First, you should determine the location of the track marked in green, and the location of the most forward point of the canopy , as shown in diagram below.
Proceed to STEP 2
Measure back 21″ from the most forward point of the track, as shown in the diagram below. This point will be your point A.
Measure back 80″ from the most forward point of the track, that will be your point C.
After finding those two points, ( location of point A and C ) you should proceed to Step 3.
Proceed to STEP 3
After finding the location of point A and point C, you should measure the beam on both points.
With those measurements, you will be able to choose your canopy size on shop pages.
Keep in mind that aluminum frames are flex and adjustable to dimensions on Shop pages.