How Fast is a Leccy Bike?

[Yorick]

Have a guess, then look at this. I had no idea this happened

https://www.roadracingworld.com/news/bi ... ed-record/

[cheb]

I'll not give the game away but the interesting bit, to me anyway, is near the end of the article.

[Yorick]

I wonder how much power it had?

Turbo Busas have about 500 to reach around 250 MPH

[Skub]

Sounds lairy.

[ChrisW]

I wonder how much power it had?

Turbo Busas have about 500 to reach around 250 MPH

About 1000 ft/lb and 430bhp according to another article. Crikey.

https://www.electrive.com/2021/11/22/vo ... e-wattman/

[Mr. Dazzle]

I wonder how much power it had?

Turbo Busas have about 500 to reach around 250 MPH

About 1000 ft/lb and 430bhp according to another article. Crikey.

https://www.electrive.com/2021/11/22/vo ... e-wattman/

Electric vehicles are usually a lot faster than ICE of nominally the same power. In an ICE the peak power only comes at a narrow rev range, we all know the feeling of being in too tall/short a gear and not being able to reach the power band.

No such problem with an EV, you've generally always got either peak power or peak torque available. At low rpm you're torque limited, at higher rpm you're power limited.

Most road going EVs are top speed limited on the motor rpm redline, not the power.

[Supermofo]

I'd race it.

Over a decent distance. I'll be able to have a bag of chips and a pint whilst it's charging

[Bigjawa]

I wonder how much power it had?

Turbo Busas have about 500 to reach around 250 MPH

About 1000 ft/lb and 430bhp according to another article. Crikey.

https://www.electrive.com/2021/11/22/vo ... e-wattman/

Electric vehicles are usually a lot faster than ICE of nominally the same power. In an ICE the peak power only comes at a narrow rev range, we all know the feeling of being in too tall/short a gear and not being able to reach the power band.

No such problem with an EV, you've generally always got either peak power or peak torque available. At low rpm you're torque limited, at higher rpm you're power limited.

Most road going EVs are top speed limited on the motor rpm redline, not the power.

I saw one of the wee Teslas, it it the model 3, utterly demolish a serious looking Porsche up a motorway slip road, it just fucked off whilst Porsche guy was revving the balls off his yoke

[Screwdriver]

Standing start quarter mile is on a par with an RD350LC...

[mangocrazy]

Standing start quarter mile is on a par with an RD350LC...

Hardly a fair comparison. The electric bike was geared to hit a 283 mph top speed.

[Screwdriver]

Standing start quarter mile is on a par with an RD350LC...

Hardly a fair comparison. The electric bike was geared to hit a 283 mph top speed.

Why does it have to be fair?

[mangocrazy]

Standing start quarter mile is on a par with an RD350LC...

Hardly a fair comparison. The electric bike was geared to hit a 283 mph top speed.

Why does it have to be fair?

Because you are trying to make a comparison. And a valid comparison needs a baseline.

[Screwdriver]

Hardly a fair comparison. The electric bike was geared to hit a 283 mph top speed.

Why does it have to be fair?

Because you are trying to make a comparison. And a valid comparison needs a baseline.

Ah, because mumbo jumbo. I see.

Well all I was actually doing (not trying to do) was to compare the standing start 1/4 mile velocity with one that I happen to know and can relate to.

We all know these electric vehicles can produce tremendous acceleration with their extraordinary torque curve and I found it interesting that this extreme top speed version would actually accelerate quite slowly. A modern sportsbike would piss all over it until this thing got into its stride and just kept going.

Gearing is irrelevant. An electric vehicle develops peak torque at 0 rpm! Weight is the key issue since the battery is going to be a significant proportion of the overall mass so it doesn't actually need a gearbox which would only add weight. Top speed will only depend on torque which fall off as the motor spins up.

So it is interesting to me that the acceleration is quite mild when the top speed is so extreme. That I assume is down to weight and of course the design parameters optimised for top speed at all costs. It will have a phenomenal amount of torque which is instantly available to the rear wheel regardless of gearing.

[Mr. Dazzle]

Gearing is highly relevant.

EVs still have a gearbox usually, albeit a single speed one. This particular bike almost certainly has its gearing dominated by the motor's RPM limit, which means it has a very tall gear and hence poor acceleration.

It's true that the motor will make peak torque at 0rpm, but that's still blunted by being in a tall gear.

Top speed is also dependent on power, not torque (RPM limits notwithstanding) in any vehicle. Gearboxes can't change power but they can change torque. If speed was down to torque I could make my car go fast just with a broom handle.

We have quite sophisticated "genetic algorithms" to go through an assess the best combination of gear, motor torque, motor power etc. For a given vehicle...we can have slightly more power, slightly more torque etc. by changing various things and there's a sweet spot to hit. Gear ratio is one of biggest lever.

Sorry Screwd, you're just wrong on this

[Mr. Dazzle]

Well put it this way....the EV I'm currently working on, among other things, is using about half it's available power when it hits its top speed (which would land you a nice prison stretch and a headline news article if you were caught doing it), set by the RPM redline.

If we geared it differently it could go loads faster, but then it wouldn't accelerate as well.

At one stage it had a 2 speed gearbox but that got binned.

[Count Steer]

Comparing bikes like that is a bit like saying a top fuel drag bike wouldn't do very well in a 12 lap race round Brands Hatch.

[Mr. Dazzle]

Comparing bikes like that is a bit like saying a top fuel drag bike wouldn't do very well in a 12 lap race round Brands Hatch.

Get ahead into the first corner though

[Count Steer]

Comparing bikes like that is a bit like saying a top fuel drag bike wouldn't do very well in a 12 lap race round Brands Hatch.

Get ahead into the first corner though

Then have to stop and repack the parachute ready for the hairpin.

[mangocrazy]

Why does it have to be fair?

Because you are trying to make a comparison. And a valid comparison needs a baseline.

Ah, because mumbo jumbo. I see.

Well all I was actually doing (not trying to do) was to compare the standing start 1/4 mile velocity with one that I happen to know and can relate to.

We all know these electric vehicles can produce tremendous acceleration with their extraordinary torque curve and I found it interesting that this extreme top speed version would actually accelerate quite slowly. A modern sportsbike would piss all over it until this thing got into its stride and just kept going.

Gearing is irrelevant. An electric vehicle develops peak torque at 0 rpm! Weight is the key issue since the battery is going to be a significant proportion of the overall mass so it doesn't actually need a gearbox which would only add weight. Top speed will only depend on torque which fall off as the motor spins up.

So it is interesting to me that the acceleration is quite mild when the top speed is so extreme. That I assume is down to weight and of course the design parameters optimised for top speed at all costs. It will have a phenomenal amount of torque which is instantly available to the rear wheel regardless of gearing.

No. The mumbo jumbo is what followed my comment, as Mr D has more than adequately pointed out. You're just plain wrong in this instance.

[Screwdriver]

Well put it this way....the EV I'm currently working on, among other things, is using about half it's available power when it hits its top speed (which would land you a nice prison stretch and a headline news article if you were caught doing it), set by the RPM redline.

If we geared it differently it could go loads faster, but then it wouldn't accelerate as well.

At one stage it had a 2 speed gearbox but that got binned.

Yes, in the cold light of day I can't see where I was going with that idea. Naturally there is an element of gearing even in a direct drive system.

I will have to eat my words. Sorry @mangocrazy.

Perhaps I might have been better off suggesting how amazing it was that it would still accelerate so hard despite being geared for a massive top end.