To give a better indication of hill-climbing ability, all the commercial bikes should be in standard trim, fully charged and the same rider rides each in turn without pedalling. Using various gradients we can then get an idea of how well each bike performs. Otherwise there are too many variables once you introduce pedalling, rider weights and fitness as well.

 

Still, we are a long way off these guys

 

I used hills like that to practice on with my power bike, but it didn't test my 58 year old legs enough. :D

 

 

That was exciting. He would have had a great opportunity to test his rollcage had he not cannily put left lock on before keeling over. There used to a Saturday morning show from Iceland with weird and wonderful vehicles doing the same thing up black, volcanic slopes. I don't recall them being that high though.

 

e.g.

 

and success (could do without the appalling music though) YouTube - Awesome ! Car Going up the hill!!!!!

Edited February 14, 200719 yr by Tim

There used to a Saturday morning show from Iceland with weird and wonderful vehicles doing the same thing up black, volcanic slopes.

 

They're a crazy lot in Iceland. My favourite visual trick of theirs is the way that they inflate a tyre on one of those weird vehicles after puncturing it, with an explosive charge! No time for pumps, only for for fun.

.

In reality, who could really be bothered to trek out to the Presteigne course with a theodolite and spirit level and then set up a bike to suit it?

Hopefully no-one but I can imagin some parties may feel under marketing pressure to make their products perform well in such an event with the media watching, not to mention all those potential buyers [insert salivating face icon here]

 

Knowing the gradients and lengths of the hills in advance, whether it be from direct experience with surveying equipment (unlikely) or via information gained from the planner or organising team somehow would give modifiers a head start.

 

Russ made the point that he'd like to see the bikes tested by the same rider without pedaling but with some, such as the Classic Twist (which were VERY well represented there in 2006), this wont be a possibility as the power assistance is related to the pedaling effort. With these sorts of bikes unless you do at least some pedalling, you're going nowhere (except for downhill of course).

Edited February 14, 200719 yr by Flying Kiwi

Could anyone explain in more detail the differences in performance between the Liv motor, and the one in the Sprint/Torq? Flecc, you wrote this:

 

Since the type of motor used in the Rider/Liv has a more "peaky" power characteristic than the Hall effect motors of the Sprint/Torq series, the actual results could be slightly below those in real world conditions, but not seriously so.

 

What does 'peaky' mean here? Is it that there is a narrower rev band over which the motor performs well? Any idea what the peak power on the Liv motor is?

 

Edit: Also, these are the ratings listed for Sprint 7-gear system:

 

Shimano Nexus Inter-7

(39, 46.2, 52, 62.4, 73.3, 83.3, 96)

 

Any idea what the equivalent numbers are for the inter-3 on the Liv?

 

Edit2: Answering my own question, I got these figures from the CTC website (CTC - the UK's national cyclists organisation)

 

244% 0.63 0.74 0.84 0.99 1.15 1.34 1.55 (Inter-7)

186% 0.73 1 1.36 (Inter-3)

 

Cheers,

Q

Edited February 19, 200719 yr by Quicken

Unfortunately the 50cycles website doesn't give the sprocket used on the Nexus hubs, only the chainwheels. However, by back calculation the Sprint uses a 19 tooth sprocket, and if the Liv's Nexus 3 uses the same, the gear inches will be 46" - 63" - 86".

 

I emphasize that's based on that assumption, though it appears right when compared to eZee's past gearing practice with the Nexus Inter 3.

 

Regarding the Liv motor characteristic, it's a brush motor. Hall effect motors tend to have a fairly flat wide-topped power curve, in comparison with brush motors which have a steeper sided power "curve" with a fairly pronounced peak, more mountain in shape rather than round top hill. The peak is usually at quite a high power, often much higher than an equivalent Hall effect motor, but because it's only sustained over a a very narrow rev point, it's not as useful as it looks, since one cannot always arrange to be exactly at that motor revs point. I can't give figures for the Liv as I haven't seen them published, I've only been able to draw some average conclusions by back calculation from the Rider weight and performance.

 

However, to illustrate the point I can quote the standard Heinzmann 200 watt brush motor. It peaks at 600 watts, while the eZee Quando/Torq 250 watt Hall effect motor peaks lower at 576 watts. Despite that, the Heinzmann falls well short of the usable power and performance that the eZee motor can produce in practice, since the latter's slightly lower peak power is sustained over a wider rev range.

 

The brush and Hall effect motor characteristics mainly result from the more consistent power transfer of the controller on the latter over the rev range, than that of the brushes which lose efficiency in that respect at other than the optimum point.

Edited February 20, 200719 yr by flecc

Nigel

 

Hi flecc

do you think the ezee liv will be on the same terms as the powabyke for performance but 10 kilos less in weight would that sum it up i can understand that a bit better then to much tecno babble do you think ezee used a brushed motor because of costs i dont mean to be negative? I am not sure any bike that is 30 kilos will be easy to pedel without power on:confused: i thought the twist was just about right BIKE weights must come down to 20 kilos all bikes all less nigel.

It's a sort of yes/no answer Nigel. The Powabyke motor is a real "juice eater", made up for by it's very large battery. It's peak power is 700 watts, a seemingly massive figure. But it's power "curve" really is a spike, straight and straight down again, so still giving the legal average. You could treat a Powabyke as a light motorbike and forget the pedals virtually all the time.

 

I doubt that's true of the Liv, I'd expect it to perform more like an electric bike with the bike part more usable. I'm sure the Liv uses that brush motor because it was already there, a proven design used before, sitting on the shelf and available to keep costs down on a quality budget priced bike.

.

nigel

 

hi flecc

i suppose if a bike company got most things right ie the perfect bike for a budget price then there wont be enough profit in it for a company to keep the product going hence giant twist lite.nigel

Probably true in part Nigel, but the perfect electric bike isn't possible, now or in the foreseeable future.

 

We want enough power to allow any capability of rider to tackle the steepest hills comfortably, but a long range as well!

 

We want the bike to have all the facilities and equipment as well as the above capabilities, but be as light as a normal bike and ride like one when not under power!

 

Ideally we'd like to have the motor free of the wheels and be driving through the gears while still being powerful. But that means whole new gearbox systems which will be much heavier!

 

You can see that those things constantly act against each other, so it's impossible even before cost enters into it.

 

The cost is just the final killer to any aspirations for technical perfection.

 

As if that wasn't enough, the legislators put in place further restrictions to design progress.

nigel

 

OH dear

not much hope then:( so at the moment would say the giant twistlite was and still is the best of the lot for the time being as a true all rounder:D

Yes, that sums it up, it's the nearest anyone has got. The basic Twist was slightly improved in one way for the USA by having the SRAM P5 hub, but could have had a further slight improvement.

 

I would have like to have seen a UK spec basic Twist with the SRAM P5 Cargo hub which is a bit stronger, coupled with a motor slightly more powerful at about 450 watts peak and 8/9 Ah cells in the same battery. That would have meant hardly any change in weight but a better climb speed performance and still with good range.

 

The hub and cell improvements I've done, but the motor one isn't possible with the same software for a privateer.

.

Nigel

 

So the million dollar question is why has no other electric bike company tried to copy its design if most of us know it was the best that would be the way to go

The answer to that is twofold Nigel.

 

First there's the correct perception that so few potential customers know what constitutes a good electric bike, so the investment wouldn't pay off as well as it should.

 

Second, so much can be achieved by other methods. For example, the Quando is capable of virtually all my heavy hauling which the Twist normally does and has immense hill climbing ability due to sheer power. It only misses out on the normal bike characteristics.

 

Other much lighter bikes like the Powacycle Salisbury and some similar bikes from other makers go a long way towards the ordinary cycle character.

 

Therefore it's understandable that manufacturers might think, why bother?

.

Unfortunately the 50cycles website doesn't give the sprocket used on the Nexus hubs, only the chainwheels. However, by back calculation the Sprint uses a 19 tooth sprocket, and if the Liv's Nexus 3 uses the same, the gear inches will be 46" - 63" - 86".

 

I emphasize that's based on that assumption, though it appears right when compared to eZee's past gearing practice with the Nexus Inter 3.

 

Regarding the Liv motor characteristic, it's a brush motor. Hall effect motors tend to have a fairly flat wide-topped power curve, in comparison with brush motors which have a steeper sided power "curve" with a fairly pronounced peak, more mountain in shape rather than round top hill. The peak is usually at quite a high power, often much higher than an equivalent Hall effect motor, but because it's only sustained over a a very narrow rev point, it's not as useful as it looks, since one cannot always arrange to be exactly at that motor revs point. I can't give figures for the Liv as I haven't seen them published, I've only been able to draw some average conclusions by back calculation from the Rider weight and performance.

 

However, to illustrate the point I can quote the standard Heinzmann 200 watt brush motor. It peaks at 600 watts, while the eZee Quando/Torq 250 watt Hall effect motor peaks lower at 576 watts. Despite that, the Heinzmann falls well short of the usable power and performance that the eZee motor can produce in practice, since the latter's slightly lower peak power is sustained over a wider rev range.

 

The brush and Hall effect motor characteristics mainly result from the more consistent power transfer of the controller on the latter over the rev range, than that of the brushes which lose efficiency in that respect at other than the optimum point.

 

So the trick with a bike like the Liv, with just three gears and a (possibly) peaky motor output, will be getting the pedalling and gear combination right to get maximum performance out of the motor. Climbing the mountain, if you will. Sounds doable...

 

Cheers,

Q

That's it Quicken, the flexibility between ideal gear points should come from the rider's power. Perhaps not as bad as it might sound though, since with three gears there's more pedal time transmitted than when going through seven.

Nigel

 

not more tecno babble gee wizz i am lost i give up with you guys:p all that over 3 gears?

But it's good fun isn't it Nigel?

 

And it's a way of still enjoying the bikes when it's bucketing down outside.

not more tecno babble gee wizz i am lost i give up with you guys:p all that over 3 gears?

 

Well, breaking it down, here's my current understanding. Motors only give their maximum power output over a restricted range of RPM. The trick is to select the right gear (probably the top one on the flat, middle one on moderate hills, and bottom one on steep hills) and peddle enough to keep the motor in the maximum power band of RPM's (so it's giving you the most help). I imagine you can hear the rpm of the motor on the bike, and use that to optimise performance (a bit like listening to your car engine to decide when to change gear). The learning curve will be in determining what motor frequency means it is giving its max output. Then you can aim for that sound by changing pedaling effort and/or changing gear. I hope that makes sense.

 

Cheers,

Q

Nigel

 

Hi flecc

would it be possibile to do a dummys guide for me? on how a electric bike works ie what does volts mean and watts and it all comes together to give 15mph PS how does the torq get that extra speed:D nigel

Wow, that's a tall order Nigel!

 

In the following, don't let the numbers overwhelm, just look at each section in turn and take your time to understand the general relationship.

 

First the speeds and hill climbing

 

Most hub motors run through a hub turns per minute (revs) range from zero to about 300 turns each minute. That's roughly true of the same hub fitted in both the Quando and the Torq which run from 0 to about 280 turns of the hub each minute, equal to 16800 turns each hour.

 

Now in the Quando the hub is in a 20" wheel, which has a circumference around it of 62.8", so with each turn it travels 62.8" inches forward. Therefore, if we allow it to turn at it's maximum of about 16800 turns in one hour, it will have travelled enough inches (16800 x 62.8") to travel just over 16 miles in distance. So it's doing 16 mph.

 

In the Torq, the same motor is in a 28" wheel, which has a circumference of 87.9", so it travels that with each turn. That means that if we allow it to turn at it's maximum 16800 times each hour again, it will have travelled more inches (16800 x 87.9"), equal to just over 23 miles. So it's doing 23 mph although it's exactly the same motor.

 

Since both motors are the same and have the same power, the Torq in travelling further has had to divide the power between more metres travelled. That means that each metre had less power applied to it. That in turn means the Torq is not as good a hill climber. To explain that further, lets say we test the Quando to find the steepest hill it can climb, using all the power per metre that it has. Now if we try to climb that on the Torq, it won't manage it, since it has less power per metre than is necessary, it will have to ask it's rider to do a lot more to make up the difference to bring it to the Quando's power per metre.

 

So why can't we just ride the Torq at the same speed as the Quando, and therefore have the same power per metre? That brings us to:

 

Peak motor powers

 

As a motor starts turning, it starts to use the battery energy, but it turns very little into driving power, most is just draining away, wasted. As it's number of turns per minute rise, it starts to turn more of the energy into power, this showing as a rising line on a power graph. At about half it's possible turns per minute, it reaches a point where most of the energy turns into power, and this is it's point of maximum torque (pulling power). This is the point we need to use to best climb hills.

 

Since the Torq uses its turns per minute to run to about 23 mph if derestricted for off road use, at half the turns (revs) it will be doing about 12 mph, and that's where its best pulling power will be. On the Quando, half it's possible turns per minutes is equal to half 16 mph, so about 8 mph, so we climb at that.

 

If we climb at a lower speed on the Torq, say 8 mph, we won't have reached that maximum torque point so will only have about two thirds of the power, so we don't gain anything.

 

Power curves and Power band

 

We've seen above how the power curve rose towards maximum torque which we climb at, about half the speed a bike can do, and in doing that wasted less and less power. From then on as the speed increases when riding on the flat for example, the pulling power (torque) starts falling again, but this time without wasting any energy.

 

Eventually at about it's maximum speed it will be using very little energy and also wasting virtually none, so we call that the point of maximum efficiency. We call the area between the Maximum Torque and the Maximum Efficiency the Power Band, since that's the best area of turns per minute to use.

 

Gears

 

As above, it's best to stay within the power band, but we also need to ride at very slow speeds. We also want to climb hills that are steeper than the bikes speed that the maximum torque point can allow. The way to best get round that is to have some way of shifting the maximum torque and efficiency points to speeds that we need to ride at to do those extra things.

 

That can be achieved by having the motor drive through gears that can be changed, so that a number of turns can result in less road speed or more, and that's the way the old Twist does it. By changing down so that the maximum pulling power appears at a lower speed, so less distance travelled over a minute, that power is spread over less metres travelled, so there's more power for each metre. That makes it possible to climb a steeper hill.

 

By changing up the gear to put the point of maximum efficiency at a higher speed, the bikes speed can be increased up to the point where wind and rolling resistance overcomes the available power.

 

Volts and Watts

 

These are often compared to mains water supply in teaching the subject Nigel. Purists need not correct!!!

 

Imagine you hold your thumb over the end of a tap and turn the water on. You can feel the pressure but it's not doing anything. Electrically that's what Volts are, a potential for something.

 

Now have your thumb off the tap and the water flows at a certain rate of gallons per minute. Electrically that's current in Amps, an amount flowing through.

 

If there's a lot flowing through at very high pressure, that's lots of power. Electrically that's watts, the current flow multiplied in power by the pressure, therefore Amps x Volts = Watts.

 

If there's less of either the volts (pressure) or the amps (current flow) the power will be reduced. That's how we control our motors.

 

Hope this has been of some help Nigel, but I think you'll need to print it out to get the best out of it with a couple of re-reads.

Edited February 20, 200719 yr by flecc

Nigel

 

Let me know if that's ok so far, and then I'll add how that electrical side comes together to make the motors work.

Nigel

 

Thats great flecc

i will print it of as you said and take it to work tonight and see if that grey matter will soak some of the imformation you have supplied many thanks nigel:)

eZee Livs have arrived

 

http://www.50cycles.com/images/images2007/liv122.jpgWe took delivery of the first eZee Livs this morning and first impression is that it's a great move by eZee to introduce a bike that performs so well at this price. Quiet and smooth power, good riding position, a neat little nexus 3-speed hub and twistgrip gear shifter - it makes for a superb electric bike package. I went for a quick test ride and ended up doing a couple of circuits of Loughborough town centre.

 

The first person to ride one in the UK was a customer who turned up here at the warehouse and decided it was the bike for him and bought one on the spot.

Edited March 16, 200719 yr by Tim