Sports: [DucatiST] tire balancing

On Sep 27, 2011, at 3:05 AM, Andy Bryant wrote:

> Nick, Michael :
>
> >Very interesting, Michael!
>
> Very interesting indeed. As a scientist, though, I have to ask if you consistently see that superior mileage now that you carefully balance your own tyres.

No, I was dissaointed with the mileage of the Tourance that I had had shop balanced.

And I saw that they had not worn smoothly.

So the next set I mounted and balanced myself.

Then I saw the difference in milage.

> Difficult to know for sure, I know, but 3k miles is a big difference so perhaps you can see it if you've fitted a few of that particular brand and model. Did anything else on the bike or usage change significantly between the two periods?

No.

> Also, although an outside chance, you may have had manufacturing variability between the two tyres (it happens occasionally in racing).

I'm assuming all tires are made using clamshell molds (invented by Michelin a long time ago). And when I sold Michelin car tires 30 years ago they were exceedingly uniform but there would be some that were off a bit from the usual. So I think it is more prevalent than you might imagine. It is a hot molded product. Things can also shift around internally during the life of the tire.
>
> Presumably the mechanism would be a periodic bounce causing cupping at just one particular point of the circumference -

I think it would have a resonance frequency and when you hit that it would pulse energy into the carcass which would manifest itself in various ways. Some tires might scrub left and right or do other things you wouldn't expect.

> is that what you have, or is it cupped all around the circumference?

On the Tourance there was what I showed in the photos.

I changed to Avon Distanzia now and like them much better in every way.

They are also wearing more evenly.

Shot below shows wheel with tube valve at 12, primary balance weight at 6 and secondary weight at 9.

http://dl.dropbox.com/u/17118061/sec.1.JPG

A little closer.

http://dl.dropbox.com/u/17118061/sec.2.JPG

Tire is wearing very evenly.

http://dl.dropbox.com/u/17118061/sec.3.JPG

But there is still a small bit of unevenness where there is a large gap between the tread blocks due to the dualsport tread design.

http://dl.dropbox.com/u/17118061/sec.4.JPG

My point is that if you have your tires mounted for you and skip the balancing you can do a much better job of balancing them yourself.

The guy tasked to change tires is the lowest guy on the totem pole.

It's shitty work and they hate it.

So you're not going to get the same degree of care and attention as the tire tech on a race team would give you.

On my next set I will end up pre-balancing the wheel before mounting the tire and then also checking the balance after about 4,000 miles.

I like the smoothness of a balanced set of tires.

Thanks,

M./

Michael Heth
mheth@motolectric.com
(415) 992-7840