I run XC & Track right now in College and I've found no problems with commuting by bike. Of course if I killed it on a hard commute or bike trip that might take a little bit of sharpness out of my workout. Honestly though, I've gone on a long-ish ride the night before an XC race and still PRd.
You can exhaust yourself and stress your body doing anything and if your tired that will affect how you perform in subsequent tasks. You gotta evaluate what you are doing in total for training. Not evaluate biking and running separately. For example, if you did a track workout and biked 20 miles, you total that, not evaluate it separately for how much you've stressed your body. If your fatigued in running you may want to cut back the biking temporarily or vice-versa to give the body time to adapt.
Hope this long answer helps. Biking has helped me maintain some fitness through several injuries. Like right now.