Looks like the space between bearings is a little to big and the
spacer is too short. No doubt comes from split rim design.

How difficult it is to "jam" wheel in to fork does not really matter
- the bolt pressure is so much greater.

Find a paper - thin washer that you can put on spacer next to bearing
inside
the wheel and see what happens. Let me know if this helps.


My rollerskis have Alu. wheels that are just a little too wide and the
washer was inside between bearing and spacer!
If i remove washer I get a slow wheel, just like you do.

I am now using Millennium rollerskis w/standard 8mm skate axle set up
-
no headache, all the skate spacers that come in 3 lengths can be used
and
I can make any wheel fast or slow depending on spacer size.

I am sure there will be plenty of people who ether object what I am
doing
or do not understand or both.