Complete eBike kit just 3.6kg weight and price £225? Surely not...

[Wingreen]

There's been threads in this forum on this question a number of times in the past eleven years. None has ever got near to resolving the issue, it's an impossible question to answer when one of the power supply elements, (human) is so grossly variable and the pedelec motor systems vary so widely.
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So it seems - but as has already been suggested, it just needs some sort of "standard test rig" (with no human involved) to come up with some sort of meaningful (though, admittedly, not universal) measurement that can be used for comparison. Presumably something that an academic institution could put together and be jointly funded/supported by all the reputable manufacturers and importers - with a test fee agreed. (Still, maybe we would just end up with the VW/Skoda scenario!)

 

[danielrlee]

This is all rather unessicary really. IMO the capacity of the battery in Wh should be enough information to compare with other bikes. The public don't have to know what a watt-hour is, but they will all know that 600 Wh is twice as much as 300 Wh.

Claiming "we've lied the same as everyone else" does not help the situation. If you have to give a number, an honest estimate of range, along with information about how a rider can increase this range (and possibly an explanation about why the competition's range figures are BS) is surely the best you can achieve and won't end up insulting a potential buyer's intelligence either.

 

[flecc]

it just needs some sort of "standard test rig" (with no human involved) to come up with some sort of meaningful (though, admittedly, not universal) measurement that can be used for comparison.

Very difficult to create a test rig for both torque controlled crank drive and rotation controlled hub motor bikes though. They are so different in the way they work.

And having different levels of switched power complicates matters, we've had pedelecs with as many as nine switched power levels while others have as little as three. Which do we choose on each to give fair comparisons? Maximum on each would be fair, but manufacturers would be deeply unhappy at the very short ranges that would result in.
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[Wingreen]

This is all rather unessicary really. IMO the capacity of the battery in Wh should be enough information to compare with other bikes. The public don't have to know what a watt-hour is, but they will all know that 600 Wh is twice as much as 300 Wh.

Claiming "we've lied the same as everyone else" does not help the situation. If you have to give a number, an honest estimate of range, along with information about how a rider can increase this range (and possibly an explanation about why the competition's range figures are BS) is surely the best you can achieve and won't end up insulting a potential buyer's intelligence either.

I do agree (sort of) - but for many people, especially those new to electric bikes, they do need a REALISTIC idea of how far a bike will take them on one charge. While each individual's proposed journey will have different ups and downs, some sort of "X miles - on a Y in Z incline" (based on an appropriate test under laboratory-type situation) would be hugely useful.

 

[flecc]

While each individual's proposed journey will have different ups and downs, some sort of "X miles - on a Y in Z incline" (based on an appropriate test under laboratory-type situation) would be hugely useful.

For me there's not very much difference between very hilly and less so, but that's because I let a bike have it's head on the downhills, using the stored kinetic energy so recovering some of what was expended uphill. For those too timid to do so who slow on the downhills, the stored energy is wasted in braking.

Sorry to keep observing these difficulties, but once again it highlights how the big differences between riders can affect range so greatly.

I do have a crude rule of thumb though, 12 Wh per mile being the average and most common across this forum over time for all riders and bikes in all riding circumstances. But the extremes ranging from the 5Wh of masochists to the 24Wh of lazy gits can mess that up.
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[Swytch Bike]

There we are, problem solved. Quote the following in pedelec specifications:

Range: 10WH * n/(n+1), with n the assist ratio.

Customers should easily understand that.
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Great! That's exactly the kind of crystal clear communication we need to reach the mass market and get eBikes out there!

 

[Deleted member 4366]

It's very simple to get a direct comparison. There's loads of variables that affect how far you can go with any ebike kit, but most of them relate to you, your rides and your bike that you fit the kit to. The other variables are probably insignificant compared with those, so if you want to compare the range that you'll get with different kits, you only have to look at the battery size (Wh). The distance you can go will be in direct proportion to the battery capacity, so you can go twice as far with a 14Ah 36v battery as you can with a 7Ah one. Simples!

The facts and calculations are simple and logical. It's the question"How far can I go on it" that's stupid, when wearing a coat can make 10% difference, though you could provide the logical answer, "probably somewhere between 5 miles and 100 miles". That's the same answer to "how long is a piece of string?" given in the MENSA book, except that it's something like between 1cm and 1km.

 

[Wingreen]

It's very simple to get a direct comparison. There's loads of variables that affect how far you can go with any ebike kit, but most of them relate to you, your rides and your bike that you fit the kit to. The other variables are probably insignificant compared with those, so if you want to compare the range that you'll get with different kits, you only have to look at the battery size (Wh). The distance you can go will be in direct proportion to the battery capacity, so you can go twice as far with a 14Ah 36v battery as you can with a 7Ah one. Simples!

The facts and calculations are simple and logical. It's the question"How far can I go on it" that's stupid, when wearing a coat can make 10% difference, though you could provide the logical answer, "probably somewhere between 5 miles and 100 miles". That's the same answer to "how long is a piece of string?" given in the MENSA book, except that it's something like between 1cm and 1km.

Agreed - but retailers/manufacturers insist on making distance/mileage claims and while they continue to do so, it seems to me that these claims need to be based on some standard "test". Rightly or wrongly, prospective purchasers (especially "newbies") really do want to get an idea of distance - even if it only allows them to conclude that "combination Z will take me x% further then combination Y, when traveling under the standard test conditions"

 

[MikelBikel]

I have a feeling that this "how far it can go" issue really needs to be placed before a wider audience.

http://www.bike-eu.com/laws-regulations/nieuws/2017/10/leva-eu-survey-on-electric-range-test-for-e-bikes-in-type-approval-10131588
..Just out of curiousity, how does the power get from the box to the wheel? I see only 2 cables, 1x brake and 1x gears?

 

[Deleted member 4366]

Agreed - but retailers/manufacturers insist on making distance/mileage claims and while they continue to do so, it seems to me that these claims need to be based on some standard "test". Rightly or wrongly, prospective purchasers (especially "newbies") really do want to get an idea of distance - even if it only allows them to conclude that "combination Z will take me x% further then combination Y, when traveling under the standard test conditions"

It's absolutely impossible, and even if they did come up with a standard test, the results would be meaningless because the test parameters would be different from any real users ones. As I said, you can draw a comparison between the battery capacities, which is definitive, so no need for any fancy tests. The best estimate you can do is 3 miles per amp-hour, but when I can get 129 miles out of my battery on one charge one day and 20 miles the next day, you can see the futility of that.