jadmt

depends on the distance and individual effort. I have run 10 marathons 2:48 fastest (portland) slowest 3:00:05 (Boston) and all the rest in the low 2:50's so not fast but not slow. I have done a 10 hour 200 miler. I don't think you can remotely compare longer distances runs to cycling, every marathon took several days before I felt like running again and longer to run pain free, the cycling I could have repeated a long ride the next day in fact we did, I know some do much better than others. But if you shorten the distances to say a 10K in the 35-36 minute range it might compare to a 55 minute 40K. I did a brisk walk yesterday so can't compare it to running but I figure I felt about the same an hour after I got home as I do when I ride 30 miles at a 20mph pace ie I know I did something but not enough to impact the rest of my day or feel it the next. this past summer I did a 110 mile bike ride and the next did a 66 mile bike ride and I am old and fat so I don't think for non elite cyclists or runners you can really do a good comparison.

john m flores 

Having cycled centuries and run marathons and ultramarathons, I've always gone by the approximation that a century = a marathon, more or less. The biggest difference is that the impact of running wrecks your legs in a much different way than cycling. For example, the day after a marathon, walking down stairs can be a challenge. I've never experienced that the day after a big ride. Soreness, for sure. But not that.

One thing that I've also discovered, is that the best thing to do the day after a big run is to go for a light spin on the bike. Seems like getting the blood flowing through your legs really aids in the recovery process.

CAT7RDR

I would think pain tolerance and joint fatigue/inflammation is very individual as well as boredom.
For instance, in my youth I could play four hours of fast paced full court pickup basketball and still be invested in the process.
If road cycling in an majestic part of the country, I could ride all day.

Running, on the other hand, after 30 minutes, due to my wrecked body, I'm done no matter what because I do not have a saddle, handle bars and pedals offsetting the impact on my joints. After two miles of what would be considered a slow jog, I'm done.

For myself, I cannot compare the two to make a logical conversion.

burnthesheep

Triathlon has a ratio of 4.3:1. I use that.

Caveat being, there is an issue of pace. Riding a bike is riding a bike, no matter how slow really (assuming you're not going down an infinite mountain). Running no longer really is running below a certain pace, it's walking. The economies of the run versus the walk makes the math different probably once you breach the "walk" threshold. The run is at some point your stride has both feet are off the ground.

One way or another though, time for time, running in most training trackers accumulates more training stress at the same intensity per unit time. Running at the same % threshold as biking accumulates more training stress. Trainingpeaks does. Someone replied to a Slowtwitch topic about this when I asked sometime last year, and the response was basically it's the metabolic cost is higher running at the same intensity as you bike. They used to or did work for Trainingpeaks as the person answering.

wheelreason

Time and heart rate is how I did it, but there is really no direct conversion, I find fitness transfers well, but power and speed not so much. I hate running, but I've always been naturally good at it, particularly XC or on uneven surfaces.

rsbob 

I know that when time didn’t allow me to cycle, I could go out for a quick run and get my workout in.

RChung

Someone once posed the question this way: "A co-worker and myself are having a friendly bike / run contest. What is a good ratio for miles ridden vs. miles run? I know it depends on pace. But I'm curious what a generally accepted range of ratios might be."

My answer was, "probably between 2.5 and 3.5 miles; the faster the runner the closer to 2.5 while the slower the runner the closer to 3.5." Here's how I got to my answer.

wheelreason

Oh man! I completely missed it was Larry asking and gave a serious answer, oh the pain, the pain....

ofajen

Sounds good. My rough approximation above indicates about 2.6 at a 6 minute mile and about 4.0 at a 12 minute pace.

Otto

Flip Flop Rider

without reading the previous threads or doing any calculations I'd say - 1 mile of running = 8 miles of cycling

SoSmellyAir

Both the reckless segments and the dumpster diving segments.

LarrySellerz

Well if I go with my 8 miles cycled = 1 mile ran, then,
100/8=12.5
26/12.5=2.08
2.08x100=208 miles. So running a marathon is like riding a double century.

tomato coupe

You could just multiply 26 x 8 = 208.

alcjphil

How much running do you do? If almost none, then The answer is not going to be the same as if you run regularly. I hate to run even though I am pretty good at it. This is a totally subjective question

LarrySellerz

... when I was doing the math I was like "theres gotta be an easier way of doing this"

Sy Reene

hmm.. 4.62197 x 7.5 = 34.66.. awfully close. Coincidence?

Sy Reene

There are a lot of folks this time of the year indoor Zwifting etc. Lunchtime or before work who enter a 10-12 mile race. It's a pretty good workout that is admittedly hard to easily do for many folks on the road, out your front door on a bike. How does this compare to a 3-4 mile run?

jadmt

Depends maybe they can be 1for 1

rsbob 

Just like any workout, it depends on how hard one pushes it. If running intervals for 3-4 miles, I can exhaust myself by mile 4. But you are right, racing, which I don’t do on ZWIFT, which I believe can be just as taxing, but I prefer to cross-train.

ScottCommutes

I'm no runner, but I don't understand how people train for marathons by running shorter distances. Doesn't it make sense to go out on a Saturday and walk 3mph for about 9 hours? If you can do it, you have completed a marathon and that is your time. Next time, try to do it a little faster. After a few practices, add some racewalking or jogging intervals to get your time down more.

tomato coupe

You should definitely do that. Report back.

Fahrenheit531 

Can't coast while running. Comparison should pretty much end there.

One Wheel

I ran a 5:15 marathon in September this last year, and rode a 6:10 century about a month later. If I was guesstimating I would say the marathon was roughly twice as hard. Two other factors for me, though:

- If I want a quick workout, as little as 15-20 minutes of running is fine, but I don't feel like I've even really gotten warmed up on the bike until close to an hour.

- I'm never interested in running more than 4 consecutive hours again, but if I get the opportunity I'll gladly jump at 8-10 hours on a bike. My endurance limit for running is fatigue, but for a bike it's schedule.

indyfabz

…and post videos.

rsbob 

Especially when going up a 10% grade.