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Flexible rider harness

by Jason Moore — last modified Nov 10, 2010 10:10 AM

I spent a couple of hour with Dave Scurti at Pacific Medical Prosthetics and Orthotics last night and we fashioned the harnesses for the flexible rider setup.

Dave Scurti has been super helpful with the design and fabrication of the flexible rider harness. I am attempting to measure three upper body motions of the bicycle rider: 1) hip roll relative to the bicycle frame, 2) rider lean relative to the hips and 3) torso twist relative to the hips. The only other rider motion that I am going to permit is the movement of the arms to control the steering. The following videos show what I'm trying to capture:

From Bicycle Dynamics
We ended up using a low heat thermoplastic that is used for making splints and casts to fashion a custom rigid hip belt and we modified a spinal brace to hold the rest of the upper body stiff. This theorectically leaves a single joint in the lower back for the lean and twist degrees of freedom. I meant to bring my bike shorts with me so that we could mold the belt as close to my body as possible, but I forgot them. I had to drop my pants repeatedly to get the belt just right and this was a bit embarrassing as my boxers didn't have a button on the fly and I'm sure Dave got a view he wasn't interested in seeing. But I figured he was a medical worker so it wasn't that big of a deal.
Belt template
We used construction paper to mock up the belt.
Cutting the thermoplastic sheet
Dave cutting the basic belt shape from the plastic sheet.
Heating the thermoplastic
Dave is placing the plastic in the oven. Two layers of the material were used for extra stiffness.
Front of the flexible rider harness
A front view of the completed hip belt and back brace.
Back view of the flexible rider harness
The view of the back of the harness.
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