EDIT: The paramsFor
method was added some time after I wrote this answer, which makes this possible. Refer to @nickiaconis' answer for more details.
If I understand you correctly, I think you're running into expected behavior. The parameters for a route are unique to that route. I'm not 100% sure why that is, but dynamic segment values don't get passed to child routes. What you should do instead is access the model directly. In your value
route, you can use this.modelFor('dimension')
to get the model that was resolved for the dimension
route.