Torq: How does the speed limiter work & when best to use it?

[coops]

Thought I'd flag up this subject, it may come to nothing but it may also help some find the best use of their Torq for them .

Although I don't have a Torq, it seems many who visit here ride them derestricted, and I was wondering how the speed limiting/restricting is produced on the Torq, and, besides usually reducing range somewhat, what other effects this may have on performance?

For example, if it is done by limiting power (i.e. voltage & current) wouldn't the limiter reduce the, dare I say it quietly, hill-climbing ability? by limiting the peak power output (by a significant amount I'd guess?) If not, I can't work out why else derestriction would reduce the range (in any terrain?) by quite so much usually?

There are possibly other more subtle effects of delimiting the speed which I can't think of but some may have experienced?

I have read many threads here, but don't recall this issue being addressed?

So anyone aware how it works? and what's the resulting best use of the Torq for which requirements?

Stuart.

 

[flecc]

Since it's a Hall effect motor Stuart, I'd guess it was by the controller limiting the maximum permitted rate of the phase power pulses fed to the motor. That's the easiest way to achieve it, it doesn't limit the power in any way, and for a given wheel size it's dead accurate.

My Torq certainly operates in accord with that when limited, no power loss but an exact 15 mph limiting without any coarse cutoff characteristics.

On a controversial note, the maximum efficiency point for that motor when in the Torq is at just about 20 mph. It follows that a restricted Torq is always being operated well short of maximum efficiency. Oh dear!

My Quando with that motor differently geared spends most of it's life near maximum efficiency, which is at about 14.3 mph.

That said, owners report increased range when restricted, probably due to not running at wind resistance power sapping speeds, so it seems that balances any efficiency loss.
.

 

[flecc]

P.S.

You can delete your other thread by clicking Edit, then use the Go Advanced button. Then select the Delete this message option, then click the Delete this message button below. That's it.
.

 

[coops]

owners report increased range when restricted, probably due to not running at wind resistance power sapping speeds, so it seems that balances any efficiency loss.
.

Hmmmmm... In that case I'd have thought the higher power needed to overcome wind resistance at ~20mph would be at least largely offset by the increased motor efficiency of running delimited at that speed, rather than the measured 30-40% increase in overall power required reducing range by a proportional amount (have I got that right?)?

I suppose there are, as ever, myriad other possible causes of loss of efficiency, though for some reason I would have thought it more likely that limiting, not delimiting, would cause inefficiency?

P.S. Thanks for the tip - I did "Go Advanced" but still can't see a "delete this message" option on the page? is it a default option or should I change editing setup?

Stuart.

 

[flecc]

The efficiency loss balancing is very much an approximation, since the range gains reported when running restricted vary widely. Some owners have only reported 2 or 3 miles, but at the other extreme, one claimed a doubling from 15 to 30 miles. These could both be true, since there's that other very big variable, the terrain.

The range gain in my very hilly area is small, but in a flat area it could conceivably be very large, since the unrestricted running would all be at 20/22 mph with wind resistance very real all the time. That flat area rider running at 15 mph could reduce consumption quite a lot from the reduced wind resistance, and from the fact that their pedal power would provide a much higher proportion of the power required..

I have posted above that limiting causes inefficiency, since the bike is held 5 mph below maximum efficiency?

That deletion method I've only tried for postings, perhaps it's not an option for whole threads. Maybe a PM to Russ (RSScott) would alert him to delete it.

Meanwhile you could use the Edit facility to change the thread title to "False Entry - Please ignore", and change the text in the thread to just a row of dots.
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[ITSPETEINIT]

testing the Torq - both modes

Although I don't have a Torq, it seems many who visit here ride them derestricted, and I was wondering how the speed limiting/restricting is produced on the Torq, and, besides usually reducing range somewhat, what other effects this may have on performance?

For example, if it is done by limiting power (i.e. voltage & current) wouldn't the limiter reduce the, dare I say it quietly, hill-climbing ability? by limiting the peak power output (by a significant amount I'd guess?) If not, I can't work out why else derestriction would reduce the range (in any terrain?) by quite so much usually?

There are possibly other more subtle effects of delimiting the speed which I can't think of but some may have experienced?

I have read many threads here, but don't recall this issue being addressed?

So anyone aware how it works? and what's the resulting best use of the Torq for which requirements?

Stuart.

My friend went out and tested his Torq in both modes on White Post Hill on B3148 south of Marston Magna and just north of Sherborne Dorset - these are his comments:

forgot to tell you on the day I went out this week I tested out the speed switch again,I started at the bottom of camel hill in bottom gear in pedal mode with throttle wide open I cycled as hard as I could going up the gears reaching 13mph half way up and 10.5 at the top.
with the switch on speed I did the same again half way up 17.5mph at the top13.5 I suppose I should have taking it slower when I measured this hill it was 1in13 at the point I measured it but it seems steeper.
Perhaps you can try it when you eventually get to come over.

My mind turned to the last time the bike was used (last Sunday) when the weather was a bit damp and we collected rather a lot of farmyard near the bottom bracket. The battery was recharged on the bike so the battery contacts were not cleaned before the test, nor did they get the benefit of being unplugged and reconnected.
A little more science is needed I think.
Peter

 

[flecc]

One problem with testing the two modes on the Torq is that of the batteries dropping voltage under high drain conditions. This is particularly true of Li-ions, where voltage drop can be from the nominal 37 down to 32 volts.

Could mess up any comparative test, with very different voltages, and hence powers, existing between modes.
.

 

[coops]

The efficiency loss balancing is very much an approximation, since the range gains reported when running restricted vary widely.Some owners have only reported 2 or 3 miles, but at the other extreme, one claimed a doubling from 15 to 30 miles. These could both be true, since there's that other very big variable, the terrain .

ok, if the gains/losses aren't so clear cut as I recalled then there's no discussion to be had about where non-existent gains/losses arise!

That flat area rider running at 15 mph could reduce consumption quite a lot from the reduced wind resistance, and from the fact that their pedal power would provide a much higher proportion of the power required...

Good point, the last one

I have posted above that limiting causes inefficiency, since the bike is held 5 mph below maximum efficiency?.

Sorry, I didn't express my meaning clearly & fully: what I meant to say is "I would have thought it more likely that limiting, not delimiting, would cause inefficiency that would lead to a decrease in range - you said that the limiter causes inefficiency, yet the (now unclear) observation seemed to be that delimiting reduced range & efficiency rather than limiting... Oh dear, too many variables again! Hope that was clearer though.......

I'm going to nip this in the bud and suggest that any curious Torq owners try both & see what works for them .

Thanks for the info again Pete, that was some fast testing there!

As Flecc said though, any comparative test would seem to be very tricky to set up & far from conclusive, but I'm interested all the same to hear if there is a sort of "reproducible" difference between the two modes...

So, whatever works for each, I guess .

One last thought, is it possible or even sensible to change the wheel size on the Torq, front or front & rear both (and would you have to regear the chainwheel/derailleur too...) since that's the main cause of the overgearing & hill trouble, or is it not possible or plain not worth it???

(I tried to edit a thread title before but no go, so I'll try to contact Russ as you said, thanks... or just die of embarassment )

Stuart.

 

[rsscott]

Hi Stuart,

I've deleted the duplicate thread for you!

cheers
Russ

 

[coops]

Hi Stuart,

I've deleted the duplicate thread for you!

cheers
Russ

Thanks Russ - just in time to save yourself reading a PM what I just wrote

 

[flecc]

Hi Stuart

Thanks for clearing that up about limiting/delimiting, I suspected I hadn't understood, hence the question mark!

I've looked extensively at the possibility of wheel size changes etc on the Torq, but the main problem is with the front due to the brake anchoring position for the 700C wheel. A change of forks for a 26" wheel would drop the front, changing the steering geometry. Changing both wheels and the forks would keep the geometry ok, but lower the ground clearance, so slightly shorter cranks could be desirable. 26" at both ends would give around 18% improvement in overall hill climbing ability, both rider and motor geared a bit lower

Oddly enough, the Torq would be fine with 24" wheels! Seems unlikely? Well, the Quando with 20" wheels and the same motor/battery/controller will keep power on until over 18 mph when conditions are suitable, and normally 16 mph. The Torq in the same conditions runs to 22/23 mph, so with 24" wheels should run on power to 19/20 mph, and at least 18 mph on the flat normally, plenty for most cyclists, and I'd be happy with that. That would really improve the motor and rider hill climbing, with around 28% improvement with both combined. That would need a complete change of frame and forks though.

Otherwise, most people change both chainwheel, cassette and rear mechanism. However, cassettes are available for the Shimano Sora with 28 or 30 tooth low sprocket in place of the standard 25, that don't appear to need the RD3300 mechanism changed according to Shimano's compatibility chart. There's also a long reach Sora actuator available to accomodate larger sprockets.

With the standard 52 tooth chainwheel, the low gear with that 30 tooth rear sprocket drops from 58" to 49". With a new 44 tooth chainwheel, the low with that 30 tooth rear sprocket goes down to 41".

There's also an 11 to 30 tooth cassette for the Sora, code HG50-1, which maintains the high gear at 112" with the 44 tooth chainwheel, the same as the present seventh of the eight gears, plenty high enough. (The standard top sprocket on the Torq is 12 tooth.)
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[Baboonking]

Do you notice any increase in torque? (acceleration or hill climbing ability?) in de-restricted mode.

If, as Flecc says, the restrictor works only by limting the duty cycle of the controller and doesn't change the current limit, then the motor will be no more or less efficient with derestriction.

To see why this is true have a play around with this simulator,ebikes.ca Hub Motor Simulator

Try changing the throttle position, this changes the duty cycle of the controller, and watch how the peak efficiency changes its position in relation to speed.

Changing the wheel size will therefore increasse acceleration and hill climbing ability but not make the motor more efficient.

perhaps the reduction is range is due to battery inefficiency and also travelling at a higher speed is more inefficient as wind resistance increase as the square of speed.

 

[flecc]

travelling at a higher speed is more inefficient as wind resistance increase as the square of speed.

I think that's most of it, plus as I mentioned above, the important factor of the rider's effort being a much higher proportion of the necessary power at the lower speed giving that advantage to the restricted mode.

 

[coops]

Hi Baboonking

Thanks for helping to clarify things, very informative .

Do you notice any increase in torque? (acceleration or hill climbing ability?) in de-restricted mode..

Not sure if you're asking me, but I'm sorry I can't answer it since as I said I don't own a Torq .

If, as Flecc says, the restrictor works only by limting the duty cycle of the controller and doesn't change the current limit, then the motor will be no more or less efficient with derestriction.

To see why this is true have a play around with this simulator,ebikes.ca Hub Motor Simulator

Try changing the throttle position, this changes the duty cycle of the controller, and watch how the peak efficiency changes its position in relation to speed.

...perhaps the reduction is range is due to battery inefficiency and also travelling at a higher speed is more inefficient as wind resistance increase as the square of speed.

Thanks, I was focusing on trying to single out causes of efficiency loss to try to explain why range seems reduced when delimited (on the acceptance that the peak power output is unchanged & so increased power drain wouldn't be an issue), and I should think the much higher wind resistance plus, as Flecc said, a lower proportion of rider legpower overall are the main factors in that respect.

But if varying the throttle on the simulator reflects varying the controller's duty cycle (as you say), in the way the limiter does (Flecc says), then with the limiter peak power output is reduced very significantly (I think the simulator red curve is power output, not input?) - e.g. almost halved on the 408 motor from 100% throttle ~22-23mph max speed, 400W+ peak @ ~12mph to 70% throttle ~15mph max speed, ~220W peak @ ~7.5mph....

So, is this a reflection of how the limiter works, and so is peak power reduced by the limiter?

Changing the wheel size will therefore increasse acceleration and hill climbing ability but not make the motor more efficient.

P.S. Yes, I mentioned changing the wheel size as a side-issue, to possibly improve acceleration and hill-climbing as you say, not efficiency per se .

Stuart.

 

[flecc]

As I've posted elsewhere, I think ultimately that as there's no point in running a Torq restricted, the relative efficiency doesn't really matter.

The Torq has been geared up by putting the Quando's 20" wheel motor into a 28" wheel, swapping nearly all of the Quando's prodigious hill climbing ability for speed up to 22 mph. To restrict the Torq denying oneself that speed AND the hill climbing is surely perverse.

Rather than a restricted Torq, better to save around £400 and have the faster and much better climbing Quando. Alternatively, if a better featured 15 mph bike is wanted, another model which retains the hill climbing ability.
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[Baboonking]

Hi Stuart,

I don't have a torq either but i would like to try one some day.Don't pay too much attention to the rest of the graph as it doesn't represent whats happening, the Clyte controllers n the chart have high current limits compared to the torq.

The way to really whats happening would be to test it for yourself.connect an ammeter or better an amphour meter like the drainbrain or wattsup meter. peak power is limited by the current limit in the controller, it does this by varying the duty cycle. I've no idea what its set at so my answer above is pretty speculative. The underlying physics should hold true that if the current isn't increased then the motor will not be anymore efficient/inefficient.

 

[coops]

Don't pay too much attention to the rest of the graph as it doesn't represent whats happening, the Clyte controllers n the chart have high current limits compared to the torq.

Thanks for clarifying once more Baboonking, I somehow overlooked the controller's vital role...

The way to really whats happening would be to test it for yourself.connect an ammeter or better an amphour meter like the drainbrain or wattsup meter. peak power is limited by the current limit in the controller, it does this by varying the duty cycle. I've no idea what its set at so my answer above is pretty speculative. The underlying physics should hold true that if the current isn't increased then the motor will not be anymore efficient/inefficient.

Yep, sounds right. Now, first thing is to get a Torq... then the other gubbins...

Stuart.

 

[coops]

Ok, I'm now inclined to believe that the 15mph speed limiter on the UK Torq works by limiting the power & speed of the motor to about 2/3 or so of its maximum, so, say, around 300W+ peak output occurring at ~7.5-8mph ish.

As I've posted elsewhere, I think ultimately that as there's no point in running a Torq restricted, the relative efficiency doesn't really matter.

The Torq has been geared up by putting the Quando's 20" wheel motor into a 28" wheel, swapping nearly all of the Quando's prodigious hill climbing ability for speed up to 22 mph. To restrict the Torq denying oneself that speed AND the hill climbing is surely perverse.

If it does work in such a proportionate way, I'd expect that a delimited Torq would simply go faster & have more torque i.e. better acceleration, but the latter at the expense of range. Hill-climbing ability would be little different, except the optimum speed would be proportionately higher.

So overall you'd go faster & if you have hills or stop & start a lot your range would likely decrease proportionally, whereas if your route is more level & at a continuous "cruising" speed, your range would not suffer as much relative to limiter on.

Rather than a restricted Torq, better to save around £400 and have the faster and much better climbing Quando. Alternatively, if a better featured 15 mph bike is wanted, another model which retains the hill climbing ability.

Yes, if you want both to utilise both the full power of the motor and have the top speed of the motor as ~15mph, there are alternatives.

However, the Torq seems to allow a choice of speed & torque ("turbo") or "economy" mode which may also be useful to those who don't require the strongest hill-climber, and who'd like a choice of good range at a moderate pace, or more acceleration & speeeeeed and a possibly shorter range.

Stuart.

 

[flecc]

However, the Torq seems to allow a choice of speed & torque ("turbo") or "economy" mode which may also be useful to those who don't require the strongest hill-climber, and who'd like a choice of good range at a moderate pace, or more acceleration & speeeeeed and a possibly shorter range.
Stuart.

I didn't stay long in the restricted mode so can't be ssure of the characteristics.
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[coops]

What I said is only guesswork really - would be good to have more definite information, like whether the delimited torq has more acceleration/torque than with the limiter on, or if the limited torq can climb similar hills (albeit at lower speeds) as when delimited... though of course that could only really be tested out by someone who has geared down the torqs chainwheel/derailleur, unless it was done by motor power only....