Use the appropriate blade for the material. 18 to 24 teeth is probably right for CroMo. A finer blade should be used for crabon.
https://diyhousehelp.com/hacksaw-blade-guide
I use the guide pictured below. Hose clamps will do if you are careful. Painters tape helps to see the line on dark colored tubes.
Be sure to deburr the cut end with a little sandpaper.
