Training run vs bike?

Triathlon Forum
1

Instead of running 35-40 miles a week to get ready for a half marathon would you get the same benefit running 20 miles and biking x amount of hours to make up for the running mileage?and is this a better way to lessen the chance of a running injury?

Since I have limited time I do not want to lay off the bike completely.

Thanks for the input.

2

20 miles of quality running should be more than sufficient for a half marathon. 30-45 is my target when prepping for a full marathon.