Castell Gravel Grinder Race October 25, 2013 News & Info, Rides & Trails The Full Grind 100K and Half Grind 50K races are taking place April 5th in the Texas Hill Country. Click here for details. Event, Info, Race Post navigation Friday PhotoLazy Sunday One thought on “Castell Gravel Grinder Race” we are very excited about this race! thank you for promoting it!! Comments are closed.