Head tube: 16.5 cm /6-1/2 inches. We include detailed pictures and accurate descriptions. If you have ANY questions, or would like additional pictures, please let us know.We're happy to help. Happy to deliver with a required adult signature if you'd like. Happy to deliver with a re. The item "Mongoose CHROME frame mountain bike 58cm top tube 55cm seat tube" is in sale since Saturday, July 3, 2021. This item is in the category "Sporting Goods\Cycling\Bicycle Frames". The seller is "fastrubberboat" and is located in Edgecomb, Maine. This item can be shipped worldwide.