I wondered why my tire was worn more on the left side

[Steve in Golden]

The last time I replaced the front tire on my bike, I noticed it was worn more on the left side than the right. I wondered why? I thought maybe it was because there were more left turns than rights on my commute, which is where most of my mileage comes from. Some might say this pattern is due to the road crown.

Neither seems to be the case according to this article.

Common Motorcycle Tire Wear Patterns

[enigmaT120]

I saw that article a long time ago, and it convinced me. I drive more miles in left turns than right because I drive on the right side of the road.

[Zombie Master]

single disc?

[Duane Ausherman]

What does a single or double disc have to do with tire wear?

I consider that article to be the best on the subject. On my website I have an article about cupping and it was there first. Had this article been out at the time, I never would have bothered to write mine. I don't want to reinvent the wheel.

[Major Softie]

single disc?

The wear pattern is normal for motorcycles (which drive on the right-hand side of the road), regardless of single or double disc, so I think we can rule that factor out.

[Garnet]

single disc?

The wear pattern is normal for motorcycles, regardless of single or double disc, so I think we can rule that factor out.

I think ZM ment that with a single disc you can't stop in time so you have to swerve to the left to avoid the car in front, hence the left side of the tire where's faster.

[Steve in Golden]

Mebbe ZM thinks if there's only one brake disc the tire & wheel assembly is heavier on that side so it wears out faster on that side.

My bike (2008 R1200R) has dual brake discs anyway.

[Major Softie]

Actually, I'm pretty sure he was speculating that the flexing of the fork on a single disc fork might cause uneven wear on the front tire, which, while speculative, certainly doesn't seem impossible, but, as I said, it happens regardless of the brake design.

Perhaps our left-side-of-the-road brethren can tell us if the right side of their front tires wears out first, but I believe I have read that is the case. Of course, this still leaves the crown theory intact, except that the wear occurs too far over to coincide with the angle of the crown - much more aligned with normal cornering angle - at least that has been my experience.

[Steve in Golden]

Actually, I'm pretty sure he was speculating that the flexing of the fork on a single disc fork might cause uneven wear on the front tire, which, while speculative, certainly doesn't seem impossible, but, as I said, it happens regardless of the brake design.

Perhaps our left-side-of-the-road brethren can tell us if the right side of their front tires wears out first, but I believe I have read that is the case. Of course, this still leaves the crown theory intact, except that the wear occurs too far over to coincide with the angle of the crown - much more aligned with normal cornering angle - at least that has been my experience.

The fork flexes more on a single disc setup? How come?

I realized my original post didn't make a lot of sense, when I said "maybe it was because there were more left turns than rights on my commute, which is where most of my mileage comes from". DUH! If there were more left turns than right on the way in, it would be reversed on the way home so would be even. Unless I took a completely different route in the afternoon than morning. Which I sometimes do.

Anyway it sure is interesting that no matter how long one has been riding, there's always something new to learn!

[Major Softie]

The fork flexes more on a single disc setup? How come?

Uhm, no, or maybe, but that's not the point. It flexes differently. When you apply the brake on a dual disc setup, the wheel tries to flex the fork forward at the caliper and rearward at the axle. When you apply it in a single disc setup, it only tries to flex one leg forward at the caliper, which applies a twisting force on the fork. How much it actually twists depends on the strength of both the fork leg, and the brake. I've ridden bikes where you could feel it want to turn a little when the brake was applied hard, and other where you didn't notice it at all, but I don't think it has anything to do with this particular wear issue.