HELP can i take the 15mph limit off a hub motor ebike

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Cugel
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Cugel »

Nigel wrote: 18 Aug 2022, 4:14pm
scotto wrote: 17 Aug 2022, 9:32pm { I'd like advice on constructing an illegal motorbike }
A poster who joined just before posting their one single posting. There's a saying "don't feed the trolls".
No doubt the OP is suspect - of what, it's not easy to say. Is it just troll-bait or is he a naughty would-be lawbreaker!?

Still, the underlying thing about the speed limitation for e-bikes and the consequences of raising it are an interesting subject. I've often wondered .... in those places where the speed limit is 25 or 30mph (in some of the US States, I believe) how does this affect the battery life of the same e-bikes we have in Europe, with the same motors and batteries? (I understand that they can be software-tweaked to allow them to operate up to higher road speeds).

Given the rapidly increasing number of watts needed as one's speed goes up, to overcome air resistance, what are the likely scenarios of an average rider going about at 30mph courtesy of his motor? Let's say the rider can sustain 200 watts leg power and the e-bike has a battery of 500Whrs. On a flat course on a windless day, at 30mph, how far before the battery goes flat? What power output would the motor need to supply? (Assume the tyres and wheel bearings are so good that they roll without resistance).

What about if the course has 500M of ascent?

Mathematicians! Do your thing!!

Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
John Maynard Keynes
Jdsk
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Jdsk »

Cugel wrote: 18 Aug 2022, 5:16pmGiven the rapidly increasing number of watts needed as one's speed goes up, to overcome air resistance, what are the likely scenarios of an average rider going about at 30mph courtesy of his motor? Let's say the rider can sustain 200 watts leg power and the e-bike has a battery of 500Whrs. On a flat course on a windless day, at 30mph, how far before the battery goes flat? What power output would the motor need to supply? (Assume the tyres and wheel bearings are so good that they roll without resistance).
30 mph is 13.4 m/s. Bicycling Science gives 500 W total power requirement for a "Sports bicycle" upright at that speed.

If the rider can provide 200 W that requires 300 W from the motor.

A totally efficient 500 W h battery would last 1.67 h. That's 1 h 40 min.

The battery to motive power efficiency is probably the biggest error.

All improved estimates welcome.

Jonathan
Jdsk
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Jdsk »

Cugel wrote: 18 Aug 2022, 5:16pmWhat about if the course has 500M of ascent?
What's the total mass of the rider and bike?

Thanks

Jonathan
cycle tramp
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by cycle tramp »

Nigel wrote: 18 Aug 2022, 4:14pm
scotto wrote: 17 Aug 2022, 9:32pm { I'd like advice on constructing an illegal motorbike }
A poster who joined just before posting their one single posting. There's a saying "don't feed the trolls".
Here we're more highbrow... we education them with maths and by doing so make them better people or bore them to death..
Either outcome is fine by me :-D
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Bonefishblues
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Bonefishblues »

Jdsk wrote: 18 Aug 2022, 6:12pm
Cugel wrote: 18 Aug 2022, 5:16pmWhat about if the course has 500M of ascent?
What's the total mass of the rider and bike?

Thanks

Jonathan
Volume x density of each and then add them together, but that's not important right now :D
Jdsk
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Jdsk »

Bonefishblues wrote: 18 Aug 2022, 6:57pmVolume x density of each and then add them together, but that's not important right now
How do you measure the height of a building with a barometer?

; - )

Jonathan
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Bonefishblues »

This one's my sort of answer:

Find the janitor who has worked in the building for years and say: “I will give you this extremely nice barometer if you tell me the height of this building.” :P
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Vantage
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Vantage »

Someone new asks if it's possible to get a bike to 30mph. He doesn't state if he wants the motor to do 30mph or the bike itself. Not one of you asked that question. I did.
Without all the details, you lot accuse him of being a criminal and a troll and have pi**ing contest to show who's got the bigger brains.
Only on the cuk forum would that happen.
You people are a joke.
Bill


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Cugel
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Cugel »

Jdsk wrote: 18 Aug 2022, 6:12pm
Cugel wrote: 18 Aug 2022, 5:16pmWhat about if the course has 500M of ascent?
What's the total mass of the rider and bike?

Thanks

Jonathan
95Kg

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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Cugel
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Cugel »

Vantage wrote: 18 Aug 2022, 7:56pm Someone new asks if it's possible to get a bike to 30mph. He doesn't state if he wants the motor to do 30mph or the bike itself. Not one of you asked that question. I did.
Without all the details, you lot accuse him of being a criminal and a troll and have pi**ing contest to show who's got the bigger brains.
Only on the cuk forum would that happen.
You people are a joke.
The OP: "i am looking into removing the limit off my Kinetic 250w hub motor driven Ebike..... i struggle to get it up to 30mph or close to it as where a standard bike i could do this no problem".

How else to read this other than a request for a procedure to enable breaking of the law concerning the speed governance of e-bike assistance provision; or to tease us all knowing we'll go tut tut?

As to the mathematicians ... well, they like precision o' the language concerning the various values, which is fair enough.

Cugel.
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
John Maynard Keynes
Jdsk
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Jdsk »

Cugel wrote: 18 Aug 2022, 9:37pm
Jdsk wrote: 18 Aug 2022, 6:12pm
Cugel wrote: 18 Aug 2022, 5:16pmWhat about if the course has 500M of ascent?
What's the total mass of the rider and bike?
95Kg
Thanks

The energy needed for the ascent is 500 x 95 x 9.8 = 465,500 J.

That's about 129 W h.

So if it all comes from the battery that leaves 500 -129 = 371 W h.

And the battery would now last 0.8 h. That's about 50 min.

Jonathan
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by cycle tramp »

Vantage wrote: 18 Aug 2022, 7:56pm Someone new asks if it's possible to get a bike to 30mph. He doesn't state if he wants the motor to do 30mph or the bike itself. Not one of you asked that question. I did.
Without all the details, you lot accuse him of being a criminal and a troll and have pi**ing contest to show who's got the bigger brains.
Only on the cuk forum would that happen.
You people are a joke.
Given the current media news stories in regards to Grant Shapp the original post fails to advance our cause and neither do any replies which suggest ways by which a law abiding e-bike could be modified to break the law.
I would like to remind you that anyone is utterly free to leave the forum at any time.
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Steve O'C
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Steve O'C »

I can not maintain 30mph on the flat and I do not own an ebike.
With that out of the way I do think there is a discussion to be had about the legislation limiting the assistance of ebike motors to 15mph. It seems to me that being able to keep up with traffic in town increases rider safety in that it reduces the temptation for drivers to make impossible overtaking manoeuvres.
20mph seems about right to me and on the flat would be possible with current motors and batteries.
There was a thread here some time ago about how the 15mph limit was arrived at and if I recall it was no more scientific than my assertion that a 20mph limit would be safer.
I suspect evidence would be hard to come by, but what the exact speed limit should be is something that it is not unreasonable to discuss here.
Steve
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Cugel
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Cugel »

Steve O'C wrote: 18 Aug 2022, 11:36pm I can not maintain 30mph on the flat and I do not own an ebike.
With that out of the way I do think there is a discussion to be had about the legislation limiting the assistance of ebike motors to 15mph. It seems to me that being able to keep up with traffic in town increases rider safety in that it reduces the temptation for drivers to make impossible overtaking manoeuvres.
20mph seems about right to me and on the flat would be possible with current motors and batteries.
There was a thread here some time ago about how the 15mph limit was arrived at and if I recall it was no more scientific than my assertion that a 20mph limit would be safer.
I suspect evidence would be hard to come by, but what the exact speed limit should be is something that it is not unreasonable to discuss here.
Steve
Yes, the e-bike speed limit is a reasonable topic for discussion. It has several aspects, from safety issues to technical issues such as the rate of energy drain and the various methods for adding motor power to leg power.

The OP's question seemed to be asking for a fix to enable the overcoming of the 25kph legal limit currently set as one criterion defining an assisted e-bike, so 50kph is possible. So perhaps this thread should first consider arguments for and against changing the current cut-off speed from the perspective of safety at this much higher speed? Such an e-bike would mean cyclists on them might habitually go about at 30mph, not the current situation with cycling in general.

As a very experienced rider of unpowered bicycles I know that many who are less experienced (novices, if you like) as well as some who have ridden bicycles for years, are not good (sometimes bluddy awful) at the riding skills. The first consideration about e-bikes, then, is looking at the potential for their added power to increase the consequences of being an inept cyclist.

Personally I feel that at speeds above 20mph those with a poor ability to control a bicycle will begin to find their window for recovering from a bad control decision is too short to make amendments. As their velocity increases, the chance of them suffering a serious consequence from one of their numerous poor control inputs will increase. In 30mph scenarios they also stand a much greater chance of coming to serious harm.

But what about those who are very good at bike control? Many can go at 25mph habitually; and all cyclists have the potential to go at up to 40mph down significant hills. If they can remain competent at those speeds on an unpowered bike, why not allow them to have assistance up to those speeds? The answer is that it's impossible to differentiate at the point of purchase between competent and incompetent cyclists.

That's a poor argument, though, because we currently allow incompetent cyclists to buy unpowered bikes that can go as fast as their riders can make them go. Some will get better at the cycling skills via slower speed cycling, as they'll not initially be fit enough to get up to 20mph. But there's plenty out there with thousands of miles under their wheels who are still far from competent, especially in traffic. And someone superfit from some other activity might be a novice cyclist but will still be able to get up to 30mph on his new and unfamiliar bicycle from day-one.

No conclusions about e-bike speed limits from me then! :-)

My personal preference is to set my e-bike motor to give no more than 200 watts (usually hlf that) and then only when I'm outputting at least that myself. I keep it for the long steep hills only, so my legs don't wither and fall off. I don't feel a need or want to be assisted to high speeds, only to shorter times (or smaller efforts) up serious hills. But many want, effectively, an electric motor bike only without all the costs of licenses, insurance et al.

Perhaps the only way forward is to allow an experiment (up to 30mph assistance in, say, Surrey) to see what the related "accident" statistics tell us. Cyclists as guinea pigs. :-) Or we could look at statistics from those US States in which 30mph, not 15.5mph, is the limit ...... ?

Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
John Maynard Keynes
Biospace
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Re: HELP can i take the 15mph limit off a hub motor ebike

Post by Biospace »

Was going to write what is above, totally agree with Cugel.

The limit is 25kph, which is a little over 15.5mph. I imagine there will have been careful consideration as to whether to make it 30kph or 25. I agree a little over 18mph would, at times, feel useful but the shortened range and additional wear and tear alone would be significant.

The slower the assisted-to, the less chance there is of these bikes remaining un-interefered with by politicians and their form-fillers. Besides, 25kph into a steady headwind or up a long gradient is pretty swift.
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