I'm building a cyclocross frame that will be used for light trail riding, commuting, and gravel roads. The seat tube is single butted 28.6 .9/.6 and 56cm in length. The frame will have a slightly sloped top tube (compact road geo type). I plan to use a mtb seat post, so will have plenty of seat post in the seat tube. Is the .6 ST top sufficient for this application? Or should I add a sleeve for extra support? Rider is 6'2" and 185 lbs. Thanks.