Originally Posted by
TechKnowGN
We're starting a very similar thing with a training plan for the Half-Iron we're doing in the fall. My wife is an athletic trainer, and we talked about the injury implications. Running is a daily part of her life, just as cycling is mine. If you're doing the commute at a pace at which you are not strongly exerting yourself, then it shouldn't be a problem. If you're doing too much, it could lead to injury. If the exertion is light, then consider it a recovery ride. Even in the middle of a large workout plan your recovery days can still be active.
That's what seems intuitively right. Looks like I'll be cooling it on my morning time trials :-)