You may get away with installing this on a 5 1/2” long frame head tube but it looks like 5 3/8” frame head tube will give you full thread engagement for top nut of headset stack. Will edit later after I cut my head tube down for better fit. Then we’ll see about performance. The look is GREAT. Weight is just about 1.4 pounds more that the RST Omega suspension fork it replaced.11/05/24. UPDATE: Wow, forgot all about this purchase. The bike doesn’t see much action now. This fork is horrible for speed and comfort. Love the look, but the lack of travel and general lack of precision feel is VERY noticeable. Great for show, not for go.