Front tire "cupping"

[Anonymous]

I was reading in this magizine that on this old bike the front tire was "cupped" and he had to replace it. Is that like cracked or worn?

[daveo]

It's also sometimes called 'scalloped' where one side of a tread block,usually leading or trailing edge, is worn more than the rest of the block,and can be caused by the tire being out of balance, misaligned, out of round, or from an ineffective shock absorber, which may allow the wheel to bounce erratically or uncontrollably

[Anonymous]

Out of balance, out of round, that bounciness when you're on a smooth road and can't figure out where the bumps are coming from. caused the tire to wear unevenly. It is easy to spot on a car tire.

[Katana]

I've known blokes who had head stem bearings replaced , bought
fork braces,invested in steering dampeners , all for the sake of a buggered front tyre !! :roll:

cheers Katana

[Anonymous]

Thanks gents

[saaz]

Cupping can be a characteristic of some tyres, but it can be caused by front suspension setup making the tryre do too much of the work that the suspension should

[focus frenzy]

Cupping can be a characteristic of some tyres, but it can be caused by front suspension setup making the tryre do too much of the work that the suspension should

The dunlop F-24 is bad about wearing unevenly,I had one on my 1000g and it "cupped", my zn1300 voyager had a F-24 on it when I got it, and it was cupped, a coworker of mine has a Hardly ableson and has a F-24 on it, and it to is cupped.

I now have a chin shin "highmax" on the 1000g and it is wearing evenly, on the zn 1300 I put a dunlop cruisemax on it and it is wearing even.

[Anonymous]

Don't know about front tire cupping, but statistical analysis of beer-drinking GSR forum participants shows that they are "in their cups" most of the time.

[argonsagas]

Don't know about front tire cupping, but statistical analysis of beer-drinking GSR forum participants shows that they are "in their cups" most of the time.

Cute, Simon.
One of those adopted terms that works for both sexes, even if the women don't drink beer. :roll:

[massakins]

Increased tire pressure is supposed to help reduce the development of cupping, but I don't have factual data to support this. I always thought it was from uneven wear due to the distortion subjected by loading. I've had street tires at the drag strip wear more on the leading edge than the trailing edge of the block because under hard acceleration it was deformed this way. Similarly I've had front tires that I used alot of brakes on that wore more on the trailing edge than the leading edge. Picture how the tread looks if you could freeze it under load and look at it from beneath a clear glass road surface. This probably represents the wear we see. Many bikes with fairings added to them seem to be hard on front tires as well; don't know if its the weight, the increased load due to wind resistance or both. As stated earlier though, this can also be caused by improper condition of other components on the bike....something bent, out of adjustment, out of balance, etc.

[Katana]

assakins said"Increased tire pressure is supposed to help reduce the development of cupping,"

wouldn't increased tyre pressure lead to decreasing grip If you already have tyres at optimum pressure ( not the max. pressure on tyre wall)

cheers katana

[massakins]

The purpose of the increased pressure was to "stiffen" the tire and reduce distortion of the carcass under load, hence reducing uneven block wear. Makes sense intuitively. Also passes more of the forces onto the suspension and further.

[Katana]

So I take from that, the pressure added is minimal so as not to be adverse to the handling of the bike?


katana

[Clone]

Cupping of a tire can be caused by poor shock absorbtion. Fork oil has water in it, unequal fork oil hieghts, old oil, broken spring, weak spring, not enough air, too much air.....
too many to list.
Check into the rebound and damping rate of the fork, it could be the culprit.