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Rear Wheel Concentricity

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GettinBetter
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Joined: 20 Jun 2019
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PostPosted: 11:46 - 13 Dec 2020    Post subject: Rear Wheel Concentricity Reply with quote

I was running in gear on the centre stand, to oil the chain, and noticed this.....

Now I've spent a large proportion of my life as a centre lathe turner where concentricity is the be all and end all of a good job.

This does not sit well with me.

Your thoughts please.
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Ste
Not Work Safe



Joined: 01 Sep 2002
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PostPosted: 12:27 - 13 Dec 2020    Post subject: Reply with quote

You're going to get people telling you how dangerous that is because if you slipped then your fingers or penis could be chopped off in a painful and messy way. Sick
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weasley
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PostPosted: 12:35 - 13 Dec 2020    Post subject: Reply with quote

Looks like a spoked wheel so when your fingers grow back you could have a go at truing it.
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Pete.
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PostPosted: 12:42 - 13 Dec 2020    Post subject: Re: Rear Wheel Concentricity Reply with quote

GettinBetter wrote:
I was running in gear on the centre stand, to oil the chain, and noticed this.....

Now I've spent a large proportion of my life as a centre lathe turner where concentricity is the be all and end all of a good job.

This does not sit well with me.

Your thoughts please.


I would turn it off and use a pointer or dial gauge and turn the wheel by hand. Running under power like that could be any number of reasons it's jumping. A tight spot on the chain, poorly seated tyre (the mould line does seem to run out with the rim).

I bet it smoothes out if you run it faster.

EDIT: Just checked the MOT guidance:

5.2.2. Road wheel condition

Check the roadwheels fitted to the motorcycle and any sidecar.

Spare wheels are not included in the inspection, but you should tell the presenter if you notice a defect.

The maximum lateral rim distortion (run out or buckling) limits are:

4mm for steel rims
2mm for aluminium alloy rims (cast or fabricated)

The maximum eccentricity is 3mm for all types of rim.

Measurements should be taken from a machined surface in the case of cast aluminium alloy rims.


What you got there is nothing like 3mm IMO, so it's within MOT spec.
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GettinBetter
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PostPosted: 13:09 - 13 Dec 2020    Post subject: Re: Rear Wheel Concentricity Reply with quote

Pete. wrote:


The maximum lateral rim distortion (run out or buckling) limits are:

4mm for steel rims
2mm for aluminium alloy rims (cast or fabricated)

The maximum eccentricity is 3mm for all types of rim.


Cheers Pete, thats what I needed.
Still 3 & 4 mm are not something I'm happy to tolerate, IMO it looks to be at those limits now. So it'll be coming off in due course,

I will put up another video for comparison when I've sorted it.
I have dti's and other test gear for measuring this accurately, although I'll be happy if it's within 1mm.
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stinkwheel
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PostPosted: 14:46 - 13 Dec 2020    Post subject: Reply with quote

Rim doesn't seem all that bad. Maybe more the tyre? Is is seated properly (even gap between the rim and indicator line all the way round?).

Remember spoked motorcycle rims generally have a "tick" on them where they were welded together, discount this from your runout.
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I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.
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A100man
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PostPosted: 18:09 - 13 Dec 2020    Post subject: Reply with quote

Check for loose/broken spokes?
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steve the grease
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PostPosted: 19:02 - 14 Dec 2020    Post subject: Reply with quote

My nephews CG125 wheel had so much loose in the spokes that I'm surprised he could ride it, it was shaking all over the place , he has only got a degree in mechanical engineering , but frankly if you sexually assaulted him with a screwdriver , he wouldn't be able to tell you which end it was....
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MCN
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PostPosted: 03:10 - 15 Dec 2020    Post subject: Reply with quote

It's one of those little things one should not bare thinking about whilst riding the hoowur. 😎
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stinkwheel
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PostPosted: 19:21 - 15 Dec 2020    Post subject: Reply with quote

You shoudl relace it with only leading spokes, trailing spokes only slow you down...
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I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.
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Easy-X
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PostPosted: 20:14 - 15 Dec 2020    Post subject: Reply with quote

This on a 125? Wheel imperfections get more dramatic at high speed and as you won't be doing that I wouldn't worry Smile
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Hong Kong Phooey
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PostPosted: 09:55 - 19 Dec 2020    Post subject: Reply with quote

You've never felt anything while riding it before now.

But after seeing it you'll be bounced out of the seat the moment you set off Very Happy
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