Reynolds 

I can ride a century easily, and I'm sure I couldn't run a marathon (but I could probably walk it). I have a friend who runs 3 marathons a year but as a cyclist has a lot less endurance than me.

pitchpole

Who wants to run a marathon anyway? I almost ruined my knees running. Sometimes when I see a jogger painfully plodding along on the bike trail I feel like warning them.

calf man

In a few months, I am going to do a marathon (Sunday) and a double century (Saturday) in the same week. When I am done, I will tell you which was harder.

Keith99

As so many have already said, it depends on the person.

Let's add in the missing leg of a tri. Swimming. Which is harder, swimming a mile, a century or a marathon? Quite a few would say the swim hands down as they would drown well before the mile mark. I would find a mile swim relaxing (as long as the water was nice).

For me a marathon would be a real problem, but then I'm built like a prop. Oh wait I am a prop and any of those marathon running types would die for sure trying to do what I do as a prop.

adaminlc

Go run a marathon and find out...

BlueJay66

I have done a century a month in 2009. I also rode two 400K brevets. I ran my first ever 1/2 Marathon the week after Labor Day. I ran my first ever Marathon on 11-7-2009. Riding a century is nowhere close to the effort I expended on the Marathon. I was thinking the 400 k's were equivillent. (250 miles) that would make the ratio 10 to 1, but after reading some of these posts I would put it closer to the 8 to 1 ratio so a 200 mile ride would be about the same. I pedal nearly constantly when riding, but there is much to be said for not being able to compare the impact forces of running against the pedal forces and ability to "coast" on a bike. That said, I do plan on running another Marathon. What a rush! It was pretty cool getting cheered during every moment of the 3 hours and 50 minutes I ran.

Mark Kelly 

It rather depends how good a runner you are. For an elite level runner / elite level rider the ratio is around 2.5 to 1 as indicated by world record times (20 km/h running, 50 km/h riding). As you come down to normal human performance levels the ratio gets larger and larger. I've run a double marathon and ridden 400 k in a day and I'd say the ride was a harder than the run but not twice as hard (even though it took twice as long), so for me the ratio is somewhere about 3 - 4.

pharasz

Ditto here - knee surgery 5 years ago. I'll still run but only 10 to 12 miles per week. To a marathoner, that's not even running, that's just jogging. By comparing equal times and then equating the distance, you are comparing amount of cardio output between the two sports. That, at best, is a very limited dimension. The bicycle is a tool which not only multiplies the work you are doing (thereby generating great speed) but also allows allows tremendous assistance brought by inertia (i.e. you can coast), but most of all, it eliminates the pounding. I ran for the first time in about two years last week. A mere 30 minute run and I felt like I was pounding my knees and ankles with a sledge hammer. How can you possibly compare that kind of physical punishment to mere road vibration, which can be dampened extraordinarily with carbon fiber bikes? It's like trying to compare boxing to wrestling.

Doubleplay

Comparing them solely with the mileage is totally useless. If you include the time into the equation it starts making a little more sense. For example: If you walk a marathon in 6 + hours and ride a century under 5 hours, riding the century will be a harder task. However if you ride a century 6+ hours and run a marathon under 5 hours running a marathon would be the harder task. I think running a marathon at 4 hours and riding a century at 5 hours are comparable.
But in any case if there is no time limit both of them are easily doable for the average or below average fit person.

InTheRain

The comparison may be very specific to the individual. For me, weight is much more of an issue in running than it is in cycling. 200+ lbs pounding the pavement while running would take a definite toll on me. However, on the bike it's not nearly as noticeable unless I'm climbing a hill. I know that I couldn't "run" a marathon. I could maybe complete a marathon using a "jog/walk" combination where I averaged about 4 mph or 15 minute miles. So it would take me about 6.5 hours to complete a marathon at this pace. I think that being in the saddle for twice that long (2 x 6.5 hours = 13 hours) would be comparable for me. The pace on the bike would have to be about 15-16 mph... so that would be a double century (200 miles.)

For me, the ratio of miles between running and biking... probably 1 mile running for every 7 miles biking.

StanSeven

What pace is your century? Since you do 400K's, I'm guessing you just ride a slow, easy pace. When people like myself say the ratio is about 4 to 1, I'm talking about both events all out - a race like situation. I'm talking about pedalling all out and no coasting - pedal hard and fast going downhill. I mentioned on another thread I'm a sub 3 hour marathoner and I equate with a solo all out century.

USAZorro

Seems pretty clear that there are lots of individual differences. I based my estimation of 6-8 times the distance on my condition when I was 20 years old, in tremendous physical condition.

You say "all out", but I have some problems accepting that. In running "all out" meant covering 100 meters in a shade over 11 seconds - something I definitely couldn't sustain for even 300 meters, much less a marathon. In cycling, carrying a finishing sprint for much longer than 300 meters very is unusual. What I think you really mean is "covering ground at the highest speed you are capable of sustaining for the duration", and there are so many individual factors involved, that a person's answer really needs to be prefaced with "For me".

Doug64

I had a chance to compare the two sports whan I was younger. I've done 27 marathons or longer runs, including six 50 km's and one 50 miler. I was thinking about it the other day-- I used to run longer in a training week, 70-90 miles, than I ride most weeks now. However, I'm 30 years older! I've also ridden several centuries and longer road races about the same period with my longest single day of 169 miles. For me the effort seemed about the same. I was not fast at about a 2:40 marathon and a 3:20 50k, but I was in really good shape. I could ride from my home to my mother-in law's-house, 103 miles, in about 5:30 (depending on winds, and hardly any hills.). I'd often run the 25 miles home from work and ride my bike back to work the next day. Stashing liquids along the route in highway culverts was always a logistical challenge. I guess I could look at it in the context of max exertion. The longest I ran, 50 miles in 7.5 hours was about all I wanted to do. My longest ride of 169 miles at about 12 hours ( with a couple of stops) was about what I could do on the bike. Just using the hours to reach about the same state would be about a little less than 2:1 ratio. However, it all depends on the day, attitude, temperature, hills, wind, rain................

BlueJay66

My Centuries this year have averaged around 6 hours riding time. I think my fastest was 5:50. I pedal nearly constantly, even down the hills, but have you ever noticed how hard it is to keep your heart rate up while going down hill? Gravity just sort of takes over and if you think you might be really hammering at 28 or 29 mph when you look at your HR it may only be at 65% to 75%.

I suppose the lesson here is it depends on the individual, their weight, their pace, their exertion, etc. You did get me to think about my ratio though. I might be willing to drop it down to a factor of 5 or 6. (My appologies to any mathmaticians for mixing my terms.)

BlueJay66

+1 ...What he said.

eggplantOG

A 2:05 marathon is literally like an absolutely insane time like almost unheard of. That's like some Bradley Wiggins ****. Like averaging 28mph area for 100mi non draft tt mode good conditions. I'd say just to get through a marathon all run might be like around 150 mi 20mph tt mode ish. Idk watts don't have a pm. But I personally find a marathon much more intensive than a hard century. A century just takes too many hours to do readily but is much easier to get through.

bwilli88 

Comparing running and biking you need to take in body size and speed while biking, the bigger you are and the faster you go the drag potential increases exponentially while no runner can run fast enough to see a difference in energy use in regard to aerodynamic shape.

The number of miles ridden divided by the conversion factor for the speed of riding equals the number of miles running to use the same amount of energy. Here’s the conversion table:
MPH:Calories per mile:Conversion factor
10: 26: 4.2
15: 31: 3.5
20: 38: 2.9
25: 47: 2.3
30: 59: 1.9
How to use the table: For riding 20 miles at 10 miles per hour, divide 20 miles by the conversion factor of 4.2 to get 4.8 miles running. For riding at 20 miles at 20 miles per hour, divide 20 miles distance by 2.9 conversion factor to get 6.9 miles running. For riding 20 miles at 25 miles per hour, divide 20 miles by 2.3 to get 8.7 miles running. For riding 20 miles at 30 miles per hour, divide 20 miles by 1.9 to get 10.5 miles running.
from Here

chasm54

I'm really curious as to what makes a new poster resurrect a five year-old thread.

unterhausen

I think google is to blame for thread resurrections. Welcome to the forum eggplantOG, hope you'll stick around.

This was a mildly contentious thread, and there are some names we haven't seen in a while in this thread aren't around any more to defend themselves, so I'm closing it.