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Hunka Hunka Burning Love

Wobbles of Doom! Lucky to have avoided a crash!

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2 hours ago, KalSeth said:

One more cup of coffee before I go.  To the Valley below.

No kidding.  I remember being chided for going over 25 km/h.  What happened to that guy?

Dump the crappy speaker.  Its placement throws off your balance enough that combined with the high speed gave the wobble.

:ph34r:  He's dead, Jim.  Not a huge Bob Dylan fan,  but it sounds very apropos!  I don't recall criticising anyone for going over 25 kph.  I might have said it could lead to more serious injuries at higher speeds.  I didn't say I was averse to breaking the Ninebot speed barrier.  :whistling:

Speaker is actually pretty decent for the money.  It just kinda gets in the way a little bit.  That's why I hope Gotway makes a new wheel with speakers in the future so we can avoid these mods.  In any case, above 35 kph or so it's so windy you really can't hear very much so maybe it's an unnecessary luxury.   Once you ride with your tunes at lower speeds it's really difficult to go back to silence...

Edited by Hunka Hunka Burning Love

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16 hours ago, Keith said:

...

However, I’ve always had a theory that beginners also tend to put their feet evenly on the peddles such that their foot is mid peddle but their leg is actually too far back. You saying that you can often stop the wobbles by going on to the ball of your foot (I.e. by moving your centre of gravity further forward) seems, to me, to suggest that a rearward stance might well be the cause?

...

Now if the rider has his weight centred behind the contact point of the wheel on the ground I cannot help thinking that would set the wheel up to be every bit as prone to directional instability as a tailwheel aircraft. Most riders, I suspect move their weight further forward as they gain experience without even knowing that they are doing it.

I wonder, if a rider takes a moment to think about it, whether there is a tendency to instinctively move further forward when riding at higher speed? Just the fact that a long ride with a more forward standing position will take the load off of the leg muscles by not needing to lean forward so much all the time might be enough to do it without thinking? I.e. further back = high manoeuvrability, further forward=improved speed and stability?

That aircraft analogy is interesting.  It does make sense when you think about it.  I wonder though whether these wobbles may be more like how on shopping carts, sometimes one of the wheels in the front ends up fluttering violently about.  It sure would be interesting to have more ride data logged about lateral G's, ride angle, and vibration data to figure out what is setting it off.

https://en.wikipedia.org/wiki/Speed_wobble

I usually place my feet slightly forwards and centred on the pedal with my ankle slightly behind the middle of the pedal support location.  Size nine shoes with toes over the front edge.  Laterally they are outwards slightly to help clear the case.  I've tried riding with feet even more forwards, and at a certain point it gets very difficult to brake as you can't apply pressure on the back half of the pedal.  

My centre of gravity is likely always in front of the contact point while in forwards motion.  If it were directly over or behind I think the wheel would be slowing to a stop or braking.

I think foot position relative to the pedal support vertical centre changes the lever forces you can apply to the pedal.  Too far forwards, and you can't stop well even if your CoG is behind the contact patch since you can't create that backwards tilt pressure on the case through the pedal supports.  Too far back, and the acute foot to leg angle gets uncomfortable while accelerating or at speed.

These wobbles I think are likely due to not being able to brace the case well enough to stabilize it so your leg muscles try to do it on an autonomic level.  With small wobbles, tilting one foot up and bracing the other leg against the case gets rid of them.  Squatting down to try to touch the ground with a hand for example prevents the legs from contacting the side panels of the wheel so wobbles can occur easier.  Or that's my theory.  I'd be curious to see if anyone else does the heel lift while riding.  You may have seen it in my video.  I pretend I'm pressing down on the accelerator pedal.   :whistling:

Edited by Hunka Hunka Burning Love

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Glad you hung on! You pretty much need to be on your A game to ride 24mph+. I’ve had days where I’m a little tired or had an injury a few days before and I really notice the difference in how robust I feel upon the wheel. Right now my left foot is sore from slamming it down hard the other day after I hit a dip in the road so I’m riding a lot more easily on the wheel. When I feel a wobble I remind myself that I don’t need to hammer it, just consistently cruise and I’ll get there in plenty of time. That communting on NYC streets of course, hitting trails would be different :)

Right now I think my Tesla has a bit of a tire bump that I need to sort out coz I’m feeling a rhythmic, vertical wobble especially at higher speeds. ? 

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Bluetooth headphones maybe?  Just use one so you can hear the warning beeps still.

If we get a police crackdown here because some idiot is blasting AC DC while wildly careening around Nose Hill park I am going to go all Glen Close on that pet rabbit of yours.

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1 hour ago, KalSeth said:

Bluetooth headphones maybe?  Just use one so you can hear the warning beeps still.

If we get a police crackdown here because some idiot is blasting AC DC while wildly careening around Nose Hill park I am going to go all Glen Close on that pet rabbit of yours.

:ph34r:  No need to go all Fatal Attraction on the furball.   I ride safely.  :yawn:  But interspersed are a few moments of sheer speed and terror!  :w00t2:  I need to get some better BT earphones.  My pair runs out of battery too quickly.  At least with the Tronsmart it lasts for a few runs before needing a recharge.  Plus there's that cool factor riding with tunes and also the no surprises something loud is coming your way element.

Good call on the AC DC!  I must add that to the rotation after Rick Astley!

Rhythmic tire bump might be a bent rim like @meepmeepmayer?

Edited by Hunka Hunka Burning Love

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Is it possible one leg is longer than the other to such a degree that when you tense up at speed you actually keep more weight on one pedal than the other? Just brainstorming here...

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Hmmm I'm not sure that would affect things that much, but it's a good theory.  I would think something like that would just make a person have to compensate and lean to the longer side kind of like when you have a battery pack on only one side of the wheel.

I usually heel toe it to help relieve pressure on the foot.  It's kind of like standing on one spot on the floor for a long time.  It's nice to bend on knee and lift up the heel now and then.  I do that on either side of the wheel, and it helps with soothing pressure spots.  I suspect I'm not bracing one side enough (speaker side) when I'm accelerating so there is a wobble introduced.  If I brace and heel lift the other side I can zoom up to speed with no issues.  That's how I hit the high speed S curve portion of my trip normally along with an exaggerated body lean to the side.

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1 hour ago, alcatraz said:

Is it possible one leg is longer than the other to such a degree that when you tense up at speed you actually keep more weight on one pedal than the other? Just brainstorming here...

 

1 hour ago, Hunka Hunka Burning Love said:

Hmmm I'm not sure that would affect things that much, but it's a good theory.  I would think something like that would just make a person have to compensate and lean to the longer side kind of like when you have a battery pack on only one side of the wheel.

Most people has some degree of leg length inequality but it’s so marginal that it does not affect us while walking. The only way to test Alcatraz’s theory is for Hunka to wear a shoe built up higher than the other while riding fast. This amount of discrepancy should work. ?

41588065375_3101a439fd_b.jpg

 

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6 hours ago, Hunka Hunka Burning Love said:

Rhythmic tire bump might be a bent rim like @meepmeepmayer?

@Roo Williams If it depends on the speed you're going (higher frequency when faster), yep might be a bend in the rim. Clicky (some pictures not working it seems?). It can be fixed completely.

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Glad u didn't have to bail, @Hunka Hunka Burning Love! U might've had to perform some hillside Tesla panel re-popping a la @Marty Backe 

And yes, after only a few days with a speaker I can agree it's addicting.. only thing is now I cant creep up on people, which I found sort of amusing... I just hold the speaker in one hand. I kind of wish it had a strap, but its surprisingly comfortable to hold anyway.

My theory on getting all wobbly when crouching down is the lower center of gravity, i.e. it's easier to balance a yardstick in the palm of your hand than a pencil.

I think wobbling happens because of unequal compensation.. never tried the foot trick, but I try to shift weight

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Leg length difference is just one asymmetrical feature people have. Knees, ankles and hips may bend differently, foot arch height and strength differences, natural foot outward angles, etc. No-one is symmetrical.

I have issues with the wheel trying to tilt left. (Changing direction doesn’t help.) When my feet get tired enough, the issue gets bad enough for me not to be able to enjoy riding. Man I hate it. I’m not sure what exactly is the issue, but I mainly suspect the right side muscles that never got back to normal after my back issues and spinal disc surgery 15 years ago.

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On 5/31/2018 at 3:34 PM, Cannings said:

When I wobbles I find clenching the wheel between my calves works to get rid of them

To me, it's the opposite. The more I cram my calves against the to padding, the bigger the amplitude of the wobble. Though I'm just 1.5week into my Tesla. Crouching creates wobble quite easy. Standing uneven length wise on the pedals seems to increase the risk of starting a wobble (IE if you step up with one foot with toe on edge end other with heel on edge like a worst case).

As squeezing with the calves increase wobble I'm going to try to remove the calf padding as my calves touch then regardless of how wide I stand (unless I force my knees into a wheel like pose, not very comfortable for a long ride) + it should decrease the "burning sensation" on my calves as the pads grind on my skin when I go off-road. Going to find some thin foam padding.. Or maybe just use the plastic (sand papering off any small unevenness that might reside in the shell)

Braking normally stops my wobble at once. Have only had one major wobble as I overtook a bike and turned in sharply in front of it, felt like I was about to be thrown off but braking mildly and NOT clamping solved it in a matter of seconds (and speed was not more than maybe 30-ish km/h).

Front or rear weight don't seem to matter much to meet, I'm quite tall at 192cms and 90kg being a frequent gym visitor, so I have the strength but I think I might be a bit "stiff" and for sure I just got my slow speed balancing (standstill for a few seconds) to work so I think part of it will go away with time.

What will allow the wheel to START to wobble though is a "soft point" between ground (solid) and the rider.

I still put my 5cents on that the weakest link is  the low sideway structural strength of a "bicycle wheel" if I compare it to riding a motor bike. Sure the rider can compensate, but with higher stiffness to begin with you have less sideway movement in the tyre side wall, less side way movement = less amplitude = less wobble (Ninebot Z seems to have addressed this with what seems to be a tubeless motor bike tire and I bet that it has reinforced sidewalls which is why people say its so darn stable...though it's just my calculated guess)

On a bike you can solve parts of it with a steering damper for the from wheel, not doing wheelies, not running with flat tyres (flat top part...example when riders turn very seldom Vs straight riding or do a lot of burnouts), but we only have one tyre (and frame..but that's another ballpark) to work with...and our body to compensate.

...or if during a turn, accelerate before wobble gets too big to put max lateral force on the wheel sidewall in ONE direction (basically to cancel out the counter force that causes the wobble) and I found that this works fairly well on a EUC as well. Powering out of turns gives a smooth turn while staying constant speed in turns can cause more or less instability/wobble. But applying acceleration very heavy and sudden will cause the side wall to give way sideways so a smooth power out of turns gives the most stable turn for me, though the sudden side shift is not too bad...as long as you know it's coming ?

Worst solution would be...crouch and squeeze with calves...at least for me as both amplify wobbling at least for me.

Like the topic as it's (for me) the biggest disturbance I have with my Tesla.

Edited by Boogieman

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Your point on the tire sidewalls being the culprit is a new one. But there are quite a few things not supporting the theory:

- Some people get and solve wobbles in opposite manners

- Some get more wobbles with high tire pressure and some with low

- To my knowledge, without exception the wobbles (almost) disappear once the rider gets more miles on the specific wheel

And:

3 hours ago, Boogieman said:

What will allow the wheel to START to wobble though is a "soft point" between ground (solid) and the rider.

I have built a few suspension systems on my wheel, cramming foam and silicone in various places between the pedals and the wheel, and tried even riding with up to three layers of thick and bouncy insoles.

At no point have I had wobbles worth mentioning at any speed below 35km/h in any riding situation.

I think the Z10 stability is mostly due to the very heavy weight of the wheel, as well as tire width. Then again, the Tesla has many times been noted as very stable even when closing in on 50 km/h.

 

Unless your tire is deformed or not seated properly (confirm by doing a free-air acceleration), there is a possibility that you are over-analyzing the situation.

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5 hours ago, Hunka Hunka Burning Love said:

Whew :efefc8626c: I nearly lost it today on my Tesla doing a slow speed turn after going up a slight ramp!

Leg and brain fatigue.  Don't under-estimate the two.  I've been riding almost every day this past week for about 19 km a run, and today I went to do some off-roading.  My legs were a little tired today, plus I don't think I slept enough last night, but usually the thrill of a ride wakes me right up. 

After my off-roading, I headed home and made a pretty routine looking right turn.  Strangely enough the wheel did not turn, but instead it headed off into the grass and down a slight slope towards a road with 70 kph traffic.  :blink:  Luckily I stepped off and grabbed the handle in time!   Talk about a near crash.  Good thing things were slow, there was no traffic, and I had about 6 feet before the road way.  Visions of the Tesla taking off on its own right into the road flashed across my mind.  :crying:

It's difficult sometimes to recognize fatigue when you're riding until something you take for granted goes horribly wrong.  :yawn:  Plus I thought I was taking things pretty slowly today,  but I guess not.  :efeec46606:  I even took a short rest break, but fatigue insidiously creeps up on you sometimes. 

 

Good reminder. I can definitely feel that my turning starts deteriorating when my legs and/or body start getting tired. I'm not sure there's a solution other than to be aware of this fact and play things a little bit safer when you're feeling tired.

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I guess it's almost like riding a roller-coaster for too long standing up in the same spot.  The thrill and motion keeps your adrenaline pumping and makes you think you're not that tired.  What I did was a upper body turn, but I must have forgotten to lead first with the feet pedal tilt.  :rolleyes:  Seems really silly especially as it was a slow turn, but wow the autopilot autonomics were not functioning correctly!  :sleep1: 

Edited by Hunka Hunka Burning Love

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Fatigue is definitely a component, along with a riding on a rough surface.

I ride the exact same path every day to work, never have any issues whatsoever, usually between 5:30 and 6:30a. When I come come on the same route at 4:30p or so I am quite often super tired. I quite commonly get some weird wobble things happening on my trip home, tiggered by the wheel bouncing around a bit from the same rough roads that I take in the morning. So for me anyway, wobbles are 100% from driving tired, and they are triggered when the wheel bounces on something that I have to correct for. A strong cross-wind can also be a trigger.

 

Edited by yegwheel
Thought of something else.

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On 5/31/2018 at 12:21 PM, WARPed1701D said:

I get wobbles on my V8 if my feet are centered on the pedal, particularly when braking. Forward placement is a much more stable ride. I liked the idea of a more rearward stance to reduce acceleration and increase breaking but not at the price of the wobbles. 

I have found that there is no ideal foot placement. 

Forward for effortless acceleration and high speed cruising, or steep hill climbing = poor braking, especially in an emergency, other weird characteristics which I can't quite explain at this time, as I haven't ridden foot-forward for some time)

Rearward for steep hill descending, good braking = poor acceleration, poor climbing, more wobble, more darty.

At best, a good foot position is a compromise.  I only move my position for hills; forward to climb very steep hills, backwards to descend steep hills under control, and with the ability to brake if necessary.  It is very hard to come to a complete stop when descending a descent hill, especially if a stop is thrust upon you by a sudden impact avoidance scenario.  My Big Foot pedals help tremendously with this.  I remember descending a steep hill in Javier Spain, and it took all I had to maintain a controlled speed.  The balls of my feet were literally flapping against the stock pedals as my heels tried desperately to maintain braking pressure.  Today, on stock pedals, I would walk that hill, out of safety considerations.  A free tumbling out of control wheel is a land missile with fearsome destructive potential.

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I just remembered, I have been getting some "new to me" wobbles.  While climbing a steep (smoothly paved) hill at speed, I get a wobble.  Slowing down eliminates it.  The only thing I can think is causing this is the contact patch of the tire has moved sufficiently forwards enough (due to the hill) that my CG is sufficiently rearward in comparison, and combined with the speed hey presto; wobble. 

It's a real 1st. world problem when your high power  EUC wobbles when climbing paved hills at speed.  A lot of the world's population hasn't even seen a paved road.

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6 hours ago, Smoother said:

Forward for effortless acceleration and high speed cruising, or steep hill climbing = poor braking, especially in an emergency, other weird characteristics which I can't quite explain at this time, as I haven't ridden foot-forward for some time)

Rearward for steep hill descending, good braking = poor acceleration, poor climbing, more wobble, more darty.

Have you tried one foot further forward and the other further back?

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Being able to ride one-footed, even for half a second, is vital for comfort and control as it allows you to positionally change your feet to your best advantage for that situation.

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