tire cupping

[Burl]

I recently put a Heli riser on my 2014,the type that you have to put a extension on the brake line. Now my front tire seems to be cupping some and it feels like I'm getting some vibration. I had the tire balanced again thinking that was what it was but didn't seem to help. Wondering if any of you have experienced anything like this?Both front and rear tires are brand new Mich PR4s.

 

[Pterodactyl]

That's like saying, I got a haircut and now I have problems with an in grown toe nail. Pretty hard to imagine a cause and effect relationship between your riser and a cupping tire. Cupping is not uncommon and there are other threads that have covered the problem in depth (hence your post now resides in NEPRT). My personal experience is that elevating the pressure to 40-41 PSI seems to reduce cupping. Another lesson learned is that once a tire gets any significant cupping it is doomed. And lastly, my experience is that Bridgestones are very susceptible to cupping.

 

[redzgrider]

My experience is that PR3 and 4 fronts cup more and faster than any other tire I've ridden. All those microsipes grip really well, wet or dry, right up until my teeth begin to shake at low speed.

 

[jmgrif]

42/42 check it daily! Bridgestones suck!

 

[SkooterG]

Many factors affecting cupping. Adding risers with a brake line extension is not one of them.

As mentioned, air pressure is #1 cause.

In my not so humble opinion, #2 cause is front braking while leaned over in the slightest.

 

[N4HHE]

Cupping is not uncommon and there are other threads that have covered the problem in depth (hence your post now resides in NEPRT).

Cupping (aka scalloping) is extremely uncommon on motorcycle tires. Cupping is caused by the combination of soft springs and far too little damping in the shock absorbers. Motorcycles are sprung relatively stiff. Cupping occurs across multiple tread blocks, irrespective of the tread pattern.

Feathering on the other hand is relatively common on wide modern motorcycle tires. Feathering follows the tread pattern wearing one edge of a tread block more than the other. Is caused by the sides of the contact patch having a different rolling diameter than the center forcing areas on the contact patch to scrub while other areas do not. Something has to give and this is largely determined by the tread pattern. Where there is a groove the tire will flex more.

You can play with tire pressures but there is no pat answer as to a cure. Higher tire pressures reduce the size of the contact patch which reduces the delta across the patch and less scrubbing. But for some reason sometimes less pressure seems to work better. YMMV.

 

[Redfish Hunter]

Now see, my ignorance is exposed again.

I thought that feathering was what I did to my hair back in the '70s.

I thought cupping was what happened when you used your hand to gently lift a mammary protuberance.

I don't know what happens with my front tire...

 

[NTXFJR]

Protuberance?? Honey, doe's this protuberance make me look fat??

 

[Denver_FJR]

...You can play with tire pressures but there is no pat answer as to a cure. Higher tire pressures reduce the size of the contact patch which reduces the delta across the patch and less scrubbing. But for some reason sometimes less pressure seems to work better. YMMV.

Which is why I think it's risky to increase tire pressure for something as trivial as trying to squeeze a few more miles out of a tire. You may only need that extra contact patch once, but when you do you will be glad you had it.

Now see, my ignorance is exposed again.I thought that feathering was what I did to my hair back in the '70s.

...

And that gave you an ingrain toenail didn't it?

 

[Redfish Hunter]

Now see, my ignorance is exposed again.

I thought that feathering was what I did to my hair back in the '70s.

...

And that gave you an ingrain toenail didn't it?

No, no ingrown toenail. I fear now that the term "feathering" was actually foreshadowing. In the '70s I feathered my hair. By the turn of the century my hair had flown off.

 

[lnewlf]

42 psi....and use a tar which has the side sipes even with each other rather that staggered....that way you can get a nice even groove around each side of the tread instead of cups..

 

[FJRMGM]

42/42 check it daily! Bridgestones ROCK!

Fixed it for ya! No problem with cupping on mine at 42 psi.