Bendix style hub round sprocket clip safety issue

Frank Lindholm

New Member
Mar 29, 2017
Anyone else with a Bendix style rear hub experience their rear sprocket falling off when pedaling very hard? After this happened to me (now more than once), and upon thoroughly examining the design of the round spring clip that holds the rear sprocket to the hub, I was very surprised at the design. It looks to be inherently flawed (when used with an off-center sprocket tooth/hub mount). The system uses an offset tooth sprocket that is not in plane with the mounting to the hub. This creates a leverage angle the can pull the sprocket sideways, forcing the round retaining clip right out of its round shaped groove (and right off of the hub). This has happened to me twice now. The second time was my wake-up call (when without any brakes I could have been badly injured if not for sheer luck in being able to stop in time by dragging my feet!). When this happened, I decided to thoroughly investigate its cause. When I called the bicycle manufacturer to talk to them, The "customer service" person was completely inept mechanically, so they failed to understand the inherent flaw in the design. In my view, either the round semi-circular groove that holds the sprocket clip needs to be deeper (in order to create a fully flat 90 degree retaining wall surface for which to resist the round shaped sprocket clip from slipping from and walking right out of its groove, OR the groove and clip both should be FLAT so as not to create a circular, variably sloping surface from which to easily slip from (given sufficient pedaling/braking torque). Anyone else have thoughts about this important safety concern? Given the speed at which motorized bikes can run (importance of functioning BRAKES), and given the increased likelihood of occasionally hard pedaling (for engine starting), this issue would be especially important to motorized bike users who wish to use this as the basis of their build.
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