The attitude in SWEDEN seems to have changed somewhat. From having been impossible to take your bike, the policy is now: "You can take as much baggage as you can carry by yourself, as long as it doesn't interfere with with other passengers travelling area"

I called the customer service... "so it's ok if I bring my bike?"... "can you carry it?"... "yes"... "then you can bring it"...

Seemed pretty clear cut to me... HOWEVER the super fast trains (X2000) do not have as much room for luggage. I would advise taking both wheels and pedals off, turning the handlebars and putting in as small a cardboard box as possible (or wrapping in a tarp) as to using a larger bike cardboard box.

Get to the train early (at terminal stations) so you can put the bike into the luggage before the baby prams and suitcases get there, make it look like your bike is a Gucci handbag (light, easy to carry), be polite to the train conductors (loosing your cool will get you nowhere, but persistent reasoning (with a hint of begging, but not desperate) works well in case they say there is no room... "please let me try, I'm sure you'll see that it won't bother other passengers" sort of thing