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cycle wheels parallel but offset..
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eli
Posted 7/11/2015 5:20 PM (#85331)
Subject: cycle wheels parallel but offset..


Member

Posts: 11
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Well, as I have been delving into the wonders of my MZ silver star gespann, I've noticed some peculiar things. One things that had me a-thinking is this:

The chain was quite loose, so tightening it was in order. No alignment marks on the swingarm, no problem, I have many accurate straightedges that I use for such matters. But when I make the rear wheel parallel with the front wheel with the bars pointed straight ahead, I notice that the wheels are paralllel but not in line! I checked repeatedly because I was sure that I was wrong, but no! It has factory rims and hubs and tires. I thought maybe someone had moved some spacers around, but there really isn't any way to do that, there are only a few spacers that I can see and if they were switched it would be completely wrong. It appears that the front wheel is parallel yet offset from the rear by maybe 1/4-3/8 of an inch towards the car. While there is certainly a chance that I've overlooked something in my measurements, I'm pretty confident the offset is as I think it is, I've worked as a finish carpenter for years and do lots and lots of layout.

It's a bike that is set up from the factory with the sidecar. It has different wheels, gearing, steering damper, fork brace. Would it make any sense if that had been done on purpose from the factory? The rig seems to have been set up with care and tracks nicely.

I'm thinking that there is probably some sort of fairly simple answer out there from those that know, even if that answer is "Eli, you're an idiot"

I'm going to go do some riding, with this little nugget of "information" jammed into my little nugget of a brain and see what I come up with in terms of how it may or may not be affecting ride. I'm also gonna measure toe-in, 2 different ways, 1 based on the premise that the two tires are in line and 1 based on the offset, after I determine exactly how much offset there is, so I have some numbers for feedback.

Thanks for your patience, all.

Eli


(list of bikes goes here? Let's just say there's a lot of little hondas and a Gilera and some jukeboxes and a 71 chevy pickup that can hold the whole sidecar rig with the tailgate up!)

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Peter Pan
Posted 7/11/2015 7:56 PM (#85336 - in reply to #85331)
Subject: Re: cycle wheels parallel but offset..



Expert

Posts: 1914
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Location: San Isidro de Heredia, Costa Rica
At least aligning a ETZ MZ rig seemed to be like a book with seven seals for me...that pressed sheet metal frame was of such poor quality it bended itself when riding harsh, so every 3 month I had first to bend back all structure parts, then the swings and last align.
The new models after 1990 (until when?) I have never seen in person, so I have not much of a clue how those are. If there is no mark, then at least there should be a tensioner set screw on each side of the back wheel shaft. Use a calliper to set both to the same length. If its only 1/4" that is in your measuring tolerance and might be out of round rims too. Close the eyes and test ride.

Remember to have your straight edges about 4" off the ground. and when you have a narrower front wheel then back up the straight edge by half of the wheel diameter.
Sven
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Hack'n
Posted 7/11/2015 10:14 PM (#85338 - in reply to #85331)
Subject: Re: cycle wheels parallel but offset..



Expert

Posts: 4833
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Location: Boise, Idaho
Be sure to measure toe-in using the rear bike wheel only, as most bikes use a smaller front wheel. The rear wheel doesn't turn, nor does the sidecar wheel so check toe-in with those two wheels. Like Sven said, with the straight edges about 4" off the floor.

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Hack'n
Posted 7/11/2015 10:22 PM (#85339 - in reply to #85331)
Subject: Re: cycle wheels parallel but offset..



Expert

Posts: 4833
2000200050010010010025
Location: Boise, Idaho
Be sure to measure toe-in using the rear bike wheel only, as most bikes use a smaller front wheel. The rear wheel doesn't turn, nor does the sidecar wheel, so check toe-in with those two wheels. Like Sven said, with the straight edges about 4" off the floor.

If both wheels are the same and the offset interferes place the bike straightedge on the other side so you are using only the rear wheel for the toe-in measurement. 3/8" to 3/4" toe-in will give the best tire wear. You can check this later by observing the center groove wear on the sidecar tire.

If toe-in is off there will be a rounded edge on one side if the groove and perhaps some feathering will show on the other side. This will tell you which way to adjust to eliminate the side drag. If both sides of the groove are the same you are in proper alignment.

Lonnie
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michaelh
Posted 7/12/2015 11:55 AM (#85348 - in reply to #85331)
Subject: RE: cycle wheels parallel but offset..


Veteran

Posts: 120
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Location: Pago Pago, American Samoa
I think what he's asking is the the front wheel is out of line/offset to the back wheel, not toe-in/out.

I know nothing about the rig (save for photo's I've seen), and can be of no help whatsoever.
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Hack'n
Posted 7/12/2015 4:24 PM (#85352 - in reply to #85348)
Subject: RE: cycle wheels parallel but offset..



Expert

Posts: 4833
2000200050010010010025
Location: Boise, Idaho
Read it again. He also was talking about toe-in measuring.

I converted a1987 Harley FXLR into a Springer (after it was totaled) with factory parts and due to the brake rotor being on the opposite side, the front wheel was nearly 1/4" offset from the rear wheel. The Harley "PHD's" said it would never handle right. They were wrong, it handled just fine for several years with no problems.

Lonnie

Edited by Hack'n 7/12/2015 4:32 PM
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Al Olme
Posted 7/12/2015 6:21 PM (#85353 - in reply to #85331)
Subject: RE: cycle wheels parallel but offset..


Expert

Posts: 1735
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Location: Minneapolis, Minnesota
eli - 7/11/2015 4:20 PM

Well, as I have been delving into the wonders of my MZ silver star gespann, I've noticed some peculiar things. One things that had me a-thinking is this:

<> But when I make the rear wheel parallel with the front wheel with the bars pointed straight ahead, I notice that the wheels are paralllel but not in line! <>



And so??? Many bikes are built that way and although you'd think it would be a huge issue, it just plain doesn't matter. I guess it it was a huge offset there might be an issue but a small offset may not be "normal" but it is common. Don't worry... just ride it an pretend. ;^)
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eli
Posted 7/13/2015 1:00 AM (#85358 - in reply to #85331)
Subject: Re: cycle wheels parallel but offset..


Member

Posts: 11
0
Thanks so much for all the responses!

The way this all came about is that I've been riding the rig the whole time, but am establishing baselines to work off of so that I can finetune the ride to the way I like it. I'm now certain that the front wheel is offset from the back wheel, while both are parallel to the centerline of the frame, I found it curious, but I don't actually care! I was wondering if that was a technique sometimes used by riggers in order to achieve (xxx) effect. But the upshot of the whole situation is that the rig now handles beautifully! I established my baselines and slowly adjusted one thing at a time, knowing that I could always get back to where I was if I kept track of what I was doing. After an entire day of incremental adjustments/test rides/incremental adjustments/test rides/whoops now its worse/incremental adjustments back the other way/test rides/incremental adjustments/ad nauseum (emphasis on the nauseum), I'm proud to say that it really handles nicely, and better (for me, and the places I'm riding and weight I'm carrying) than when I got it a week ago! I'm gonna keep an eye on tire wear patterns as I put some more mileage on the bike.

I really do appreciate the responses, fear not, I'm a big advocate of "ride it and pretend"! I've won the MotoGiro 65cc class five times in a row, not through any great skill, but because I'm the only guy dumb enough to "ride it and pretend" a pushrod Honda 50 for 300 miles at full throttle!

I like this forum! And I'm really liking sidecars! Finding a nice middleweight rig was really the key for me, and when this one showed up I knew I was doomed to own it.

Eli


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Peter Pan
Posted 7/13/2015 10:02 AM (#85363 - in reply to #85331)
Subject: Re: cycle wheels parallel but offset..



Expert

Posts: 1914
1000500100100100100
Location: San Isidro de Heredia, Costa Rica
Hello Eli,
if your front wheel is more to the left then the back wheel, "between front and s/c wheel) that is possibly a "intended missalignment"
(but mainly caused because you force on right handers the frame to bend inside The back wheel is that takes most of all riding force and with a sporty rider it suffers a lot.):
That way the push wheel helps a little to distribute the traction to the s/c wheel too. (mentioned in the German manual on the link site)
If the back wheel is further outside of the front wheel then I would search for bent front forks/tubes due to a former accident or so.

Side note: On the Ural the engine is 1/2" further to the right side intentionally installed. for weight and shaft clearance reasons.
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