Measured rear offset

[Cadman]

OK, I just wanted to see for myself. I was told years ago that the 1200 rear wheel is 5 ½” and offset to the right, and the 1100 models were lined up correctly with their 5” wide wheel. I didn’t question that the face of wheel would be ½” more to the right when aligned with the front wheel until I saw Chris’s (ZRX24) post stating it was 10 mm. I realized then that the tire could be anywhere relative to the hub.
Fine, I will check it out. I decided to level the bike, find the center of the frame, and drop something through a hole at that point to find the center of the tire over the axle centerline.
There are a lot of things that could go wrong when doing this.
1. Frame could be bent.
2. Hole might not be in the exact center.
3. Swing arm could be tweaked.
4. Might not mark the exact center of the tire.
While I do measure things for a living, it doesn’t mean I can’t make a mess of it. I tried hard to get a correct result, just the same.
I shimmed the wheel on the stand with a level across the frame. I made a cardboard strip to insert between the rails as it is hard to measure a round item. I measured and marked the center point on the strip. I marked the fender at the half way point and drilled a 1/8” hole. I inserted a new 1/8” rod and set it plumb with a level. I have a 300’ fiberglass tape and draped it across the tire from edge to edge and marked the center with chalk. After getting a result, I remembered I had a plumb bob and rigged it through the hole. You can see the line overlaying the mark on the cardboard strip.
While there are too many variables in this to call it science, I got about 5 mm with both methods. I don’t know where he got his info, but for me, this means that Chris is absolutely correct about the 10 mm offset at the right side.
I have been doing it wrong all this time and I pledge to change my evil ways.
Thanks Chris!

[KWICK]

Just to throw something in:

The swingarms on ZRXs, 1100 or 1200, are always outta whack.
Usually the eccentric hole/swingarm pivot are in line in relation to the wheelbase. And most times the eccentric holes are level in relation to the pivot when measured to a flat table.
But, the shock mounts are always around 1/4" out. One shock will go in, the other you'll have to compress the suspension, or pry the shock shorter.

And, the "spread" where the wheel fits there is a big variance. Sometimes the eccentrics are 1/4" too wide. Sometimes the eccentrics will stick out of the swingarm because it's too narrow. If you loosen the pinch bolt and pull out and the tighten, you can line it back up....but...the swingarms are never true left/right because of this. The one I'm using right now was so far out that I put a scissors jack in it to spread it a bit...before I sent it to Cmikimoto to weld it. But, which way did it spread? Left, right or even? I haven't a clue.

Cmikimoto and I have seen these variances in every swingarm to one extent or another. I will be bracing swingarms soon, and I'll probably have a worksheet and pictures pre-weld just to not be shot during KWICK Season.

Personally, unless there is a serious issue, like a wreck, I never string or even worry about whether my wheels track straight. I know they aren't perfectly in alignment. It's usually not an issue though.

In the auto bodyshop biz, we had a lazzzzer alignment setup that located on the car frame with dedicated fixtures. After a big hit, we could make cars WAY straighter than they came outta the factory.

I have no info on the frame alignment/assembly/variance.

...carry on

[Cadman]

So, there's that and the wheels might not be aligned vertically either due to the eccentrics. I didn't consider that when choosing an extra tooth up front. It's a wonder that I can get it out to the street with all this potential misalignment.
The closer the alignment is to being correct, the better the feeling should be while rolling into a turn. So I will continue to try to make it as good is I can.
I have a couple of things to check tomorrow.

[Mike L]

Your experiment lines up with what I have come to believe, Bill. I'd heard that the center of the 1200 wheel is offset about 1/4 inch to the right. Assuming the 1100's 5-inch wheel is centered i the frame, and assuming (semi-educated guess on my part) that to keep sprocket alignment on the 1200 without changing the engine sprocket position, the 5 1/2-inch wheel would have to be moved to the right. If the left side is kept at the same location, the center would in fact be 1/4 inch right, very close to your 5 to 6mm measurement. Thanks for the confirmation!

But I'm not sure how you would get perfect alignment. If you machine spacers to center the wheel, the rear sprocket would be 1/4 inch offset to the left, very bad for chain life. Keeping the sprocket in line and moving the wheel left would put your tire very close to the chain, if not interfering. Spacing the front sprocket 1/4 inch outboard to line up with your re-aligned rear wheel might not leave enough room to the sprocket cover and would require relocating the chain guide on the swingarm. Maybe it's all doable -- but I don't think we've had any issues with the 1/4-inch offset. Why not just go riding instead?

[Cadman]

Mike,
I don't know that they kept the alignment the same on the left side of the wheel. It's a different wheel and they could have moved the tire to the left as much as they dared toward the chain. That's what you would have done, right? Well, you and I might have moved the primary sprocket out so it would all line up, but that would have cut into our profits on an inexpensive, low production bike.
I have complicated the issue by running an extra tooth up front. With the axle shaft in vertical alignment with the eccentric center (stock setup), moving one of the eccentrics, relative to the other, would have little vertical effect on the shaft and therefore the angle the wheel runs at relative to the frame. Looking at the picture with the stand above, you can see what will happen if I rotate one eccentric relative to the other. The axle will tilt relative to level.
If I have time today I will set it back up and check that (if I can), before and after moving the alignment at the front wheel to 10 mm. The theory is; if 10 mm is the magic number then the wheel will also be strait vertically. Of course it's early in the day and I have had only one cup of coffee.
BTW: I lost power for a minute right in the middle of this post. The battery backup gadget I bought for the office I used to work in is under this desk. Back when Enron was ripping everyone off they used to shut the power off to try to convince us that there was a problem and our rates needed to be higher. We were not fooled, but we had to stop working and wait or go home just the same.

[Copyguy]

Cadman, if you haven't already seen it, you should take a look at: http://www.zrxoa.org/forums/showthre...ghlight=offset

especially Silly hillbilly's contributions re: shaving/modifying/spacing, etc. to correct the offset and bring the wheels into line. Don't know if the fix ever came to pass. The offset is my only beef about the ZRX and I'd love a fix to make it more neutral in turns. (yes, after riding my speed triple and vfr with perfectly neutral handling, I notice it) Sounds like somebody who measures for a living and calls himself cadman could put something like this on the market

[Cadman]

I am not a competent machinist nor do I have the interest to go much deeper into it. My bike had been in pieces for four months and as I put it back together I was trying to get the stuff back where it is supposed to go. My desire to understand what is going on has cost me a lot of time and I struggle to keep up with things as it is.
It is not likely that I will be able to feel the difference in the changes I make later today as I have ridden so little since my crash on October 1st. I'm just trying to make it as good as I can without getting too carried away.
I will check out the thread you mentioned.

[John T]

And WHY exactly does any of this matter?

it is what it is...
you would be better served reviewing last years tax returns...

[dimora]

And WHY exactly does any of this matter?

it is what it is...
you would be better served reviewing last years tax returns...

I'm with the grief counselor on this one, although - if a fix existed - you know I would have to have it.

[Copyguy]

I'm not giving up - I ride for multiple reasons, including the joys of neutral handling. Riding around even minor issues harshes my riding mellow. We have enterprising guys on here, with more stopping by, so hope springs eternal that one of them will want to tackle the challenge.

[eddie lane]

- if a fix existed -

i think i just bagged my limit with this one................

[KWICK]

i think i just bagged my limit with this one................

I already posted in this thread, see above

[eddie lane]

Personally, unless there is a serious issue, like a wreck, I never string or even worry about whether my wheels track straight. I know they aren't perfectly in alignment. It's usually not an issue though.

stop thinking of only yourself and "FIX" this for the collective!!
i'm just yankin' yer chain man, i know EWE're working on it............

[Cadman]

And WHY exactly does any of this matter?

it is what it is...
you would be better served reviewing last years tax returns...

Yes, taxes were on my list for today, but I spent all the energy I had left doing yard work. I got way behind on things while I was healing.
Why it matters: I have made trouble for myself by moding the bike. The eccentrics are flipped and with an extra tooth on the primary there are no marks to line up. That is what led to aligning the rear wheel by relation to the front. I would rather it be correct if I can make it so. Next time I'm in there I will cut a mark on the bottom using the eccentric as a guide.
I'm toast, worked on the Camaro Friday night, my bike and Ken's bike yesterday, and the yard finished me off today. That crap will have to wait for next weekend.

[KWICK]

stop thinking of only yourself and "FIX" this for the collective!!
i'm just yankin' yer chain man, i know EWE're working on it............

I saw probably the best license plate ever in the In-N-Out Burger drive thru the other nite. It said:

DINE ME

I was laughing my ass off over it!

[Cadman]

So when she says, "Wine me and dine me" it doesn't mean what I thought?

[KWICK]

So when she says, "Wine me and dine me" it doesn't mean what I thought?

...depends...

[zaneyzrex]

Maybe really over thinking this ... Both my Zrx's like the eccentrics 1/4" different one side to tbe other after doing string alignment. (stock/zx11/zx7r rims) the zx7r rims are prob offset more than any stock wheel on my bike but then maybe not.... Point is after my ride yesterday in the tight twisties I sure didnt notice it if they are offset or not.. Bike railed left or right corners the same n felt very planted....

[zrx24]

That's interesting, Bill. What has me puzzled though is that my measurements revealed 10mm offset by comparison of the center of the rear and front tires. Assuming that the frame at that location is centered on the front wheel, your measurements would indicate that there is only a 5mm offset.

One day Marvin and I had some time on our hands and added up measurements taken from 1100 and 1200 swingarms and spacers and came up with a 5mm of difference. We didn't compare the hub location of the two wheels, so I just presumed the other 5mm was made up by hub offset.

I'm now wondering if you've just found that additional 5mm offset is actually in the frame at that particular location. I know the shocks are offset slightly to compensate for the wheel offset. It would certainly make sense that the 1200 frame may be offset a tad as well. The 1100 and 1200 frames are subtly different in many ways after all.

[Cadman]

Unfortunatly, this isn't over yet for me. Next weekend I will set it up again and look harder. It wasn't until Kwicks post that I realized the wheel may not be vertical. Does anyone have a frame that is straight? Maybe not many, and that could be part of it.

Also I thought you were saying that there was a 10 mm offset at the front relative to the right side of the rear wheel and I agreed with that. Whatever the distance, I will be making a shim to lay up against the front wheel/tire and measure from there to the tube at that side. I will post pictures of the setup next weekend.

For most of us here, it doesn't matter. They can just use the marks. I need to align mine so I can make a mark on the swingarm for next time.

[zrx24]

It wasn't until Kwicks post that I realized the wheel may not be vertical.

Yep. And more importantly, it's vertical alignment of the front and rear wheels that is most critical to handling.

[KWICK]

Yep. And more importantly, it's vertical alignment of the front and rear wheels that is most critical to handling.

I like NASCAR, and my bike's set up to take left-hand turns

[zrx24]

Next time I'm in there I will cut a mark on the bottom using the eccentric as a guide.

Or just slap a flat t-square on there and mark the front where the tick marks already are.

[Cadman]

Good idea. My plan was to place a mark 180 degrees from the OEM as there are marks there too and if I go back to a 17 tooth the marks would be in the center.
If the wheel is in perfect vertical alignment with the frame, the offset might take care of itself? Si? and vice versa.

I'm supposed to be working. I have to get away from it now and then. I'm learning to draw 3D with AutoCAD Architecture. What a bitch. Do use a 3d program that you like? I've sampled 3 so far by drawing the same guest house with it.

[zrx24]

I'm not a CAD operator, but have had experience with 3D CAD designs in the petrochemical industry when I used to do structural design work. It had a "walk thru" function that was pretty cool. Pretty handy at finding conflicts in design between the different disciplines. In particular between the civil/structural design, piping and mechanical. Seeing a pipe or structural beam sticking through the side of a vessel was a pretty tell tale sign that something was amiss.

[Cadman]

Some of the new programs, like Revit, will look for and alert you to conflicts. This is really helpful in a team environment.
I called tech support and asked about a few issues I was having, "Yeah, we know." Great, and this is with a $1,200 add on to a $2,900 upgrade I bought. It was 45% off because I already had AutoCAD. The 2005 program was $3,500 back then. If the construction community ever finds a better program, these guys will be out of business overnight. He told me I needed the Architectural add on AND Revit for $2,400. No I don't. Want and need are different things.
I told the contracter that we should get a young woman with large qualifications to draw this crap. We only need a rendering a couple of times a year.
Oh well, if I wasn't doing this I would be sweeping the floor everyday or sitting at home. That still could happen.

[DaddyDave]

Let me reiterate; I've said it before. If it's out only slightly, the bike don't seem to mind.

I noticed on the old 1100 (that was sorted), if I got too crazy w/the burnouts & wheelies, it would pull the left eccentric & the bike would start wallowing/wobbling. It wouldn't stop it until I re-adjusted the alignment. Each & every time I would find the left side pulled forward toward the countershaft a little (like mm or 2.) Once straightened, it would go back to normal & carve up twisties/track w/o a twitch.

This leads me to believe it's not that critical on the ZRX. At least it wasn't on my old 1100 (not experienced this on the 1200 yet), so maybe it was specific to that bike? I donno, but I'd be curious if anyone has experienced the above like I have, before you go bonkers on straighting/truing? FYI, I also used the old "string-method" on all my bikes going back decades...

FWIW, IMHO,

-dd

[Wolfman]

Really simple here guys. I took two 8 foot light bulbs, and get eaqual measurements the edges of BOTH rims ,left and right and front to rear of each rim, in relation to the tubes.
I got almost exactly 10mm of "offset" at the rear rim, in relation to the front rim.
Now WHERE the offst originates, is not clear. Frame ? Swingarm? Rims ? Hub ? I cannot say.........
I also really am not concerned ,as I can only ride just so well.
I will add, after riding into my carport, as straight as possible with wet tires, it is quite obvious as well that there is offset as well.
Heck, my BMW sez allowable facory tolerance/offset is almost 25 mm !!!!!!
I will also say that I offset the swingarm eccentrics to get a string alignment "correct" 50,000 miles ago and promptly wore out a new chain. I think I will just line 'er up by the marks. 90,000 and counting.

[Mike L]

When I first got my '01 ZRX, I used the string/straight-edge method to align the rear. It put one eccentric about a notch or notch-and-a-half ahead of the other. The chain ran a bit to one side of the rear sprocket, but not too bad, and the bike seemed to track OK. Then I found out about the designed-in offset, and tried an experiment: With the axle fully torqued (not loosened), and leaving one pinch bolt tightened, I loosened the other. That eccentric literally jumped about a notch-and-a-half, and was now at the same mark as the side with the tight pinch bolt. Since then, I've always torqued the axle before adjusting chain tension with the eccentrics, and my chain runs dead-center now. I don't notice any difference in how the bike tracks or turns. At least this way I think the axle is parallel to the swingarm pivot, and aligned vertically. Though the right side of the rear wheel is about a half inch further outboard than the left.

That's why I'd like to understand how any attempts to re-align the rear wheel keep the axle parallel with the swingarm pivot. Twisting it with the eccentrics would move it slightly out of parallel.

[Copyguy]

Ahh, the annual spring regurg of offset and alignment - I feel like a time traveler.