Project Q bike

[coops]

I'm stealing from Leonardo's words, but bravissimo flecc! Or, in more modern parlance, respecc flecc! (hehehe! - been saving that one ).

Really impressive, and as you said before, its what it does & the way it does it that counts, and by adding the "legpower" gearing to the bike plus all the other mods added together the Q is not only highly practical & flexible for transport with or without loads on almost any gradient, but aesthetically there is a harmony of rider, bike & terrain working together which must, as you say, keep the smiles coming all the time - plus a choice of gears, speeds and load-carrying methods too!

I've wondered what the Quando plus gears would be capable of, and you've shown what, and then some! What a result on the range too, I've been impressed at the good efficiency of the Torq motor at a medium throttle setting, but in the Quando's wheels the motor must be fully at home and even more efficient :-) add the cumulative effect of all your mods and the Q is some bike I must say - more efficient than the Twist indeed!

I also get a bit lost in the engineering involved (you're not alone mike :-)) though I sort of understand the main ways you've improved the efficiency. Now the first question I'm very curious about the ease of pedalling to higher speeds and how that has been achieved: what would you say are the main factors? the efficiency of your large chain & cog wheels, or motor tuning, or that the motor is in 20" wheels (which I would have thought should make it harder to pedal to higher speed, compared to larger diameter, or have I got that completely wrong?!) or a combination of all the above?! Or something else entirely! The changes you've made, when added together, seem to have improved efficiency beyond simply adding gears, would you agree?

I must say I'm not surprised your other bikes are languishing in the garage ;-).

Congratulations on your new Q and the fun I'm sure you're having (long may it last!), and most of all for showing just how good a well-designed and implemented electric bike can perform. Let's hope that the Q bike inspires more of the same

[richard]

What a load of rubbish Flecc, you expect us to believe all these words and pictures ???
All I can say is God Bless You.... You are showing the way to designers and manufacturers, It just shows the knowledgeable analytical practical and innovative approach that is required to to push boundaries forward. I hope some body sits up and takes notice. I have !!
Congratulation for your labours.
Richard

[flecc]

Thanks very much for your generous responses Stuart and Richard, greatly appreciated.

On the efficiency of pedalling Stuart, the motor isn't involved other than it's accurate internal alignments not adding any unnecessary drag.

The elements are in two parts, first the general "rider-regardless" improvements which on this bike will enable any rider to realise almost all of it's abilities. Then there's the added rider matching, which adds an additional performance dimension. The two are together in the following and you'll recognise them in each where both exist.

1) The way in which the derailleur ratios match the bike's requirements, and also the fact that my abilities are matched in as well. You'll appreciate that top competition riders have their bikes for the Tour de France and the like individually made for them. We should ideally have the same. Choosing the ratios is part science, part black art, a bit like that in any field of racing.

2) The difference between the Kenda 2.125" tyres and the expensive but vastly superior Schwalbe Marathon Plus 1.75" ones. That improvement in rolling resistance is also enhanced by the thinwall latex low loss innertubes, in comparison with the thick rubber Kenda jobs. Accurately chosen tyre pressures also contribute here.

3) The vital element of the rider to bike geometry, which you will have noted I've carefully matched. We all have limited powers, whether Lance Armstrong or a pensioner, and the vital thing is that not a scrap of energy is wasted through body to bike mismatching. For that to be fully realised, it's necessary to feel totally at home with every aspect of the bike, both the physical elements directly bearing on the pedalling, and with every feature and function. The slightest element of being ill at ease affects performance, the psychosomatic factor.

4) Finally there's the additional matching of the physiological elements for the rider, the crank length to cadence preference matching for example.

Plus the parts efficiencies I've already specified in the main article of course, sprocket sizes etc.

[Baboonking]

Interesting Stuff Flecc,

Would I be correct to Sum up as:

comfortable, well designed base bike + correctly optimised motor + good range of gears = Very efficient long range electric bike?

You put my 'more amps plus more volts' philosophy to shame

[flecc]

I'd put it a bit differently Baboonking. Taking the elements you've mentioned:

The comfortable bit in terms of the choice of rear motor has been kept from the original, but the other comfort features like the heavily padded saddle and spring seatpost have been scrapped of put out of action because they are inefficient and definitely undesirable. So comfort is a bad start point.

Well designed base bike ONLY applied to the motor and some of it's associated parts and the full size wheelbase basic frame, otherwise the detailing was terrible from a bicycle efficiency point of view.

Apart from my ensuring the best build, the motor was already perfectly optimised for legal e-bike use.

The good range of gears doesn't of itself ensure efficiency, the ratios, component choice and matching are as important. A bike can have a correct range of gears but still perform below par because of wrong ratios, or low efficiency and/or mismatched parts for a particular application like megarange for example.

It's the sum of this attention to small details that makes the difference between the good products of experienced cycle manufacturers and the assemblers of poor bike parts thrown together for the discount market.

A lot can be discerned from looking at top race bikes. You'll never see a padded saddle, or a sprung seatpost, or any form of suspension, or for that matter a disc brake.

Those soft elements are missing because they are rider energy absorbers. The disc brake would just be extra weight because the rim is already the largest disc brake possible, so it's best to use what's there.
.

[FatMog]

It looks great Flecc - I don't pretend to understand the finer technical detail but I am (as ever) in awe of the depth of your knowledge and its practical application. We are lucky to have you, for both your patient responses to our endless questions here and for your contributions to wider world of e-biking.

We are not worthy...

[coops]

Nice one, fatmog :-)

Originally Posted by flecc

Thanks very much for your generous responses

I think the plaudits are well-deserved & well-earned

Thanks for the rapid & full reply to my query. I hesitate to continue this line of enquiry, for fear that the Q bike is becoming the mysterious "X bike": "how does it achieve these feats of endurance?!" but curiosity is getting the better of me...

So would I be right in saying that the lion's share of the Q bike's speed "gains" without the motor on (apart from the new gears, obviously) are due to its customisation to your body-frame and riding style, allowing (for you) improved "pedalability" & hence more efficient conversion of your legpower to speed? Since you are a strong cyclist, that could account for quite a high speed gain, no?

Given what's been said about the relatively increased drag of a hub motor at higher speed, I'm quite happily surprised you can do 24mph without motor assist!! All I can say is, unless for some reason there is less drag from the same motor in a 20" wheel than a 28" wheel (and as I said before, logically I would have expected more, not less? - due to faster rotation of the hub relative to a 28" wheel) you must be able to give it some welly to achieve that sort of speed!

I wouldn't say I'm a fit cyclist, nor have I really tried to pedal a Torq to high speed, and my frame size (6ft near enough) may suit a Torq a bit better than yours, but like you I also start to struggle beyond 13mph: and that's for a bike with similar weight & the same motor as the Q bike, but 28" wheels and minimal rider customisation.

So you can see why I'm surprised, and I'd like to understand the factors that assist your efficiency on the Q bike better (note the careful wording - because I'm aware now that it's you and the bike together, not just about the bike now, is it ).

Stuart.

[allotmenteer]

Hello Flecc

Still haven't got through all the article yet but looking at the pictures that motor looks awfully similar to my hub motor kit. I also cut the thread for the band brake off but haven't yet rebuilt the wheel with an offset as you have so my rear brakes don't work very well, though the cheap pads and v-brakes may have something to do with that.

When I bought my motor kit my intention was to use it on my high quality Marin MTB but I hit problems with the width of the motor and the gears etc but my idea was to electrify a bike which had very high quality components and frame rather than make do with a cheap and poor quality one which I have ended up doing. This has detracted from my enjoyment of the kit (though I do get a lot of use out of it). I think you have hit the nail on the head in improving the non-electric parts of the bike and thus indirectly improving the performance of the whole.

Hmm, if the motor is the same as mine then that's good news as all I have to do is get a 36V battery + charger and I'll have a Torq kit. I reckon my controller will take it as the MOSFETs are rated at 60V and 42A (at 100 degrees C) so it could be a cheap(ish) upgrade.

However, taking on board your article, perhaps it'd be better to improve the efficiency of the bike before ramping up the power. Particularly since at speeds over 20mph most of the power is wasted fighting wind resistance. There is certainly room for improvement on my setup so your article has given me lots to think about.

Many thanks

Paul

[flecc]

No, most of it is the bike Stuart, the rider optimisation is the lesser part by far.

The mechanical differences between a good bike and a bad bike are often very small. Because our power is so small, slight losses in efficiency can have quite a severe effect. In terms of sustained power at my older age, keeping the output at 200 watts for a while is quite tough, so it doesn't take much of a mechanical inefficiency to knock a small hole in that.

There's a good comparison here with the Gossamer Albatross, the pedal powered plane that flew the Channel. The rider's power and the craft's efficiency were just enough for it to happen, but the minutest loss of the craft's efficiency would have brought it straight down. In other words, the difference between success and total failure was miniscule.

I'm not a very powerful rider, but up to just over three years ago I was able to ride an unassisted but quite efficient bike up to 24 mph with an effort, but I couldn't keep it there, dropping back to 19/20 mph. Equally I could get the Twist up to 23 mph in a burst as it's quite efficient, again dropping back to 19/20 mph, and I can still ride the Twist at 19 or so mph for a three quarter mile flat stretch on Kent Gate Way. That now also applies to the Q bike, both the 24 mph burst speed and the sustained speed.

In another example, the Torq as an unpowered bike has nowhere near the same bike only efficiency as the Q bike. It's main energy loss is the standard tyres that are still fitted, there's a further loss from it's high profile, and more due to it's derailleur, which is over-high geared for manual only use because it's matched to the motor's over-gearing. It's larger wheel could only be more efficient if suitably tyred and at a size equalised pressure, but even then, it would still be slower on acceleration due the higher energy needed to accelerate the rim/spoke mass that's at an 8" greater radius. Now add to that the lesser element of the rider not being matched to those features, plus the effect of the rider energy drain due to the front wheel gyroscopic forces and the motor wheel's unsprung weight bounce and you can see the scale of it's total shortfall. But it's also clear that most of it is the bike, not the rider matching that's the cause of then lower performance.

The same applies in the opposite direction, that of efficiency gains, most is the bike, only a smaller part is the rider matching.
.

[Mike Robinson]

I presume it's called a Q bike because of "Q cars" which are supposed to look ordinary but are fitted with powerful motors and running gear to have higher performance.

There were also "Q ships" in WWII which looked like ordinary freighters but instead were heavily armed to knock out German subs.

Of course it may just be because you just got tired scrapping the letters off the frame of your donor bike the Quando.

Mike