Other options...
Lava ledges are great-when my chin was younger and I worried more about him falling, I put one between shelves so he could jump to that and then to the next shelf. It's also fantastic for their teeth and nails, plus a little entertainment. Mine bites, scratches, rolls in the dust and crumbs that come off, and then does it over and over again throughout the day. Now that he's older, I've made them a shelf of their own that he jumps to and sits on to chew on his door (wood) or something. He uses it a lot. He has 2 and 1/4 at the moment
And yah, I just found the other thing I was looking for-I always forget if it's from Petco or Petsmart, lol.
http://www.petsmart.com/product/index.jsp?productId=2754305
I don't know if they still have more than one size, but they used to have a small and large. I believe that's the size he has. Yes, it is very unsafe how they sell it for a chinchilla, but I fixed mine. I put a think peice of safe wood so iit'd cover the platform, then screwed it on (make sure no screws stick through to poke a landing chin's foot) with those round things that go at the base of the screw to hold it in place (so sorry I can't remember what the heck they're called). Then I tightened the hooks where it hooks to the cage so it isn't bouncy. It's a little harder to move that way, but safe for the chin. Do not use a heavy peice of wood-as thin as ply wood is better or it'll make it bouncier as well-I made this mistake at first and had to fix it when it bounced off when he was going wild one day-I also tightened the hooks more after that. Now they're totally safe, though-he has 2. And if the chin(s) are crazy chewers, you just replace the wood, but the metal will last forever. It just fit just about any cage. I still LOVE the lava ledges more (and my chin would strongly agree, lol), but I think they screw on the same as leaping ledges, so they may not work.
The chins should get a hang of the big jump eventually. Mine does over a foot jump in his cage sometimes, or uses the side of the cage to boost him up, or another ledge. But if they don't the 2nd option should definitely work if done right (like I described). Younger chins sometimes take a little longer to 'get the hang of thinngs', too