Passar parâmetro de rota para componente filho como entrada em Angular 2

Eu tenho um componente pai que obtém um valor de id de um parâmetro de rota. Eu quero passar isso para um componente filho, então estou fazendo isso por meio de um Input()decorador no componente filho. No entanto, estou tendo problemas para passar o valor do parâmetro de rota para a criança. Se eu embutir um valor no código e passá-lo para o filho, ele funcionará, então tenho certeza de que a ligação e a lógica do componente filho estão corretos; Acho que é apenas um problema de como / onde estou definindo o valor dinamicamente.

Este é o componente pai completo com alguns comentários:

import { Component }                                                from '@angular/core';
import { HTTP_PROVIDERS }                                           from '@angular/http';
import { provide }                                                  from '@angular/core';
import { Routes, Router, RouterUrlSerializer, ROUTER_DIRECTIVES }   from '@angular/router';
import { Location }                                                 from '@angular/common';
import { XHRBackend }                                               from '@angular/http';

import { ContentNode }                                              from './content-node';
import { ContentTreeComponent }                                     from './content-tree.component';
import { ContentDashboardComponent }                                from './content-dashboard.component';
import { ContentEditComponent }                                     from './content-edit.component';

import { ContentService }                                           from '../services/content.service';
import { InitService }                                              from '../services/init.service';
import { RouteNames }                                               from '../services/route-names.service';

@Component({
    selector: 'my-dashboard',
    template: `
        <div class="tree-panel-container">
            <div class="tree-panel-content">
                <content-tree [startNodeId]="startNodeIdContent" [currentNodeId]="currentNodeId"></content-tree>
            </div>
        </div>
        <router-outlet></router-outlet>
    `,
    directives: [
        ContentTreeComponent, 
        ContentDashboardComponent, 
        ROUTER_DIRECTIVES
    ],
    providers: [
        HTTP_PROVIDERS
    ]
})
@Routes([
    { path:'/',    component: ContentDashboardComponent },
    { path:'/:id', component: ContentEditComponent }
])
export class ContentComponent {

    _currentNodeId: number;

    constructor(private router:Router, private routeSerializer:RouterUrlSerializer, private location:Location) {
        router.changes.first().subscribe(() => {
            let urlTree = this.routeSerializer.parse(location.path());
            let urlSegment = urlTree.children(urlTree.children(urlTree.root)[0])[0];
            if(urlSegment != undefined){
                let id = urlSegment.segment;
                this._currentNodeId = id;
                console.log('_currentNodeId', this._currentNodeId); // This works - it logs the correct id from the route param
            }
        });
    }

    startNodeIdContent = InitService.startNodeIdContent;
    currentNodeId = this._currentNodeId; // This doesn't work - it just results in 'undefined' in the child component

    // The following line works; it passes 123 to the child component, so I know the binding and the child input is set up correctly:
    // currentNodeId = 123;
}

... e aqui está o componente filho:

import { Component, Input, OnInit }         from '@angular/core';
import { Router, RouteSegment, RouteTree }  from '@angular/router';

import { ContentNode }                      from './content-node';
import { ContentService }                   from '../services/content.service';


@Component({
    selector: 'content-tree',
    directives: [ContentTreeComponent],
    template: `
        <ol class="tree">
            <li *ngFor="let contentNode of contentNodes" class="tree__branch" [ngClass]="{'tree__branch--has-children': contentNode.HasChildren}">
                <a *ngIf="contentNode.HasChildren" (click)="contentNode.toggle=!contentNode.toggle" class="tree__branch__toggle">
                    {{ !!contentNode.toggle ? '-' : '+' }}
                </a> 
                <a class="tree__branch__link" (click)="onSelect(contentNode)">{{ contentNode.Name }}</a>
                <content-tree *ngIf="contentNode.toggle" [startNodeId]="contentNode.Id"></content-tree>
            </li>
        </ol>
        <div class="error" *ngIf="errorMessage">{{errorMessage}}</div>
        <p>{{test}}</p>
    `
})
export class ContentTreeComponent implements OnInit {

    constructor(
        private _contentService: ContentService,
        private _router: Router,
        private _currSegment: RouteSegment
    ) { }

    errorMessage: string;

    @Input('startNodeId')
    private _startNodeId: number;

    @Input('currentNodeId')
    private _currentNodeId: number;

    contentNodes: ContentNode[];

    ngOnInit() { 
        this.getContentNodes();

        console.log('_startNodeId = ' + this._startNodeId);
        console.log('_currentNodeId = ' + this._currentNodeId);
    }

    onSelect(contentNode: ContentNode) {
        this._router.navigate([`./${contentNode.Id}`], this._currSegment);
    }

    getContentNodes() {
        this._contentService.getContentNodes(this._startNodeId)
            .subscribe(
                contentNodes => this.contentNodes = contentNodes,
                error =>  this.errorMessage = <any>error
            );
    }
}