Project Q bike

[flecc]

The snag with that sort of electrical solution is the increase in consumption making range suffer kraeuterbutter , and that's why I wouldn't use it. We do have some brushless motors like that on the market, and that's why I know the consumption problem.

In the case of my Q bike there's no point anyway, since it can climb anything met with ease, and it's good range is valuable.
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[kraeuterbutter]

The snag with that sort of electrical solution is the increase in consumption making range suffer kraeuterbutter

??

why.. don´t understand this point...
it should improve your range not other way round..

because: on hills the efficience would be much greater,on the flat it would run like always..

the torque is effected by the squareroot of 3
so at same given voltage and same ampere:
torque * 1.732
rpm * 1/1.732

http://www.elektrikforen.de/attachments/grundlagen-der-elektroinstallation/81d1162770834-leistungsschild-vom-drehstrommotor-drehstrom1.jpg

a bike without that would fall of with torque, efficience will go far down..

so: if this is intelligently made (controlled by the controller) that would for sure improve things and distance..

 

[kraeuterbutter]

to make picture that says maybe more than some forumlas:

a bike that goes with 26mph in the flat and comes to a hill,were it can go only 13mph at full throttle (50% loose of rpm compared to flat)
==> the efficience would be HORRIBLE to say at least.. less than 50%

so more than half of the energie out of the batts is generated to heat

when you now swith to star-configuration,
the same bike would drive only ~16mph in flat
on the hill it will maybe go up only with 10-11mph.. (so only ~35% loose of rpm, eff. much higher)
BUT: the efficience would be for that much higher, not generating so much heat

thats how it is made for lehner-motors:
triangle:
picture 1

star:
picture 2

this configuration must be done by the controller.. when it would be a intelligent design,
it starts always with star-configuration and switches when the 100% speed is reached to triangle for further speed
the controller knows the rotating field (hall-sensors or by measuring the induction-currents of the unused windings anyway)
and so a switch should be possible without beeing noticed by the user on the bike
that would result in more power, better efficiencet motors without higher weight

it was used already for competition use on rc-planes this way to get most efficience for long-flying-records..
so the motor does not need to run with partial load, but also on reduced rpm with full throttle = most efficience, much less iron-looses and eddy current from partial load

 

[coops]

@ flecc: I think kraeuterbutter may be suggesting it for the Torq Radical project, which has lately invaded this Q thread .

@kraeuterbutter: Hi, I think flecc may refer to losses in efficiency due to a compromise "switching" setup, plus the method would not be necessary for the Q as he said, but if your idea is aimed at the "Torq Radical" project hinted at on this thread lately, the details & comments on that are now in that thread; full details of the project on flecc's T bike pages .

P.S. can we abbreviate your name please?! I'm always concerned at mis-spelling it!

Stuart.

 

[flecc]

I think that as usual there are differences in the theory, RC models and the practice in E-bikes kraeuterbutter.

I agree with the theory, but know of what has happened in bike use.

It's rather like the battery situation where you insist that newer types are far more efficient, showing that graphically like the manufacturers do, but when the e-bike manufacturers try them, the reality is different.

There's a very real difference between an RC model and a power assisted bike, and that's the cyclist. There's no pilot pedalling in the RC model.

Present a cyclist with a hugely powerful motor as you suggest and they often treat it like a motor cycle and don't pedal.

But if they have to pedal with a motor that's weaker on a hill, they can put in an amount of effort which evens things out.

The two will never compare.

 

[Fat Girl]

How about weight?

Hi Flecc
your enthusiasm for this bike is catching and its making me think about a purchase. I was wondering what you weigh? I don't mean to get too personal, Its just that I'm 15 stone and need to know if I can get the same performance on my cotswold hills as you are reporting
Mil

 

[flecc]

I'm 70 kilos Mil, just over 11 stones, so the extra 4 stones will certainly make a big difference. Bear in mind that you cannot buy a Q bike and it's very unlikely that a dealer would or could produce one for you. The standard product is the Quando, and that's a very good hill climber on motor only, but as it has no rider gears, it's limited on the steepest hills since the single gear is only suited to the rider helping at about 9 to 14 mph.

I found that ok on motor only on 1 in 8 (12%) hills, A to B magazine found the same with a similar weight rider. Having 10 kilos of shopping on board would reduce that to 1 in 9, so it's likely the extra 40 kilos would reduce it to about 1 in 12 (8%) on motor only. Adding your cycling effort could get that back up to 1 in 10 or 1 in 8 if you are quite strong.

A better option but much dearer are the newly introduced eZee F series bikes, since they have motors about 25% more powerful that usual, plus 8 speed rider gears. The models are the Forte with hub gear and the Forza with derailleur gear, but both are crossbar bikes.

If you wanted a step through frame, the eZee Sprint is a little bit less powerful than the Quando, but has 7 speed hub gear, so as long as you can provide a reasonable contribution it climbs quite well.

As ever though, there's no substitute for trial rides, preferably in hilly country similar to your own. 50cycles have a number of users who are prepared to offer trial rides in various areas, so it's worth contacting them and asking. Here's the contact webpage.
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[Fat Girl]

Hi Flecc
thanks for your advice
I've contacted the shop and await their reply
mil

 

[john]

is it legal?

Hi Flecc,
I read your q-bike project on your web site and some of this thread, but one thing puzzles me:
You said that you wanted to make a street legal bike and so didn't go for a kit. But I think I read that your q-bike motor helps up to ~18mph. To be legal the motor needs to be rated at 200W (or 250W) continuous (whatever that means) and cut out at 15 mph.

Cheers, John

 

[flecc]

Hi John

I didn't in any way alter the motor drive side of the Quando for performance purposes, or change it's gearing to raise it's speed.

There's lots of manufacturer interpretations of the 15 mph limit, and the most common is not to actually limit the speed but to gear the motor so that it attains approximately 15 mph on the supply voltage, electric motor speeds being controlled by that.

This can be interpreted as having 15 mph at the freshly charged voltage, gradually slowing as the battery charge reduces, or 15 mph at the battery's lowest voltage, meaning it goes faster when the battery is freshly charged. eZee use this second interpretation on their models, and the market is roughly split along those lines, lower powered motors geared for the lower interpretation, higher powered ones the other way.

The Quando was originally designed with a nominal 36 volt NiMh battery, which has a peak of around 39 volts which drops the moment it's put under load, and with that the bike did about 17 mph on the flat when freshly charged. Later the Li-ion battery was introduced to all models, and that happens to correspond to 37 volts nominal, with a peak of over 41 volts which doesn't drop so fast under light load. Therefore the bike does about 18 mph or a little more with a battery freshly charged, though as the content is used up, it too drops to 15 mph eventually.

In saying I wanted my bike to be road legal, I meant as supplied legally to the market, as distinct from using the usual performance route of a motor deliberately designed or changed to break the law.

In fact few hub motor bikes actually have a specific speed limiter cutting the power at 15 mph, and it could be said that there are hardly any that actually comply strictly with the law. That states that the power should phase down well before 15 mph, normally from around 12/13 mph, gradually subsiding to zero at 25 kph (15.5 mph).

The only bikes that do that completely at present are those using the Panasonic standard crank motor unit, even those ones with the higher power option not observing the law strictly.
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