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ACM wobble at high speed


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Hi guys,

I hope you are taking advantage of the good weather to have ride :)

I've been out a few times, outside the city to the coutryside, I've noticed something a little strange but maybe it's normal, when I get above 40-42kph real speed with my ACM, it wobbles from front to back quite quickly, I can't figure out if it's a normal thing or not, my battery was at 64%.

I got the final alarm at about 44kph with this percentage of battery, I usually don't ride faster than 40kph with my ACM so maybe this was present since I got it but I can't remember. I've pushed my Monster up to 48kph the same day with no wobbles. I don't think it's because I'm moving my legs, I'm not anxious during those ride. Another thing, I've added an (ugly)little speaker for music on top of the ACM (see picture below) do you think this could cause the issue ?

What do you think ? Is this a normal behavior @meepmeepmayer, @Marty Backe and other owners of ACM ?

JhhIJrk.jpg

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I hate the dreaded wobble, but I'm convinced that it comes from poor riding posture. Sometimes it'll develop when I'm going around a curve at high speed or even straight. But in general my ACM does not consistently wobble at very high speed. My Monster has never wobbled :thumbup:

Maybe you need to put on a few pounds - eat bigger breakfasts ;)

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It either depends on...

  • PSI
  • If you're distributing weight evenly amongst both pedals
  • Posture (I find making myself more aerodynamic I create less drag which can transfer down to the wheel itself).
Edited by Eddrush
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I've always attributed the wobble to improper foot placement on the pedals.

Make sure your feet are placed correctly / symmetrically on the pedals relative to the axle.. and keep your knees slightly bent.

Q~

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5 minutes ago, meepmeepmayer said:

Guys he's talking about front-back "balancing" wobble, not the sideways wobble from bad posture or leg muscle tension or whatever.

<snip>

You're right! I totally misread that.

I've never experienced anything like that. I've also never experienced tilt-back at very high speed. Could it be related to tilt-back? It does not sound normal.

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Thanks for your replys !

So, to answer your questions, my tire pressure is at 3.2 bars. I don't think I have a bad posture because then it would do the same thing on the Monster. My feet distribute my weight equaly I think.

@Marty Backe Great idea it would just reduce my top speed so I can't reach +40kph anymore so no more worries, genius !! :D

@meepmeepmayer I've lifted it, and the tire looks uneven and it seems imbalanced because at +40kph (holding the EUC) I can definitely feel the wobble, I think I found the issue but not sure how to fix it though...

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On 6/8/2017 at 10:24 AM, FULspeed said:

My ACM 1300 has more wobble at high speed if I have a pressure tire around 4 psi, more stable instead with 3.4 psi...

Which is your?

  It is possible a speaker magnet could affect the IMU/Gyro base calibration. Not sure how close it has to be before it is a problem.

but I think the ACM board is far down and away and should not be a problem.

http://www.sensorsmag.com/components/compensating-for-tilt-hard-iron-and-soft-iron-effects

Edited by Carlos E Rodriguez
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On 6/8/2017 at 11:40 AM, meepmeepmayer said:

Use English subtitles. This guy uses tire magnets (car acessory) for balancing. Maybe an idea.

Speaking of good weather, you just have convinced me to go wheeling for a bit. Until later (unless I die;)).

I had the wobble thing all the time at the beginning. And then it went away and then once in a while would appear. I believe it's just muscle fatigue and muscles still in the process of learning the new way to balance. 

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Thanks guys !

I forgot I've placed a magnet on all of the wheels, for the bike computer to be able to sense the rotation of the wheel, it must weight about 5g, maybe less, do you think this little thing could be inbalancing the wheel therefore causing the wobble ? On my Monster it doesn't seem to have the same effect as on the ACM but maybe it's because the wheel is much bigger and that the rim is heavier ?

It's not muscle fatigue because the wobble seems to be present when spinning the wheel freely.

 

Edited by Pingouin
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From my tests, the wobble is present on 3 out of 5 wheels I've tested (while spined freely), the Monster (that has a magnet) & the MCM3 (that hasn't got a magnet) don't seem inbalanced while spinning the wheel freely, the MCM4, ACM & MCM2s all have a magnet and seem inbalanced...I think I've figured out thanks to you guys that the inbalanced wheel is the reason and that this is probably caused by the magnet, I only have the MCM3 with me right now but as soon as I get back home I'll check it out.

While this inbalance is perceivable at high spinning rates, I can't feel the wobble on other EUC than the ACM while riding, but it's probably because they are "slow" EUC's not capable of more than 23kph ?

If removing the magnet solves the issue, then I'll have to place a something the same weight on the opposit side. I'll keep you updated, I really hope that this is the issue, because it's an easy fix !!

Edited by Pingouin
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4 minutes ago, Pingouin said:

From my tests, the wobble is present on 3 out of 5 wheels I've tested (while spined freely), the Monster (that has a magnet) & the MCM3 (that hasn't got a magnet) don't seem inbalanced while spinning the wheel freely, the MCM4, ACM & MCM2s all have a magnet and seem inbalanced...I think I've figured out thanks to you guys that the inbalanced wheel is the reason and that this is probably caused by the magnet, I only have the MCM3 with me right now but as soon as I get back home I'll check it out.

While this inbalance is perceivable at high spinning rates, I can't feel the wobble on other EUC than the ACM while riding, but it's probably because they are "slow" EUC's not capable of more than 23kph ?

If removing the magnet solves the issue, then I'll have to place a something the same weight on the opposit side. I'll keep you updated, I really hope that this is the issue, because it's an easy fix !!

Cool. Keep us informed on the final outcome. Good to know that those speed magnets potentially can affect the ride.

The ACM is such a finely tuned beast of a machine, best not to alter it :laughbounce2:

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2 minutes ago, Marty Backe said:

Cool. Keep us informed on the final outcome. Good to know that those speed magnets potentially can affect the ride.

The ACM is such a finely tuned beast of a machine, best not to alter it :laughbounce2:

You're such a Gotway lover you know that right ? :D

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15 minutes ago, Marty Backe said:

Oooops. You weren't supposed to read that :facepalm:

 

12 minutes ago, meepmeepmayer said:

Yep he was totally not supposed to read that;)

No hurt feelings! It was just an ACM. Now it's the ACM Turbo XL5000!:laughbounce2:

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12 minutes ago, Rehab1 said:

 

No hurt feelings! It was just an ACM. Now it's the ACM Turbo XL5000!:laughbounce2:

I'll believe it when I actually see you riding it ;)

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Hi again !

I just tested out if the wobble is still present without the magnet, it's still there, if it's an unbalanced wheel then I guess that it's serious. I can still ride like that knowing that very rarely go above 40kph.

I'll try to buy some magnets to stick on the wheel and do the trick like on the video,  but I'm not sure what weight to stick on the rim. I'm tempted to leave it like it is.

@Marty Backe when you go above 25mph do you feel this same wobble, or at least a vibration while going in a straight line ?

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