Mom needs to stay in with the baby until it is weaned. Wheels can be dangerous for kits, many kits have been killed by being flung from a wheel so please don't put the kit and mom in the cage with the wheel.
Mom will be just fine without the wheel for another seven weeks, and appreciate it even more when she gets back to her daily exercise regimen! Mom's do a lot of other very important things than just birth and feed babies! They help keep them warm, which helps keep up their immune system until they get it built up from exposure, as well as cleaning, and sometimes helping their kits void. The benefits of leaving mom with the kit, far exceed any benefits she might receive running on her wheel.