I read his most popular one under Google Images. It is entitled Bike Boys. The main characters are young motorcycle bikers whose lusty lovers are slightly older, maybe in their 30's. There's scenes are very explicit! Not for the prudish at all. Dubious consent is present in some stories.

https://www.barnesandnoble.com/s/%22Zack%20Fraker%22;jsessionid=890C771C756FE1FB7F29407D8786DF35.prodny_store02-atgap12?Ntk=P_key_Contributor_List&Ns=P_Sales_Rank&Ntx=mode+matchall