I've received a new carbon fork and I'll have to cut it to adjust its height. Am I assuming correctly that the cut should be a little (2-3mm) below the top level of the stem, so the steering headset is going to lay on the steering pipe but also it will not stick out above the stem?
by brekol
6 Comments
Yes you are correct. You want it such that the top cap interfaces with the top of the stem, not the steerer tube so that when you tighten the bolt on the top cap it pulls the entire headset assembly together, removing any play. You then tighten the stem bolts to secure it all in place.
1. assemble frameset with a complete headset and stack spacers (not exceeding manufacturers max safe stack).
2. add stem (barstem) on and lightly preload by hand so that the parts dont just dangle loose.
3. mark the steerer tube where it exits the stem on the top
4. disassemble completely
5. look for the mark on the steerer and deduct few mm for the slack AND the stack that expander will add to it when sitting on the top of the steerer tube – mark the actual cut point
6. cut, file away burrs, possibly seal the edge to avoid fraying in the future
7. reassemble as in point 1. and ride
TL.DR: Your steerer tube must be few (<3mm) millimeters shorter than the stack of your frameset, headset and expander combined to allow for the top cover of the expander to tighten the parts together.
note: any steerer tube + expander sitting on top of it would need to be covered by additional spacers – creating so called chimney.
Yes, I assume you understand that the headset cap and the expansion plug are two separate parts. Ideally you want to install everything and mark a line where it intersects the top of the stem, then subtract the protrusion upward of the expansion plug and downward of the stem cap,
Three_seconds_ago is correct, but honestly just follow a YouTube tutorial so you don’t mess it up
You are correct, HOWEVER: many people (including myself) actually prefer cutting the steerer 2-3mm above the stem and add another 5mm spacer on top of that. It doesn’t make much of an impact visually but will increase the strength of that connection significantly. This is not necessary but just some food for thought.
Some fork manufacturers recommend/require a 5mm above the stem. Some stems are made with carbon forks in mind and will incorporate that space in their design.
I recommend you consult the manufacturer for each of those respective parts before you start cutting.