A 6 mm Bikebits shock shim has now been installed on my Blackbird by my dealer (with whom I am generally pleased). Now, when the bike is on center stand, the rear tire just barely comes into contact with the pavement whereas without the shim the rear wheel of course rotated freely with stock clearance. Dealer said this is to be expected as the rear of the bike is now taller. Does this sound right to you? I know my dealer will make it right, I just want to know if I need to investigate further.

Perfectly normal, you did just raise the rear end. You'll find it leans over farther on the side stand as well, careful with that until you get used to it.

I did notice that. I forgot to mention that I had a new set of tires mounted as well. PR2s front and rear. This is reassuring, so I thank you. I took it for a quick spin around the neighborhood and noticed it does seem to lean in easier. God do I love this bike. Thanks again....

I'd have to double check, but I'm not sure that happens with mine. What do you define as "barely?"

I put one on mine and I have a good 1/2" of space between the tire and the floor.

Oh, Christ, here we go.

Disclaimer to my original post- the actual amount of space beneath your rear tire while on the center stand may vary dependent on several factors, which include, but are not limited to- brand and model of tire, size of tire, wear on tire, levelness of the surface motorcycle is placed upon and exact thickness of shim installed. With all these variable in mind, it is a fact that your rear tire will be closer to the ground while the bike is on the center stand after the installation of any shim.

Happy now?

Didn't mean to kick the lid off of anything. The problem is that I am more or less Ziggy when it comes to things mechanical. Between the new tires and the grubby garage floor and the lumpy, angled driveway, and the new shim, I am getting the feeling from this that what I observed is within the range of "normal" variability. Sound OK?

Sorry, that was aimed at Zero and his complicating the discussion unnecessarily, which could in turn have you thinking your situation isn't within the norm.


Your results are totally normal. Depending on what tire I was running and its level of wear I was anywhere from barely resting on the floor to maybe 3/8" of clearance. Go ride that bitch.

When I did mine, I had tire touching with new rubber. When the tire got some miles, it stopped. It's the natural build up of the wearing surface of the tire. Nothing to worry about.

Measure the distance between the chin of the bodywork, just behind the front tire, and the ground, for me. Both of you. When on the centerstand, and level ground.
And the distance the tire is off the ground at the rear, if any.

I am keeping track. For research.

Please.

Stan, not sure what you're up to, but would a measurement at the rear axle be better? Removes the tire variables discussed here.

This is my "can-o-worms here !

I sold the 6mm shim and received the PM asking me my opinion on the rear tire touching after the install.
With 3 sets of Pilot Road II tires, I have never personally had my rear tire touch the ground with the shim
installed on level ground.

The center stand still keeps my rear off the ground and the tire also !!

I told Nick to post the question up here for other opinions as I had never heard of this occuring before.

It gives a relationship, to the fork location in the trees and spring preload, and weight on the front, and rear tire. As the centerstand is fixed heigth.

Been playing with mine. And due to the work I did for you I built a honda top triple to fit the zx forks, yesterday. Moved the forks up in the trees 1/2" from stock zx location and removed some, well almost all rear spring preload. And went for a two hour ride around town. Really changed the way it handles, and I can touch the ground and push now. Holds a line and tips so nice. Was a little scary at first, due to the cold pavement.

The rear tire was just touching, and now has 1/2". Need to measure the front. Was looking at the post where I asked for information, and most was a lot higher than mine was, and now it is less.

Just seams that it puts everything into perspective.

What do you think?
other post

When I had a 6mm shim in my tire touched the floor on mainstand. I replaced it eventually with a 4mm plate, and the problem went away.

I found that I can get the bike on the mainstand the N1K way though - way easy even with my skinny 200lb arse on it.

What's the difference in length between the ZX and XX forks in their stock positions? You'd need a measurement from the front axle to a fixed point on the frame, like the bottom of the steering head. Without that number it's a lot of guessing, and millimeters count here. What's the difference in offset, if any?

You need to get sag numbers front and back. Taking all the preload out of the rear may or may not be a good idea for you, but I'm not a fan of adjusting ride height via preload. Get your sag in the right range first and then mess with ride height via moving the forks in front and shims (or linkage if you want to drop it) in the back.

Don't want to beat a dead horse but it goes up on centerstand and there is a little bit of free rotation. It does lean over a bit further on sidestand too. My peabrain tells me that as the new tires break in and they flatten out, there will be more space between the tire and the ground on centerstand. Strikes me I need to use more diligence in where and how I put it on sidestand. My habit is to use the centerstand whenever and wherever I can. I don't trust sidestands as a general matter unless I am pointing distinctly uphill. Life is full of tradeoffs so I am assuming the handling improvement is worth all this. It's not like I am some super-aggressive canyon carver.

A good burn out will "clearence" the tire!

Post shim I had my son the welder add a steel plate to the bottom of the side stand. Picked the bike up more and doesn't sink in the ground as much.

Can't find my notes for some reason. But, from memory, they were the same length, forks. And the offset was less, so less trail and more angle. A rc51 top tree was close. The stem hole was smaller diameter and farther away from the tubes, so that when you opened it up to the correct size the back side of the hole was still the same place. Moved the front wheel in some, so quicker steering, and easier to turn in, but holds a line without anymore input, and picks backup with little if any effort. More like a sport than tour.
The acutual number not counting anything else axle to frame was the same, stock locations, unloaded. But, the trees are quite a bit different where they bolt to..
Angles of the forks are little different, 26 deg for xx and 24 for zx, with the before height. Zx swingarm is longer but set the height the same as the xx, on the centerstand. Built two linksets to try the feel and that makes a lot of difference in fork angle, weight distribution, you name it. Tire touching and 1/2" off the ground, on the centerstand, with the loss of 1/2" to chin from the trees offset, from stock xx trees. But, that was before we, Eric and I , took some preload off the rear shock. The rear tire was clearing ground in bumps from being to hard. NO sag. Gave it some and was better, But, I just gave it more and is much better.
I could go on for ever, but that should be enough, since it ain't my thread....I know I am bad.

But, it is relative to the OP. and could give some in-site to the causes..right?

Coulda sworn the ZX's were shorter when we were swapping measurements way back when, but my memory is crap.




No, less offset= more trail. Counterintuitive, I know, but true. Don't make me draw a picture. Angle shouldn't be affected- forks/trees on both bikes are parallel to the steering stem, no? You'd see a slight increase in angle with a shorter front fork, but the triples are in line with the steering stem, always, so angle would be set by the frame.





How'd that move the front wheel in? Did you change the bottom triple? Unless you changed upper and lower triples, you should still be parallel to the steering head.




Hate to keep saying it, but the angle shouldn't change unless you've dropped the front or raised the rear.





So the rear swing arm angle is much flatter now? Wheelbase is longer? That right there will have some effect on the whole package. The effects of a longer wheel base are obvious enough. Guys much smarter than I will play with swing arm angle to tune the rear- but that's getting into stuff way over my head....okay, even more over my head than this conversation already is.


Rider sag should be set at 25-35% of total travel. Harshness after that is a damping issue or the wrong spring rate- address the problem there once the sag is sorted.





I need to ride that thing, dammit. I gotta make OzarXX with my gear and a tape measure just to play with your project.



I think the OP got his answer, and this is interesting. Hopefully a mod doesn't come by and bitch about the OT responses.

Looks like you got the max quotes in on that post Tim.
The zx trees, and most sport bike trees are closer to the frame. The rc51 was like .1" farther than the zx. The xx is twice as far away. about 2 inches in front of the stem.
I guess the difference in the angle was from the higher rear. But, it is not much and I guess it is all gone now.

The bottom tree on the zx is not flat like the xx is. So it was hard to get and accurate measurement comparing the two setups. that is where the chin measurement came from. It and angle on the centerstand of the forks put it all in the same ballpark. But, with the trees closer moved the wheel closer, and may have been shorter from the axil to the frame, as the top tree is higher away from the frame. If Alan ever finds the zx bearing and gives me the distance, I will know if I can fit it on top of the frame with an adapter. It looks like there is enough room.

And the rear tire still gave the same if the difference from the ground was the same even if it was farther back.

I just thought it would have been softer, more leverage. But it was not. Linkage changes, I guess. Or lighter bike than the zx..

Yeah, I would love to have some more input. Tomek rode it and it was bad. I dealt with the problem then and was much better. So bring the gear. Hopefully, it will be good. Weather and setup. I will get somebody here to help me check the sag and get some new measurements.