Is 250w enough power for modest speed up steep hills

[jois]

[

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

[Carlton green]

So, given 250 Watts and an assisted speed limit of roughly 15 mph, what arrangement (some gearing, makes and models would be good) will make the best use of motor power and battery life?

[peterb]

[

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.

- I think I understand what you mean, perhaps it would be better to say:

'I mean there is no prescribed limit of 25kph on any bike. If you can't go faster it's your physique preventing you.'

- or am I still misunderstanding?

[Vantage]

So, given 250 Watts and an assisted speed limit of roughly 15 mph, what arrangement (some gearing, makes and models would be good) will make the best use of motor power and battery life?

Depends on the terrain you'll be riding on.
Rough, rocky, hilly areas and your motor will thank you for low gearing. In fact, that probably is correct for any sort of cycling as the motors perform best at higher rpm.
Where that gearing has a downside is when pedalling beyond the 15.5mph limit unless you like spinning.

One thing I have noticed since fitting my quite illegal 48v 750w motor though...
Detuning it to 240w (I don't need 750w as that's ridiculous) is giving me a brilliant battery life. Battery fully charged comes out at 50v. I've put 20 odd miles on it and the battery is still at 50v which is why I did it. Even with the 15.5mph limit set it's still illegal but that's a chance I'm willing to take for the range increase.
I used an online electric power calculator thingybob to work out that 48v X 5amp = 240w. If any leckie geniuses here could confirm that I'd be grateful.

[Jdsk]

Yes, 48 V x 5 A is 240 W (with appropriate assumptions).

Jonathan

[jois]

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.

- I think I understand what you mean, perhaps it would be better to say:

'I mean there is no prescribed limit of 25kph on any bike. If you can't go faster it's your physique preventing you.'

- or am I still misunderstanding?

You seem to have the gist of it. But I'm not at all sure your rewrite is better to be honest. Physique applies to the appearance of your body proportions. That doesn't seem to have a great deal of influence on your speed capacity.

[jois]

So, given 250 Watts and an assisted speed limit of roughly 15 mph, what arrangement (some gearing, makes and models would be good) will make the best use of motor power and battery life?

Depends on the terrain you'll be riding on.
Rough, rocky, hilly areas and your motor will thank you for low gearing. In fact, that probably is correct for any sort of cycling as the motors perform best at higher rpm.
Where that gearing has a downside is when pedalling beyond the 15.5mph limit unless you like spinning.

One thing I have noticed since fitting my quite illegal 48v 750w motor though...
Detuning it to 240w (I don't need 750w as that's ridiculous) is giving me a brilliant battery life. Battery fully charged comes out at 50v. I've put 20 odd miles on it and the battery is still at 50v which is why I did it. Even with the 15.5mph limit set it's still illegal but that's a chance I'm willing to take for the range increase.
I used an online electric power calculator thingybob to work out that 48v X 5amp = 240w. If any leckie geniuses here could confirm that I'd be grateful.

Why is it still illegal ? Or rather which of the legal requirement are you missing ?

[Vantage]

As I understand it, the motor mustn't be capable of more than 250w for prolonged use. It can only peak at more power for short periods such as hill climbing etc.

[Jdsk]

As I understand it, the motor mustn't be capable of more than 250w for prolonged use. It can only peak at more power for short periods such as hill climbing etc.

In Great Britain the requirement and wording is:

maximum continuous rated power of the electric motor must not exceed 250 Watts.
https://www.gov.uk/government/publicati ... tion-sheet

Jonathan

[Vantage]

Thanks Jdsk

[peterb]

I mean there is no prescribed limit of 25kph on ebikes. If you can't go faster that the laws of physics preventing you.

- I think I understand what you mean, perhaps it would be better to say:

'I mean there is no prescribed limit of 25kph on any bike. If you can't go faster it's your physique preventing you.'

- or am I still misunderstanding?

You seem to have the gist of it. But I'm not at all sure your rewrite is better to be honest. Physique applies to the appearance of your body proportions. That doesn't seem to have a great deal of influence on your speed capacity.

OK would you prefer 'strength', 'fitness'. So, you're saying there is no limit to the speed one can ride any sort of bicycle except one's strength and fitness? Very true!

[peterb]

So, given 250 Watts and an assisted speed limit of roughly 15 mph, what arrangement (some gearing, makes and models would be good) will make the best use of motor power and battery life?

My Ribble has 50/34 chainrings and 11-32 cassette, just as in the unassisted version. The motor gives me enough assistance so as to approximate the experience I used to have riding an unassisted bike, with a bit more help on the hills.

[jois]

- I think I understand what you mean, perhaps it would be better to say:

'I mean there is no prescribed limit of 25kph on any bike. If you can't go faster it's your physique preventing you.'

- or am I still misunderstanding?

You seem to have the gist of it. But I'm not at all sure your rewrite is better to be honest. Physique applies to the appearance of your body proportions. That doesn't seem to have a great deal of influence on your speed capacity.

OK would you prefer 'strength', 'fitness'. So, you're saying there is no limit to the speed one can ride any sort of bicycle except one's strength and fitness? Very true!

Strength isn't really the issue either. Power mass and air restance are the main issues those seem like physics issues to me.

Strength has a high degree of physics in it as well as you can nether produce or measure strength without using levers. Bio mechanics is still mechanics

And no I think there is a limit to how fast a bike can go.

[yakdiver]

So, given 250 Watts and an assisted speed limit of roughly 15 mph, what arrangement (some gearing, makes and models would be good) will make the best use of motor power and battery life?

No my trike that weighs a ton I fitted one of these
https://youtu.be/gQ3woJHv9kw

[peterb]

jois wrote:
Strength isn't really the issue either. Power mass and air restance are the main issues those seem like physics issues to me.

And no I think there is a limit to how fast a bike can go.

What is that limit 50mph? 60mph? 82mph? https://holsteinsharley.com/bike/what-i ... er%20hour.