PeteHski

No, this doesn't make sense. What does make sense is running shorter distances at first and then slowly building up to running a full marathon. That's what pretty much everyone actually does. I do the same with cycling. Most of my key events are Centuries, but I rarely ride full Centuries in training. Most of my training rides are well under half that distance.

Jughed

Never tried "running", not built to be a runner... Can't comment on the differences.

What I can comment on - I know a few runners that came over to the cycling world & the main issue they had was with food/feeding themselves. 3 hour events are different than 5-6 hour events... I see the same cracks with people jumping from a metric to their first century - mile 70-80 seems to be the point of bonking.

Your reserves get depleted, and you need the ability to keep up with fueling for the next 45 min of work. For many of us, it takes some training to be able to do that.

LarrySellerz

is walking 26 miles in 9 hours even a marathon? I feel like I could do that

tomato coupe

So many jokes, so little time ...

seypat

A marathon doesn't really get any easier the slower you go. No load on your cardiovascular system. It's all on the muscles at that pace. It's probably the easiest somewhere between your PR pace and 30 seconds slower. Once your pace gets around a mimute + slower, it starts dragging and is awful. The real hardcore people are the ones at the back walking trying to stay ahead of the sweepers. They have to push pace the whole way. The contenders at the front just have more talent, which enables them to train harder, longer, etc. Otherwise, the contenders get the best of everything at the event. The best weather, best of the SAGs, crowds, etc. The 3 main things you have to learn to have a successful marathon are: Pacing, fuel and hydration. You don't get those right and it will be a bad, long day.
In the fall of 2020, Richmond VA still ran an altered version of their marathon. We had this big, O-line looking guy that signed up for one of the full training teams. He told me he'd lost around 100lbs before the start of the training schedule in June. He still weighed 300+ lbs. That guy showed up and ran every long run on the weekends and did his regular runs during the week. The total training miles not including the actual marathon on that team is 596 miles. He'd leave 30-60 minutes before the rest of the teams and finish about 30 minutes behind. On race day, the temps started in the mid 50's and ended in the mid-high 80's. Some of the later SAGs ran out of water. The dude finished in 6:37 something. The crowds were gone when he crossed the line. His family was there. A lot of the team went back out and walked/ran the last couple of miles in with him. The drive that guy had to finish was inspirational. What he did that day was way more impressive than whoever had the fastest time!

The Richmond Marathon Training Teams have a walking team. All of the coaches are former running team coaches. They'll tell you that walking it is way, way harder. Hats off to all of the military people who had to endure those long marches.

rsbob 

Somewhere, sometime I heard the 70% rule or is it the 80% rule? Train up to say 80% of the distance and you can expect to do the other 20% without much difficulty. Probably an old wives tale, but it served me fine when training for centuries.

wheelreason

Yeah, that works, you can even go 50-60% if you add some short duration HIIT, and roll tempo on the long ride.

BobsPoprad

I think the easy way is to look at the iron man distances. The swimming/cycling/running/ were measured out that way for a reason. Well, probably not.

PeteHski

I find metric centuries are plenty long enough in training. I usually do one full century event per month anyway during the season. The idea of only doing full event distance century rides/marathons is nonsense to me.

ZHVelo

With power data you can get pretty accurate energy consumption for cycling. 29-32km/h (18-20mph) on a flat will require more than 480 calories unless you are Dan Bigham aero. Reasoning - it felt low so I found the first ride I could of mine that is on a flat. 33 minutes 29.7km/h 305kJ which is more less 1:1 to calories. That's 554 scaled to one hour. And the speed is in the lower third of your range. To get to 31km/h or even 32km/h one would need to spend disproportionately more energy to overcome draft so that would be around 600 calories per hour. To check that I actually looked for a ride where I had that speed and found it, 32.2km/h in 29:59 was 307kJ so yes, 32.2km/h for an hour would be 614 calories in this instance.

Taking your upper calorie per hour estimate for running, 900, then that means at a speed of around 32km/h a 4 hour marathon would be a 6 hour ride.

However, that is just energy. I dare say a 4 hour run is harder on the body than a 6 hour ride, if the ride is flat. I have done 5+ hour rides with climbs and I dare say they are pretty tough, but on a flat? Don't think that feels right to compare.

john m flores 

There's a fundamental difference between running and walking in terms of muscle groups engaged. I ran a hilly 50k some years ago and I made one mistake in training. My plan all along had been to power walk some of the uphills, but I had not done much walking during my training. So during the event, when I tried power walking, I found my walking muscles to be lacking and fatiguing quickly. So, quite ironically, I had to run up the hills because I could not walk them.

If the goal is to run a marathon, training by walking won't work all that well.

seypat

Quoted for truth.

PeteHski

I just looked at my last century ride. Averaging 32.7 kph I used 3,420 calories over 4 hrs 53 mins. So that’s exactly 700 calories per hour.

base2 

I was pulling the ~8 calories per minute from memory. I think you are right. It felt low-ish when I typed it. That's probably a more appropriate estimation for 12-14mph. About 10 to 12 (or more) calories per minute for higher 18-20mph efforts is a better estimation. Depending on efficiency, aero, RR, etc...of course.

ofajen

Here’s a link to a blog on calculating running power and relating that to expected race time:

https://blog.stryd.com/2020/01/10/ho...-target-power/


About one-third of the way down is an equation that estimates race time based on distance and target power during the race, expressed in SI units.

From this, I derived 27.9 as the product of a runner’s pace in minutes per mile and target power ratio in Watts/kg. Similarly 17.3 would be the product of a runner’s pace in minutes per km and Watts/kg.

Otto

RChung

Very nice. Those are close to my rule-of-thumb that running pace in m/s is about equal to watts/kg. My "equivalent" ratios would be 26.8 and 16.7, i.e., about 4% different. I would say that 4% difference in rules of thumb ain't bad.

Fredo76

Running = cycling + 2/3 running distance in feet X a baseball bat hitting the bottom of your shoes.

WaveyGravey

I am a runner as well as a cyclist. The most I have run is a half marathon. Have also cycled a century. I believe running the half marathon is far more difficult.

The Chemist

I've ridden 350km in a day, but the most I've ever run is about 11km. It took me much longer to recover from my longest run than it did to recover from my longest bike ride. I don't think I'm cut out to run marathons.

ofajen

Good to know. This will help me develop more intuition about running speed in m/s. I have a rough sense for where I am in W/kg at various perceived efforts.

Otto

kcjc

42

terrymorse 

That ratio sounds way off.

At a fairly easy jog, one can run a mile in 8 minutes. Do you think you can pedal a bike 8 miles in 8 minutes? Because you can't.

ofajen

Yeah we established that in terms of power requirements it will depend on speed because wind drag becomes so dominant at higher cycling speeds. The ratio is roughly 2.6 to 1 when cycling 26 mph on a road bike versus running 10 mph, which require similar W/m. It could reach 4 to 1 when cycling 20 mph versus running 5 mph, which are each roughly half the W/kg.

Of course, there is a threshold question of whether someone who can cycle can actually run for any relevant period of time. Also a question of the effect of the impact trauma from running which affects how long a person can run and how quickly they can recover compared to a presumably less traumatic cycling effort.

As an aside, the fraction of people who regard running a mile in 8 minutes as an easy jog (like a zone 2 effort) is fairly small. That is about 3.5 W/kg.

Otto

LarrySellerz

for me cycling 8 miles is easier on the body than running a mile, if both are done at a “mild to moderate pace.” For me running that’s probably like a 10-12.5 minute mile, I probably couldn’t even run an 8 minute mile right now, used to be able to break 6

rsbob 

If it is a sanctioned event, you will not make the time cutoff by a mile or 5.