Scatcat

Second hand GT16, interesting mix of highs and lows

129 posts in this topic

On 6/2/2017 at 10:12 AM, Scatcat said:

If the darn tire touches the shell when I get on, I doubt it will behave well when somebody 40kg heavier does the same.

I can't believe such a bad design! Would it kill them to make the space 1/16 inch bigger??

0

Share this post


Link to post
Share on other sites
On 6/12/2017 at 10:07 PM, Scatcat said:

I also found the culprit for the tire-against-chassi-sounds. It turns out the distance between the heatsink and the tire on top of the wheel is really, really small. You could see exactly where the tire had scraped against it, and I took a file and filed those parts down a millimeter or so.

Only a little testing should have revealed this to the Rockwheel designers!

0

Share this post


Link to post
Share on other sites
24 minutes ago, MaxLinux said:

Only a little testing should have revealed this to the Rockwheel designers!

Oh, they probably had their 150lbs tester drive it up and down ramps forever... ūüėā

0

Share this post


Link to post
Share on other sites
On 17/06/2017 at 7:50 PM, Hunka Hunka Burning Love said:

I think all these higher speed, higher wattage wheels emit their own distinctive hum.  I think people get used to it, but as a plus at least it warns people to get out of the way as they can hear you approaching?  I bet at higher speeds you probably won't notice it as the wind noise would be louder.

I have noticed that they all whine. But in the video the Rockwheel GT16 whine can be heard loud and clear still when the rider is far away at the end of the (noisy) street. In the ACM video the whine seems more manageable.

I ride on beautiful bicycle roads in the woods almost every night, so a loud whine would ruin the moment a bit. That's the main reason I installed a switch for the beeper on my Lhotz.

Seems that my choices are now down to KingSong KS-16S and Gotway ACM.

1

Share this post


Link to post
Share on other sites

I wonder whether insulating the inner sides of the motor covers with sound deadening material like Dynamat would help reduce the sound coming out.  There are adhesive pads that people use for car door dedeadening.

 

1

Share this post


Link to post
Share on other sites
8 hours ago, Hunka Hunka Burning Love said:

I wonder whether insulating the inner sides of the motor covers with sound deadening material like Dynamat would help reduce the sound coming out.  There are adhesive pads that people use for car door dedeadening.

 

I wouldn't. Those things look like they're going to make heat regulation harder. If there is one thing we don't need in our more powerful wheels, it's higher temperatures.

1

Share this post


Link to post
Share on other sites

Maybe try touching the motor cover shell after a long ride.  I wonder if it gets warm if at all.  One concern would be creating an imbalance and vibration if the sound material is placed unevenly.  Maybe it's something more for a manufacturer to consider as long as it can be secured well and evenly to avoid imbalances.  Then again, it could be another weak spot for failure if it ever becomes loose so likely it isn't a great idea.

0

Share this post


Link to post
Share on other sites
11 hours ago, Hunka Hunka Burning Love said:

I wonder whether insulating the inner sides of the motor covers with sound deadening material like Dynamat would help reduce the sound coming out.  There are adhesive pads that people use for car door dedeadening.

 

As far as i understood this by now, the whining sound comes from the torque ripples created by the PWMed signal - so the whole motor/(wheel) is "shaking" and producing the sound. It's not produced somewhere isolated in the inside so that it could be insulated...

The only help is a different firmware (slightly modified hardware) to reduce this sounds.

For the hardware not so steep slopes of the PWM signal reduce the generated torque ripple(==sound), but on the other hand increase the switching losses - no idea if some "sweet spot" can be found.

The second is from the firmware side to modulate the pwm differently so that it is better "adjusted to the motor characteristics".

Would need quite some experience and testing to see if and what's possible. Could be that "our" firmware developers come soon to a state where they will test exactly this "sublety" ...

Maybe the only possible solution is to increase the pwm frequency above the "limit of audibility", which would again increase the switching losses...

2

Share this post


Link to post
Share on other sites

Posted (edited)

I wonder if it is mainly the coils creating the sound rather than the entire motor.   After reading this article:

http://www.jimhendershot.com/Jim_Hendershot/Articles_files/causes%26sources of audible noise in elec motors.pdf

and browsing over these:

https://books.google.ca/books?id=SUVuBwAAQBAJ&pg=PA308&lpg=PA308&dq=dampening+coil+noise+electric+motor&source=bl&ots=D6M4Kz3uL3&sig=Y4tyuSNH_aP8zUMhl_hRexcI3Yc&hl=en&sa=X&ved=0ahUKEwjKjN2xv8nUAhVjxoMKHYv2DDwQ6AEIRzAF

https://books.google.ca/books?id=0tL8BAAAQBAJ&pg=PA96&lpg=PA96&dq=damping+electric+motor+coils+reduce+sound&source=bl&ots=f-QhPMGord&sig=LnK97G7be6AWNkAXmRqE-zJxkX8&hl=en&sa=X&ved=0ahUKEwio49mEw8nUAhUj4oMKHdXpDnoQ6AEIPzAD

 as well as searching online a little I wonder if coil vibration could be the primary cause.  I believe that the coils are not impregnated with damping epoxy if I recall Rehab1's motor photos correctly.  According to those articles, magnetostriction and coil vibration can cause coil whine.  I've also seen some coils coated with a glue like substance holding the copper coils together, and I've always wondered why that is.  I believe it is to reduce coil whine through damping.

Perhaps if the motor coils were impregnated with resin we would have much quieter rides.

Edited by Hunka Hunka Burning Love
1

Share this post


Link to post
Share on other sites
On 17.6.2017 at 9:40 PM, Hunka Hunka Burning Love said:

Oh I forgot - it has that weird crackling sound inside the motor too with the GT16?  Is that very noticeable at slower speeds?  I hope that's not due to sparks arcing through the lacquer copper wiring insulation... :efee96588e:

 

On 17.6.2017 at 9:45 PM, meepmeepmayer said:

My ACM arcs like crazy too (more than the first one I believe). But only at basically standstill. Learned to live with itB)

 

On 17.6.2017 at 10:01 PM, Hunka Hunka Burning Love said:

Really?  I haven't heard of anyone mentioning that the ACM does that.  Do you have any video?  :popcorn:  I wonder if it's arcing or maybe noisy bearing ball bearings shifting around or something else.  Is it definitely electrical sounding?

 

On 17.6.2017 at 10:52 PM, meepmeepmayer said:

It's definitely electrical. You can hear, and it can't be mechanical anyways as it happens when the wheel is perfectly still. Made a video but you can't really hear it there, so I guess it's not that bad. I mainly noticed as my first ACM motor didn't do that (or I didn't hear it).

But some arcing is definitely there when the wheel is still or nearly still, sounds like the Gotway magic gnomes have a tiny tumble dryer full of tiny rocks;) Interestingly, it gets notably louder when you switch on the light (heard that with my old ACM too), so if you ever come across an ACM, you can try.

edit: as per the light thing, it may or may not be the actual motor itself doing the sound.

Maybe time again for a seperate EUC noise topic?!

That crackling/sparking sound is also produced by my KS16. As it is still up and running i take this as another hint that it has to be "eletrical". For a real spark either the voltage has to be higher and something definitely gets destroyed (like the lacuquer copper wiring insulation, or it could come from a connector. But both of this possibilities would already have noticeable "destroyed" my wheel in the meantime... So by exclusion of possibilities it should something nondestructive.

I'd guess again, like for the whining sound for torque-ripples. Since i also notice it mainly at stand-still and very slow speeds, it could be the "change" from one magnet to the next - with (maybe) some back and forth movements (as there is ?gyro noise? and/or the movement direction is not definitely clear at this very slow speeds?).

As far as i remember this crackling/sparking sound is not at every wheel position, but comes and goes - i have to try/verify that again at home...

2

Share this post


Link to post
Share on other sites
12 minutes ago, Hunka Hunka Burning Love said:

I wonder if it is mainly the coils creating the sound rather than the entire motor.   After reading this article:

...

as well as searching online a little I wonder if coil vibration could be the primary cause.  I believe that the coils are not impregnated with damping epoxy if I recall Rehab1's motor photos correctly.  According to those articles, magnetostriction and coil vibration can cause coil whine.  I've also seen some coils coated with a glue like substance holding the copper coils together, and I've always wondered why that is.  I believe it is to reduce coil whine through damping.

Perhaps if the motor coils were impregnated with resin we would have much quieter rides.

Is definitely also a (possible) source - produced by the same cause. Current changes create changing magnetic ?field/flux/...? which applies a force to the magnetic parts. So the coils (and whatever else can move) which start to move along the change and produce by this the sound. The same is true for the whole wheel...

To see which cause contributes how much to the noise needs some empiciral tests or someone more experienced. From my readings i'd assume the whole motor being the main bad guy, but who knows...

1

Share this post


Link to post
Share on other sites
15 hours ago, Hunka Hunka Burning Love said:

I've also seen some coils coated with a glue like substance holding the copper coils together, and I've always wondered why that is.

Coil Dope was a must-have for flyback transformers that drove the old CRT monitors and TV sets. Otherwise you got a high-pitched squeal.

2

Share this post


Link to post
Share on other sites

Yeah that's exactly the stuff I was talking about.  I wonder if they resined up the motors whether it would help mute them.

1

Share this post


Link to post
Share on other sites
6 hours ago, Hunka Hunka Burning Love said:

Yeah that's exactly the stuff I was talking about.  I wonder if they resined up the motors whether it would help mute them.

AFAIK there is no resin in our motors, which it should be.

Or rather, which there could be if we wanted to get rid of some of the noise. But I'm not sure if there are other things that is negative about using such resin.

Edited by Scatcat
nuancing...
1

Share this post


Link to post
Share on other sites

So would you say that the GT16 is a reliable wheel ready for prime time?  I wonder what caused the reported cutouts that the French dealers were mentioning.  Does anyone know what became of that?

Have you attached a trolley handle to it yet?  Maybe trolleying it while powered up would help you transport it over some rough spots rather than carrying.  What's your average cruising speed?  Have you taken it up to over 40 KPH yet?  I really like the GT16, and I'm dying to upgrade so I'm very curious about it.

Edited by Hunka Hunka Burning Love
0

Share this post


Link to post
Share on other sites
On 6/19/2017 at 3:56 AM, Hunka Hunka Burning Love said:

I wonder if it is mainly the coils creating the sound rather than the entire motor.   After reading this article:

http://www.jimhendershot.com/Jim_Hendershot/Articles_files/causes%26sources of audible noise in elec motors.pdf

and browsing over these:

https://books.google.ca/books?id=SUVuBwAAQBAJ&pg=PA308&lpg=PA308&dq=dampening+coil+noise+electric+motor&source=bl&ots=D6M4Kz3uL3&sig=Y4tyuSNH_aP8zUMhl_hRexcI3Yc&hl=en&sa=X&ved=0ahUKEwjKjN2xv8nUAhVjxoMKHYv2DDwQ6AEIRzAF

https://books.google.ca/books?id=0tL8BAAAQBAJ&pg=PA96&lpg=PA96&dq=damping+electric+motor+coils+reduce+sound&source=bl&ots=f-QhPMGord&sig=LnK97G7be6AWNkAXmRqE-zJxkX8&hl=en&sa=X&ved=0ahUKEwio49mEw8nUAhUj4oMKHdXpDnoQ6AEIPzAD

 as well as searching online a little I wonder if coil vibration could be the primary cause.  I believe that the coils are not impregnated with damping epoxy if I recall Rehab1's motor photos correctly.  According to those articles, magnetostriction and coil vibration can cause coil whine.  I've also seen some coils coated with a glue like substance holding the copper coils together, and I've always wondered why that is.  I believe it is to reduce coil whine through damping.

Perhaps if the motor coils were impregnated with resin we would have much quieter rides.

Any cable even a straight cable will vibrate as the high currents flow through it. Specially if running next to a magnetic metal like the inner motor cast. 

All high reliability high quality motors are epoxy dipped after the coils are wound. This reduces or eliminates all noise and increases the reliability or the motor. All noise is vibration. Any non epoxied motor coils will eventually start to fail because the vibration eroded the varnish of the magnet wire of the coils. Adding the epoxy improves reliability but it cost more.  

Also air gaps inside between the cable and the insulation will cause ionization and arc that dobdegrade the insulation. 

I wondered about those crisp pop sounds in the GT16 also. I feel they are electrical and should not be there. But it's just speculation. 

Edited by Carlos E Rodriguez
2

Share this post


Link to post
Share on other sites
7 hours ago, Scatcat said:

My legs are like jello! For the last three weeks I've been commuting ~16 miles/~25km five days a week, doing another 8 miles a day in the weekends. I think I took it a bit too far yesterday when I climbed a hill and had to lift the GT16 the last 150 meters up, then down over rocks and mud.

Let me say it gets really heavy really fast. Afterwards my legs were shaking from exhaustion for the last run homewards. It was almost a bit scary, but not bad enough that I felt out of control.

I tend to ride as if I ride downhill on skis, bent legs and hunched a bit forward. At 30 kmh anything else means bumps in the road will kill my knees and mean a serious risk of face-planting. My muscles haven't really caught up with my new demands yet, but on the positive side is that I have lost 4-5 pounds in the last month.

Who said this was effortless? :roflmao:

Actually I like the idea of a bit of effort and developing new muscles.  As long as I don't rip them up in a fall!

And I'm at the age where losing weight is almost always a good thing.  I look forward to seeing if my EUC gets me a little more fit.  

And I wouldn't mind having better balance either, just on principle.  You need that all your life and even more as you get older.

0

Share this post


Link to post
Share on other sites
7 hours ago, Hunka Hunka Burning Love said:

So would you say that the GT16 is a reliable wheel ready for prime time?  I wonder what caused the reported cutouts that the French dealers were mentioning.  Does anyone know what became of that?

Have you attached a trolley handle to it yet?  Maybe trolleying it while powered up would help you transport it over some rough spots rather than carrying.  What's your average cruising speed?  Have you taken it up to over 40 KPH yet?  I really like the GT16, and I'm dying to upgrade so I'm very curious about it.

I have a trolley, but climbing over big f-ing rocks and loose stones is not something the trolley can handle.

No I have not taken it over 38 kph approx. Didn't have the app out, but I've set the tilt-back to start at 38 kph and have just taken it to the edge of tilt-back. So I cannot attest to how the wheel handles when it's on "the edge" of its envelope. I probably won't for the foreseeable future ‚Äď I want heavier protection before I¬†take it to higher¬†speeds.

Ready for prime-time? Weeelllll, are¬†any of the wheels today truly ready for prime-time? So far, I haven't seen any electrical problems popping up:¬†my wheel has the whine, but no crunching, popping noises, and if the app should be trusted the temps have not gone above ~50¬įC at any time - not even uphill. Maybe I got lucky and got a good one, I hope so. But then again, I avoid long climbs if the voltage has gone below ~70V or so. Going the 12 km to work dips the voltage from 84 to approx 80V, maybe¬†a little less¬†if I've run the whole way at close to 30 kmh. The app has a meter for power used, out of 100%, and so far I have not exceeded 60%.

The downside of that is that the main reason the board and cables stay cool is the air ducts and heat-sink, which in turn are the main cause of the things I don't like about the wheel: the sensitivity for small pieces of debris that sticks in the heat-sink, and make it sound like it's coming apart when they rub against the wheel.

Having said that, I think the motor cables are a bit flimsy given the powers they conduct. The rest seem okay, but those cables are limited by the axle diameter (wow, is that an old story by now?).

I think the later production GT16's are probably mechanically and electrically about as reliable as Gotways. They have their own quirks, like the heat-sink tolerances and the unusable mud-flap; like the shape of the covers that are stupidly ridged just about where you have your ankles; like the too small pedals that grind against the shell and so on. But none of that is something that makes me worry about a cut-out.

What I would like to see is a GT16 mark II, with a 2.5" wheel width, padding at the ankles, softer and wider padding at the shins, bigger pedals, a little bit more space between wheel and heat-sink (maybe let the heat-sink extend outwards and down the sides a bit), a usable mud-flap, internal layout that is easier servicing, a larger axle and heavier gauge motor-wires.

To sum it up, the wheel doesn't make me very nervous the way I use it now. It may still fail, but I don't expect it to.

 

2 hours ago, Dingfelder said:

Actually I like the idea of a bit of effort and developing new muscles.  As long as I don't rip them up in a fall!

And I'm at the age where losing weight is almost always a good thing.  I look forward to seeing if my EUC gets me a little more fit.  

And I wouldn't mind having better balance either, just on principle.  You need that all your life and even more as you get older.

Oh, yes, I fully concur. My poor muscles just need to catch up to the demands. At 50 I'm very grateful for every pound I lose, so that is just a plus. And balance goes out the door if you never use it, I'm quite happy training mine to stay where it's supposed to ;) 

Who knows, next time I stand in the shower and try to balance on one leg while closing my eyes, I might actually feel comfortable :D 

3

Share this post


Link to post
Share on other sites
11 minutes ago, Scatcat said:

And balance goes out the door if you never use it, I'm quite happy training mine to stay where it's supposed to ;) 

Who knows, next time I stand in the shower and try to balance on one leg while closing my eyes, I might actually feel comfortable :D 

That's actually a terrific exercise.  I used to do that a lot when I was younger.  Maybe the shower is a little dangerous, though. :o

Anyway I think being able to ride any kind of unicycle, electric or regular, is pretty braggable.  When I get to that point, I'm going to think of myself as pretty studly for it even if everybody is laughing at me as I glide down the street. :D

1

Share this post


Link to post
Share on other sites
1 hour ago, Scatcat said:

So would you say that the GT16 is a reliable wheel ready for prime time?  I wonder what caused the reported cutouts that the French dealers were mentioning.  Does anyone know what became of that?

I drive mine back and forth to work every day and have had no problems so far. Today I passed a ninebot going 30-35ish. When we met at a red light a bit further up the road he looked at the wheel with big eyes and asked 1000 questions about it :P

IMHO the GT16 does not sound loud at all. It is definately quiter than the first version Msuper.

1

Share this post


Link to post
Share on other sites
25 minutes ago, Lorents said:

I drive mine back and forth to work every day and have had no problems so far. Today I passed a ninebot going 30-35ish. When we met at a red light a bit further up the road he looked at the wheel with big eyes and asked 1000 questions about it :P

IMHO the GT16 does not sound loud at all. It is definately quiter than the first version Msuper.

I don't feel the sound is that high either. Sure when I come home and roll it into the hallway, you can clearly hear it, but while driving, not so much.

0

Share this post


Link to post
Share on other sites

So now I've driven about 500 km on the wheel, and so far it just smiles at me. What's a bit exhilarating is that the battery drains slower than I suspected, Starting out at 84V, it drops less than half a Volt per mile, or about 0.25V per kilometer, as I'm driving it. When I come home, after driving 25km I'm still usually at about 78V, which translates to about 3.9V per cell.

That efficiency seem very high, and I wonder if there's anything I missed? It would translate to about 100km at 20%, which is faaaaar higher than it should be.

BTW, I bought a pair of Nike Protegga Flex, just for the ankle-leggings:

ankle-protection.thumb.jpg.b380da970cc90c47f5bdd0d9394c1ecf.jpg

They pad my ankles and achilles tendons with a thick rubber padding, allowing me to wear low shoes without risking bruises at the first bump in the road. Given the ridges on the GT16 shell, these are real life-savers. Sorry for the Nike-plug, I am not affiliated with them in any way. But look for soccer shin guards, some of them comes with this kind of ankle protection.

2

Share this post


Link to post
Share on other sites

@Scatcat Nice!

Just broke 1km here on my early March '17 shipment GT16, and I concur, no major issues here. (just minor ones, like how I need to DIY the pedals to stay folded).

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now