V10F wheel need balancing?

[Robotuner]

Hi:

I recently go a V10F and am learning to ride.  I'm not entirely a newbie.  I've ridden a scv v3Pro for two summers.  Nevertheless, consider me a slow and cautious learner.  Anyway, I beginning to go faster on the V10F and it feels like the wheel become wobbly at higher speeds.  If I had to describe it further, it's like what happens when your driving a car and your tires need balancing or need to be aligned.  I'm not ruling out that it's just me being jittery, ... 

Has anyone else experience anything like this at higher speeds on any unicycle?

[Keith]

7 hours ago, Robotuner said:

Has anyone else experience anything like this at higher speeds on any unicycle?

Yes, everyone has!

If the wobbling is up and down or like a vibration it might be wheel imbalance. However if, as I suspect, it is a side to side movement it is impossible for the wheel to generate that, it has to be the rider. For a new rider there seems to be a “wobble barrier” a speed where wobbling occurs and can get worst as you go faster, possibly throwing you off.

Untrained muscles, feet too far back (centring your feet on the peddles instead of centring your mass over the middle of the wheel) just nerves as you go faster, all seem to play a part yet it seems to just go away by itself almost as you gain experience.

Search on “wobble” to see just how much it is discussed: https://forum.electricunicycle.org/search/?q=Wobble or just this recent post:

 

[Elder Meat]

I dunno. An imbalanced wheel can/will cause lateral wobble. By definition, the motor applies torque in a vector aligned with the axle. However when the entire wheel assembly is not balanced around that axle, the difference between that axle and the wheel's moment of inertia axis will induce a lateral wobble. When that happens to your car's front tires, your steering wheel vibrates left/right as a result.

Car wheel balancing machines spin the wheels at 10-15mph to detect any imbalance. That's getting into what we call high speeds. But there's no way to tell if that's the issue in this case.

I think decreasing tire pressure might reduce wobble (regardless of cause) as it gives a larger contact patch to resist lateral play.

[Keith]

6 hours ago, Elder Meat said:

When that happens to your car's front tires, your steering wheel vibrates left/right as a result.

I had a private bet with myself that someone would say the above. A car front wheel is hanging out at the end of a steering arm so an imbalance at the rim of the wheel will, of course, pull the steering left/right as it is happening at a considerable distance from the wheels steering pivot point. And yes, wheel balancing equipment can detect which side of of a much wider car wheel is out of balance.

However, the imbalance cannot possibly be more than an inch or so from the centre line of a 16” wheel. Even chronically out of balance it would have a tiny sideways pull.

[Mono]

I once had a "wobble" from a defective tire sidewall. However, this was clearly a specific kind of wobble. It was very regular, periodic with a frequency directly proportional to speed. I don't think it should be too difficult to differentiate between the "typical speed wobble" which may or may not come out of the blue and may go away like that as well and a wobble based on an imbalance of the wheel.

[Kristof Willen]

My experience with my V10 is that (side2side) wobbling occurs in the following 2 situations :

 

• Check your tire pressure : if too high, wobbling has a higher occurence chance.  I increased my tire pressure to 40 psi when I received my wheel, I've later lowered this to 32 psi.  Much better.  Finding the 'sweet spot' wrt tire pressure is crucial imo
• Your feet are not properly aligned on the pedals. 

I'm a newbie myself, I have my V10 now for a month, 400 km mileage....

 

[Elder Meat]

17 hours ago, Keith said:

However, the imbalance cannot possibly be more than an inch or so from the centre line of a 16” wheel. Even chronically out of balance it would have a tiny sideways pull.

I still maintain an imbalanced wheel can/will cause lateral wobble, and that there is no way to tell if that's an issue in this case. Here's another data point: multiple people have noted that adding too much slime will induce dangerous wobble at high speeds. 

[Mono]

On 9/27/2018 at 5:43 PM, Elder Meat said:

Here's another data point: multiple people have noted that adding too much slime will induce dangerous wobble at high speeds. 

Were these speculations or actual before-after experiences? Searching the forum didn't bring up anything like that for me.

[Elder Meat]

 

[Papa Schultz]

Had the same with my V10, same as Kristof said, decreasing the tyre pressure did a great part of the trick. 

Due to it having a high center of gravity by design (battery pack mounted on top), I am still not completely at ease, which still leads to some wobble from time to time in my case. It’s getting better, though.