Setting a Standard?

[onmebike]

I've moved this from another thread to save going off topic.
The question was asked regarding range/battery capacity, isn't there a simple way of setting a standard means of measuring the ability/range of ebike's so the consumer can judge suitability. I came up with the following idea as a starting point, maybe some of you have similar or better idea's.

What about adapting a non powered running machine[bike drives track] with variable resistance.
It could be set to simulate say, flat terrain and an average weight rider using throttle power only to drive the rolling road at a set resistance, it would provide some measure of achievable range.
Using throttle power only, eliminates the complications of rider weight/input, gearing, terrain and wheel size, so could be applied to all type's of ebike's as an average measurement of ability.
In fact a small unit with two rollers at a set resistance under the driven wheel would suffice, you only need measure in time or distance. It may at least set some form of standard.

 

[eddieo]

Or take a third of manufacturers claimed figures and that will give you a more accurate assessment of range... a bit like cars really

 

[Fecn]

Using throttle power only, eliminates the complications of rider weight/input, gearing, terrain and wheel size, so could be applied to all type's of ebike's as an average measurement of ability.

Unfortunately using throttle power only would also eliminate the Panasonic and Yamaha systems from testing as they don't have a throttle-only option at all. I think we need to include a motor with a set output power to turn the crank too.

It would also be necessary to measure the power used at the crank due to the power-phase-down on the panasonic system as the cadence increases. (e.g. if you span the pedals at 70rpm then the panasonic system will give no assistance)

I think to get a meaningful figure, we'd need to fix a rider weight, and fix a course profile (some flat, some uphill, some downhill etc) which would give different systmems the ability to perform at a different range of efficiencies more closely matched to real-world conditions.

 

[eTim]

Why bother with adapting a running machine, they already make bicycle trainers with variable resistance.

Here's a question related to running machines and bicycles that I was discussing with work colleagues a few weeks ago, we think we figured it out but are still not sure - When running on a running machine, a runner can increase the workout level by raising the front of the machine and simulate running up a slope, we think this works due to the actions of gravity and friction on the runners shoes. If a bicycle is put onto a bicycle trainer and the front is raised, would it have the same effect of changing the work effort required to maintain the same speed? I argued not because the bike would just rotate around the rear axle and the rider would feel no difference in resistance and I'm sure that there is no way of simulating a slope without having a resistance roller for the front wheel, but even then I'm sure this would make no difference ?

This is just one of the many daft discussions I have with work colleagues

 

[eTim]

Unfortunately using throttle power only would also eliminate the Panasonic and Yamaha systems from testing as they don't have a throttle-only option at all. I think we need to include a motor with a set output power to turn the crank too.

For those machines with a throttle option, then a different set of tests and therefore a different set of results would apply to those ebikes. This would not affect the standard tests applied to the pedelec only performance.

Similar to machines with several power setting options on pedelec there would need to be a standard way of applying the tests, probably on low medium and high power over the same route OR using manufacturers recommended setting for the terrain. For example on my Cytronex it is recommended to use low power when the speed drops below 12mph on a hill.

I'm sure hill resistance could only be simulated by increasing roller resistance to the point where the rider needs to select a lower gear to maintain the agreed cadance and match the speed standard agreed for that particular test.

So for example:

Level and Flat, high power, speed 15mph, any comfortable gear, cadance 70rpm
Moderate Hill, high power, speed 12mph, any comfortable gear, cadance 55rpm
Moderate + hill, medium or low power (recommended), speed 8mph, any comfortable gear, cadance 40 rpm
Severe hill, low power, speed 6mph, lowest gear, cadance 20rpm

And split the riding into 30% flat, 40% moderate hills, 20% moderate + hills, 10% severe hills.

 

[Fecn]

If a bicycle is put onto a trainer and the front is raised, would it have the same effect of changing the work effort required to maintain the same speed?

It would have the same effect as pulling a wheelie... no real difference to the work required...

However.. if you put the driven wheel(s) on a slope, then additional effort is required to counteract the force of gravity and maintain the position on the slope.

Think of it like this... If you'd roll down a hill at 5mph due to gravity, but wish to go up the hill at 10mph, then you need to put in about 15mph worth of effort to maintain your 10mph speed.

 

[eTim]

It would have the same effect as pulling a wheelie... no real difference to the work required...

However.. if you put the driven wheel(s) on a slope, then additional effort is required to counteract the force of gravity and maintain the position on the slope.

Think of it like this... If you'd roll down a hill at 5mph due to gravity, but wish to go up the hill at 10mph, then you need to put in about 15mph worth of effort to maintain your 10mph speed.

But there is no practical way of fixing a bike on a slope to use gravity without using ropes!! It would be easier to simulate the work effort and resistance required to cycle a slope by using resistance rollers on the driven wheels.

 

[Fecn]

But there is no practical way of fixing a bike on a slope to use gravity without using ropes!! It would be easier to simulate the work effort and resistance required to cycle a slope by using resistance rollers on the driven wheels.

Totally agree. I was more answering the theoretical question than suggesting it was the solution for standardised testing.

Whatever solution we think up, needs to have both wheels in contact with the 'road' surface, as we'd need to cater for front and rear hubs, and also crank drive.

If the test rig was done right, we could provide a set of figures for unfit and fit riders by using different crank input power levels... and also get a measure of the maximum gradient a bike could climb.

No idea how we'd handle the bike's gears though... and that could be a big factor when it comes to the efficiency hub versus crank systems as hub motors tend to be least efficient at low speeds, whereas crank gets the ability to use the gears to keep the motor at efficient speeds.

 

[monster]

those running machines don't accuratly simulate running. theres no resistance from wind or gravity. even when you set it for "up hill" you are not having to move your whole body up a hill, just your feet and legs. its cheating. its probably very dependant on how you use it as well.

there should definatly be a standard for battery range on electric bikes because they are lieing to consumers at the moment. i think it should be set at top legal speed (15mph), all flat terrain (velodrome) with no pedaling. if the bike doesn't work with out pedaling then hack/replace the controller to make it work. oh, and the rider would have to wear some standard suit of armor to eliminate body shape drag profie differences! i guess they could use a treadmill and wind tunnel to simulate wind resistance and use a dummy with training wheels? failing that, we will have to test just the batteries. maybe consumer magazine "which?" could do the independant tests.

 

[Mussels]

The problem with a standard test is that bikes will be designed to get the best figures for the test. This has affected IC vehicles quite a bit where they are optimised for the tests and it doesn't give a true picture for most of the time.

• Noise is tested at set engine RPM so exhausts are tuned to make less noise at those revs.
• Emissions are tested at set RPM so engine mapping is adjusted to make less emissions at those RPM.
• 0-60 time is often quoted so performance vehicles are designed to get the best headline speed.
• Economy is measured under very specific conditions so that is all that matters.

So a car that has good test results can be uneconomical, noisy and polluting. I doubt the 0-60 optimisation will have any real effect but it can wrongly make one car look quicker than another.

 

[eTim]

The problem with a standard test is that bikes will be designed to get the best figures for the test. This has affected IC vehicles quite a bit where they are optimised for the tests and it doesn't give a true picture for most of the time.

• Noise is tested at set engine RPM so exhausts are tuned to make less noise at those revs.
• Emissions are tested at set RPM so engine mapping is adjusted to make less emissions at those RPM.
• 0-60 time is often quoted so performance vehicles are designed to get the best headline speed.
• Economy is measured under very specific conditions so that is all that matters.

So a car that has good test results can be uneconomical, noisy and polluting. I doubt the 0-60 optimisation will have any real effect but it can wrongly make one car look quicker than another.

It's a good point, I'm not sure how much it will apply to the current phase of ebike design, maybe in the future it would apply if a set of standard tests was implemented. The alternative is anecdotal evidence to determine ebike range which is what we have at the moment.

 

[Patrick]

It's a good point, I'm not sure how much it will apply to the current phase of ebike design, maybe in the future it would apply if a set of standard tests was implemented. The alternative is anecdotal evidence to determine ebike range which is what we have at the moment.

Another alternative would be for the people selling bikes to admit that range figures are meaningless on their own and to explain the conditions under which any ranges they quote were achieved.

I don't think standard measurements would be much use unless the people buying bikes had standard requirements, because unless your requirements match the conditions being modeled in the tests then the results aren't relevant.

Patrick

 

[BertYardbrush]

It would be quite simple for the product manufacturers association recently formed to agree to some basic test parameters for measuring the energy efficiency of their bikes.
If they really want the potential purchaser to see that it is worth investing a not insignificant sum in their product they should give us the facts.

So get round a table and sort it out. And whilst you are sat at the table you can talk about standard battery sizes.

 

[Straylight]

And whilst you are sat at the table you can talk about standard battery sizes.

Totally agree, along with connectors and controller/motor wiring colour definitions .

 

[Mussels]

Another alternative would be for the people selling bikes to admit that range figures are meaningless on their own and to explain the conditions under which any ranges they quote were achieved.

I know this is the stance Wisper have taken and I think others have openly said similar.

 

[lemmy]

I don't think there can be any meaningful test except battery capacity and an informed estimate of the load and usage conditions on a particular genre of bike.

Any rider simply wants to know how far an e-bike will take him, personally. The attempts outlined here would be no more (or less) useful than the estimated fuel consumption figures of the car industry. For me, not very useful.

With the far greater relative influence of rider weight and load carried such figures for an ebike would actually be even less informative than the mpg ones.

Sometimes standardisation clouds rather than clarifies the issue as all over-simplifications do.

I gained a very good insight into the likely range of my Kalkhoff from Flecc's observations and that ultimately influenced my choice of machine.

But even my own range on a fully charged battery varies greatly with temperature, my willingness to pedal hard, the terrain I'm riding in, my success at anticipating traffic light changes, avoiding braking, even, lastly, after losing a 6 kilos of blubber in the last 6 weeks.

I'm not being negative here, I find these discussions very interesting.

 

[NRG]

I think the whole exercise whilst admirable is ultimately pointless as there are so many variables involved. Focussing on Wh is probably the best indicator of range and the 10~15Wh quoted in other posts would probably cover the majority of typical E-bike riders and bikes, however, even this is variable as Flecc has pointed out. But with that in mind a typical 36v 10Ah / 360Wh battery would give a 24~36 mile range.

 

[onmebike]

Unfortunately, taking all the variable's into account only serve's to complicate.
If all ebike's were tested under the exact same average conditions, keeping all the variable's to preset figure's, eg, weight, speed, terrain, 0 wind, temperature and battery Ah etc. Wouldn't that at least give an informative judgement of each ebike's ability or is it not as simple as, the best performer under average conditions, would be the better all rounder?
Couldn't this then be applied to different catagories of ebike such as, folder, tourer or offroad etc to come up with best of class.
I thought it would be relatively simple to set a standard, maybe not?

 

[Mussels]

Unfortunately, taking all the variable's into account only serve's to complicate.
If all ebike's were tested under the exact same average conditions, keeping all the variable's to preset figure's, eg, weight, speed, terrain, 0 wind, temperature and battery Ah etc. Wouldn't that at least give an informative judgement of each ebike's ability or is it not as simple as, the best performer under average conditions, would be the better all rounder?
Couldn't this then be applied to different catagories of ebike such as, folder, tourer or offroad etc to come up with best of class.
I thought it would be relatively simple to set a standard, maybe not?

This standard sounds expensive and with little real benefit.

 

[onmebike]

This standard sounds expensive and with little real benefit.

Your probably right.