone in control of that much mass on any kind of downslope has a literally much heavier responsibility for the safety of others - regardless of what motor-assist speed they may be permitted. With greater power comes greater responsibitity, so licensing and resistration seems entirely appropriate: for any heavier and/or more powerful vehicle even if the motor is limited to 25kmph. However I think that it would be sensible to let 25kmph-limited cargo cycles into pedestrianised shopping streets 24/7, along with bicycles, and not just during specified delivery hours. So I think there's some merit in maintaining a distinction between speed-pedelecs and those that are also more powerful but not also faster.
Chris Juden
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Cugel
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Re: Is 250w enough power for modest speed up steep hills

Post by Cugel »

Jdsk wrote: 24 Sep 2022, 4:17pm
Cugel wrote: 24 Sep 2022, 4:07pmI find it hard to understand why you feel limiting the speed at which assistance is given is less dangerous than limiting the total power instead.
In shared use spaces it's the actual speed that affects other people, not the total power.

Jonathan
Well then you must propose laws limiting non e-bikes to 25kph on shared use paths. How will you arrange that without limiting non-e-bikes to that speed when they're not on shared use paths? Or are you, in effect, saying that bicycle speeds above 25kph are dangerous in all circumstances?

Your position on this matter seems to lack both coherence and the effects of the commonly-found experience that bicycle speeds above 25kph are not very dangerous at all.

Cugel
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Cugel
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Re: Is 250w enough power for modest speed up steep hills

Post by Cugel »

Jdsk wrote: 24 Sep 2022, 4:24pm
Cugel wrote: 24 Sep 2022, 4:07pmWhat is the metric-informed logic around this 25kph limit that results in the opinion, "That sound (sic) right to me"?
My comment was as much about a single limit covering all devices as about 25 kph.

Unfortunately the answer is only personal experience and observation of what happens in shared use spaces. And it being the current (!) limit.

As above, if better data become available than I'd happily change my mind. Are there any reports or studies that I've missed?

Jonathan
Jonathan - you don't need "a study" to make decisions on every matter under the sun. Try experience (I'm sure you do in reality) which will tell you lots of things allowing quite sensible, useful, accurate and generally "correct" decisions to be made about, oh, all sorts. :-)

I feel there is a danger, in taking the academic approach, of ending up like those Schoolmen of yesteryear, debating how many angels can dance on the head of a pin.

Cugel
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Cugel
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Re: Is 250w enough power for modest speed up steep hills

Post by Cugel »

peterb wrote: 24 Sep 2022, 6:33pm
jois wrote: 24 Sep 2022, 4:12pm [

To be fair ebike speed isn't limited to 25 kph by the law of the land. Just generally by the laws of physics for which you can't really hold the government responsible
I assume you mean assisted speed? Limited by the laws of physics? How is it my Orbea Gain has an assisted limit in the UK of 15.5mph, yet exactly the same model of bike in the US has an assisted speed limit of 20mph?
And you can pedal both to even higher speeds if your legs feel up to it, eh? "Laws of physics". He he.

Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
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Jdsk
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Re: Is 250w enough power for modest speed up steep hills

Post by Jdsk »

Cugel wrote: 25 Sep 2022, 2:16pm
Jdsk wrote: 24 Sep 2022, 4:24pm
Cugel wrote: 24 Sep 2022, 4:07pmWhat is the metric-informed logic around this 25kph limit that results in the opinion, "That sound (sic) right to me"?
My comment was as much about a single limit covering all devices as about 25 kph.

Unfortunately the answer is only personal experience and observation of what happens in shared use spaces. And it being the current (!) limit.

As above, if better data become available than I'd happily change my mind. Are there any reports or studies that I've missed?
Jonathan - you don't need "a study" to make decisions on every matter under the sun. Try experience (I'm sure you do in reality) which will tell you lots of things allowing quite sensible, useful, accurate and generally "correct" decisions to be made about, oh, all sorts.
...
I've just said that my current view is based on experience. I've emboldened that to make it easier to find.

Jonathan
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Cugel
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Re: Is 250w enough power for modest speed up steep hills

Post by Cugel »

jois wrote: 24 Sep 2022, 7:25pm
peterb wrote: 24 Sep 2022, 6:33pm
jois wrote: 24 Sep 2022, 4:12pm [

To be fair ebike speed isn't limited to 25 kph by the law of the land. Just generally by the laws of physics for which you can't really hold the government responsible
I assume you mean assisted speed? Limited by the laws of physics? How is it my Orbea Gain has an assisted limit in the UK of 15.5mph, yet exactly the same model of bike in the US has an assisted speed limit of 20mph?
I mean there is no prescribed limit of 25kph on ebikes. If you can't go faster that the laws of physics preventing you.

The USA has lots of different laws and legal limits to the UK . Some of them for the better some for the worse in my opinion.

As I understand the issue. The dispensation for ebikes was aimed at allowing the less able to enjoy cycling. Since then it's changed somewhat with most of the people I see on them being in the prime of life. Rather than being a two wheeled version of a mobility scooter.

Where should the limit be? If anyone asked me, which they didn't I would have set it at 12mph same as mobility scooters. But it clearly has to be somewhere and where ever it is someone will think it should be higher or lower.

Having got a dispensation from the tiresome matter of insurance etal. I don't think it's reasonable to campaign for a higher limit when you could just as easily get a faster bike and pay the insurance if going faster is that important to you. They go faster than I can manage for more than a few hundred yards , I honestly can't see why that isn't fast enough
E-bikes were never intended as another form of mobility scooter but rather, as you mentioned, "...aimed at allowing the less able to enjoy cycling."

What does that mean, in essence? Personally I can find no better definition than, "...able to keep up with the normally-able cyclists in all normal cycling circumstances". That would mean an ability to keep being assisted up to any normal cycling speed. It might also mean, preventing the assisted bicycle and its rider from being able to exceed the normal power range of normal-ability cyclists.

So, that begs the question: what is the normal ability range of normal ability cyclists? I would suggest that such a range should be something like 75 - 250 watts of leg power sustainable over one hour (i.e. an FTP range of 75 - 250 watts). I know plenty of cyclists who populate that range - and some who can actually go significantly higher than 250 watts for an hour but let's admit that they are a very small minority of cyclists so should be excluded from the "normal ability" category.

You would fall in that power range, eh? But, should your particular power-generating ability be the singular benchmark for limiting e-bike power for all cyclists? You may not feel the need to have more power and to therefore be able to go faster than a mobility scooter but plenty of other cyclists do, quite legitimately. It's why they practice, train and otherwise get better at it. And they do so not just to be able to race or go on club runs with other fit fellows but to be able to go to the shops faster, get up the hills and otherwise find that happy compromise of time, effort, fitness and several other factors that all sorts of cyclists seek for themselves.

Why would anyone want to stop e-bike riders from finding that compromise with the help of their motor, as long as they don't cease to be cyclists going at typical cyclist speeds but motorcyclists going at typical motorbike speeds.

Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
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Jdsk
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Re: Is 250w enough power for modest speed up steep hills

Post by Jdsk »

Cugel wrote: 25 Sep 2022, 2:12pm
Jdsk wrote: 24 Sep 2022, 4:17pm
Cugel wrote: 24 Sep 2022, 4:07pmI find it hard to understand why you feel limiting the speed at which assistance is given is less dangerous than limiting the total power instead.
In shared use spaces it's the actual speed that affects other people, not the total power.
Well then you must propose laws limiting non e-bikes to 25kph on shared use paths. How will you arrange that without limiting non-e-bikes to that speed when they're not on shared use paths? Or are you, in effect, saying that bicycle speeds above 25kph are dangerous in all circumstances?

Your position on this matter seems to lack both coherence and the effects of the commonly-found experience that bicycle speeds above 25kph are not very dangerous at all.
I don't know a way of controlling that for eBikes depending on setting. In the real world.

I do know a way of decreasing the number of people and devices travelling faster in shared use spaces. In the real world.

Laws and regulations don't have to be perfect. They're all compromises. They have to be better than not having them.

I've emphasised the need for pragmatic solutions for the real world. Of course rhetoric is a different domain.

Jonathan
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Re: Is 250w enough power for modest speed up steep hills

Post by Jdsk »

Cugel wrote: 25 Sep 2022, 2:33pm ...
Why would anyone want to stop e-bike riders from finding that compromise with the help of their motor, as long as they don't cease to be cyclists going at typical cyclist speeds but motorcyclists going at typical motorbike speeds.
Because in some settings such as shared use spaces the additional assisted speed that some riders will adopt will put others at risk.

Jonathan
jois
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Re: Is 250w enough power for modest speed up steep hills

Post by jois »

Cugel wrote: 25 Sep 2022, 2:16pm
Jdsk wrote: 24 Sep 2022, 4:24pm
Cugel wrote: 24 Sep 2022, 4:07pmWhat is the metric-informed logic around this 25kph limit that results in the opinion, "That sound (sic) right to me"?
My comment was as much about a single limit covering all devices as about 25 kph.

Unfortunately the answer is only personal experience and observation of what happens in shared use spaces. And it being the current (!) limit.

As above, if better data become available than I'd happily change my mind. Are there any reports or studies that I've missed?

Jonathan
Jonathan - you don't need "a study" to make decisions on every matter under the sun. Try experience (I'm sure you do in reality) which will tell you lots of things allowing quite sensible, useful, accurate and generally "correct" decisions to be made about, oh, all sorts. :-)

I feel there is a danger, in taking the academic approach, of ending up like those Schoolmen of yesteryear, debating how many angels can dance on the head of a pin.

Cugel
A study is a good way of gaining exsperiance. Ie it allows you access to lots of other people's exsperiances and commonly puts them into a data set.

Personal exsperiance as a tool for decisions making is a bit hit and miss. It tends to carry an emotional element and quite a lot of sample bias. Unsuprising with a sample of one.

I can't tell you how many times I've heard "ive been roofing for 30 years and haven't fell off yet, " which is indeed their exsperiance. It's not however a good prediction of future events when you can get a data set of how many roofers fall off in a year
Jdsk
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Re: Is 250w enough power for modest speed up steep hills

Post by Jdsk »

CJ wrote: 25 Sep 2022, 1:14pm...
I think that cargo e-bikes - including tenbikes' log hauler - should come under the same regulatory regime as this new category of vehicle. They are a significantly heavier vehicle than even a loaded touring bike. Normal bicycle tyres and brakes are not really up to the job and someone in control of that much mass on any kind of downslope has a literally much heavier responsibility for the safety of others - regardless of what motor-assist speed they may be permitted. With greater power comes greater responsibitity, so licensing and resistration seems entirely appropriate: for any heavier and/or more powerful vehicle even if the motor is limited to 25kmph. However I think that it would be sensible to let 25kmph-limited cargo cycles into pedestrianised shopping streets 24/7, along with bicycles, and not just during specified delivery hours. So I think there's some merit in maintaining a distinction between speed-pedelecs and those that are also more powerful but not also faster.
Very interesting. Thanks.

I agree about the importance of driving (!) these categories and decisions from what affects the safety of others.

Jonathan
Jdsk
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Re: Is 250w enough power for modest speed up steep hills

Post by Jdsk »

jois wrote: 25 Sep 2022, 2:37pm
Cugel wrote: 25 Sep 2022, 2:16pm
Jdsk wrote: 24 Sep 2022, 4:24pm
My comment was as much about a single limit covering all devices as about 25 kph.

Unfortunately the answer is only personal experience and observation of what happens in shared use spaces. And it being the current (!) limit.

As above, if better data become available than I'd happily change my mind. Are there any reports or studies that I've missed?
Jonathan - you don't need "a study" to make decisions on every matter under the sun. Try experience (I'm sure you do in reality) which will tell you lots of things allowing quite sensible, useful, accurate and generally "correct" decisions to be made about, oh, all sorts.

I feel there is a danger, in taking the academic approach, of ending up like those Schoolmen of yesteryear, debating how many angels can dance on the head of a pin.
A study is a good way of gaining exsperiance. Ie it allows you access to lots of other people's exsperiances and commonly puts them into a data set.

Personal exsperiance as a tool for decisions making is a bit hit and miss. It tends to carry an emotional element and quite a lot of sample bias. Unsuprising with a sample of one.

I can't tell you how many times I've heard "ive been roofing for 30 years and haven't fell off yet, " which is indeed their exsperiance. It's not however a good prediction of future events when you can get a data set of how many roofers fall off in a year
Well said.

I'd like all policies to be based on evidence. But there are several fallacies that rapidly appear when this approach is taken.

1 We can't do anything because we don't have high quality evidence. This is WRONG. We often have to make decisions on inadequate evidence. The only requirements are that we should recognise that state of ignorance and then try to reduce it.

2 We don't need studies because we already have personal experience. This is WRONG. Many types of study provide better evidence than personal experience because of precisely the biasses and sampling problems that you describe.

Jonathan
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Cugel
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Re: Is 250w enough power for modest speed up steep hills

Post by Cugel »

jois wrote: 25 Sep 2022, 2:37pm
Cugel wrote: 25 Sep 2022, 2:16pm
Jdsk wrote: 24 Sep 2022, 4:24pm
My comment was as much about a single limit covering all devices as about 25 kph.

Unfortunately the answer is only personal experience and observation of what happens in shared use spaces. And it being the current (!) limit.

As above, if better data become available than I'd happily change my mind. Are there any reports or studies that I've missed?

Jonathan
Jonathan - you don't need "a study" to make decisions on every matter under the sun. Try experience (I'm sure you do in reality) which will tell you lots of things allowing quite sensible, useful, accurate and generally "correct" decisions to be made about, oh, all sorts. :-)

I feel there is a danger, in taking the academic approach, of ending up like those Schoolmen of yesteryear, debating how many angels can dance on the head of a pin.

Cugel
A study is a good way of gaining exsperiance. Ie it allows you access to lots of other people's exsperiances and commonly puts them into a data set.

Personal exsperiance as a tool for decisions making is a bit hit and miss. It tends to carry an emotional element and quite a lot of sample bias. Unsuprising with a sample of one.

I can't tell you how many times I've heard "ive been roofing for 30 years and haven't fell off yet, " which is indeed their exsperiance. It's not however a good prediction of future events when you can get a data set of how many roofers fall off in a year
All true - but there is such a thing as shared experience gained, compared, considered and amended outside of the mechanism of "a study". We do this every day, being the highly social animals that we are.

Moreover, "studies" so often embed the answers they would prefer in the questions and the structure & language in which they're posed. I know you don't agree, but my own, er, experience is that many of the self-claiming scientific academic disciplines that generate such studies are far from scientific in their outlook and conduct. They're more like philosophers re-imagined. In fact, "imagination" plays rather a large part! :-)

Cugel
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Jdsk
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Re: Is 250w enough power for modest speed up steep hills

Post by Jdsk »

Cugel wrote: 25 Sep 2022, 2:52pmMoreover, "studies" so often embed the answers they would prefer in the questions and the structure & language in which they're posed. I know you don't agree, but my own, er, experience is that many of the self-claiming scientific academic disciplines that generate such studies are far from scientific in their outlook and conduct. They're more like philosophers re-imagined. In fact, "imagination" plays rather a large part!
There is no evidence-based position that insists that anything labelled as a study is always better than personal experience. Studies should always be assessed for their quality. Bad studies should be ignored. The methods of sorting studies are steadily improving.

But that's an enormous way from the assertion that good studies can't provide better guidance than personal experience.

Among the many things that should be studied in this debate are the effects on health of eBikes (looking good so far) and the effects of eBIkes and eScooters and other micromobility devices in shared use spaces (and if I'm wrong about that I'll change my views).

Jonathan
jois
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Re: Is 250w enough power for modest speed up steep hills

Post by jois »

Cugel wrote: 25 Sep 2022, 2:33pm
jois wrote: 24 Sep 2022, 7:25pm
peterb wrote: 24 Sep 2022, 6:33pm

I assume you mean assisted speed? Limited by the laws of physics? How is it my Orbea Gain has an assisted limit in the UK of 15.5mph, yet exactly the same model of bike in the US has an assisted speed limit of 20mph?
I mean there is no prescribed limit of 25kph on ebikes. If you can't go faster that the laws of physics preventing you.

The USA has lots of different laws and legal limits to the UK . Some of them for the better some for the worse in my opinion.

As I understand the issue. The dispensation for ebikes was aimed at allowing the less able to enjoy cycling. Since then it's changed somewhat with most of the people I see on them being in the prime of life. Rather than being a two wheeled version of a mobility scooter.

Where should the limit be? If anyone asked me, which they didn't I would have set it at 12mph same as mobility scooters. But it clearly has to be somewhere and where ever it is someone will think it should be higher or lower.

Having got a dispensation from the tiresome matter of insurance etal. I don't think it's reasonable to campaign for a higher limit when you could just as easily get a faster bike and pay the insurance if going faster is that important to you. They go faster than I can manage for more than a few hundred yards , I honestly can't see why that isn't fast enough
E-bikes were never intended as another form of mobility scooter but rather, as you mentioned, "...aimed at allowing the less able to enjoy cycling."

What does that mean, in essence? Personally I can find no better definition than, "...able to keep up with the normally-able cyclists in all normal cycling circumstances". That would mean an ability to keep being assisted up to any normal cycling speed. It might also mean, preventing the assisted bicycle and its rider from being able to exceed the normal power range of normal-ability cyclists.

So, that begs the question: what is the normal ability range of normal ability cyclists? I would suggest that such a range should be something like 75 - 250 watts of leg power sustainable over one hour (i.e. an FTP range of 75 - 250 watts). I know plenty of cyclists who populate that range - and some who can actually go significantly higher than 250 watts for an hour but let's admit that they are a very small minority of cyclists so should be excluded from the "normal ability" category.

You would fall in that power range, eh? But, should your particular power-generating ability be the singular benchmark for limiting e-bike power for all cyclists? You may not feel the need to have more power and to therefore be able to go faster than a mobility scooter but plenty of other cyclists do, quite legitimately. It's why they practice, train and otherwise get better at it. And they do so not just to be able to race or go on club runs with other fit fellows but to be able to go to the shops faster, get up the hills and otherwise find that happy compromise of time, effort, fitness and several other factors that all sorts of cyclists seek for themselves.

Why would anyone want to stop e-bike riders from finding that compromise with the help of their motor, as long as they don't cease to be cyclists going at typical cyclist speeds but motorcyclists going at typical motorbike speeds.

Cugel
I don't think my view that the limit should be lower is any more or less valuable than yours that it should be higher

They are both relatively informed opinions based on years of cycling. We can't agree, it seems where ever the limit is set someone will disagree. Probably nearly everyone will disagree.

Call it 20 mph and the why not 22 debate will start. This is a much related mantra with the similarly arbertary speed limits.

I don't agree that the intended purpose was to allow riders to keep up with a lot more able friends. The answer to that is to get better friends who make allowances for you.

Rather what speed is a reasonable speed to allow the less able to have a reasonable cycling exsperiance and be a useful mode of transport and of course be within their skill set to control.

Many ebike riders have the reactions of fighter pilots, you can't reasonably set the limit to accommodate them ,some are a complete liability in anything but a large empty field. They really shouldn't have them at all.

In the middle ? That sounds like 25kph, it's a compromise some are very frustrated some a great danger to themselves and others. I can't think of a better way other than some sort of licence restrictions
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