K2C & e-bikes

[Eldron]

It seems to support my thinking:

 

100kg all up weight (conservative and on the higher performance end)

Power Pack 500

Active line motor

eMTB selected

 

for an average speed of 17km/hr you'd get 108km of range at best in ECO mode.

 

to get any sort of race winning performance out of the eMTB you'd need to have around 1300W.hr pack since its going to be more than x2 as heavy as a the Power 500.

 

Most e-bikers are going to be pottering around the mid to back of the field anyway just be virtue of the battery limitation. Ain't no body "racing" there

 

Everything is relative and it depends who is on top of the bike.

 

Spesh LEVOs run 504kwh batteries. Basically 100w per hour for 5 hours - that is an enormous amount of power when considering competitive guys will run 250-300w.  30% faster for the entirety of the race is a lot of extra horses.

 

Pop that battery on a road bike and you could have an extra 200w for the whole race - insane! Sub 3 hour 100km road races would go from a decent challenge to a doddle. Even for an intermediate rider.

[Grease_Monkey]

It seems to support my thinking:

 

100kg all up weight (conservative and on the higher performance end)

Power Pack 500

Active line motor

eMTB selected

 

for an average speed of 17km/hr you'd get 108km of range at best in ECO mode.

 

to get any sort of race winning performance out of the eMTB you'd need to have around 1300W.hr pack since its going to be more than x2 as heavy as a the Power 500.

 

Most e-bikers are going to be pottering around the mid to back of the field anyway just be virtue of the battery limitation. Ain't no body "racing" there

That's 100% true, but that's with current tech. In a couple years we will see smaller, higher output batteries and higher powered motors. Just a matter of time till the average Joe can do a 100km race at 30km/hr.

[Eldron]

That's 100% true, but that's with current tech. In a couple years we will see smaller, higher output batteries and higher powered motors. Just a matter of time till the average Joe can do a 100km race at 30km/hr.

 

I reckon anyone who can a 4 hour 100km will happily roll a sub 3 on today's tech.

[Grease_Monkey]

I reckon anyone who can a 4 hour 100km will happily roll a sub 3 on today's tech.

For sure, based on the time I've spent on e-bikes I'm confident that I can do a sub 3 100km ride (elevation dependent and on the road), and that's on a Spaz Levo with 3.0" tyres. Big statement - I won't bet my house on it, but I'm reasonably confident.

[DieselnDust]

Everything is relative and it depends who is on top of the bike.

 

Spesh LEVOs run 504kwh batteries. Basically 100w per hour for 5 hours - that is an enormous amount of power when considering competitive guys will run 250-300w.  30% faster for the entirety of the race is a lot of extra horses.

 

Pop that battery on a road bike and you could have an extra 200w for the whole race - insane! Sub 3 hour 100km road races would go from a decent challenge to a doddle. Even for an intermediate rider.

 

 

I''m  sure Eskom will be interested in this 504KW.hr battery  ...

A 504 W.hr battery won't get any racer further than around 35-40 km at 24km/hr. The energy saved will certainly be of benefit but then he/she has to pedal that weight uassisted....that's going to be a huge drag.

to klap it at higher speeds then they're likely not suing a Class 1 motor which I would not advocate anyway but the same problem remains. How to get the bike + rider mass to go the full distance.

 

But that said, why do you keep defaulting to a "race" analogy when that was covered under CSA/UCI/OC rules.

 

 

As for range. Lithium Polymer battery tech has come a long way in terms of recharge input amperage increasing and impedance reducing. This allows the battery to be recharged faster with less internal damage to electrolyte and electrododes. But they have not come down in weight and that's simply because higher capacity means more lithium-ions and hence more lithium. Higher voltage means more cells.

Cells are lighter but they have a lower limit in high current draw applications due to the casing needing to be strong enough to resist bursting should a cell vent and rupture the casing.

Motors also haven't gotten much lighter, the gearboxes have and these are pretty much where the price performance ratio is and will remain for sometime until someone comes up with a breakthrough in either materials or battery tech I.e. a completely new battery chemistry.

What we see as big gains in e-bike battery tech is really just the industry catching up to where other industries have been for a while, i.e. cordless industrial tool, golf karts, toy cars, boats , planes, drones, UAV's, electric cars. Tech from those industries has only started flooding into e-bikes in the last two years as demand has grown for e-bikes. Bespoke gearboxes also helped reduce weight as no one needs a gearbox for a 250kg golf kart on a 120kg e-bike. The torque requirement is different.

[Eldron]

I''m  sure Eskom will be interested in this 504KW.hr battery  ...

A 504 W.hr battery won't get any racer further than around 35-40 km at 24km/hr. The energy saved will certainly be of benefit but then he/she has to pedal that weight uassisted....that's going to be a huge drag.

to klap it at higher speeds then they're likely not suing a Class 1 motor which I would not advocate anyway but the same problem remains. How to get the bike + rider mass to go the full distance.

 

But that said, why do you keep defaulting to a "race" analogy when that was covered under CSA/UCI/OC rules.

 

 

As for range. Lithium Polymer battery tech has come a long way in terms of recharge input amperage increasing and impedance reducing. This allows the battery to be recharged faster with less internal damage to electrolyte and electrododes. But they have not come down in weight and that's simply because higher capacity means more lithium-ions and hence more lithium. Higher voltage means more cells.

Cells are lighter but they have a lower limit in high current draw applications due to the casing needing to be strong enough to resist bursting should a cell vent and rupture the casing.

Motors also haven't gotten much lighter, the gearboxes have and these are pretty much where the price performance ratio is and will remain for sometime until someone comes up with a breakthrough in either materials or battery tech I.e. a completely new battery chemistry.

What we see as big gains in e-bike battery tech is really just the industry catching up to where other industries have been for a while, i.e. cordless industrial tool, golf karts, toy cars, boats , planes, drones, UAV's, electric cars. Tech from those industries has only started flooding into e-bikes in the last two years as demand has grown for e-bikes. Bespoke gearboxes also helped reduce weight as no one needs a gearbox for a 250kg golf kart on a 120kg e-bike. The torque requirement is different.

 

 

Hahaha damnit - how did that k sneak in there?

 

I keep defaulting to what we know and we know that an extra 100w is a bucketload.

 

Is that bolded part with zero input from the rider? 504w giving you a range of 35km at 24kph sounds WAY too little.

[DieselnDust]

That's pedaling at 60rpm in TURBO mode. I.e it's giving the best calculated range based on the terrain at max power with max assist from the battery. The riders input may extend that a few km at best. Remember the faster you go the more power you need to maintain that speed. So a lot of electrons are just there to get Air out of the way. Then the motor and battery are going to run hotter which increases the battery's impedance which again leads to reduced efficiency.

It very difficult to run an e-bike battery at full tilt without a proper cooling system. The packaging makes this very difficult. There are a more than a few expensive problems to overcome, by which time you end up with a e-motorbike and the problem of bicycle racing is taken care of.

[Eldron]

That's pedaling at 60rpm in TURBO mode. I.e it's giving the best calculated range based on the terrain at max power with max assist from the battery. The riders input may extend that a few km at best. Remember the faster you go the more power you need to maintain that speed. So a lot of electrons are just there to get Air out of the way. Then the motor and battery are going to run hotter which increases the battery's impedance which again leads to reduced efficiency.

It very difficult to run an e-bike battery at full tilt without a proper cooling system. The packaging makes this very difficult. There are a more than a few expensive problems to overcome, by which time you end up with a e-motorbike and the problem of bicycle racing is taken care of.

Something doesn't stack up.

 

A sub 3 Argus in a bunch takes between 230 and 350w depending on how much you weight, when you get dropped etc.

 

A 504whr battery {assuming 100% efficiency on a new battery} can supply 168w for 3 hours so on your ebike you need to lay down between 68 and 182w to break the magic 3. 68 is barely a warm up and 182w shouldn't be hard with a day or two a week of training.

 

If you can't manage 68w for 3 hours then you should be looking at mobility scooters or coffins not ebikes.

[DieselnDust]

You're just thinking battery. You need to consider the drivetrain efficiency.

 

Also battery efficiency improves with lower current draw it's, not linear and it varies with temperature of the battery pack. Battery alone can dip as low as 80% efficiency.

Then you have the gearbox, chain.

Then dynamic load. The Bosch range calculator assumes best case by using an overall efficiency. That's why your numbers are different to mine or the bosch model. Conservatively you can assume efficiency as 80% and see where that gets your rider.

 

Another aspect to consider is that the model is assuming constant load usage. Out on the trial you're going to have a lot of variable loads. The rider bouncing up and down creating drive train shunt and spiking the battery output.

 

So yes your ebike racer is going to have more energy when he's battery runs out than the push bike rider... BUT he /she then has to Propel that weight without assistance.

I've pedalled one of those Giant ebikes up to the block house.... I nearly died. 27kg is a lot to haul around.

[Eldron]

You're just thinking battery. You need to consider the drivetrain efficiency.

 

Also battery efficiency improves with lower current draw it's, not linear and it varies with temperature of the battery pack. Battery alone can dip as low as 80% efficiency.

Then you have the gearbox, chain.

Then dynamic load. The Bosch range calculator assumes best case by using an overall efficiency. That's why your numbers are different to mine or the bosch model. Conservatively you can assume efficiency as 80% and see where that gets your rider.

 

Another aspect to consider is that the model is assuming constant load usage. Out on the trial you're going to have a lot of variable loads. The rider bouncing up and down creating drive train shunt and spiking the battery output.

 

So yes your ebike racer is going to have more energy when he's battery runs out than the push bike rider... BUT he /she then has to Propel that weight without assistance.

I've pedalled one of those Giant ebikes up to the block house.... I nearly died. 27kg is a lot to haul around.

Ah. Cool. Thanks for that. The numbers get interesting when it goes from theoretical to real world!

 

Have you ridden one yet? Rocket ships I tell you. Sure they're not going to turn medical cases into Tour de France winners but if you have a decent level of fitness you'll happily destroy your peers without too much sweat.

[DieselnDust]

Yeah I have. Had one on loan for a weekend. A real blast to ride. The weight is great on single track descents as the bike stays planted. Hard to bunny hop though.

Climbing they can be rocket ships if you want to get to the top of the trail head before your Pals. But then we regroup anyway. So I did that once or twice but eventually just stuck with them.

 

I don't think I'll get one though as the novelty wore off quickly. A weekend was enough to get me too "not for me."

But then I some older people riding in tokai with smiles and attempting the single-track then I think "hmmmmmm ya something for everybody"

[Eldron]

Yeah I have. Had one on loan for a weekend. A real blast to ride. The weight is great on single track descents as the bike stays planted. Hard to bunny hop though.

Climbing they can be rocket ships if you want to get to the top of the trail head before your Pals. But then we regroup anyway. So I did that once or twice but eventually just stuck with them.

 

I don't think I'll get one though as the novelty wore off quickly. A weekend was enough to get me too "not for me."

But then I some older people riding in tokai with smiles and attempting the single-track then I think "hmmmmmm ya something for everybody"

 

Same experience here - maybe when I'm older or if I make a bunch of pro friends and need to ride without snot/blood/sweat escaping from all over my body.

 

Some of the Rapha boys here in Denmark know how to ride a bicycle!

[DieselnDust]

In my time in Northern Europe I had my bum handed to me by the amateur ladies...

 

I'm thankful for good health and the ability to ride bikes as hard as my limited training time allows. So for now I would just like to enjoy the gift as much as possible before enlisting assistance.

But having a category to still participate and maybe even compete would be superb. Rome wasn't built in a day even if it's not being built for me yet.

[shaper]

[RocknRolla]

This exchange between "numbers on paper" (Eldron) and real world experience and practical knowledge (DieselnDust) is the best I have read on the hub in a long time!!!!

[TIB]

This exchange between "numbers on paper" (Eldron) and real world experience and practical knowledge (DieselnDust) is the best I have read on the hub in a long time!!!!

 

Son: Dad, what is the difference between theory and practice?

 

Dad: Ask your mother and sister if they will sleep with Sol Kertzner for a million dollars.

 

Son: They said they will do it.

 

Dad: In theory we are millionaires but in practice we are sharing the house with prostitutes.....