I've had an epiphany on front tire left side wear, anyone?

[Polo]

Anyone care to discuss this otherwise never ever if seldom discussed subject?

 

What cylinder is further forward on the R engine?

[NonComp]

That would effect front-back weight distribution, but not left-right. Same mass left and right of the bilateral divide.

[Polo]

My thought is more along the lines of momentum and not weight.

[NonComp]

If it affected momentum, then it should pull to one side during braking or acceleration.

[upflying]

I previously had an epiphany on the PTTR phenomena as being caused by the P-Factor. I was shut down in that opinion by others supposedly more knowledgeable. Now that I mention it, how about gyroscopic precession? This opinion comes from the longitudinal placement of the crankshaft in relation to direction of travel and the small aircraft design of the boxer engine. You can feel that torque trying to twist this bike when you rev the engine.

more here

http://wiki.flightgear.org/index.php/Understanding_Propeller_Torque_and_P-Factor#Gyroscopic_Precession

[Goomicoo]

Me thinks it's something much simpler to explain. How about the crown of the road (high point at the center divider). We are always on the right side of the crown with the bikes leaning to the left. The easiest way to confirm this is to ask our British brethren if their tires wear on the right side. How about it over there. Pipe up.

[KDeline]

I previously had an epiphany on the PTTR phenomena as being caused by the P-Factor. I was shut down in that opinion by others supposedly more knowledgeable. Now that I mention it, how about gyroscopic precession? This opinion comes from the longitudinal placement of the crankshaft in relation to direction of travel and the small aircraft design of the boxer engine. You can feel that torque trying to twist this bike when you rev the engine.

more here

http://wiki.flightgear.org/index.php/Understanding_Propeller_Torque_and_P-Factor#Gyroscopic_Precession

 

Finally! I have always thought that. Riders on the other side of the pond have the same wear even though they are on the other side of the road.

[NonComp]

P-Factor shows up as prop-walk in motorboats. If the RT was propeller driven, then...

 

They mention that Gyroscopic Precession is minimal in a typical aircraft. It is transient, isn't it? Only present during acceleration/deceleration and due to inertia?

 

A reporter was badly injured a couple of years ago, when he sat on an idling Boss Hoss and gunned the engine. It flopped over on him.

[tallman]

There are a number of factors.

An in depth analysis was done by MCN.

Some possibles; left turns are longer than right hand ones.

A search may turn it up.

A better question would be to ask multiple marque owners if all of their bikes show the same wear pattern.

If not that would bring suspension, telelever, wheel offset, etc. in to play.

[NonComp]

I don't think that it shows up on R models. The roadsters are immune as far as I know.

[dirtrider]

Just remember on a single track vehicle (one wheel behind the other) there is no sideways thrust tire drag going down the road so the part of the tire that is wearing MUST touch the road to be wearing in that area.

SO, unless you are leaning the bike w-a-y over riding down the road to allow the wearing part on the tire to touch pavement it can’t be wearing until that part of tire touches the

pavement.

 

So if PTTR is causing the bike to lean t-h-a-t far over while riding down the road then that might be the cause. If one cylinder head being farther forward is causing you to ride down the road with the bike leaned over far enough to wear the tire that far off center then that might be the cause.

 

It should be a simple thing to find the why-of off center tire wear. Just get some help and lean the bike over until the wear area is touching the ground. Now just figure out what you are doing when the bike is leaned over to that angle. If that is how you ride it going down the road then you have your answer, if you only lean it that far over when doing something else than you again have your answer.

 

If it isn’t touching the road it CAN’T be wearing, simple as that.

 

[dan cata]

Me thinks it's something much simpler to explain. How about the crown of the road (high point at the center divider). We are always on the right side of the crown with the bikes leaning to the left. The easiest way to confirm this is to ask our British brethren if their tires wear on the right side. How about it over there. Pipe up.

 

Maybe someone from UK cand confirm that his front tire is not wear on the l/h side.

[tallman]

Pretty certain they've chimed in on this many times in the past.

Pretty sure they get the same USA and other drive on the right wear pattern so crown effect is minimal.

[oldyam]

Tallmans correct more wear on the left of the front tyre here in ireland too .......... its an effect of the grass colour and the amount of rain ;-)

[Polo]

Me thinks it's something much simpler to explain. How about the crown of the road (high point at the center divider). We are always on the right side of the crown with the bikes leaning to the left. The easiest way to confirm this is to ask our British brethren if their tires wear on the right side. How about it over there. Pipe up.

 

This has been suggested in the past, and discounted as bikes on the other side of the pond where they drive on the left, also wear the same.

[notacop]

Small aircraft seem to experience the same tire wear. Strange isn't it?

My sidecar rig does not have this wear pattern, the primary balance is better and it cancels out any perturbations of primary disenchantment. Runs straight and true too!

And the actual amount of uneven wear one experiences is on the bulky Boxer models, the 800ST wears tires evenly. Good reason to downsize in this difficult time.

 

[David R]

All my bikes wear the tire on the left more. I find left turns easier to make. Front and rear tires show it.

 

David

[Skywagon]

fly in the ointment. I have had a few sets of tires on each bike and they all wear evenly. My 1150RT pulls to the right on speeds below about 50..so I am sure I lean or crab left. Above 50 you can take your hands off and it runs true. So my simple mind is those who rack up lots of miles at less than freeway speeds lean to the left. I do most of my mileage above 50 and it isn't an issue.

 

My 79R100RT runs true at all speeds and tires wear evenly.

[Linz]

My R1150RT wore the last ME880 out badly on the left but not the Bridgestone I had on before that. The only difference was, the Bridgestone was fitted by the dealer and they did the "bounce" before final tightening of the appropriate parts. I fitted the wheel with the ME880 and forgot the bounce. It chopped out badly.

My R1100RT never wore unevenly and I have no explanation for that. My K100RT also wore evenly so I'm discounting any influence from the shaft drive ( for what that's worth).

The latest tyre on the R1150RT is a PR2 and it got the bounce. I'm leaning toward wheel alignment as the demon. I don't say that it's the cause but I think it can make PTTR worse.

Linz

[kmac]

Here is one thought and goes along with some other comments on right and left turns.

 

My brother in law is newer at riding and is doing really well, BUT, he is still uncomfortable with right hand corners because he cant see around them as clearly as he can a left hand corner.

He slows down alot more on right handers than he does on lefts.

When you are going faster you are scrubbing the tire more.

So if you take left handers out in the canyons faster you are scrubbing more tire than you are if you slow down and roll the right handers more.

 

I have quite even wear on my bikes left and right sides even on my shaft drive boxer RT.

Just a thought on one possibility, no facts to support the theory.

[Boffin]

Me thinks it's something much simpler to explain. How about the crown of the road (high point at the center divider). We are always on the right side of the crown with the bikes leaning to the left. The easiest way to confirm this is to ask our British brethren if their tires wear on the right side. How about it over there. Pipe up.

 

Left-side wear over here too. It is not the crown, nor more spirited left-hand curves. It is down to the bike. Some folk have found re-aligning the front fork as per the BMW manual. Others have found an offset in the rear wheel and corrected that by shimming the swingarm. I just live with it.

 

Andy

[AndyS]

Some possibles; left turns are longer than right hand ones.

.

 

Not in the UK! - and I'm with Andy on his final sentiment too.

 

Andy

[tazplas]

When i brought the bike, it was noticeable wear on the left hand side of the front tyre (apart from extremely flat on the rear).

 

With all the other comments. i'm not sure, but when the cruise control is engaged, the bike still shows PTTR. I have to offset with body weight which means i can't just turn around and and try and sort out the luggage without actually stopping or at the very least, stepping onto the left hand side foot pegs with both feet to equalise

 

Cheers

 

Steve

[Survived-til-now]

Nope - I have just checked mine with a depth gauge and with 2mm remaining there is no noticeable difference on my front tyre between left and right side.

[NonComp]

I've never seen uneven tire wear on my bikes. If it is the rider, leaning more on left-hand turns, then it should show up as uneven chicken strips on the rear tires. That should be easy to measure.

 

I like Dirtrider's suggestion. Lean the bike to the point where the wear matches the lean. Since it is always left-side wear, you should be able to do this (with care) by shimming the sidestand. Now sit on the bike and see if that feels familiar or foreign.

[oldyam]

I've never seen uneven tire wear on my bikes. If it is the rider, leaning more on left-hand turns, then it should show up as uneven chicken strips on the rear tires. That should be easy to measure.

 

I like Dirtrider's suggestion. Lean the bike to the point where the wear matches the lean. Since it is always left-side wear, you should be able to do this (with care) by shimming the sidestand. Now sit on the bike and see if that feels familiar or foreign.

 

Thats not quite so easy, as the tyre position in relation to the road surface will be different with the sidestand down and shimmed and the suspension compressed. more a two person job.

[NonComp]

That's true. Even then, you won't get the dynamic compression of the suspension that you would get from going around a corner at speed. But it would be an approximation of the lean angle, which should not change.

 

I wonder if it is counter-steering force applied during a turn. Perhaps more force is applied going left vs. right, so the tire is digging in more at the same relative angle.

[4wheeldog]

I previously had an epiphany on the PTTR phenomena as being caused by the P-Factor. I was shut down in that opinion by others supposedly more knowledgeable. Now that I mention it, how about gyroscopic precession? This opinion comes from the longitudinal placement of the crankshaft in relation to direction of travel and the small aircraft design of the boxer engine. You can feel that torque trying to twist this bike when you rev the engine.

more here

http://wiki.flightgear.org/index.php/Understanding_Propeller_Torque_and_P-Factor#Gyroscopic_Precession

 

P factor is a result of the left side of the propeller taking a smaller "Bite" of air, due to the angle of the plane being up at the front on the runway, and while climbing. It is related to the change necessary in the pitch of heliocopter blades as they rotate so they do not get excess lift on the right as oppose to the left when traveling forward. Look up "Retreating blade stall." This problem is what limits the forward speed to conventional 'copters, the V22 Osprey being the solution.

 

Neither has anything to do with motorcycles with inline engines. The torque effect of the motor is just Newton at work, and is not significant when the bike is moving.

[comstockrider]

I figured out mine wears like that because I primarily drive in a northern or southerly direction. With the earth's rotational force and the pull of gravity and the added heat because I ride north during the heat of the afternoon to go to work. Then at night, I ride south to go home and the roadway has cooled and the crown on the roadway has increase,(shrinking) thus the wear is of the same direction. Simple ! ! !

[Polo]

I figured out mine wears like that because I primarily drive in a northern or southerly direction. With the earth's rotational force and the pull of gravity and the added heat because I ride north during the heat of the afternoon to go to work. Then at night, I ride south to go home and the roadway has cooled and the crown on the roadway has increase,(shrinking) thus the wear is of the same direction. Simple ! ! !

 

Finally a logical explanation!

[David R]

I am still convinced its me. No chicken strip on the left side of the rear tire and a small on 1/8" on the right.

 

I did remove the spacer and do load my bike a little more on the left side (rain gear, tools...) This fixed the pttr, but not the wear. I posted a picture of a worn out tire and the entire carcass looks odd to me.

 

Rear tire is on the right. Picture is taken from the drivers seat. Right is right

 

 

David

[NonComp]

Well, that certainly would indicate that, in your case, the bike is seeing greater maximum lean to the left then to the right. Whether or not this has any bearing on tire wear in general may or may not be related. But I think it is a good clue.

[Goomicoo]

I previously had an epiphany on the PTTR phenomena as being caused by the P-Factor. I was shut down in that opinion by others supposedly more knowledgeable. Now that I mention it, how about gyroscopic precession? This opinion comes from the longitudinal placement of the crankshaft in relation to direction of travel and the small aircraft design of the boxer engine. You can feel that torque trying to twist this bike when you rev the engine.

more here

http://wiki.flightgear.org/index.php/Understanding_Propeller_Torque_and_P-Factor#Gyroscopic_Precession

 

P factor is a result of the left side of the propeller taking a smaller "Bite" of air, due to the angle of the plane being up at the front on the runway, and while climbing. It is related to the change necessary in the pitch of heliocopter blades as they rotate so they do not get excess lift on the right as oppose to the left when traveling forward. Look up "Retreating blade stall."

 

Also referred to as "dissymmetry of lift"

 

http://www.globalsecurity.org/military/library/policy/army/accp/al0966/al0966b0024.gif

[kmac]

I am seriously thinking it may have to do with tracking. If the front and rear are not dead in line it will cause a slight need to counter steer, which will put pressure on one side of the tire more than the other.

 

On a chain drive bike if you get the rear adjusters set wrong you can actually see a bike crabbing or dog legging down the road. With a single sided swing arm and no real adjustment, if it were built or set up even a small percent off it could cause the same crab effect. May not even be enough to feel but can cause wear on the opposite side of the front tire.

Possible?

[NonComp]

That would fit with what some claim to have success with: changing/removing the shim from the rear wheel.

[kmac]

Personally i dont know if it would be the front wheel as much as the rear wheel IMHO. If the swing arm were jigged incorectly by even a fraction of a degree it could cause crab tracking.

You have the swing arm pivots, the actual swing arm, and the rear bearing and bearing machining that could all be a potential culprit.

 

I have no support for my theory, just past experience with regular swing arms and them being off causing the crab track.

 

I would say have a buddy follow you, and see if he can see anything, you need nice flat straight stretch of road. You could also use a desolate spot and have a buddy stop and kneel down in the middle of the road and you point straight at him and ride towards him and see if he can see from the front...of course have a prearrainged plan for which way you will veer of as you get close...dont want to hear you ran over a buddy.

[dirtrider]

Afternoon Kmac

 

 

 

Lots of bikes come from the factory with the rear tire not in-line with the front (by design). Just look at the older belt drive Harley electrglide series. The rear wheel is way offset to allow belt clearance past the tire. I have set them up both with a straight offset (both front and rear wheels tracking straight ahead but not in line with each other and both following the same track but the bike frame tracking slightly offset. Neither seems to have much effect on L/H side tire wear.

 

For your crab effect theory to have much influence you would have the bike riding down the road leaned way over to the left (probably 15° or more). I have seen a few BMW’s with bad PTTR leaning very slightly but no way near the angle required to wear the front tire that far off center.

 

As I mentioned above get some help and lean the bike over until that front tire wear area touches the pavement. That is how that bike must be leaning going down the road or around corners to get the wear in that area.

 

[kmac]

I disagree, not trying to argue with you DR, just discussing this, if the rear wheel were cocked on a slight angle, not offset thru the frame but cocked on an angle it will cause you to counter steer to keep the bike going straight and cause the front wheel to drag slightly and wear more on a side.

 

I understand your idea that there is no drag on a two wheel vehichle as oppossed to a 4 wheel, but even if it is just in the corners that you have to add extra input to counter the rear wheel cock that could cause extra wear....but i am not an engineer, i just have been riding for 40 years and have personally witnessed odd side wear on bikes only to find out that the rear chain adjuster blocks were upside down, or simply machined wrong from the factory. Suzukis were known for this a few years back. The adjustment blocks were machined about 8mm off and it was causing front knobbie wear on one side of the RMZs

[Keithbob]

This topic comes up on lots of M/C forums. Sport-touring seems to bring it out the most. I notice it most on my Honda VFR800, which likes to fly low on the 2-lanes. The left side of the front tire can be worn smooth when the right is just reaching the wear bars.

 

The idea that we have better sight lines through left handers makes the most sense to me, although it doesn't explain it for those riding on the opposite side if they indeed have more wear on the left side of the tire.

 

This same wear pattern occurs on the GS, but not such a drastic extent as the VFR, and the GoldWing shows little difference side-to-side. This also makes me think that better sight lines and thus higher speeds through left hand bends is what causes the differential wear pattern, as I tend to be more of a plodder on the Wing and don't push the tire very hard.

[oldyam]

The idea that we have better sight lines through left handers makes the most sense to me, although it doesn't explain it for those riding on the opposite side if they indeed have more wear on the left side of the tire.

 

I have the same type of wear as described here on the LHS of the tyre and that doesnt hold up as far as sight line through bends goes, as if that were the case the wear would be on the RHS of my tyre not the left.

 

[NonComp]

Assuming that riders, for whatever reasons, don't simply ride more aggressively on left-hand turns, then perhaps there is something about the dynamics of the machine that either makes it either easier to lean further to the left (more lean = more wear) or that causes more wear relative to the equivalent lean angle to the right.

[Quinn]

Anyone for the theory that it's the molding process for making the tire? Maqybe the left side is at the top of the mold and the rubber is less dense toward the top.

 

----

 

 

[BFish]

it all has to do with the hemisphere and rotation of the earth.

 

by the time we all agree on cause, we'll all need new tires.

 

happy holidays.

[NonComp]

Predominant westerly winds and everyone riding south for the winter??

[scoops]

Here is someone who has put a lot of thought into tire wear problems.

 

His conclusion is "Left hand turns have a larger radius than right hand turns in right side driving countries, hence you ride farther (and likely faster) turning left than turning right with subsequent increased side band wear on the tire's left side. The left side of your tire has more miles on it (in some extreme cases, twice as many) than the right side of your tire."

 

http://www.rattlebars.com/tirewear/index.html

 

Randy

[oldyam]

Unfortunately left hand turns have a smaller radius where I live, so how does that equate to the heavier left side wear on my front tyre ?

 

And the theory would propose the exact opposite wear pattern in countries that drive on the left.

 

Like the UK, Ireland, Australia, New Zealand etc.

[kmac]

It is a government conspiracy that forces tire companies to put softer compound on the left in order spur on the economic recovery by forcing us to buy more tires. Same reason we dont have the 100 mpg cars we all KNOW exist...

[Keithbob]

The idea that we have better sight lines through left handers makes the most sense to me, although it doesn't explain it for those riding on the opposite side if they indeed have more wear on the left side of the tire.

 

I have the same type of wear as described here on the LHS of the tyre and that doesnt hold up as far as sight line through bends goes, as if that were the case the wear would be on the RHS of my tyre not the left.

 

Well, the sight-line theory has a puncture, then. Thanks!