Could my hub be oval!?

[Windmill John]

Hi All,
Before I go out and spend money I haven't got on new spokes, new tire etc. Could my hub the oval?
Actually, just bought wheel bearings and it wasn't them!
Basically at 30 to 40 mph you can feel like a keystone cop
At 10 to 20 mph you can definitely feel pulsing from the back end.
At other speeds you can sense it.
Have tried with clutch in, so is back end.
My wheel is not round..... Ah well there you go then! It is out by about 10 mm at one point, but the effect feels stronger than that.
From all of your vast experience could it be the hub, or is the 10mm out at one point on the rim enough to feel like a clown's car?.
As the wheel is out, I will true the wheel, but before spending £70 plus carriage for Spokes, then to find out it was the hub, I'd rather buy a wheel!
I am running the enduro competition tyre it came with. I could try changing this, but I have ridden off road tyres on the road before but they didn't feel like this.
Your answers on a postcard please

[Matt-Tenere]

The problem will be with the tyre and/or rim.I had a DR 350 with off road tyres that were never balanced.The wear on the rear was so uneven after months of use,the wheel was hopping off the road at speed.Off road tyre clamps can throw the balance off by quite a lot.Especially when the valve and the clamp positions are close to eachother.If the rim is out,with the tyre removed,you will see the run out of the rim when you spin it.Hubs can go oval on the inside of a drum brake hub but I really don't think this is your problem here.

[xtzrick]

You can check your hub with a pointer taped to your swingarm inline with the outer edge of the hub, turn the wheel & see if the hub is oval.

The vertical (oval) & lateral (side to side) LIMIT for your rims is 2mm, 10mm is like running over a stone every time the wheel goes round.

Rick

[jibber]

You could do the same with the rim and tyre to narrow down your search

[Windmill John]

Thanks all.
I did put the wheel on my balancer and you can see the rim run out. I didn't check the hub then, so the run out could be that and not the rim.
I will pop it back on the balancer and test the hub too.
Thanks all again, just for interest I will report back on the hub and if all good will get spokes.
As one spoke is missing, so I'll need to do this anyway for the MOT later in the year.

Rick, your comment about the stone makes total sense.

John

[Windmill John]

Just an update on the hub. Lateral movement, zero. Vertical play on one side, zero. Vertical play on the other side, possibly imagined! Less than a mm; still think it was imagination, therefore rim it is, not helped by an enduro tyre.

Thanks guys, I will get spokes next month, subject to funds, might stick a Tourance or TKC on there.

John

[xtrider]

If you have a broken spoke, you'll have others loose and offset torque pulling the rim . Once you put the new spokes on and true it up , it'll be good again. Once you have the rim/hub laced up put it on a balancing stand to find the heavy spot . If the tire you get has a yellow, blue, or maybe red dot on it , line that dot with the rims heavy mark . Normally it goes to the valve stem , that because they assume the rim is lightest there ,(most are close from the couple I've checked since starting this) but when a person pre checks that they know exactly where the heavy spot is instead of guessing .





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[Windmill John]

Thanks for that xrider, I would have lined it up with the valve, but your reply is interesting; still waiting for the spokes.....

[steveloomis]

Very good, JJ, Thanks for sharing.

[acertainalias]

And at certian speeds your 10mm vertical run out will cause spring compression at or close to the resonant frequency of the spring and you could experience quite wild oscillations which would feel way bigger than the 10mm oscillation of the rim. Like the blue block in this high school physics animation.

http://www.acs.psu.edu/drussell/Demos/S ... force.html