Determining electric bike range and hill climbing ability

I have ridden both the Salisbury and the Cambridge for long periods of time and the Salisbury feels much less powerful than the Cambridge at low levs, acceleraion and generally starting and getting quick out of junctions. Although both bikes are rated at a nominal 200W the Salisbury needs to be rolling at full speed before the power takes full effect, so overall it feels a bit geriatrtic compared to the Cambridge.

As a plus point -the Salisbury has a better quality feel than the Cambridge, does not rattle as much, the tyres are smooter, the suspension works better and it is lighter by 1kg.

However it does not have an integral light (strange on a bike where you carry a big heavy battery) and the battery indicator is awkwardly positioned under the seat - not much use when you are riding - also it tends to stay on 'Empty' during use regardless of the state of charge. In contrast the Cambridge has a nice 6W 24V light that does an excellent job lighting your path with a voltage indicator that is quite informative as you tend to remember its state under different conditions and judge the state of your battery.

I guess until the industry matures choosing a bike will involve a lot of guesswork. There needs to be a unified preformance test quoted for electric bikes, something like:

0-15.5 mph in so much seconds with fixed weight

top speed on the flat without pedalling

range in miles without pedalling

These are important characteristics that no manufacturer quotes at the moment - so you do not know what you are really getting. Specs like 'range - 15-20miles with gentle pedalling' mean next to nothing when chosing a bike.

Ideally Chazpope what we need is a clearly defined test route against which all bikes can be tested. In fact, we need more than one course, probably 3:

Flat

Moderate inclines

Very Hilly

We would also need shorter sections to compare hill climbing ability i.e. 1000 yards at 10%, 6% etc..

All tests would involve a fully charged battery, riders of the same weight and rely on throttle only. Perhaps a with-pedalling test could also be included but this would have to involve the rider maintaining a certain speed altrhough this could be problematic for those bikes that also have variable throttle in pedelec mode.

The above would be quite a logistical challenge! Also which suppliers would be happy to involved with such a process ?

well what I suggested is achievable and repeatable without any great logistic support - all you need is a chronometer, an average cyclist + a bag of bricks to even out to the standard required weight of x kg as necessary.

for the range test you would need to go on a track where you can circle untill the battery gives up - with average speed and mileage being the result figires

pedalling should be tottally excluded from this process - what we are after is the 'power' peformance of the bike.

also I don't think we need an inclined test - most 200w bikes would not climb an incline unaided anyway while the 0-15 test would be indicative enough of the motor's low rev/high-torque ability. Actually, because most bikes would not go up to 15 miles without pedalling - the test should be - 'distance covered in 60 secs from a standstill'

Carl of Powacycle explained previously that the motor's internal gearing of the Cambridge is different.

It's a balance of options, more top speed or better acceleration and climbing.

The eZee Torq is the most extreme case of this in practise, a high top speed gained at considerable cost to acceleration and hill climbing.

.

so who is up for this then? All we need to find is a local school running track which we can whizz about on. I think an incline test would be useful, there are a few bikes out there that could do it at least that way we have a definitive answer that everyone could rely upon.

thanks

Jed

just to clarify - going on just the throttle the Cambridge also has a higher top speed that the Salisbury - it is totally better dynamic performance in every way

as to the range - you cannot guess what it would be untill you test it - and so far there is no definiton of 'range' - what is gentle pedalling for one would give someone else a heart attack - so all this talk from the bike co's is b/s I am afraid

also I don't think we need an inclined test - most 200w bikes would not climb an incline unaided anyway while the 0-15 test would be indicative enough of the motor's low rev/high-torque ability. Actually, because most bikes would not go up to 15 miles without pedalling - the test should be - 'distance covered in 60 secs from a standstill'

I don't know what e-bikes you've experienced chazpope, but this is so far from the truth that I can scarcely believe you think it so. Only a very small number perform that badly.

The majority of 200 watt e-bikes will climb 8% (1 in 12) easily without pedalling. A high proportion will climb 10% (1 in 10) without pedalling, some doing better and even much better. For example an eZee Quando will not only climb a 12% (1 in 8) slope unaided, it will even do a no pedalling restart on that, carrying a 75 kilo rider, and it's done it for me with a load of shopping on the back as well. With a freshly charged battery it will even handle 13% unaided, and I'm supported in that by A to B magazine who found the same. I can think of at least two other bikes which can nearly match that.

As for "most bikes would not go up to 15 miles without pedalling", by which you seemed to mean 15 mph, nothing could be further from the truth. The great majority of twistgrip 200 watt e-bikes will do that and sometimes well beyond, often to 16, 17, and even 18 mph.

An incline test is exactly what is needed to test climbing, this often being the most important factor in most peoples' purchasing, and a standardised climb test would give directly comparable facts.

I agree that range quotations in isolation are virtually worthless.

.

is anyone going to try this out. I have a Torq and one day this week i am going to ride it around the village on throttle only. there is a route i have worked out where I won't have to stop and can whizz aorund the corners full speed plus it is all flat. Perhaps we can all try this and report back on the forum and see what averages we come up with obviously each bike is different.

thanks

Jed

Hi Jed

Your enthusiasm is admirable however... I don't wish to dampen it, and please don't feel this post is aimed at you but some issues need highlighting here.

Even something as seemingly simple as a range test, which is part of what seems to be being proposed, has so many possible different variables - involving both terrain and rider factors (even when not pedalling!) such as slopes (even on an apparently flat road!), bends, acceleration and deceleration, throttle use etc. that the results would be no more than subjective: what one rider can achieve, and just that; even if near complete objectivity could be achieved, the methods & lengths gone to would be so far removed from reality as to render any results artificial and hence almost meaningless. There would be other major limitations too: some bikes benefit more than most from pedal assistance, for example, and the benefits they give would be less than apparent from motor only tests and hence riders who intend to mostly pedal, however little, would find such results insufficient at best and misleading at worst.

Right now the most useful guide to range/speed of any particular bike to me would be from real-world usage, by experienced ebikers with good power management (purely to narrow the spread of results and to show a bike's full potential when ridden with economy) and with a quantitative evaluation of the type of terrain, hilliness & stops/starts for instance, to help interpret the results. The thread on Torq range shows what I mean, and that covers both limited and delimited use too yet still remains a useful guide.

Yet another limitation of owners attempting to provide useful performance data is that, for some bikes, there would likely be a lack/absence of owners to do so, which would again leave the big picture incomplete, being not fully representative in all senses. I've said elsewhere that I feel strongly the onus is on suppliers to provide such data, if they want their products to be given serious consideration as reliable vehicles for effective transport use rather than leisure toys for low-demand situations, lacking the quality needed for real-life performance.

I think an incline test would be useful' date=' there are a few bikes out there that could do it [/quote']

 

More than just a few I hope! Though limited by the number of bikes owned by members on this site, and further limited to those suited for gradients on motor only, with some attention to detail such as battery type, voltage, charge level etc. and obviously constant gradient and road condition, this could be a useful exercise, but it needs to be well-planned for most useful results e.g. speed of different bikes on a standard, chosen gradient may be more useful and achievable than simply steepest slope that can be climbed, but realistically since a standard gradient will be impractical, speed of bike on a constant gradient, both accurately measured, on a standard quality road surface, should be good enough to make some useful comparison (though only between bikes of same design e.g. hub motor bikes).

 

EDIT: Rider weights, weather & road conditions would have to be standardized etc. On the other hand, such data can be quite accurately and more easily guestimated from information about motor peak power output & gearing, or one could simply ask on the forum all are possibilities, in the absence of full information from most suppliers; those (very!) rare exceptions are praiseworthy for their efforts to provide such information.

 

It should be noted though that range in hilly (and even stop/start urban) terrain is quite variable and (if the hills can be scaled!) usually much reduced from range on flat for a given bike; such range variation is also useful for comparison between bikes for mixed terrain use, though usually a quality bike with good motor gearing and peak power output will perform best all-round in those circumstances.

 

I hope that's useful, and is received positively and constructively, as it is intended

 

Stuart.

I think there'd be too many differences Jed. Route variations, road surface, rider bulk and therefore wind resistance, tyre type and pressures, state of battery charge etc.

I think it could be difficult to read anything of value into the results.

N.B. Just seen Stuart got in before me to make similar points.

.

hehehe! but you were so much more concise flecc! And I've had to edit my post to almost backtrack after further thought anyway!

I was trying to make a general point really, not directed at Jed and a bit off-topic I know, but just wanted to get the points down while they were clear to me

EDIT: Any comments are welcome .

Stuart.

Edited June 11, 200718 yr by coops

hi flecc and stuart. it is ok my spirits are not dampened! I understand that unless we can get all the bikes together at the same place at the same time with the same rider in the same conditions it will never be truly scientific. I doubt pedelecs or A toB could manage that feat so in the absence of that kind of test i still think it is useful for the rest of us to at least do something. We all know that we'll never get the perfect answer but if we can build up a library of results then we can at least it will give newbies something to go on. If we record general weather conditions and rider weight then we can offset that against other results. If some bikes do better at pedelec mode then the test should be repeated with pedalling but perhaps the rider mustt keep as close to a certain speed as possible. i'm no expert but when choosing my bike that sort of thing would be very useful in my decision,.

thanks

Jed

it is ok my spirits are not dampened!

I'm very relieved to hear it Jed!

I'm also all for channeling enthusiasm and a proactive approach, in the almost total absence of necessary performance data for most from bike manufacturers and suppliers, and all for having a useful performance guide for prospective new ebike owners, which we all are: even those of us with three ebikes, or more! (cough, cough! ahem! )

The clear need for a guide is a big recurring topic, but how to go about it and tackle all the complexities and variables in a practicable and useful way is not easy to resolve.

My suggestion, if you really want to give it a go, would be to decide what performance criteria you'd want to measure, while bearing in mind how you'd sidestep or tackle the many different variables indicated in order to produce useful and fair results which can be a useful guide to performance in real-world situations.

With a sufficient number of accurate results, and given an objective way of standardizing them, like offsetting for weight etc. as you say, the consistency of results (so long as the tests are done "blind" to others' results!) would indicate to their accuracy and any irregularities should be easier to spot and discount if necessary.

That's another issue though - for the most reliable and representative data we'd need multiple measurements on multiple different bikes of each "model", or at the very least multiple runs on one bike: we'd be limited to information only on bike models we already own, so many models may be excluded, and only those models with many different owners testing would be very fairly represented. But on the other hand, if we were to be successful and influence bike sales, it may encourage some suppliers to be more forthcoming with information or, better still, improve their bike quality first! :-) think big, eh?! I really believe that the silence from some suppliers speaks volumes about their bikes' quality....

The most important thing is the accuracy and evenness of the results, since an inaccurate guide no better, and possibly worse, than none :-).

So, your mission, should you choose to accept it.... (cue music)!

Stuart.

The thing that threw me was your mention of a flat route Jed. Some of us don't have one!

What many accept as flat around here is a slope of 2% in fact. That might seem like nothing, but it means my torq will run to 24 mph without pedalling one way, but barely 17 mph the other. 5 mph is quite a difference.

The Twist is easy to pedal at 18 mph one way on that same apparently level stretch, but 14 mph the other way is about it, so even with that slower bike the difference is substantial.

What we really need is for the manufacturers/suppliers to give us three things the correct net power output in watts, the point at which peak torque occurs in mph, and the precise weight of each bike as supplied. Then a very accurate comparison chart would be easy to produce.

The motor industry has supplied their parallel facts honestly for years, so there's no excuse in our marketplace, where the lack of consumer information is a disgrace. I exempt no-one from this, there isn't one supplier making even the slightest effort to provide adequate information. Many seem to think hype is an adequate substitute, and even the best seem to believe that stating a motor is legally 200 watts or 250 watts is of value, when of course it's completely useless.

There will never be an accurate figure for range, simply because there never can be. The fact that a rider's assistance can vary from as little as 10% of a motor's power to as much as 200% or more of that, depending on the rider's ability, means it's impossible.

.

Edited June 11, 200718 yr by flecc

I totally agree flecc, except for one thing...

I exempt no-one from this' date=' there isn't one supplier making even the slightest effort to provide adequate information. [/quote']

 

I'd say thats almost universally the case; at least one or two do give the information you've specified (and I agree those are precisely the data we need), or at least make some effort to give a hill-climbing and range guide.

 

It seems to me that the electric bike market is very much in a situation where the buyers are often more informed (especially with sites like this!) than those selling: all the more reason to be proactive in giving and receiving advice on tremendously useful assets like pedelecs .

 

Stuart.

I don't know anyone giving the information that I mentioned Stuart, so I'm a bit puzzled at your mention of some doing that? Any names?

.

even the best seem to believe that stating a motor is legally 200 watts or 250 watts is of value, when of course it's completely useless.

.

I totally agree Flecc, in fact limiting the speed to the UK limit either by electronic or gearing methods allows the manufacturer to state the nominal output is 200W because that is the most the motor will develop powering a heavy rider at 15.5 mph on the level.

As you say peak power, and the speed at which it occurs is what really matters and the only place I've seen that quoted is here.. and not by the manufacturers.

Yes flecc: I hope I've not misunderstood your remarks, but when I say one or two either giving the info or making an effort, I mean that! I'm not sure if you only meant complete bikes, excluding kits, but the nanomotor site has a pdf (right click the link and choose "save as" to download, left click to just open) which has a torque graph showing the net output power and rpm at peak torque; motor weight is also given. 50Cycles deserve credit & a mention for making an effort to provide a useful & accessible comparison on hillclimbing aswell as range of the ezee bikes, and their specs pages provide useful information including controller current and voltage limits.

Other than those, I can't think of any other information made available as you say.

Stuart.

Edited June 11, 200718 yr by coops

That's it Stuart, kits yes, those manufacturers realise they have to give that information, though most don't do a very good job of it.

But the e-bike suppliers don't supply the motor information, and that's really not acceptable on a motorised vehicle. It is after all the most important thing.

50cycles do indeed make an effort at the other information, and that's what I meant when I said "even the best", since there's only the same bland statement of 200 watts substituting for motor information.

.

But the e-bike suppliers don't supply the motor information' date=' and that's really not acceptable on a motorised vehicle. It is after all the most important thing.[/quote']

 

Yes, I totally agree. I hope they either see sense, respond to consumer demand to do so (if electric transport ever reaches that level of uptake) or market forces dictate suppliers' business models to require it.

flecc, how many electric bike suppliers actually make the motors themselves? it seems to me that many parts we see on bikes over here that are made in china are used by lots of different companies. Are there companies there that just manufacture the motors and then the bike companies obviously buy them and fit to their bikes? Could we not go straight to them for the specs

thanks

Jed

Yes, the parts bin bikes are commonplace Jed, but Chinese companies often aren't very easily contactable by individuals. There are intermediary companies like Abracadabra who act as the web forwarding agent.

Enter a Chinese company name in Google or similar and you'll end up with the intermediary who forward messages. If you're not a company with a serious quantity inquiry, you don't get an answer. I've tried many times. The companies that are more easily contactable are all too often the junk manufacturers.

Just finding out who does what for whom is often impossible.

.

thanks Flecc, so for the most part it looks like we are back at square one then back to us to determine the range etc as best we can.

thanks

Jed

Guys

I still think you can get consistent results that would be indicative of the bikes' performance under different conditions by just doing simple tests. The conditions of the tests can be consistent enough I think - certainly car tests don't happen in vacuum and some spread is assumed there too.

Most towns (sorry flecc) have an 'industrial estate' with straight asphalt roads that is unused on weekends. I appreciate that bikes can have a varying top speed therefore we could have a 0-to-distance test with the result in seconds. I have been doing a similar thing on my bike every day on the same route and get fairly consistent results.

So how about this:

Standard Test 1 - 0 to 100 meters. From a full stop simply turn the throttle to max and measure the time when you reach the 100m mark.

this will give you a pretty good idea of the bike`s power delivery from start and at low revs, torque curve and this sort of thing which is important in everyday use and pulling out of junctions.

Standard Test 2 - top speed sustained over 100 m. Get to the throttle-only top speed before the first mark and measure the time to the second mark - then work out the speed in mph.

How to achieve consistent test conditions:

Cyclist weight: 75 kg - simply weigh yourself wearing a rucksack full of bricks/water bottles (that you can get rid of on the way back)- untill you get to 75 kg. If you are heavier get your kids/wife/gran to do it.

Battery condition: Charge the battery to full and cycle to the 'test range' on muscle power only

Wind / Not-quite flat effect: do the test in both directions on a non-so windy day.

Tyres: should be pumped up to bike manuf specs

Time measuring: use a simple stop watch

Data recording: do several tests and average - excluding any single wildly inconsistent results

Distance measuring: preferably do not use bike computer for this unless you measured and entered the actual distance covered per 1 rev while you are sitting on the bike as circumference

Now on the 'Range' test - I see it can get fuzzy - you will need to ride the bike around the block until it stops - obviously speed here will have a huge effect on results i.e. there would be speeds that get you further than others.

However I think the above 2 tests will also indicate the range performance - because all bikes are rated at constant 200w the only other things that would affect the range are battery size and 'mechanical efficiency' - which is tested in tests 1 and 2 especiallly.

obviously I intend to lead by example and have a go at this myslelf

As I posted before, the 200 watt rating is meaningless in performance terms, so comparison there is invalid. There are huge differences in the bikes on the market, some power curves being over double others, a more than 2 to 1 difference. Had you realised that peak motor powers on the market go from 272 watts at the bottom to 700 watts at the top? Any attempt at range assessment using 200 watts as a guide is worthless.

While I agree that a precision acceleration test with a fixed weight gives a roughly valid indication of hill climb ability, it's worthless to potential buyers. How do they relate the result to their own hill climb circumstance? In short, they can't.

The three tests I've just read do make sense for them. On the same 1 in 5 hill, one bike barely had the power for it's own weight, leaving the rider working as hard as if they'd ridden an ordinary bike. The second bike was better but still demanded quite a lot of work from the rider, while the third bike climbed it easily with only moderate assistance. That customers understand, your results they wouldn't.

The other problem is that people are notoriously bad at judging a flat road. Probably no-one can judge 2% from flat, and that makes a huge difference to performance. On the Torq theres a 4 mph differential between the up and down directions on 2%, on the Quando or Twist it's 3 mph differential. The results would again be worthless whenever someone inadvertently included a gentle gradient not perceivable by eye. The acceleration time difference between one on 2% up and another on 2% down would be very large.

I realise that you are trying to set up a system where we can publish results from our own bikes which can be compared, but the chance of actually achieving people sending in truly accurate timings on absolutely flat land is close to zero I think, especially given the weight adjustment procedure you propose.

In my case, I'd have to ride with the sack of bricks, bottles of water etc for six miles to get to the suggested factory estate, and even there the flat runs aren't precisely so, and are very short as much of it is on sloping ground.

.