Rear wheel balancing

Mr K said:
...and why do they balance car wheels/tyres??

:nenau
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Yes. But you can generally tell when a wheel is out of balance; excessive vibrations through the steering wheel (or handlebars) when driving (or riding), accelerating and braking. If you can't feel the vibes, then nothing to worry about.
 
Thanks for all your posts

Cheers folks, it's interesting that there's so little concensus on this subject - or is it that those who really know just like watching the banter....;)
 
IMHO

Gents, IMHO it is not a question of wether they in principle should be balanced. The question is tolerance. IIRC BMW specs 5g tolerance for the front and 25g for the rear. That said, you may live well and long with a little bit more :D
 
Mr K said:
Any boffins help?

If your wheel/tyre is say 10g unbalanced, how much effect/force does it have/do/cause as you whizz along at 70mph?

:topic

:type


PS: As I once told a prospective Mrs K, just because you can't feel it, doesn't mean it's not there....:augie
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Wouldn't call myself a boffin, but I'd think you'd work out the force like this.

The force from the 10g weight is sufficient to put the wheel in balance, hence this is equal and opposite to the out of balance force. This force is the centripetal force required to accelerate the balance weight. Wikipedia tells me the equation for centripetal force is F=mv^2/r, I guess in SI units. m is balance weight in kg, v is velocity in m/s, r is radius in m of rim. F is then the force in Newtons on the axle. I'm on my iPhone so can't do the calc easily, but I think at 100kph it's about 8 newtons or 0.8kg of force.

..........I'm sure somebody will along in a minute to correct me :)
 
I'm sure the guy just didn't have the adjustment cone for his balancing machine to take the big hole common on bikes with single sided swing arms. Pity he felt the need to bullshit.
 
Bike wheels being narrower than cars will not as a rule wobble the steering (for the front - left to right). That leaves a center line ballance issue. If it is not too great then the suspension will take most or the vibes that the rider would feel unless of course it is massive, which with todays manufacturing methods is unlikely.
As has been said, manufacturers mark the heavy spot on their tyres and this is so that the tyre is placed on the rim with the heavy bit opposite the valve.

The problem is the bearings. They are designed to roll over each other and the rollers/balls distribute the weight relatively evenly, but they are not designed for the constant hammering from an unballanced wheel.
As has been said, if the imballance is 0.8kg (and I have not worked it out) and the circumference of the wheel is about 2m then at 100mph the bearing is getting shunted up and down about 80,000 times per hour that is not needed.

If you transfer that to a years riding of 12,000 miles then that is multiplied up to a mad figure (albeit not all at 100mph) but....

Could this be the cause of rear wheel bearing failure at 30k miles or whatever ?
 
i want my rear wheel balanced, just like i do the front and all four wheels on my car.

if the tyre shop doesn't have the kit (and my favourite place actually doesn't), i go somewhere else.
 
WindyChuffer said:
Yes. But you can generally tell when a wheel is out of balance; excessive vibrations through the steering wheel (or handlebars) when driving (or riding), accelerating and braking. If you can't feel the vibes, then nothing to worry about.
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agree,,,,,,,,,,,,,
 
Martyn B said:
Nearer .0795 M8 but a brave effort.:D
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now I've looked at it again, still on the iPhone:

m=10/1000=0.01
v=27.7m/s (100kph), however given a 17" rim, with a 150/70 tyre the radius of the tyre is .32m whereas the rim and weight is at a radius of .216 hence the velocity of the weight is reduced to 18.68m/s at the rim

r=0.216 (17" rim diameter)

F= 0.01 x 27.7^2 / .216 = 16.2N

or 1.65kg equivalent.
 
Old Git Ray said:
Bike wheels being narrower than cars will not as a rule wobble the steering (for the front - left to right). That leaves a center line ballance issue. If it is not too great then the suspension will take most or the vibes that the rider would feel unless of course it is massive, which with todays manufacturing methods is unlikely.
As has been said, manufacturers mark the heavy spot on their tyres and this is so that the tyre is placed on the rim with the heavy bit opposite the valve.

The problem is the bearings. They are designed to roll over each other and the rollers/balls distribute the weight relatively evenly, but they are not designed for the constant hammering from an unballanced wheel.
As has been said, if the imballance is 0.8kg (and I have not worked it out) and the circumference of the wheel is about 2m then at 100mph the bearing is getting shunted up and down about 80,000 times per hour that is not needed.

If you transfer that to a years riding of 12,000 miles then that is multiplied up to a mad figure (albeit not all at 100mph) but....

Could this be the cause of rear wheel bearing failure at 30k miles or whatever ?
Click to expand...


But they are intended to be hammered off road...
 
...from a reliable source ... Protyre have the machines to balance one sided wheels and the recommended by BMW as they are their supplier ...

Worked for me.. I even got to do it myself... with supervision of course!
 
Canuck said:
...from a reliable source ... Protyre have the machines to balance one sided wheels and the recommended by BMW as they are their supplier ...

Worked for me.. I even got to do it myself... with supervision of course!
Click to expand...

Yes, i sometimes use Protyre in Bristol. And they insist on balencing my wheels, even though I protest that i don't want ugly weights stuck to my lovely wheels...the blighters:rob
 
My last BMW an R1150RT I serviced for 6 out its 7 yrs ownership myself but always paid for tyres to be fitted and balanced.
My new GSA which is now just a year old I intend to service myself and fit and balance tyres myself, that way I not only save some money but more importantly I know exactly what work has been done on it.
My RT I sold to a friend who was more than happy with my lack of BMW service history trusting more in my fastidiousness (if thats the right word).
A friend turned me on his lathe the boss to fit the rear wheel so that could check the balance on my new wheel balancer recently purchased.
As a matter of interest I decided to take both wheels out and firstly check if the boss fitted, it was perfect! and secondly how in balance the wheels were? The front was spot on, but the rear, get this! the weights had been put on the wrong side of the rim by the tyre fitter (30gm) so in essence, my rear wheel was out of balance by 60gm (2oz) (which cannot be good, at speed it will clearly put load onto the FD). Since then I have bought some very nice spoke weights off ebay and again rebalanced them. It is easy but takes a little patience to get it spot on.
My advice, DIY everything.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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