I've searched and read going back as far as possible, but I haven't found the solution to my situation.
I have a 2006 883R Sportster with a Spyder sidecar. I've experimented a bunch with various toe and lean settings, and along the way I've listened to some people who are way more knowledgeable than I am. I know these settings are always a compromise, but so far I have not found the optimum settings.
Originally I ran 3/4" toe in with 2 degrees of lean out. The rig tracked reasonably well and got 40-41 mpg (it got 50 mpg before installing the sidecar), but it would still pull to the right a little at highway speeds. Over Memorial Day weekend I went to the Hack'd open house for a couple of hours and some cupping/feathering of the right side of my rear tire was brought to my attention. A couple hours later I'd received quite an education about improvements I could make to both the rig as well as my measuring process. I decided to give it a try.
I reduced toe in to 1/4 inch (as measured at back of the rear wheel and the front of the front wheel), and wound up setting lean out to about 3.5 degrees to make it track straight at highway speeds. I followed suggestions on how to make my measurements, i.e. with the bike and sidecar loaded with the weight they would normally carry, the bike on 1" boards to simulate road crown, setting the bike tire pressures near maximum, etc. The end result is it now drives beautifully, better than it ever has before. Gas mileage on an 1100 mile trip this last weekend was the best ever, with an average of 42-43 mpg and a high of 46.92 mpg on one tank of fuel. The only problem is the rear tire. It has 6200 miles on it and is now due for replacement (about 3000 of those miles were before I installed the sidecar), but the wear is not even. The left side of the rear tire is rounded, and the right side is feathered and cupped much more significantly than it was when I was at the Hack'd open house. I've looked everywhere trying to find out if the feathering of the right side of the tire is an indication of too little toe in or too much. I suspect it means I have too little toe in, but before I go screwing up something that is driving so well I'd like to know for sure. Also, since this same wear pattern was occurring to a lesser degree when I had 3/4" of toe in, does that mean I need to run even more (perhaps an inch of toe in)? Even tire wear is great, but I'm also interested in fuel mileage. Also, because this is an 883 Sportster I don't have a heck of a lot of extra power in reserve at 65-70 mph, and the reduced toe in this weekend seemed to allow the bike to cruise with less effort at 70 mph. I sure don't want to give that up if I don't have to!
Any comments would be appreciated.
If the rear tire is rounded on the left side it indicates that it is being pulled to the right. An indicator of too little toe in.
3.5 degrees of lean-out to compensate for a minimal toe in seems a little drastic to me. I seldom use more than 1 degree with the rig loaded for normal usage.
Lonnie
Northwest Sidecars
So looking at the whole alignment equation inversely, if I were to set toe in to make the rig go straight with only 1 degree of lean it would probably have around an inch of toe in. Wouldn't the drag caused by that much toe in negatively affect gas mileage and require more throttle to maintain highway speeds?
Optimum tracking will give neutral steering and an even tire tread wear pattern. Regardless of the numbers.
If these two events occur, that's about as good as it gets with an asymetrical vehicle such as a sidecar outfit.
Dragging one or more tires sideways uses more fuel, more throttle, more tires and puts excess strain on the whole rig.
Lonnie
I prefer to run less toe in when possible. Ususally 3/4" max.
Tracking can be adjusted by lean out. This is why lean adjustors (most are really tilt adjustors today) work so well.
Couple of things to think about are that softly sprung rigs are much more sensitive to road camber changes, bike and sidecar loading.
Too much toe in can be run and kill tires on rig that seems to handle quite well.
Some spoke wheeled rigs seem to like a little more toe in.
A rig that has no titl adjustor or no swaybar can only be set up to work the best under the most common conditions it will be driven in. The 'compromise' is set according to this and there is not a whole lot that can be done from there. On the fly th efriver may be able to compensate soem by adjusting road position but other than that it can be iffy. Again, thsi is much more prevalant with a softer sprung rig than not.
If you make changes try and record you starting place so you can return to it.
