Tip: Method for weight balancing an EUC

[mrelwood]

Since the beginning I have been pondering on how to weight balance my EUC to minimize the wobble created by an unbalanced wheel. "Beginner legs" or tense legs do ofcourse cause wobble, but I don't want the wheel to add to it. This has also been asked a few times here, and today I've finally found a decent, reproducible way to do this!

You need a kitchen scale with a precision of 1 gram, and ofcourse the weights. I bought the weights from a local store that sells parts and accessories to cars and motorcycles, among everything else.

First determine which side to use for the weights:

1. Put a strip of masking tape to the tyre, from the air valve across to the other side.

2. Set up a (phone) camera to record video, as in the pic above. Slow motion video works best.

3. Sit on a chair and start the EUC.

4. Use both hands on the handle to rise the EUC from the ground. Find the balance so that you can keep the tire still.

5. Very slowly start to accelerate forward. When you feel the wobble at it's strongest, hold on to that speed for 5 seconds or so.

6. Stop and watch the video. You should see the wobble, usually both up-down and sideways. If the EUC turns right when at it's low position, attach the weights to the right side. If left, attach to the left.

Now locate the spots for the weights.

A kitchen scale rarely measures past 5 kg or so, so you need to distribute the weight of the wheel. Most rigid half a meter long things will do. I used a leftover piece of an in house floor board. Make sure none of the parts of the system touches anything soft, as this will mess the measurements.

1. Place the EUC on it's side on the very end of the board. Face the handle to the free end of the board.

2.  Place the kitchen scale under the other end of the board. Place a small rigid box (or any suitable thing) between the scale and the board.

3. If the weight on the scale is out of range, move the EUC even further to the end of the board.

4. Turn the wheel by hand to locate the masking tape, and write down the number on the scale.

5. Very carefully rotate the wheel forward to the next motor bolt. This is usually 1/12th of a full cycle. Write down the number on the scale, and repeat until you are back at the masking tape.

6. Locate the position where the weight on the scale is at it's high point, and place the weight to the wheel. Repeat part 5 until the weight difference is under 5 grams or so.

Now turn on and lift up the EUC again. If there is still a notable a side-to-side wobble, shoot another video. Locate the spot that is facing forward when the wheel turns to the side the weights are on. Move the closest weight to the other side, and check if the wobble went away.

 

With the above process I was able to minimize the wobble to a tiny shake at full speed.

[FULspeed]

Hi,

until point 6 of the first paragraph I was following you, but after...

The second part (locate spots) is sincerely out of my understanding capacity.

Thanks for an eventual supplementary explanation.

[mrelwood]

Don't blame yourself, English is not my native language so I probably use wrong terminology. I guess I should make a video of the process. Meanwhile, perhaps an additional picture helps:

- Now write down the weight on the scale.

- Rotate a wheel a bit and write down the new weight on the scale. Repeat until the wheel has gone a full cycle.

- Locate the spot where the weight was the highest.

- Attach a weight to the wheel and start over.

 

I hope this was easier to understand.

[mrelwood]

Finally, my video showing and explaining the process:

 

[Smoother]

@The Fat Unicyclist just linked this thread.  This is brilliant stuff.  Very clever, and well documented.  Well done.

[King Llama]

This is a great thread, thank you for the video.

I understand the weight balancing part of the process (really brilliant way to do it using a plank).

However, I still don't understand the left/right part of the balancing process. Can someone who does understand it explain it more clearly?

When the front part of the wheel turns to the right, we want to move the weights from the front section of the wheel to the right side? Is this correct?

I've drawn a very crude picture to explain what I'm talking about.

[steve454]

On 2/22/2018 at 7:42 PM, King Llama said:

This is a great thread, thank you for the video.

I understand the weight balancing part of the process (really brilliant way to do it using a plank).

However, I still don't understand the left/right part of the balancing process. Can someone who does understand it explain it more clearly?

When the front part of the wheel turns to the right, we want to move the weights from the front section of the wheel to the right side? Is this correct?

I've drawn a very crude picture to explain what I'm talking about.

Really, I think you should not worry about balancing the tire.  The high speed wobbles are caused by wrong foot position and weak leg muscles.  I used to get them sometimes at high speed and they were scary, almost lost control had to slow way down.  You just need more hours on the wheel, and in the meantime don't ride quite as fast, and if you do get wobble, slow down to very slow speed and try repositioning  your feet and see if that helps.

But it might be a fun project to do, I have no idea about how best to do it though.  Good luck with the wheel.

[King Llama]

On 2/28/2018 at 7:34 AM, steve454 said:

Really, I think you should not worry about balancing the tire.  The high speed wobbles are caused by wrong foot position and weak leg muscles.  I used to get them sometimes at high speed and they were scary, almost lost control had to slow way down.  You just need more hours on the wheel, and in the meantime don't ride quite as fast, and if you do get wobble, slow down to very slow speed and try repositioning  your feet and see if that helps.

But it might be a fun project to do, I have no idea about how best to do it though.  Good luck with the wheel.

Agreed. It's mostly the fact that I build my own road bike wheels and so I have a compulsive need to make sure the wheel is properly built and balanced 

The high speed wobble has mostly gone away with a little more practice riding and also properly inflating my tire.

[mrelwood]

On 2/23/2018 at 3:42 AM, King Llama said:

When the front part of the wheel turns to the right, we want to move the weights from the front section of the wheel to the right side? Is this correct?

I've drawn a very crude picture to explain what I'm talking about.

Yes. But I have learned that it’s a bit more complicated than that, as the speed of the wheel affects wether the exess weight is on that spot or 90• before. Trial and error seems to be the best bet...

For disbelivers: Most wheels/riders do not need this process. And many would gain too little to make difference. But if you buy a replacement tire from China that has been in a twisted position in a tight packaging for months, this really can help a lot.

[Hunka Hunka Burning Love]

I wonder if these beads might make things easier?

https://www.walmart.com/ip/Counteract-Tire-Balancing-Beads-MK2-2-3/747346778

[Rehab1]

49 minutes ago, Hunka Hunka Burning Love said:

I wonder if these beads might make things easier?

https://www.walmart.com/ip/Counteract-Tire-Balancing-Beads-MK2-2-3/747346778

Very interesting! Wonder if that would work on YOUR TESLA? Come on Hunka...be the first one in the community to try them out and experience that buckshot pinging sound rolling down the road.