First, I did note a few misspellings and maybe accidental word usages. Square brackets will me placed around the words that need correcting in the actual sentence.
+You forgot the "e" in adrenaline: "[Adrenalin] surges, I pop into high gear and crank away."
+Replace the colon with a semi-colon: I drop a gear and push out at a steady beat trying to keep them in view when it hits me[:] none of them are using any sort of lights.
+Did you meant to say "guys" instead of guess?: I say, “James, nice to meet you. Do you [guess] do this regularly? I’ve never seen you before and I’m around a lot.”
+I'm not sure if a few more words were missing, if not remove "it": Each stroke gets weaker, [it] each time water splashes against my face I drink it in. I almost let go and slip under.
Now I will move on to the review. When it came down the story and how it flowed, I liked it very much. The interaction between the other characters was believable and the ordeal with the bikes was a nice touch.
You asked whether you should tone it down; I'm guessing you're referring to the sexual references? Personally, I think they are fine considering the context of the character. You didn't go overboard with it and kept it within the lines to where it didn't become a vulgar mess just for the sake of such.
I also enjoyed when he learned what exactly it was he had encountered. I felt it was a nice change on the typical ghosts and monsters. Overall, I felt the story was well done, grabbing and maintaining my attention throughout. Good job!