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John Chew

"Torque Reaction" or "Lever Effect" problem rears head again.

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I was interested to hear that young Austin Marhold was disappointed that he was able to "out lean" the GotWay MSuper - despite the fact that the MSuper has a 1500w (continuous), 3000w (peak) motor.

 

I was also interested to hear that he found it far more difficult to "out lean" one of the Rockwheel models that had significantly less power.

 

I started thinking about this, and I think I understand the "problem".

 

For a long time I've been regularly talking about the problem of large diameter wheels and hill climbing ... and I believe that what Austin has come across is ANOTHER EXAMPLE OF THIS SAME PROBLEM.

 

With large wheels what limits the power the motor can deliver is NOT the actual power of the motor - it's the ability of the rider to lean forwards hard enough to "demand" that power from the motor.This I describe as the "torque reaction" problem, and other people have described as the "leverage effect". It doesn't matter what you call it - it's very real, and very fundamental.

 

Basically, as you lean forwards the motor's OWN TORQUE REACTION resists your lean - and when that torque reaction has risen enough to COMPLETELY resist the lean, that's ALL THE POWER YOU GET.

 

Big diameter wheels give rise to a bigger torque reaction than small diameter wheels.

 

I strongly suspect that NO 18 INCH EU EXISTS that Austin will not be able to "out lean". In fact no such 18 inch EU CAN exist - if it's designed the same basic way as our current wheels.

 

Even if Austin found himself on an 18 inch wheel with a 10kW motor and LIGHTNING FAST response he would STILL be able to "out lean" it - because the "problem" is not the motor, or the response times, or the electronics, or the battery. It's the fact that it HAS AN 18 INCH WHEEL.

 

This is why Austin finds the MUCH lowered powered Rockwheel less easy to "out lean". The small wheel allows him to USE the power it has - while the "torque reaction" problem means that he simply CANNOT USE the 1500/3000W that the motor of the MSuper has to offer.

 

I suspect it doesn't matter WHAT the motor is. WHAT the electronics are. WHAT the response and settings are. Austin will ALWAYS be able to "out lean" an 18 incher.

 

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 I don't really understand your description:

 

 "Basically, as you lean forwards the motor's OWN TORQUE REACTION resists your lean - and when that torque reaction has risen enough to COMPLETELY resist the lean, that's ALL THE POWER YOU GET."

 

If the motors torque reaction completely resists your lean then how can you then out-lean it?  Isn't that a contraction?

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John,

 

I think I understand what you mean.

Basically, if that is the problem with an 18" wheel, then it might be solved by place the pedals closer to the axis of the wheel (the pedals should be higher).

 

That way, the rider would put LESS torque (leverage) on the wheel when he (she) leans forward.

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I am not really agree with John, but hard for me to explain in english:

 

It is a fact of power. If you would put a child on it (eighter EU from GW) if would not be able to out lean it!

Not we are talking about how tall something (as example 10 Kilogramm) can reach OR how heavy it is must be to reach the point to outlean it.

 

It has to do with the "Hebelgesetz" in english I found the translation "lever rule"

 

So if you use a more geared EU (more geared then the Rockwheel GR12) Austin will not be able to out this EU, but comes another guy is 5 inch taller or/and/or 50 pounds heavier he is able to outlean THIS EU!

Edited by ^tom^
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I'm not sure what any of these terms mean?

'Out lean'? Does that mean you can lean more on it & therefore it has better acceleration & is more manoeuvrable in corners?

I am torn between the Gotway 18 or 14, the Ironbot One & the Airwheel X8 at the moment.

I will probably mainly use it on roads & pavements (sidewalks) but would like to be able to go offroad with it.

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I've actually done this.  Was going up a hill which was steeper than the rated angle of the unicycle.  A hill which I have been up many times quite slowly, but for this particular day and being over confident I decided to lean far forward to get up the hill faster.  Didn't get up the hill any faster as I done a major face plant.

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A unicycle is not a elevator!

There is a point at this sort of unicycle (motor to small and/or battery capacity not big enough) where it is not able to do it.

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It's the easiest and safest way to test the limits of your wheel if you have a steep enough hill nearby.

Safer because the required speed to "outlean" the wheel is relatively low and also ground that you might face plant into if you fail to run it off is that much closer.

The worst way to test the limits is when you go down a steep hill too fast and a bump or hollow accelerates you past the braking capabilities of the wheel. Then they just shoot off in front of you in a sort of freewheel and leave you to either get your legs up to speed or do a seat drop onto the hard tarmac! :)

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I think I understand the problem here.    The lower the pedals are below the axle, the less torque is produces from pressing down on the front.    If the pedal is fixed directly the axle, and you apply your weight the front of the pedal, this produces maximum torque (which increases with pedal length).  If you take the same pedal and lower it 10 feet below the axel (obviously not really possible), then your weight on the front of the pedal produces much less torque.   So increasing the wheel size (while keeping the pedals near the ground) decreases the ability of the rider to apply torque to the wheel.   Does that make any sense to anyone else?

 

One way to counter act this would be have some kind of clamp or grip so the legs could grep the wheel.  I've noticed that when my toes are tired riding up hill it is possible shift the forces from the toes to the calves by squeezing the wheel between the legs.

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Now that I own the Gotway M18 I know what you are talking about, and thinking about it (maybe over thinking again) as all eucs tend to have the pedals about 100 mm from the ground and all pedals are within a centimeter or so the same length when you apply your weight to the front edge on a 14" wheel the centre of gravity is being put maybe 5-10% forward of the perpendicular whereas if you do the same on an 18" wheel then your weight is only 3-8% for forward of the perpendicular so you are in effect providing less forward motivation.

As Sam Clegg says something to enable you to grip more easily with your legs would allow you to get more leverage at the pedals, I was thinking along the lines of two short cow horn shaped foam protrusions just in front of you legs as high as possible on the body of the euc. They wouldn't need to be very large, maybe protruding an inch or two should be enough.

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I'm thinking of slicing one of these in half, vertically & sticking them on for my legs to fit inside.

http://m.ebay.co.uk/itm/like/200847388886?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=m&rlsatarget=kwd-103170256866&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108&ul_ref=http%253A%252F%252Frover.ebay.com%253A80%252Frover%252F1%252F710-134428-41853-0%252F2%253Fipn%253Dicep%2526icep_id%253D67%2526mtid%253D1673%2526kwid%253D1%2526crlp%253D64198248666_563391%2526icep_item_id%253D200847388886%2526itemid%253D200847388886%2526icep_meta_categ_id%253D159912%2526icep_etrs%253DN%2526icep_epid%253D-999%2526icep_ctlg%253D-999%2526icep_cond%253DNew%2526targetid%253D103170256866%2526rlsatarget%253Dkwd-103170256866%2526rpc%253D0.12%2526rpc_upld_id%253D47510%2526device%253Dm%2526icep_msku_flag%253Dy%2526icep_cbt%253Dn%2526adtype%253Dpla%2526gclid%253DCjwKEAjwgcipBRDgxK_3ztrBty8SJACRuv4dr2VTcerREfg6RrK77urZwWHnuELNjEwDfdDlVwBoCSsnw_wcB%2526srcrot%253D710-134428-41853-0%2526rvr_id%253D816711981523&ul_ref=http%3A%2F%2Frover.ebay.com%3A80%2Frover%2F1%2F710-134428-41853-0%2F2%3Fipn%3Dicep%26icep_id%3D67%26mtid%3D1673%26kwid%3D1%26crlp%3D64198248666_563391%26icep_item_id%3D200847388886%26itemid%3D200847388886%26icep_meta_categ_id%3D159912%26icep_etrs%3DN%26icep_epid%3D-999%26icep_ctlg%3D-999%26icep_cond%3DNew%26targetid%3D103170256866%26rlsatarget%3Dkwd-103170256866%26rpc%3D0.12%26rpc_upld_id%3D47510%26device%3Dm%26icep_msku_flag%3Dy%26icep_cbt%3Dn%26adtype%3Dpla%26gclid%3DCjwKEAjwgcipBRDgxK_3ztrBty8SJACRuv4dr2VTcerREfg6RrK77urZwWHnuELNjEwDfdDlVwBoCSsnw_wcB%26srcrot%3D710-134428-41853-0%26rvr_id%3D816711981523

Edited by Shady Tools

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I think I understand the problem here.    The lower the pedals are below the axle, the less torque is produces from pressing down on the front.    If the pedal is fixed directly the axle, and you apply your weight the front of the pedal, this produces maximum torque (which increases with pedal length).  If you take the same pedal and lower it 10 feet below the axel (obviously not really possible), then your weight on the front of the pedal produces much less torque.   So increasing the wheel size (while keeping the pedals near the ground) decreases the ability of the rider to apply torque to the wheel.   Does that make any sense to anyone else?

 

One way to counter act this would be have some kind of clamp or grip so the legs could grep the wheel.  I've noticed that when my toes are tired riding up hill it is possible shift the forces from the toes to the calves by squeezing the wheel between the legs.

 

Isn't it actually the opposite of what you are saying?

 

The closer that the pedals to the center of the wheel the better the wheel can handle the torque when you lean forward.  Its when the pedals are far from the center is when the problem starts.  As John said originally that Austin could out lean a big wheel like the Gotway Msuper's 18" Wheel compared smaller diameter wheels .

 

Would actually be interested to know if Austin could out lean the Gotway M5 which as the name suggest has a 5" Wheel.  Thus the pedals are really close to the center.  Only problem that I can foresee is that the wheel might not be fast enough to stop Austin to fall anyway.

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Isn't it actually the opposite of what you are saying?

 

The closer that the pedals to the center of the wheel the better the wheel can handle the torque when you lean forward.  Its when the pedals are far from the center is when the problem starts.  As John said originally that Austin could out lean a big wheel like the Gotway Msuper's 18" Wheel compared smaller diameter wheels .

 

Would actually be interested to know if Austin could out lean the Gotway M5 which as the name suggest has a 5" Wheel.  Thus the pedals are really close to the center.  Only problem that I can foresee is that the wheel might not be fast enough to stop Austin to fall anyway.

 

I think you miss-read my post.  I'm suggesting exactly what you say.  Closer to the axel == more power torque.    that is why that mSuper suffers from this problem more than other wheels.

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