How do I get past the spikes in the clockworks?

In the clockworks level there is the hallway where you get the teddybear in the present. in the past it is intact with a lot of spikes blocking the way. however I know there is a way to get over there because there are ropes and such which allow me to get back -- but I can't get there because I can't run far enough to get to the ropes. How do I get over there? It's driving me nuts!!

I'd let you see a screenshot, but apparently I'm so new I'm not allowed to, so you'll just have to imagine it!!!!!!!!!