Most powerful eBike for long uphill journeys?

[GLJoe]

200W is roughly the energy needed to cycle unassisted at 15mph.

Sorry to keep questioning things, but is this figure correct?
It seems high to me. I thought pro riders could only pump out 400-500W for half an hour or so, and they are WAY more powerful than a normal person, who should be able to maintain 15mph for a decent time.

Wouldn't you only need about 100W to cycle at 15mph?

 

[soundwave]

and how heavy is a pro riders bike 7-8kg

 

[GLJoe]

and how heavy is a pro riders bike 7-8kg

I would have thought the weight of the bike would be pretty insignificant if we're talking about maintaining a steady speed on the flat ?

 

[soundwave]

I would have thought the weight of the bike would be pretty insignificant if we're talking about maintaining a steady speed on the flat ?

more waight more effort required it also makes you slower going dh on off road tracks as you just cant flick and hop the bike around so just end up slower.

 

[Trevormonty]

more waight more effort required it also makes you slower going dh on off road tracks as you just cant flick and hop the bike around so just end up slower.

Yes and no to going slower DH. Tight sections definitely slower, but quicker acceleration on long straight sections and more stable.

When weight comes down to around 17kg in few years as drives and batteries get lighter, then difference in handling won't be so marked.

 

[Woosh]

Can someone confirm whether their Bosch CX still makes 400W at 120 RPM?

that does look too good to be - well you know what I mean.
The Yamaha plot is the one that looks 'normal'

 

[anotherkiwi]

Yes and no to going slower DH. Tight sections definitely slower, but quicker acceleration on long straight sections and more stable.

When weight comes down to around 17kg in few years as drives and batteries get lighter, then difference in handling won't be so marked.

Yes batteries may get lighter but copper isn't going to unless you are aware of some new physics that has slipped under the radar? So motors won't lose much more than they just did.

 

[Trevormonty]

Yes batteries may get lighter but copper isn't going to unless you are aware of some new physics that has slipped under the radar? So motors won't lose much more than they just did.

The new prototype Focus road bikes are 1.5kg for 60nm motor in down tube with 1.5kg 250wh battery. So 15-17kg FS eMtB is not unrealistic. I personally would settle for light 50nm motor plus decent gear range.

 

[Woosh]

In a CD motor, the gearbox weighs more than the electric motor.
If you can design a better, lighter 100:1 gearbox, now is your chance to make zillions.

 

[GLJoe]

more waight more effort required

Bearing in mind you replied to this "I would have thought the weight of the bike would be pretty insignificant if we're talking about maintaining a steady speed on the flat ?", can you explain how more weight means more effort is required?

 

[Zlatan]

Higher power density motors are in the way....
"Siemens' experts scrutinized all the components of previous motors and optimized them up to their technical limits. New simulation techniques and sophisticated lightweight construction enabled the drive system to achieve a unique weight-to-performance ratio of five kilowatts (kW) per kilogram (kg). The electric motors of comparable strength that are used in industrial applications deliver less than one kW per kg. "

And lighter weight high ratio gearbox is already here. Have a look at Rotrex superchargers. They don't give much away but call gearbox in their chargers friction drive. It spins impeller at upto 150, 000 rpm from a shaft speed of upto 6000 rpm. No gears and transfers around 3 bhp. They are tiny aswell but have to be oil cooled. ( internal not by engine oil) Maintenance free aswell.

We could see lighter components if companies believe there is a market.
The technology is already here.

 

[basicasic]

Post removed.

 

[Croxden]

I think it's just you.

 

[basicasic]

I think it's just you.

Yeah, you're probably right.

As you were folks.

 

[soundwave]

if my bike runs out of power im walking as its to fkn heavy just spent 40 quid on new rear axle to save just 50g lol

 

[Gaz]

.... can you explain how more weight means more effort is required?

Okay, so you're on a linoleum smooth, dead flat surface, with all the room you could possibly need and nothing in your way.

In your left hand you have a green krpytonic roller skate wheel. In your right hand you have a 10' high earth mover tyre.

You have them both rolling at 10mph. And you have a 2' long piece of dowel rod to keep pushing them along with. So you push each one, one after the other, with the dowel rod. And pretty soon it becomes clear which one is harder to keep moving.

It's called rotational inertia. It's harder to get something heavier moving, and keep it moving, than it is something that is lighter.

SW's picture of the Flintstones car is the pictorial version of this analogy.

Gaz

 

[Deleted member 4366]

Okay, so you're on a linoleum smooth, dead flat surface, with all the room you could possibly need and nothing in your way.

In your left hand you have a green krpytonic roller skate wheel. In your right hand you have a 10' high earth mover tyre.

You have them both rolling at 10mph. And you have a 2' long piece of dowel rod to keep pushing them along with. So you push each one, one after the other, with the dowel rod. And pretty soon it becomes clear which one is harder to keep moving.

It's called rotational inertia. It's harder to get something heavier moving, and keep it moving, than it is something that is lighter.

SW's picture of the Flintstones car is the pictorial version of this analogy.

Gaz

If I understood what you're saying there, Gaz, it's not right. The inertia only has an effect when you try and change speed, at a constant speed on the flat, weight/ mass or inertia makes no difference.

 

[Gaz]

If I understood what you're saying there, Gaz, it's not right. The inertia only has an effect when you try and change speed, at a constant speed on the flat, weight/ mass or inertia makes no difference.

Ed Zackary

The greater mass of the earth mover tyre, wind resistance, gravity and friction will all have a greater effect than on the roller skate wheel. The tyre will have greater forces on it that are causing it to slow, requiring more effort to keep it going.

It's like going from 17" wheels to 19" wheels on a car, getting a bigger tyre footprint on the road, and wondering why performance has been adversely affected.

Guess we'll have to agree to disagree on that one d8veh.

Gaz

 

[Gaz]

Double post - web page slow to respond.

G

 

[Zlatan]

Post removed.

I missed this...Post removed ? Was the Bursar involved ???
Must have been bad. Come on somebody give me a clue !