On the redesign and material selection of a pedal spindle used in bicycles: a case study

摘要

A case study, obtained from McMahan Titanium Company in California, examines the failure of a pedal spindle for use on a standard Titanium alloy B265 grade 5. A stainless steel ring is press fit onto the spindle as a support for the bearings. The spindle is designed to hold the bearing required for the pedal itself. A plastic sleeve slides over the spindle to provide a threaded surface for the attachment of the pedal. A stainless steel race with ball bearings sets over the stainless steel ring already on the spindle. The bearing covers connections between the two sets of bearings and is kept in place with a small attachment. The whole assembly is kept in place when the pedal is attached. A problem occurred when the pedal spindle began to fail at the point where the stainless steel ring is attached. This failure was apparently a fast freacture of the solid titanium alloy shaft. The reason for the constant changes in diameter of the original design was to maintain a minimum weight for the spindle. A design change is suggested in this report along with an analysis of the material selectrion.