Quote:
Originally Posted by Trent B
Wouldn't the hex holes in the plaction wheel help absorb some of the shear force over a circular spacer that was barely unable to fit in the hex holes?
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Not really. Technically yes if the tips of the hex extended further from the centerline of the fastener than a round spacer (which wouldn't extend to the 'points'), but that would be very little help.
It has to do with lever arms and resistance to bending. A very thin spacer would be able to more easily move/tilt due to the torque of the wheel (that is, in the shear direction). A wide spacer (or the neat device Joe Ross linked to - thanks Joe!) wouldn't tilt as much (or at all).
Shear over a wide area is bending. Think of a bolt sticking out an inch, force on the end of that bolt will bend the bolt. Apply that same force at 1/16" from the supporting structure and it won't bend as much. That's why someone said that adding spacers to put the sprocket further out from the wheel makes things worse.