One particular type of step-through frame is called a mixte. In a mixte frame, the top tube of the traditional diamond frame is replaced with a pair of smaller tubes (lateral tubes, or lats) running from the top of the head tube all the way back to the rear axle, connecting at the seat tube on the way. The normal seat stays and chain stays are retained. This provides the lower standover height of a step-through frame bicycle while avoiding some of the additional stresses the step-through frame bicycle places on the seat tube.
A variant on the mixte uses a single, full sized top tube running from the upper head tube to the seat tube, but retains the middle set of stays.
"Mixte" (pronounced ) is a direct appropriation of the French word meaning "mixed" or "unisex". The usual North American bicycle industry pronunciation of this loan word is /ˈmɪkstiː/.
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