R1100rt - Bad front tire treadwear - fork alignment?

[crnagel]

The treads on the left side of my front tire are gone while the right side has about 1/8" left to the bottom of the grooves. As a matter of fact the left side has worn the rubber on a wavy pattern. Could this be a due a bad front fork alignment? I have noticed nothing while riding.

 

Can someone provide a link to a front fork aligment procedure for the r1100rt bikes?

 

Thanks ahead of time!

[dirtrider]

Evening crnagel

 

Your front tire can only wear when the part that is worn touches the pavement.

 

SO, if you think you are riding down the road with the tire leaned over to the angle it is worn off center then something is definitely bent and should be quite notable.

 

A quick check is to have a helper help you lean the bike over so the worn part of that tire is flat on the ground. That will give you the lean angle that would have been needed to wear the tire in that area. Now all you have to do is ride the bike and see when you lean it over that far. (what ya bet it is left hand curves and corners)

 

Your lower forks are tied together through the axle so if that pretty well dictates the angle that the wheel can operate at relative to the fork angle. Unless the holes are drilled crooked through the fork lowers or the axle is bent pretty difficult to have a crooked wheel in relation to the fork lowers.

 

 

 

[crnagel]

 

Thanks dirtrider for your reply. The wear is from the 10:00 to the 12:00 arch (I tried uploading a pict, but no avail). That would imply that I ride leaning at aprox 15 degree agle to the left, and that's not possible.

 

I think the forks may not be aligned (parallell) and the tire may be dragging a bit, and in the curves it drags a lot! That's my theory, but how do I test for it an correct it?

[dirtrider]

Evening again crnagel

 

With only one tire on the front how could it drag? A bike steers by leaning once it gets over about 5 mph. In order for it to drag that would mean it was reacting against some other force (like a tire on the other side). Now if you are stuffing it into a curve fast enough to cause it to slide that is a different story. Even then that isn’t dragging it is sliding.

 

Again—if it is wearing at 15° off center then it is LEANING at that 15° during the wear process.

 

Strange that most motorcycles in the US wear the L/H side of tire more then the right hand side. Must be they all have fork alignment problems.

 

 

[Sweendog]

As DR alludes to, in countries where we drive on the right-hand side, tires will wear more on the left side. Almost every left-turn you make will have a significantly longer radius than almost every right-hand turn. Consequently, the left side tends to wear out first.

 

A fun article about tire wear: http://www.rattlebars.com/tirewear/index.html

[dirtrider]

Evening again crnagel

 

 

 

And if you want more reading about asymmetrical tire wear on BMW’s just put “tire wear” in the search box at top of the page, be sure to use the quotes on each side of tire wear____ “tire wear”.

 

You will get about 45 pages or so of mostly left side tire wear to keep your eyes watering.

 

[Selden]

On your next set of tires, try running them at higher pressure than recommended in the manual (33 psi, if I remember correctly). Most people report much less cupping with something like 36-38 psi front, 40-42 rear.

 

Sweendog's link had a lot of good tire information, and confirmed something I had suspected -- rear punctures are more common because the front tire kicks up debris that gets embedded in the rear -- such as this piece of oak that ruined a very nice ride along Skyline Drive last October.

 

[crnagel]

Very interesting, thanks a lot for all the replies and info. I never got to thinking that the left hand curves are longer than the right hand curves for us riding on the righ hand side of the roads. In addition, I ride curb (shoulder side) of the road, almost to the white line, that would make the curves even longer! Further, Arkansas roads are very abrassive, just like sand papaer... Oh well!

 

Thanks you for the link above, good educational reading. I will put a new tire tomorrow and get back to riding my motorized horse!

[Redbrick]

Consider road crown effect?........

[Fraidycat]

I can't believe it---about every month or two for the last 10 years--or more---somebody writes in wondering about left side tire wear on a 1100 RT---and every time this results in a discussion of possible causes. What makes me laugh is that every time this happens somebody mentions 'road crown', weight bias, alignment, and a host of other possible causes . I always wonder why these things attacks only the left side of R1100 RT Tires? There must be a hundred other models of bikes out there but it is only RT riders who ever complain of left side tire wear? One thing should be clear now and that is that there is a cause/effect relationship involved in left side tire wear on an RT.

 

Let's do a survey (I don't know how to start one in this forum so I'll need some help setting that up---anyone? )

How many of us RT riders have experienced extreme left side tire wear on our front tires? How many of us have cured the problem? What did we do which cured it? Let's see how many of us know what caused our problem and were able to cure it- and how many of us are on our 5,6,7th set of tires and have no answer? Maybe by putting our heads together we can find out how to cure the problem ---even if we continue to debate what caused it.

 

[Boffin]

I cured my left-side wear (yes, left-side in the UK where we drive on the correct side of the road) by removing the fork-leg to suspension arm bolts (needs heat) cleaning them up and re-installing with blue loctite to lightly snug, not tight - then releasing the axle clamp bolts. I then bounced the front wheel firmly against a wall three or four times before torquing the fork bots and axle clamps.

 

Now my tyre wear is even and the PTTR has gone.

 

Andy

[boatzo]

This subject has been posted many times in the past. I can only tell you my experience as I'll defer all the theoretical/technical stuff to those much smarter than I.

 

My front tire was wearing on the left side, I also had considerable PTTR. I asked the dealer service manager about it and was told" they all do that, its the crown in the road".

 

On advice from an independent M/C mechanic,I decided to remove the front wheel. In doing so I discovered that the front axle was very tight and difficult to remove. I did remove it and found that I could not slide it freely from right to left. I loosened the fork bridge bolts and got the axle to slide freely, tightened everything up, checked the axle again and reinstalled the wheel. The PTTR diminished, tire wear evened out and life was good.

 

Try checking if your front axle will slide freely from one side to the other with out being forced. MHO

[outpost22]

Good info on the axle/pivot /etc.

An interesting observation is that my bike had this left front wear with a Z6 after I bought the bike, but not with other tires. Maybe the axle assembly was "relieved" when I changed the front shock and re-torqued the front end after the Z6 experience???

[Polo]

I can't believe it---about every month or two for the last 10 years--or more---somebody writes in wondering about left side tire wear on a 1100 RT---and every time this results in a discussion of possible causes. What makes me laugh is that every time this happens somebody mentions 'road crown', weight bias, alignment, and a host of other possible causes . I always wonder why these things attacks only the left side of R1100 RT Tires? There must be a hundred other models of bikes out there but it is only RT riders who ever complain of left side tire wear? One thing should be clear now and that is that there is a cause/effect relationship involved in left side tire wear on an RT.

 

Let's do a survey (I don't know how to start one in this forum so I'll need some help setting that up---anyone? )

How many of us RT riders have experienced extreme left side tire wear on our front tires? How many of us have cured the problem? What did we do which cured it? Let's see how many of us know what caused our problem and were able to cure it- and how many of us are on our 5,6,7th set of tires and have no answer? Maybe by putting our heads together we can find out how to cure the problem ---even if we continue to debate what caused it.

 

I joined back in 2002, there have been these discussions ever since. This is one of those great life misteries that will probably go unsolved and become a legend in its own right, just like "Does the refrigerator light stay on after you close it?", or "if it's made out of wire, why is it called a paper clip?", "if you're traveling at the speed of light; what happens when you turn your headlights on?", etc.

 

All RT's do that!

[dirtrider]

Wow, all these BMW’s with fork alignment problems and not a one with right side tire wear— very strange indeed, almost mystical.

 

 

 

[GrayNFast]

I removed the spacer between the rear wheel and final drive years ago.

 

Also run tire pressures toward the high end.

 

Got rid of the PTTR and uneven tire wear.

 

 

[crnagel]

Well, I spent most of my rainy day in Arkansas tinkering with the bike. I got a new front tire installed, and Yes, I found my front wheel axle not perfectly aligned with the fork holes, so I got them all aligned (as good as possible). So, after I get the tire broken in (500 miles or so) I will spray paint (washable paint)the crown of the tire and take the bike for a spin. For sure I'll post the result and pictures (by the way, what is the procedure to post pictures?)

 

A survey also sounds good, this is an interesting subject, finding the root cause of the problem, and what some folks have done to resolve it, would benefit lots of people.

 

 

[Fraidycat]

I completely cored my left side tire wear problem and PTTR syndrone at the same time (after ruining 5 or 6 tires of different manufacturer)

 

I did a very accurate alignment procedure which required the insertion of a slightly wider spacer at the rear which put both tires on the same centerline.

 

In the process of doing the alignment I had loosened up all the bolts on the front end and shook the wheel violently to allow it to settle back in in case it had been tweeked crooked at some time---then tightened everything back up

 

One or the other---or both---ended my problem Now I get 10K miles or better from the same brand of tires that were previously scrapped clean on the left side between 3000-4000 miles. Nothing else changed----same road crown, same weight bias, same everything else.

[Boffin]

Wow, all these BMW’s with fork alignment problems and not a one with right side tire wear— very strange indeed, almost mystical.

 

 

 

All the forks are put together in the same factory on the same jig.

 

 

Andy

[Eckhard Grohe]

Hey guys look up PTTR and you will see that this has been under discussion since the beginning of the board in the late 90s. There is even something in the FAQs. You can also look up the following website,Bob's PTTR cure, where Bob Silas, a retired mechanical engineer and bike nut investigated this and eventually cured it. It can be diminished and cured but the level of effort isn't trivial.

 

Next let's talk about oil.

[dirtrider]

Morning Andy

 

I somehow doubt ALL the BMW forks are put together on the very same equipment or same jig. I even have my doubts there is some mysterious assembly alignment jig used to assemble simple unsprung forks. No special “tool” or jig required at dealer level to re-assemble, just the axle for angular alignment and a given spacing to alleviate bushing drag.

 

But even if they were that would also mean that single fork assembly jig equipment hasn’t been adjusted, or changed, or tuned in 11 years of assembly (anybody else find this odd, even for BMW?)

 

But even if they “all” were assembled on the very same jig at the very same factory I don’t know of anybody in the U.S. here that sends their bike back to the factory to have a new front tire installed or to have that same “factory” equipment used to put the forks together after a fork seal replacement.

 

Still seems mighty strange that on a “single track vehicle” the forks being out of alignment can cause tire wear 15° off-the-center-line and if it could why no excess right hand tire wear reported. Maybe the pull of the moon is causing everybody to assemble them with the tire leaning 15° to the left.

 

[boatzo]

"quote Maybe the pull of the moon is causing everybody to assemble them with the tire leaning 15° to the left." quote

 

Maybe we need to hear from some of our contributors in the southern hemisphere about their tyre wear?

[Linz]

The last tyre installed prior to my new PR2's were ME 880's. The front chopped the left side out on the tyre in around 4000 miles or slightly less.

 

With the ME 880's, I fitted the wheel after the dealer fitted the tyres and I forgot to do the front end bounce.

 

On the PR2's, there's no apparent wear on the left, greater than the right and the bounce was done. It also doesn't feel as if it's pulling to the right as much either. Unfortunately, time will tell.

 

I don't see the road crown as being the issue. I have several other bikes, not BMW's and they ride the same roads with no uneven wear to the front or back. I also believe that both in the US and Australia, the bad wear is still on the left front tyre, that takes out the issue of riding on the left or right side of the road.

 

I think we're left with either poor tracking or uneven weight IMHO. I'll look at the spacer at the rear wheel to see if increasing the width would line the wheels better. A string-line would tell what was going on.

 

Cheers,

 

Linz

[crnagel]

Amazing information and work reported Bob's PTTR cure. I force my brain to picture how could the misalignment and mass imbalance he ecountered would make the bike wear the front tire 15 degrees off center. In any event, I'm have no time to follow his procedure.

 

While getting my tire changed at a multi-brand but mainly Harley bike shop, I asked the mechanic if he had withnessed this problem often, and to my surprise his reply was a quick NO. That makes me believe it may be inherant to BMW's? I also have a r1200c which has the same problem, although not as severe as the R1100RT. I get about 10k miles from front tires and about 5K miles for rear tires regardles of the brand.

 

We got lots of rain, otherwise I would paint the tire now and take the bike for a ride to evaluate the wear, but we have 3-4 more days of this nasty weather, therefore have no choice to wait...!

[dirtrider]

Morning Linz

 

The bounce is for stickiness in stroke (relieve side loading on bushings to tubes) not to change fork alignment to chassis. If the lower fork brace bolts are not loosened you can bounce that thing like a basketball and won’t change the basic fork alignment to chassis.

 

[Linz]

Morning Linz

 

The bounce is for stickiness in stroke (relieve side loading on bushings to tubes) not to change fork alignment to chassis. If the lower fork brace bolts are not loosened you can bounce that thing like a basketball and won’t change the basic fork alignment to chassis.

 

Aha!!. Still something to learn eh? I'll take a look at the lower fork brace bolts and give it another try. Thanks DR.

 

Linz

[boatzo]

Well Linz has proved that tyre wear is not affected by which hemisphere one rides in so it must be the phase of the moon as D.R. suggests

[Polo]

I don't have actual knowledge of this being a frequent occurrence with other brands, and also not with other models than RT's.

 

I once commented on the fact that the RT 1- is heavy, 2- has a paralever, and 3- the right piston is further forward than the right one.

 

The paralever negates the independent action of the left fork tube, thus forcing the tire down more evenly than on a bike with traditional suspension. This added to the fact that left turns are actually longer than right ones may be a definite factor.

 

Right cylinder forward was discounted under the premise that once the engine is running there shouldn't be any effect from this.

 

I just want to bring this up again to be rehashed. Given that things often aren't the way they should be.

 

If things were always what they should, I would be extremely wealthy, my wife would be frugal, my kids would call me at least ever other day, my friends would buy me lunch and give me cigars and bottles of scotch as presents, and my grass would never need mowing nor fertilizing. Right?

[Clive Liddell]

With a full tank of fuel R11xxRTs are heavier on the RH side because that is how the plastic tank is designed. On the LH side the glove box and the air intake duct has to be accomodated so the tank is scalloped accordingly.

 

Simply checking PTTR with a full tank and then later with the reserve light on will prove this.

 

I carry a layer of 2 (or 2.5oz) wheel balance weights spread across the bottom of my glove box. I find that this just allows me to remain perfectly upright towards empty tank wheras a full tank still requires me to lean to the left to allow "no hands" riding.

 

BTW riding on the left in South Africa my front tires all wear on the left anyway?

[upflying]

Ok, I'll add my two cents. Gyroscopic effect from the longitudinal placement of the crankshaft. You can feel the effect when you rev a boxer engine. This loads the left side of the motorcycle. Could that have an effect on left side tire wear?

[Selden]

Let's do a survey (I don't know how to start one in this forum so I'll need some help setting that up---anyone? )

How many of us RT riders have experienced extreme left side tire wear on our front tires? How many of us have cured the problem? What did we do which cured it?

8800 miles on a Pirelli Diablo, and (as far as I can see), pretty much the same wear on both sides. I pulled the mystery spacer disk from the rear hub a couple of years ago (thus moving the wheel a mm or so the right), and I generally carry more weight in the left side case than in the right, so almost no PTTR. [Mis]-alignment seems the most likely explanation for the wear differences reported by various people. I have not yet removed the fork brace, although I plan to at some point, because it's badly pitted, and needs repainting.

[nrp]

Gyroscopic effects from a longitudinal crankshaft running steady state at high speed will only show when the bike is rotating about a vertical axis (i. e. Yaw rotation).

 

If I've done my vectors correctly, yaw to the right will cause the bike front to pitch down. Correspondingly, yaw to the left will cause the front to pitch up. Somebody feel free to check me on this..............

 

Does the bike pull to one side? Might the frame be twisted? The front fork bearing axis should be be perpendicular to the rear swing arm.

 

I'd say it's time to project if the tire patches are tracking in a straight line. Stretch strings on the left side and right sides forward from the rear tire sides and see if the front tire is in the middle between them. They should be the same distance to the front wheel within like 1/8 inch.

 

 

[Sweendog]

I'll just mention that RTs aren't the only bikes w/the issue. It happened on my Silverwing scooter's front tire, and I've seen pictures on numerous web sites of similar wear on many other makes and models of bike.

[Fraidycat]

My best guess is that removing the spacer is an offset to the right side weight bias and, at the same time, increases the mis-alignment of the centerline of the tires. It seems to me that the effect of removing the spacer is like adding weight to the left side---this tends to negate the PTTR and may at the same time allow the bike to run with the tires more perpendicular to the road which should reduce left side tire wear----the theory being that the rider is normally riding with a slight 'list' to the left as a natural effort to counter the right side weight bias built in to an RT. My BMW shop foreman told me that BMW's 'spec' allows the rear wheel to run in a line to the right of the front wheel---and he thinks BMW's tolerance there is intended to counteract the right side weight bias---and as long as it doesn't run too far out of line the mis-alignment of the wheels is worth the sacrifice.

All of this said, it would be interesting to have someone actually measure the offset of wheel centerlines on his bike to see what the actual number is? I've done that---and on my bike I found the rear wheel running .1175 inches to the right of the front wheel and this was well within the BMW spec. My objective was to put the wheels in line---and to do this I had to add .1175 inches to the spacer---which I did. When I finished I no longer had the PTTR nor left side tire wear---but now that I think about it I'm more inclined to think that it was probably the loosening of the front end ---shaking it violently to allow it to settle to a neutral position before tightening back up which produced the 'cure'. I didn't actually measure the 'plumb' on the front wheel before I did this----but did verify that it---and the rear wheel were both perpendicular to the level road surface before moving on to make the measurement of the rear wheel mis-alignment.

As I've mentioned previously the real benefit of these conversations is to 'cure' the front tire wear ----that accomplished the discussion will probably go on for as long as they make RT's as to what causes the problem.

PS---I'm thinking that because there is a difference in width between the front and back wheels, and because of the 'overhang' of the tires in relation to the rim---that it would be very difficult to get an accurate measurement with the tires on the rims using a string line?????? (and it creates other problems with the tires off and the rims on the level ground because it's a bear to get the bike back up on the center stand later after the measurement is made) What I'm saying here is that careful planning is required if one intends on making this measurement.

[dirtrider]

What am I missing here?

If the PTTR makes it lean right therefore pull to the right then leaning it to left must make it go left and pull to the left. So a reasonable reasoning person would think that when a rider is countering PTTR he would just be holding the bike straight up with the front wheel pointing straight forward.

 

Somehow I can’t seem to get my understanding up to speed here— you guys with PTTR, or fork alignment problems, or rear wheel offset (on a single track vehicle no less) must have serious alignment problems to be riding down the road with the bike leaned over 15° to the left if your front tire wear is 15° off the tire center line.

 

 

 

[nrp]

Fraidycat - How did you measure the front/rear offset?

[Selden]

Fraidycat - How did you measure the front/rear offset?

I'm curious about this, too -- I have absolutely no doubt that I could not make an accurate alignment measurement to 4 decimal places (.1175 inches).

 

I did, however, do some A/B comparisons on PTTR with/without the spacer (2mm thick), and concluded that removing it made a small, but noticeable difference.

[Fraidycat]

Dirt Rider----See why I didn't particularly want to discuss cause/effect but was content to ask "How do you cure left side tire wear?" I have concluded that there is a cause---but don't understand the physics of weight bias and tire alignment in relation to left side tire wear. What I can tell you is that RT machines do have a weight bias to the right side but I don't know exactly how that translates to tire wear. I do know that my riding partner riding behind me always told me that I appeared to be riding with a slight list to the left as if I was riding against a wind from left to right when, if fact, there was no wind. Whether this was caused by weight bias or by wheel misaligned I do not know. I do know that I was not aware of riding with this 'list' as it felt like I war riding straight up? But if I were to let go of the handlebars the bike would immediately head for the right borrow ditch. Now it doesn't do that.

[Fraidycat]

NRP and Seldon

Such a simple question---but it requires a very detailed answer. To keep it short and to the point here I'll summarize and then answer any questions you may have. I took four digit measurements with a micrometer---but the forth digit is admittedly outside the accuracy obtainable with this test procedure .

First---I removed the tires and tubes and set the bike down on a perfectly flat and level surface--wheels resting on the surface. (this is not easily done and requires that you provide means to get it back up to the center stand later after the testing is finished). Then with a machinist's level I verified that both wheels were perpendicular to the level surface. (I had to loosen the front end, shake it, and retighten it to get that right.) Next, one has to insure that the front wheel is pointing exactly straight ahead---and is pointing exactly the same line as the rear wheel. Note that the rear wheel is wider than the front wheel. Two string lines stretched very tight and just touching the rear wheel (front and rear and on either side) extend forward beyond the front wheel and encompass the front wheel. These string just barely touch the rear wheel at its front and rear and so are the same distance apart as the wheel is wide. Take great care to insure that these lines are parallel by measuring the distance between them behind the bike and also in front. Turn the front wheel left or right as necessary such that the string is equally distant from that rim front and rear on one side. Now the front and rear wheels are pointing in the same direction. Use a machinists level again to verify that the wheels are perpendicular to the floor. Now proceed to measure the distance from the strings to the front rim on both sides ---on the right side of the wheel and on the left. (this time the numbers will be the same whether measured at the front of the wheel or back toward the rear wheel ---because the wheel is pointing straight). Knowing the the width of the two wheels and now having measured the distance to the strings on the front wheel you can compute just where the front wheel centerline lies in relation to the centerline of the rear wheel. I will grant you that the micrometer measurement to the string must be done very carefully --and is only as accurate as the measuring tool you are using----and gets mighty touchy when it gets to that last digit if using a micrometer.

 

The offset that I reported in my last post was within the BMW spec and would not have required any attempt at alignment according to the BMW tech I talked to .

[tallman]

Tires and tubes?

[dirtrider]

Tires and tubes?

 

Evening Tallman

 

Well looking at his profile he has ‘90 R1100RT so maybe that tells us something right there.

 

[nrp]

Fraidycat - The string method you described is what I would have done too except maybe to have made a last minute check on the uniformity of the front and rear tires by marking a single reference point on each side of each tire or rim, and rotating each wheel so the reference point is used to establish parallelness (what a word!) of the strings. That way you can eliminate any non uniformity of the tires or rims.

 

I suspect that even if the wheels are rotating in a common plane, if the steering head bearing and rear swing arm axes are not perpendicular, the bike will still pull to one side due to the rake and trail dimensions.

 

Good job though

[Fraidycat]

Yes the rims are sitting on the level cement surface. Tubeless tires of course have no tubes---which requires no further explanation. I.E. you have removed the tires and put the wheels back on the bike sans tires. If there is a better way to measure alignment with the tires still on the rims I didn't know what it was. Still don't.

[Fraidycat]

Dirt rider----If my profile says 90 RT I'll have to correct it----my bike is a '99 model. R1100RT

[boatzo]

Well, that test is the most in depth test I have heard of. Sounds like you really did your home work, thanks for sharing.

 

Now, with all these posts, I am fogged.

 

Do I understand correctly that you have solved your PTTR?

 

I assume that you have not had sufficient time to observe tyre wear?

 

What was the final fix that corrected the PTTR?

[dirtrider]

Lets see, in this thread alone —

 

We had a couple of riders remove the spacer & move the rear wheel to the right removing some weight from right of center and curing PTTR and L/H side front tire wear.

 

We have had one add thickness to the spacer and move the real wheel to the left therefore adding more effective weight right of center and cure PTTR and L/H side front tire wear.

 

I see a lot of other single track vehicles-- like GoldWings wearing out the L/H side of the front tires (seems a fairly common thing). See Valkyrie’s and VTX’s wearing the left side of front tires (again a common thing), see a parking lot full of Harley’s with more left side tire wear than right. Maybe they all just need there rear tires moved “somewhere” to stop all the mysterious left side tire wear.

 

 

 

[Selden]

The answer is "43".

[Polo]

Dirt rider----If my profile says 90 RT I'll have to correct it----my bike is a '99 model. R1100RT

 

I didn't think there was a 1990 R1100RT.

[Polo]

Lets see, in this thread alone —

 

We had a couple of riders remove the spacer & move the rear wheel to the right removing some weight from right of center and curing PTTR and L/H side front tire wear.

 

We have had one add thickness to the spacer and move the real wheel to the left therefore adding more effective weight right of center and cure PTTR and L/H side front tire wear.

 

I see a lot of other single track vehicles-- like GoldWings wearing out the L/H side of the front tires (seems a fairly common thing). See Valkyrie’s and VTX’s wearing the left side of front tires (again a common thing), see a parking lot full of Harley’s with more left side tire wear than right. Maybe they all just need there rear tires moved “somewhere” to stop all the mysterious left side tire wear.

 

 

 

Could it be a strange coincidence of enlarged liver? It's to the left of the body it would cause additional weight as you lean left?

[Fraidycat]

Boatzo. Since making the adjustments I reported I have had considerable time to evaluate the change. On my next set of tires I got slightly over 10,000 miles on my front tire. It wore pretty evenly with very slightly more wear on the left than the right. That was an immense improvement for me as all my previous front tires had wore out on the left side with 4000 miles or less. Also, the Pull to the right was 'essentially' gone---the bike will still pull very slightly to the right but not violently as before and I can now move my but a couple inches to the left and correct any remaining PTTR.

I emphasize that I don't know the mechanism that produced the correction for me. Whether it was the alignment or the front end shakeout. In either case I believe it is very important to have both wheels running exactly perpendicular to a level road surface--in my mind that fact negates any contribution to the problem originating in the clamps or steering head. Again, I am not claiming to know what caused the problem but only what seems to have cured it for me-----my goal of running a front tire for 10K miles has been met.

I am aware that others have removed the spacer to produce positive results---the opposite of what I have done. In those cases, I have not seen anyone document what their misalignment numbers were before or after making that change---whether their rear wheel was running to the right or left---so to speculate on cause and effect of that change seems pointless?