I use a 3" sewer drain pipe,not as heavy as schedule 40 PVC.And keep you package under 84" total,that is length plus girth.If over you will be hit with an oversize charge.The 3" pipe will fit most longbows and milder R/D longbows.The hybrids and other bows that are highly R/D won't usally fit in a 3" pipe.For those I look for a 4" pipe or carpet tube,bigger girth but usally a shorter bow so the total length will be under the 84" limit.I like to measure and weigh my packages before I get to the Post office so I know what to expect.USPS has a postage calculator right online.