Looks like you could drill through the arm of the headwind unit and just have a bolt for the bumper wheel, instead of the plastic block that I used (which is backed by a piece of sheet iron BTW). There might be just enough clearance for a lock nut underneath that headwind unit's arm to avoid interfering with the axle nut, but double check to make sure.

The bumper wheel on mine just overlaps the groove where the headwind unit's belt goes, but there is still about 30 degrees of clearance underneath the bumper wheel where the belt runs. On mine, the center of the bumper wheel is just over 1 inch above the top of the roller...high enough so that the wheel hits the middle of the braking surface on my rim. But you could raise the bumper wheel up a little higher if needed, as long as it hits your rim.

Also you'd need to put a wheel under the headwind unit, and could raise the headwind unit so that the arm is parallel to the ground (to make the bumper wheel bolt vertical).


BTW - A couple of things I learned on this project:

1) Drilling the frame holes is the hardest part of the project. The Kreitler frame is tough to drill through. I would not recommend even attempting it without a drill press, with the frame clamped securely, and a drop of oil to help lubricate the (HSS) bit.

2) To make sure the holes were the same height on both sides of the frame legs, I made a little cardboard jig w/ a screw through it to score the paint. It's more accurate than measuring 12 times. Also I was very careful positioning the drill.. Even so the holes weren't perfectly aligned, but were good enough.

Also, an update: I did replace the wooden blocks on my setup with ABS plastic ones (used a 1 1/4" bit to form the curvature to match the 1" PVC) and joined w/ PVC cement, which worked well.