Training & Nutrition - Cycling-running

I don't know if there are any runners here, but here is my question.

How much cycling would you need to ride to equal running a marathon? ie.. distance and elevation gain...

It differs due to the mechanical nature of your bicycle. The human body is only built to run up to 20 miles. The final 6.2 miles is what makes a marathon truly great.

So, to equal a marathon, I suggest you ride until your body hits "a wall" and add 25%-30% of the distance you just rode.

you can cycle about five times longer than you can run so say one hundred and twenty miles or so. The reason for this I believe is the reduced impact that cycling has on your legs.

I don't know if there are any runners here, but here is my question.

How much cycling would you need to ride to equal running a marathon? ie.. distance and elevation gain...Here you go...

http://www.trainright.com/page.asp?page_id=content&page_content=A-8&CategoryID=66&ArticleID=2#article

Most people just do a 3 to 1 conversion but that doesn't reflect wind resistance.

I've never run a marathon, so I can't compare from my own experience. Given that comparing cycling to running is an apples-oranges comparison, there are still some parallels. I think a century roughly corresponds to a marathon. In my experience, the "wall" effect hits around mile 65 or 70. If you're in decent shape, have decent endurance, and have done some distance so your body is used to using fat as fuel, you don't experience it.

Other runners will probably disagree, and I'm not much of a runner any more in any case, but I always felt like 7 miles on the bike corresponded to 1 mile running. (disclaimer: at *my* running and cycling speeds). Or, an equivalent workout on the bike takes about twice as long. That in no way agrees with Dr. Burke's article. That's based mainly on perceived exertion and how I feel after, say a 1/2 hour, 3.5 mile run vs. 1 hour, 20 mile ride.

I agree - no real comparison. However, the Ironman folks have done it for you. The event is designed to provide relatively similar experiences in the swim/bike/run portions: 2.4 mile swim, 112 mile bike, marathon run.

I don't necessarily agree that the body was only made to run 20 miles - but I think you are partially correct. After around 20 miles, the glycogen stored in the muscles is depleted and runners hit what they call "the wall". If, however, you replenish the glycogen as it is depleated, the human body can run until it's fat stores or exaustion sets in. Pam Grier just ran 300 miles without stopping - the longest anyone has ever run without stopping, and she did it by eating and drinking on the run.