I wanted to give a visual demonstration to prove a point that I had made in a previous post. I had stated that bikes with seatstay pivots (Faux Bar Links) don't require bearings in that pivot because of the limited movement they experience. In fact, something like a DU bushing (used on rear shocks) are probably the best option. First, here are two pictures of my Jamis XLT...one before compression and one after compression (125mm travel). I have traced a white line over the lines I made on the frame to make the movement more visible.
At full extension:
At full compression:
According to my calipers, the movement was 0.3mm. The pivot is squarish and 23mm top to bottom. If you make that the diameter of a circle, it would give it a circumference of 72.3 mm (rounded to the nearest tenth). So the rotation of the pivot was 0.4% (.004) of the total circumference. Multiply this by 360 degrees and you have a total rotation of 1.44 degrees.
So why does a bearing designed for full 360 degree rotation need to be there again?
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Thread: Seatstay Pivot Motion
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