Custom Frame Headtube and Fork

[Demogorgon84]

G’day,

I have a couple of questions. I want to install Fox 40 29” on a new custom made frame. Frame not made yet.

The headtube will be straight headtube 44mm round 120mm or 135mm in length. What length would be best?

I’m looking at zs44/28.6 zs44/30 headset. Would this be the right headset for the tube and fork?

Also any tips on how to installing the fork and headset?

Does the upper crown sit on top cup?

I’ve been told to add spaces. Where should I add the spaces? Under the upper crown?

I’ve cut tubes on forks before and installed headsets but not on downhill frames.

Thanks for any answers.

[ChaseCal]

okay, so this will either help you or confuse you more. But I will Try.
this is a complicated question... there's a lot of components and stuff that you are looking at simultaneously here.
so first off the fox 40, I think has a range of stack height from 105 to 165 mm so either tube length should be okay. except with that, you need to look at stack height for the headset too. from what I can tell, that headset would work, you might want to look at the cane creek short one though just to ensure that you have the right amount of room. as long as you are within the stack height range, you should be fine without spacers. From what I think I know you won't need them. It is going to have rubber bumpers though, slide those on so you don't back your fork into the frame.
the top crown should sit on the top cup of the headset, much like a slammed stem would on a normal bike. And cutting them is the same as a normal fork, but you just want to make sure you have everything on there first obviously.
I hope this helped, if not I know fox has some diagrams online but they are slighlty confusung.