Hunka Hunka Burning Love Posted May 31, 2018 Share Posted May 31, 2018 Good thing I wore my big boy diaper pants today. It was cold and a little rainy, but I decided to go for a spin along my usual route anyways. I was a little tired from today so I thought what better way than a ride to help revitalize the energy levels. Halfway into my ride and stopping briefly to secure my BT speaker at the top of a slight downhill path, I hopped back on and headed down the slope like I've done many, many times before. What I didn't expect was encountering a really bad case of the wobbles while accelerating to about 40 kph. I've had some minor oscillations before, but those were nothing like this. I nearly had to bail as the wheel approached the edge of the pathway and the dropoff into the valley below. The Tesla was veering quickly side to side about a foot in either direction. Add to that I'm headed downhill, and it was very hard to brake during this crazy shimmy. Usually during a mild wobble I'll lift up one of my heels off the pedal and tilt it onto the ball of the foot which tends to stop the wobbles right away. The oscillation is definitely self-induced. With the cold weather and slight fatigue I had the worse case of wobbling I've ever experienced. In this case there was no way I could lift a heel up - it was wobbling so bad. I don"t think my speaker placement helped matters. Luckily I rode through it and brought it under control. Here's some telemetry data. The battery started at 100% and ended at 31% after 19 km. You can see where I stopped to adjust my speaker. I didn't realize you could pinch to zoom out and in on this graph. Anyways, just in case someone else encounters these wobbles, if they aren't severe, try the foot tilt up trick and see if it works for you. For extreme oscillations just try your best to lean back and slow down. If anyone else has some tricks, post them up! Link to comment Share on other sites More sharing options...
Marty Backe Posted May 31, 2018 Share Posted May 31, 2018 Ah, the Wobbles of Doom. I like it, and a very appropriate name. Glad you came out the other end in one piece Thanks for the data - the wobble is clearly seen at 21:09 Link to comment Share on other sites More sharing options...
alcatraz Posted May 31, 2018 Share Posted May 31, 2018 Is the wheel losing traction and trying to compensate? The jerky wobbles are skary but in essence it wants to stay upright. You just have to try and slow down gently or ride it out. Like pushing the clutch when you feel your wheels just spinning. Am I completely off here? What was it about you think? Link to comment Share on other sites More sharing options...
meepmeepmayer Posted May 31, 2018 Share Posted May 31, 2018 53 minutes ago, Hunka Hunka Burning Love said: The battery started at 100% and ended at 31% after 19 km. Forget the wobbles, this ist the real shocker here! How is this possible? Are you riding on one half of one of the two battery packs? Link to comment Share on other sites More sharing options...
meepmeepmayer Posted May 31, 2018 Share Posted May 31, 2018 8 minutes ago, alcatraz said: Is the wheel losing traction and trying to compensate? Nothing to do with the wheel, these are sideways wobbles. It's the legs correcting with a frequency that amplifies instead of dampens the sideways imbalance, which naturally is bad. Usually happens with unrelaxed legs (cramped, tired, new rider, ...). Try bending your knees when riding like you want to sit down on your wheel, that's when I start wobbling, so you can maybe reproduce an example this way. Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted May 31, 2018 Author Share Posted May 31, 2018 There wasn't any loss of traction. I think part of it has to do with my speaker placement. I tend to not brace the side panel on that side much since it tends to move the speaker around. When going above 30 kph it seems to start an oscillation where it is difficult to correct, almost like when you fishtail on black ice. The wheel was extremely wobbly to the point of me losing control of it. I think I likely accelerated downhill too quickly and allowed the wobbles to get too far along before being able to slow things down in time. You can see after the stop, I zoom up to about 40 kph, but then it dips down under 20 kph where I gain control again. Regarding the battery it was about 13 degrees C, and I was gunning it since the trails were clear of people. Riding at above 40 kph really kills the battery down quickly. The same ride when it was 20 C ended up at 71% so there's quite a variance. I am finding 40% difference when there are prolonged fast riding and quick accelerations. Link to comment Share on other sites More sharing options...
meepmeepmayer Posted May 31, 2018 Share Posted May 31, 2018 You can empty a 1020Wh battery in 20km??? Holy **** Didn't know it could be this bad!!! 13°C isn't even that cold! (For the batteries, for riding it is, you have my sympathies.) Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted May 31, 2018 Author Share Posted May 31, 2018 It's probably a lot to do with the cold evening temperature and head wind tonight in addition to the higher average speed of 30.8 kph over my trip. Also I was accelerating up some stretches of hill. The Tesla power is addicting and crazy. It just gives and gives when you ask it to. I gotta remove my speaker as it isn't helping. Here's the telemetry from the same route, but it was warmer and the average speed was lower. Link to comment Share on other sites More sharing options...
Keith Posted May 31, 2018 Share Posted May 31, 2018 6 hours ago, Hunka Hunka Burning Love said: Usually during a mild wobble I'll lift up one of my heels off the pedal and tilt it onto the ball of the foot which tends to stop the wobbles right away. Whilst we know there are a number of mechanisms that cause wobbles, and obviously the most likely is similar to Pilot Induced Oscillation in an aircraft I.e. where the slight lag in correction by the pilot means he corrects at the same point that the aircraft’s stability starts to correct resulting in an amplified over correction, this continues getting worst unless the pilot stops trying to correct at all. I can see this happening easily on a wheel at speed, especially if there is a degree of nervousness by the rider at that speed. But what exactly causes the wobbles to start in the first place in order to then start over correcting them? We also know that beginners nearly always experience it, usually on reaching a certain speed and it’s often put down to untrained muscles as it generally goes by itself with time and practice. 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? There is a correlation to this with aircraft as well. Nose wheel aircraft track straight when taxing or landing even in a crosswind as their Centre of Gravity (CofG) is forward of the main wheels and any sideways disturbance is self correcting. Tail wheel aircraft cannot handle much crosswind at all and even with no wind, pilots have to learn to be VERY quick and positive on the rudder peddles to keep them straight. This is because their CofG is behind the main wheels any disturbance is amplified, I.e. once (say) a slight movement to the left develops the mass operating as if at the CofG moves out to the right and pulls the aircraft further left, etc. If the pilot isn’t fast enough correcting, or over corrects this can develop easily into a complete 360 degree ground loop. 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? Link to comment Share on other sites More sharing options...
mrelwood Posted May 31, 2018 Share Posted May 31, 2018 Keith’s theory makes sense, but hiw about the crouch wobbles? It’s very common to experience wobble when crouching down far enough. It will unavoidably lift the heels a bit, which moves the centre of contact forward. Link to comment Share on other sites More sharing options...
RockyTop Posted May 31, 2018 Share Posted May 31, 2018 As a beginner I was worried about this wobble thing until I experienced it the first time. I was tied and sore from learning when it started. I could tell it was a feedback loop error on my part. AKA what Keith said. That and loose ankle joints. I thing you can also turn out of it. Or zig zag like Chooch Link to comment Share on other sites More sharing options...
WARPed1701D Posted May 31, 2018 Share Posted May 31, 2018 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. Link to comment Share on other sites More sharing options...
Rehab1 Posted May 31, 2018 Share Posted May 31, 2018 5 hours ago, Hunka Hunka Burning Love said: Luckily I rode through it and brought it under control. Here's some telemetry data. The battery started at 100% and ended at 31% after 19 km. Ou are lucky! Glad your safe! Are there any irregularities on the terrain were you were riding (ie: stick, tree root, stones...etc?) Personally I would go back to the scene and inspect the area. Situations like these weigh heavily on a rider until there are some sound answers leading to the cause. 3 hours ago, Keith said: But what exactly causes the wobbles to start in the first place in order to then start over correcting them? That is a great question. I know in my case it was a hitting a large pothole. In Hunka’s case who knows. I find it hard to fathon that attaching a BT speaker to Tesla’s body would initiate a wooble. Link to comment Share on other sites More sharing options...
Cannings Posted May 31, 2018 Share Posted May 31, 2018 6 hours ago, Hunka Hunka Burning Love said: Good thing I wore my big boy diaper pants today. It was cold and a little rainy, but I decided to go for a spin along my usual route anyways. I was a little tired from today so I thought what better way than a ride to help revitalize the energy levels. Halfway into my ride and stopping briefly to secure my BT speaker at the top of a slight downhill path, I hopped back on and headed down the slope like I've done many, many times before. What I didn't expect was encountering a really bad case of the wobbles while accelerating to about 40 kph. I've had some minor oscillations before, but those were nothing like this. I nearly had to bail as the wheel approached the edge of the pathway and the dropoff into the valley below. The Tesla was veering quickly side to side about a foot in either direction. Add to that I'm headed downhill, and it was very hard to brake during this crazy shimmy. Usually during a mild wobble I'll lift up one of my heels off the pedal and tilt it onto the ball of the foot which tends to stop the wobbles right away. The oscillation is definitely self-induced. With the cold weather and slight fatigue I had the worse case of wobbling I've ever experienced. In this case there was no way I could lift a heel up - it was wobbling so bad. I don"t think my speaker placement helped matters. Luckily I rode through it and brought it under control. Here's some telemetry data. The battery started at 100% and ended at 31% after 19 km. You can see where I stopped to adjust my speaker. I didn't realize you could pinch to zoom out and in on this graph. Anyways, just in case someone else encounters these wobbles, if they aren't severe, try the foot tilt up trick and see if it works for you. For extreme oscillations just try your best to lean back and slow down. If anyone else has some tricks, post them up! When I wobbles I find clenching the wheel between my calves works to get rid of them Link to comment Share on other sites More sharing options...
eddiemoy Posted May 31, 2018 Share Posted May 31, 2018 I went for a ride today in the rain, not by choice. I dropped off my car for windshield replacement and they didn't have a loaner. I decided to ride home on my KS18S. In the beginning I really felt the difference between dry pavement and wet. It almost feels like when I'm riding on grass. I got the wobbles right in the beginning. I quite them and they come right back a couple of times. I wasn't tired or anything, it was kind of chilly. The wobbles I had today seem to be due to the slippery surface. I also caught some air going over this uneven pavement on the sidewalk, landed with both my heels an inch or two more forward than I'd normally stand. That caused some serious wobbles. The ones I though I wasn't going to get out of. I did emergency break and re-positioned my feet. Riding on wet pavement isn't fun. They teach you in motorcycle class that during the first few minutes of rain is the most hazardous. When the water mixes with the oil on the ground. At one street, I could see the oil on top by the rainbow of color. Link to comment Share on other sites More sharing options...
Bob Eisenman Posted May 31, 2018 Share Posted May 31, 2018 6 hours ago, Hunka Hunka Burning Love said: I nearly had to bail as the wheel approached the edge of the pathway Yuck... Link to comment Share on other sites More sharing options...
Rotciv Posted May 31, 2018 Share Posted May 31, 2018 When you guys say wobble, is that when the wheel is moving side to side and making tiny “s” turns or is it rapid front/back tilting? I get side to side movements when I try to squat on the wheel. I’m not sure how to prevent that, any advice would be helpful. I experienced rapid front/back tilting once on my nb1s1 just before it died. Luckily, it was very slow speed and I was able to get off without getting hurt. Link to comment Share on other sites More sharing options...
Bob Eisenman Posted May 31, 2018 Share Posted May 31, 2018 7 hours ago, Hunka Hunka Burning Love said: it was wobbling so bad The thought comes to mind that the pneumatic tire is uniquely the only 'non-rigid' part of the moving EUC. Perhaps the unique elastic (rubber sidewall) and pneumatic properties of an inflated EUC tire, under the circumstances of EUC wobble, creates reactively oscillating and turning forces that dampen at lowering speeds. At 50 psi (arbitrary psi choice) the 170 pound rider with a 30 pound EUC has a footprint of about 4 square inches pushing against the rotating sidewall (slightly deformed?). You do the math for your specific tire and combined rider+EUC weight. Monster's tire is 32 psi and has wobbled when the riders center of gravity is rapidly lowered to a some specific point above the Monster at a speed below 20 mph but above 10 mph. ??? Link to comment Share on other sites More sharing options...
Marty Backe Posted May 31, 2018 Share Posted May 31, 2018 You've really turned into a speed demon @Hunka Hunka Burning Love Link to comment Share on other sites More sharing options...
eddiemoy Posted May 31, 2018 Share Posted May 31, 2018 27 minutes ago, Rotciv said: When you guys say wobble, is that when the wheel is moving side to side and making tiny “s” turns or is it rapid front/back tilting? I get side to side movements when I try to squat on the wheel. I’m not sure how to prevent that, any advice would be helpful. I experienced rapid front/back tilting once on my nb1s1 just before it died. Luckily, it was very slow speed and I was able to get off without getting hurt. you can think of it as fishtailing but not slow like a car, fast like a real fish. lol Link to comment Share on other sites More sharing options...
WARPed1701D Posted May 31, 2018 Share Posted May 31, 2018 8 hours ago, Keith said: There is a correlation to this with aircraft as well. Nose wheel aircraft track straight when taxing or landing even in a crosswind as their Centre of Gravity (CofG) is forward of the main wheels and any sideways disturbance is self correcting. Tail wheel aircraft cannot handle much crosswind at all and even with no wind, pilots have to learn to be VERY quick and positive on the rudder peddles to keep them straight. This is because their CofG is behind the main wheels any disturbance is amplified, I.e. once (say) a slight movement to the left develops the mass operating as if at the CofG moves out to the right and pulls the aircraft further left, etc. If the pilot isn’t fast enough correcting, or over corrects this can develop easily into a complete 360 degree ground loop. I used to teach safe boat trailering and what you describe can also apply to them. I used to emphasise the need for a positive weight on the hitch of about 10-15% gross trailer weight. Why? Because it meant the CoG of the trailer was ahead of the trailer axle and therefore closer to the pivot point of the hitch and was between the rear wheels of the car and the trailer axle providing road contact points both forward and aft of the mass. If a trailer were to become destabilized though road camber, wind etc and move out from behind the tow vehicle then having a large CoG further from the hitch and behind the trailer axle provided the CoG mass a large lever length to multiply its effect and only one point of contact to resist it. The self correction motion of the trailer pulling back behind the vehicle ends up gaining too much momentum and energy and subsequently self corrects too much by swinging out the other way....and so the fish tail is born. We of course only have one point of contact on the road so the best way to stop providing a large mass (us) any kind of lever through which to multiply its force is to place yourself directly over the wheel. Ankles next to the axle and feet hanging off the front of the pedals. Link to comment Share on other sites More sharing options...
Bob Eisenman Posted May 31, 2018 Share Posted May 31, 2018 More armchair thoughts on wobble: When wobble occurs the EUC cyclically twists back and forth below the mounted rider in a harmonic way. The law of Conservation of Momentum (a vector quantity) seems to be appropriate in describing wobble. Before wobble starts the 'twisting wobble vector is zero in magnitude'. A 'Half-wobble momentum seems to be created by various forces on the EUC tire footprint as a result of the riders center of gravity, the riders pedal input at the axel, motor torque, etc. A half-wobble momentum change in the opposite direction follows as various forces dissipate the initial half-wobble energy. The net twisting wobble momentum vector equals zero for one complete cycle of wobble (conservation of momentum). Wobble is harmonic when it happens. It cycles back and forth. The EUC itself also has a substantial forward momentum vector. The rider is more or less loosely attached to the EUC during wobble and the net controlling effect of the riders downward pressure on the pedals is apparently reduced during the time that wobble occurs which is alarming and sometimes dangerously unsafe. Since the forward momentum vector is so large (vector quantities map head to toe consecutively and vector length is proportional to its magnitude) the riders path (vector sum) continues more or less on a straight path during wobble. At decreased speed wobble seems to go away. Link to comment Share on other sites More sharing options...
Bob Eisenman Posted May 31, 2018 Share Posted May 31, 2018 I'm out on a ride. This story came to mind. Ancient EU lore recalls the story of the scorned infant Wobble who was the mutant love child of Princess Osmo of the Gimbals and Crown Prince Hathaway of the Shirts. Wobble's spirit lived on and was known to fear certain disruptions and to cause chaos around him when perturbed in certain ways. Link to comment Share on other sites More sharing options...
KalSeth Posted May 31, 2018 Share Posted May 31, 2018 One more cup of coffee before I go. To the Valley below. 3 hours ago, Marty Backe said: You've really turned into a speed demon @Hunka Hunka Burning Love 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. Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted May 31, 2018 Author Share Posted May 31, 2018 5 hours ago, Marty Backe said: You've really turned into a speed demon @Hunka Hunka Burning Love It's all those months limited to 20-22 kph on the ol' Ninebot One E+ that had me yearning to break that speed barrier! With more pedestrians there's not much chance to sustain prolonged higher cruising speeds so it's nice on these gloomy days when you have the pathways to yourself. 7 hours ago, Rehab1 said: Ou are lucky! Glad your safe! Are there any irregularities on the terrain were you were riding (ie: stick, tree root, stones...etc?) Personally I would go back to the scene and inspect the area. Situations like these weigh heavily on a rider until there are some sound answers leading to the cause. That is a great question. I know in my case it was a hitting a large pothole. In Hunka’s case who knows. I find it hard to fathon that attaching a BT speaker to Tesla’s body would initiate a wooble. Thanks! I'm glad I didn't crash. It was just like those motorcycle oscillation videos but worse.... The pathway is very smooth on this downhill stretch so I didn't think much of it. I blame it on uneven foot positioning, my speaker, and leg fatigue. I usually have my toes overhanging the front of the pedal so nothing really was different there. Man, the wheel was flailing side to side like a crazy bronco buck. I'm surprised I didn't crash. Link to comment Share on other sites More sharing options...
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