Motorcycle Wheel Balancing Stands
They are separate as to be able to adjust for different width wheels.
The distance from the bottom of the axle to
the top of the 2 X 4" bottom support, is 16 1/2". The rear wheel of the Road Star is approx 13" from axle center to the edge of the tire, this with 
a 160/80-16 tire. 
The stand should be fine for most motorcycle
wheels.
The cost is approx $20 to $30, give or take a few bucks, depending on what you have on hand and what you should be able to scrounge for free from a sheet metal shop or scraps your friends have.
I personaly think you can build it closer to the $20 buck level as I did. The bearings being the most expensive parts at $17.00, if you have a source for some bearings the stands could be build for virtually nothing.
The main piece of the balancer is a 2"X 2" by
3 1/2" long piece of 80 thousands thick metal angle. (obtained from metal building supplier)
The holes to mount the bearings are 3/8" dia.
they are 1 1/4" apart and centered, 1/4" down from the top edge. The bearings are held on
the bracket with 3/8" hex cap screws, 3/4" in
length and hex nuts.
List of parts.
2 ea (A)  13 1/2" wood 2 X 4
2 ea (B)  4" X  9" piece of 1/4" plywood
2 ea (C)  8" piece of wood 2 X 4
2 ea (D) 2" metal angle 3 1/2" long

(4 ea) 1614-DCSR12 bearings.
           The bearings are 3/8"ID, 1 1/8"OD
           Actually you can purchase any size in this
           approxamate size range just change your
           hole locations to accomdate the different
           sized bearings.

(4ea) 3" long sheetrock screws

(8ea) 1/12"long sheetrock screws
To build center item"C" to item "A" and attach using 2, 3" long sheetrock screws.

Notch out Item "B" to fit over base "C"and 
attach with 2, 1 1/2" sheetrock screws.

Drill 2, 1/8" holes in bottom of 2" metal angel
and place bearing side flush with edge of
item "A" and attach with 2, 1 1/2" sheetrock
screws..

using 2, 3/4" cap screws attach bearings to 
2" metal angle, notice in the second picture I ground out a small area at the area inbetween 
the bearing mount holes , this to give plenty of clearace for axle if needed.
This project is a pretty simple deal, the purpose
of the bearings is mainly due to grease seals that are on some wheels and cause drag. The bearing cradles reduce most any friction to allow a easy balance of your wheel.