Light, fastest, climbs mountains, and pretty efficient

[prState]

I had an idea for this. I know everyone is skeptical (even me). There is at least one tradeoff though.

First you have one hub motor, in the style of flecc's Torq bike. I'm not sure what you could reasonably maximize top speed to, but let's say you do that.

The other hub motor on the other wheel (and this is key to strength), would be as small as possible, yet geared to only run about 6 mph (roughly a third of the Quando).
And that's the catch. You could climb probably any manmade road, not only without pedaling, but using very little battery energy (efficiency), because you're geared so extremely low but you also wouldn't move too fast.

And here's another trick for the engineers. Even on level ground the bike could start off with the first small hub motor up to 6mph, and then switch automatcally to the larger faster hub motor on all speeds above that.

So, essentially, you have a fast torg, with bottom end grunt and a little extra weight -- if you can do the tricky electrical shift between two motors somehow. You also need a small hub motor, maybe half the size and weight of the quando/torque to use, geared planetary-wise to work as described.

 

[prState]

I'm hoping that my understanding of planetery gearing is correct, and you could make a slower smaller powerful hub. But not really sure.

 

[pgbw]

Isn't this essentially an attempt to replicate the advantage of a crank-mounted motor that drives through the gears?

Your suggestion is essentially an electric/electronic 'gear box', which may be a way to go - it may be the only way that's feasible now, but it must be more to carry, more to go wrong, and more of a compromise?

Now, if hub motors are good, we need a hub motor with a gear box (but that's still duplicating the pedal's gears (where fitted) - or can the pedal gearing and the motor gearing be combined in a single hub? Or am I missing something more significant?

 

[coops]

Hi prState & pgbw

In case it adds useful information to this discussion, adding a second motor to a bike, specifically a Torq (starts a few posts into that thread) has cropped up before, a while back in pre T-bike times , though no conclusion drawn as I recall: also some of the ideas mentioned in that thread have since been pretty much discounted as non-starters, such as the cyclone chain-drive.

I believe your idea echoes, in principle, what flecc said towards the end of JohnInStockie's "what makes an efficient road bike?" thread regarding hub motors needing only 1 or perhaps 2 gears to cover a reasonable speed range (depending what your desired top speed is :roleyes: ), with one at around 8mph for hill torque.

I'm not sure either about hub motors, gearing & torque, but I suspect that even a low speed high torque 2nd hub motor will add weight & possibly drag too to a bike, so some compromise on top speed may be required unless a hub motor with internal gearbox comes along .

To be honest, I feel for an electric bike there is a natural "ceiling" for speed, given current battery capacities & weights: unless you want to carry many kg of batteries, or recharge often or just make very short, rapid trips, then very high speed isn't really an option? even 20mph uses around twice the power of 15mph, on the flat! Halving your range.

The choice is yours, as they say .

Stuart.

 

[flecc]

That's perfectly possible prState. The Torq uses the Quando motor which was designed for a 20" wheel, hence it's 40% overgearing in a 28" wheel and corresponding speed.

I believe it's already been done by occasional owners, and one UK owner has a Twist with a high speed version of the Heinzmann motor in the front hub as well, giving him switching of Heinzmann for 19 mph, Twist for climbing, or both together to go mad! He didn't stop there either. As well as the two batteries on board, there's a tiny Honda generator on the rack throwing it's bit into the ring.

From memory it was 37 kilos, still within the legal weight limits, but wildly illegal in just about every other respect.
.

 

[flecc]

Reference pgbw's post, there is another excellent solution which the entire industry has missed due to the failure to think outside the box. One day one of them might wake up and have a eureka moment, but meanwhile I just stand back smiling at such widespread failure to realise and foolishness.

This is a challenge to you all. Can you beat the industry and spot what I'm speaking of?
.

 

[coops]

More challenges, I don't know... .

I'm not very engineering minded, flecc, but since pgbw asks "can the pedal gearing and the motor gearing be combined in a single hub?" to avoid duplication of gears, is it that hub pedal gears could be incorporated into a rear hub motor somehow? (Just don't ask me how! )

I'd have thought that would've been done though, if possible, since it seems quite a self-evident idea to me??

Stuart.

 

[flecc]

since pgbw asks "can the pedal gearing and the motor gearing be combined in a single hub?" to avoid duplication of gears, is it that hub pedal gears could be incorporated into a rear hub motor somehow?

Stuart.

In a vague sense that's already been done in the Swizzbee, but with derailleur too.

No clues on my above challenge, but you don't particularly need to be mechanically minded to solve it. It's one of those "Of course, why didn't I see it before!" things. There's none so blind as those who won't see.
.

 

[pgbw]

I can see that a shaft drive would be able to move the weight off the wheel, so it could go somewhere better. There was a report in a Velovision magazine about a (non-electric) bike with shaft drive, but I've never seen one out or in a shop.

Is that warm?

 

[Miles]

Reference pgbw's post, there is another excellent solution which the entire industry has missed due to the failure to think outside the box. One day one of them might wake up and have a eureka moment, but meanwhile I just stand back smiling at such widespread failure to realise and foolishness.

This is a challenge to you all. Can you beat the industry and spot what I'm speaking of?
.

........

 

[ITSPETEINIT]

Now, if hub motors are good, we need a hub motor with a gear box (but that's still duplicating the pedal's gears (where fitted) - or can the pedal gearing and the motor gearing be combined in a single hub? Or am I missing something more significant?

This is a challenge to you all. Can you beat the industry and spot what I'm speaking of?

I AM NO ENGINEER!!
Does not pgbw 'all but' give the solution?
Suppose one makes the centre of the Motor Hub a Hub Gear, then the Motor turns the spoked wheel as if the centre were fixed (same ratio as before). BUT, the ratio of the hub case (the bit that turns the rim) to the sprocket (rider's gear) is increased or decreased according to the gear selected by the rider.
THUS, the motion (rim speed) that is influenced by the relative ratios of the hub gear internals applies to both the motor and the rider, proportionately (or is that 'inversely proportionate'?).
Is this twaddle? (Be kind!)
Peter

 

[pgbw]

Methinks that we want the motor on the same side as the pedals, so that the power from both goes through the gears to get to the wheel - the pedaler(?) has a soft spot for power, and so does the motor. The gears should keep both in their soft spots.

BTW, yes, I'm an engineer, but not mechanical. I'm thinking is 'systems' terms,m rather than physical implimentation.

 

[flecc]

Not shaft drive pgbw, nor related to it. The drive you've seen is the Zero, quite widely available. I think a Birmingham base here and also in the USA.

As an afterthought, I will give one clue. I spotted this years ago because as an engineer I'm a polymath with experience in many fields. The industry hasn't spotted it since they have electric motor systems designers and cycle designers (of a sort, real cycle designers being as rare as hens teeth). Neither has a clue about each other's discipline, the latter not much about their own as well.

That makes it easier for members here who have just a little bit of knowledge of both to spot what I speak of.
.

 

[flecc]

Not twaddle at all Peter, but not the answer. Sorry. Actually that's almost Swizzbee again.

Again no, pgbw.

It really is a eureka type thing, blindingly simple once seen, but not easy to guess.
.

 

[coops]

A wild guess, and again I've no idea of its feasibility, but why not bung the whole lot motor, gears & all in the crank? That may be wrong, but its a little outside the box, isn't it? Seems simpler too?

 

[flecc]

A wild guess, and again I've no idea of its feasibility, but why not bung the whole lot motor, gears & all in the crank? That may be wrong, but its a little outside the box, isn't it? Seems simpler too?

Feasible again Stuart, but not the simple answer, which almost exists but for the failure to see that it does.
.

 

[prState]

Put all the batteries in a round vacuum case, using their weight to create a flywheel as part of the crank, and conserve energy? Like it keeps spinning after you stop, or perhaps spinning up the weight with a braking system using the flywheel batteries to stop

I'm pretty sure that's not it, if it's simple and suppose to actually work!

 

[flecc]

As you say prState, not it, since as I've said, it already almost exists.

The rotating flywheel idea has often been proposed but isn't practical on bikes due to weight, complexity, low speed and range requirement etc.

The only practical flywheel implementation I know of is on a bus route in Switzerland. On that route there are energy coils buried into the road at each bus stop. When the bus stops, a corresponding induction coil picks up the electrical power, using it to spin a large underfloor flywheel up to speed. That flywheel energy then drives the bus to the next bus stop.

One obvious benefit is that it's an effective way of ensuring bus drivers stop for those waiting at bus stops rather than sailing straight past, though I doubt that was the benefit the designers were thinking of.

There's also the possibility of incorporating regeneration on downhill stretches.

Other than that the only advantages I see are relatively silent operation, and no need for infrastructure like overhead lines. Otherwise, it can't be an energy efficient system.
.

 

[coops]

I can see what you're saying flecc, that a lack of a multidisciplinary approach could blind the industry to potential avenues of development that someone with experience of both fields could easily see... but I'm none the wiser as to what it is!

I take it that the solution somehow "bridges" the two disciplines of electric motor & cycle design, rather than a cycle designer "taking a ready-made electric motor & fixing it to the bike"... .

Is it some sort of electronic gearbox, like pgbw said?

Have you solved it then Miles?!

Nice try prState .

Stuart.

 

[flecc]

Is it some sort of electronic gearbox, like pgbw said?

Have you solved it then Miles?!

Nice try prState .

Stuart.

1) No

2) I don't know if he has, but think he's indicating he's putting his very capable mind to it.

3) Yes, prState showed more imagination than our e-bike designers seem to.

As you say Stuart. Once when I was still quite young I received the sneering comment, "Jack of all trades, master of none". Having considered that at length, I realised that the person saying that was an idiot. In our complex modern world that's exactly what everyone needs to be, instead of knowing one or two things well and being completely ignorant of virtually everything else around them. That led to my very diverse career and wide ranging interests, enabling me in so many ways denied to so many others. "Jack of all trades, master of none" is the highest possible attainment for an engineer.
.