Yeah I've gotten a lot of feedback on that, the key is pressing when the cages are at their lowest points, judging from how many people how this same problem it's clearly broken and I will rebuild it for a future update, busy going through all the feedback I've received right now :)
I actually ran into a problem where sometimes I would press left (or right) and they would simply...not push the cage, and I lose all my momentum. It's probably related to the timing/momentum calculation (that is, I noticed you can't push left while the cage is moving right), although maybe the timing between the cages?