Originally Posted by
well biked
This is a rather unusual threadless stem setup. There is what is essentially a sleeve on the outside of the steerer tube that the stem can be adjusted up and down on, without juggling spacers.
But underneath the stem and the notched sleeve lies an ordinary threadless steerer. You should be able to remove the stem and sleeve, buy an end cap and the spacers you need, plus the riser stem (with 1.125" steerer clamp) of your choice.