How do you setup fore aft saddle position. My saddle no have any marks in the rails

Most don't . Use a constant like your fore-arm or drop a weighted string from the front of the saddle and see how far behind your bottom bracket it is. Drop a weighted string from the front of your knee and try to get it centered on your pedal axle when the pedal is forward (3 o'clock). You've got options.

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thank you for the answer