Why do I never get DOMS (delayed onset muscle soreness) from cycling but I do after walking?
Let’s look at the definition of DOMS:


  Delayed onset muscle soreness (DOMS) is the pain and stiffness felt in muscles several hours to days after unaccustomed or strenuous exercise.
  https://en.wikipedia.org/wiki/Delayed_onset_muscle_soreness


If you cycle all the time, but rarely walk, then walking more than typically (e.g., a couple hours) could result in DOMS. Cycling and riding use your leg and hip muscles differently, especially in regards to range of motion. Cycling is a very constrained range of motion, compared to walking, especially when it comes to the posterior chain.

DOMS manifests when you use your muscles in ways you are unaccustomed to, this can mean what muscles you use and/or how strenuously you use them.  

This is why I suggested in comments to ride at a high intensity for a period longer than you are accustomed to if you wanted to experience DOMS from cycling.