Laser alignment

I use two Lazer Levels that came from China (Harbor) Freight on sale. 😉

After fastening them to the side of the rear wheel and sidecar wheel I measure the beam width using a tape measure at two points. Depending on what you are used to use the same distance seperation on the beams, ie 8' or 10' etc. You can start at any point on the beam and simply make the next measurement at your standard distance form that point.
You can aim the Lazer Levels either to the front or rear depending on the work area. Of course if you measure with them aimed to the rear it will be beam spread that you are looking for which should be the obverse of what you would measure to the front.
The Lazer Levels I have put out a very wide beam and are easy to measure on the floor with a tape measure. It is even easy to put down two tape measures at your standard distance if you want to.

The only problem may be is the tires are not seated on the rims well or the side walls are out of true with the rims. To check that I rotate the wheels while holding the Lazer Levels against them and observe any notable change before deciding on the tire position I fasten them to.
An option would be to add a block of wood or metal on the edge of the levels so that they are held against the rim and not the tire but I have had good luck with the tire sidewall attachment method so far.

The laser bit is overkill. You only need one straightedge if you place the front wheel straight ahead (one can sight down either side of the front wheel to check this) and measure from the center of the wheels directly below the axles to the straightedge that is against the sidecar wheel. I prefer this method since there is usually a lot of junk in the way of the rear wheel on the cycle side and not always easy to get a clear shot high enough on the wheel/tire to work with. Also many wheels have a center flange which eliminates the wheel/tire width variation of the front and rear wheels since you measure from center wheel to your straightedge.

Low tech Lonnie

Lasers may seem impressive but a piece of string will do this job just as accurately and somewhat cheaper.

The reason that I like the laser method is that it is compact. I haven't found an eight foot straight edge that I can put in my pocket. Besides, lasers aren't really all that high tech any more, time and tech marches on. Just think if we were communicating like this before lasers existed we'd be using snail mail. Also consider that the laser that I use cost only $9 and has other uses it's not only appropriate technology but also thrifty. ;^)

BTW, using the tire is "iffy" as you mentioned. Working with the laser resting on a chord of the rear wheel is very accurate (much more than necessary)

Originally written by Al Olme on 8/17/2008 10:57 AM

The reason that I like the laser method is that it is compact. I haven't found an eight foot straight edge that I can put in my pocket. Besides, lasers aren't really all that high tech any more, time and tech marches on. Just think if we were communicating like this before lasers existed we'd be using snail mail. Also consider that the laser that I use cost only $9 and has other uses it's not only appropriate technology but also thrifty. ;^)

BTW, using the tire is "iffy" as you mentioned. Working with the laser resting on a chord of the rear wheel is very accurate (much more than necessary)

I agree. I have a small one on a magnetic base and and a two foot level with a laser built in. I think the "expensive" one was $9 at Menard's.
Over the last 30 plus years I've used everything from string to aluminum square tubing to neon tubes. My question wasn't what to use, it was how to best use the laser.

Originally written by SidecarMike on 8/17/2008 12:08 PM

>

My question wasn't what to use, it was how to best use the laser.

'Sorry Mike.

I use the laser on the rim of the rear wheel. I'l gie you the one lser vesion.

1. Put a piece of tape on the floor just in front of the front wheel and make a mark where the laser crosses.

2. Turn the laser down to a spot just behind the tire patch of the real bike tire and set another mark on tape.

3. Using the same laser against the sidecar wheel and set another piece of tape and another mark behind the tire patch of the sidecar wheel.

4. The distance between the rear marks is measured and noted.

5. Then set a tape measure so that it is perpendicular to the bike and the zero point is over the tape mark left in the front.

6. Use the laser against the sidecar wheel and read where the beam crosses the tape.

7. The difference between the rear and front readings is the toe-in.

Please remember that the actual measurement doesn't really mean much. The important thing is the delta in the readings before and after you make an adjustment. Also, the exact place where you make the measurements has a big effect on the actual measurements. Consistency is the important thing. It would be great if we had a way to measure the ANGLE of the toe-in. That could be compared from one rig to another and would have much more meaning. Unfortunately that would be a lot hardr to do but its fun to think about.

Although I haven't personally done this, I had a fellow tell me that one of the cheapest ways to make a straight edge for alighnment is to use a set of florescent light bulbs. He claimed they are straight and won't lose their edge for straightness. I guess I broke too many of them as a kid, so I have not played about in using them, but the fellow said he used them all the time to alighn rigs. He said that the aluminum ones that I had seen used in various shops were very prone to getting bent over time. Just an idea, but he swore it works well. I believe he also said he just hooked them up with a set of large rubber bands.

I don't like the idea of using the bulbs for several reasons.

I would be concerned about this method if he just strapped them to the sidewall of the tire versus using spacer blocks to reference off of the rim of the wheel itself.

There is too much variability in the sidewall of a tire, from moldings (lettering, bead lines, etc.), to variation in the windings of the carcass causing differences in the sidewall width.

Also, there is mercury inside of florescent tubes...
Don't breath much if you break one...
(which isn't hard to do...)

AND, I am not so sure that I would trust how straight and true I would trust the extrusion process of a very thin walled glass tube not designed to be used as a straight edge in the first place... They may be fine, but I would want to check them with a known good reference. (like a laser...)

The magnetic laser is working fine. I stuck one on the rear rotor and one on the rotor on the sidecar. I have an expansion joint in the garage floor that I'm using as a reference point and will be able to set it up now. Thanks for the input, everyone.

BTW, Karl is right. We checked flourescent tubes in the past and found that they are inconsistent. Some varied by as much as a quarter inch in 4 feet. The eight footers aren't exactly cheap either.
I don't measure anything when I bolt it together. Too many people get obsessed with fractions of an inch. I adjust till it feels right and performs properly.
Once everything feels right I'll record the measurements. With the laser I'll be able to set things up and take my readings at a consistant horizontal plane 8 feet ahead of the wheel.

Mike,
I'm scratching my head and thinking about your process here.
(As I've said before, I'm kind of wood fired.)
It would seem that your method of measuring from the rear rotor (center) to a point 8' ahead of there (after the alignment of the rig was tweaked) could yield an angle ratio that would be of use with other rigs with different wheelbases for presetting the toe-in.
I may be barking up trees here but "I was just sayin'".

Lonnie

Perhaps it could, but I would think not. My point earlier about not getting too hung up on measurements was that what feels right for me, a 250 pound rider with a normally empty sidecar is not going to be right for my 90 pound daughter with two kids in the sidecar and a third on the pillon. Likewise, the sidecars I've owned that carry car tires tend to need less toe than the ones that had motorcycle treads. Even replacing straight ball bearing races with tapered ones make a difference. Or am I way off in my thinking. You've done a lot more of these than I have.

BTW the 8 foot mark was actually measured from the front of the rig. The metal expansion joint that I roll the back tire back against is actually about 12 1/2 feet back from the door that I measure to.

Mike,
My thoughts were a presetting angle (or formula) that might be later tweaked a bit to accomodate some of the variables you mention.
Starting with a road weighted rig and using prescribed distances to arrive at a "Rule of thumb" angle that might be useful to others such as the way the 2/3rds bike to 1/3rd sidecar ratio is used.
If I could afford one of those expensive $9.00 lazers and had more free time, I'd fool with the idea.

Still scratchin'

Lonnie

In that case, when I get that far I'll make some notes and post them here. Don't expect me to compute angles though. I think of Algebra and such as Weapons of Math Instruction and want nothing to do with them

Sincerely,
Emily Littela

Originally written by Hack'n on 8/19/2008 6:39 PM

Mike,
My thoughts were a presetting angle (or formula) that might be later tweaked a bit to accomodate some of the variables you mention.
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Lonnie

Lonnie,

We played around with that idea about a year ago and I think it is a basically good thought BUT as it turns out you end up dealing with a very small number of degrees that are very difficult to accurately measure in the small space that most people work in [a garage for instance]. The convergence point for the virtual triangle that you are measuring may well lay several hundred feet away.

The bottom line is, use what ever method works for you. Don't overthink it, make notes and use your tools to compare settings, not to start out with some theoretically correct toe-in setting. Your rig is unique and will require it's own tuning to make it work best.