can I run a 2:37 off mostly biking?

I think you probably want to run 45-50 miles per week in your buildup, with possibly a 12-15 mile long run once every week or two. Then it is possible for sure.

You clearly have the ability to run 2:37 based on your half and 10k. The biggest issue will be preparing your body to maintain pace after 20 miles. I'd keep your basic training structure with a tempo day and "long run" day, but modify the long run progression to prepare your body for running fast past 20 miles. Alternate weeks with a medium long run 14-16 miles one week then the next week a longer run with a fast finish in the last 1/4 or 1/3 of the run. Build this over the three months from 18 up to 24 miles. Plan a peak distance long run 3 weeks before the race.

Just addressing the title. You need a considerable amount of impact type exercise to be good at the Marathon.

That being said I do know a guy who ran 20-30 miles per week that ran under 2:30 but he was a 13:40 guy.

I think you could run a 2:37 800 with ease

I did it on 35 MPW. You are putting in more equivalent training than that.

It’s not that easy to transition from cycling to running. But assuming you can handle the mileage/distance, you might succeed.

About 6 months after running a 2:45, I had an injury where I couldn't run, but could use a stationary bike (this was before pool running was popular enough for me to know about it). I wanted to run a certain marathon so I did all my training on that for a couple months except for a few runs right before the race. My training volume and quality dropped off some (it was boring!) I managed 2:51. I had weird soreness on the outside of my quads after the race, but otherwise it was unremarkable. Since you know what you are doing on a bike, I bet you could get closer to your running best than I did.

No, you cannot. Running a half and full marathon are worlds apart. You can “fake” a solid half with that 10k PR, but will get chewed up and spit out by the marathon if you haven’t trained properly for it. Save yourself the agony and do a proper buildup. There are no shortcuts to 2:37.

For sure. I did it last year. Max running volume was 40mi/wk.

I did 2hr long runs every week at moderate pace (avg ~7min/mile) for about 2 months leading into the race with some faster stuff built into the long run (goal is to teach the body to be able to recover at marathon pace, so I would do 1min @5k pace to get HR up, 3min @marathon pace x4-5 starting at 90mins into the run). Mid-week workout was either hills or fartlek. Strides on Fridays (similar pace strategy as the workout during long run—20sec @5k pace, 40sec @marathon pace x6-8 with no stopping). Wanted to teach my body to be able to run hard on tired legs which is tough to do on low volume so i would do a zwift race the night before the mid-week workouts. 2-3 days completely off from running every week. About 6hrs on the bike each week, mostly z2 aside from the aforementioned races on the night before run workouts.

Legs felt great the entire build. Ended up crushing some souls on race day. But legs were pretty effed for the last 5-6mi because they weren’t used to the volume, still ran even splits from first half to second half.

The key is not getting out too fast on race day because if you don’t have the training volume your legs aren’t going to be able to take that kind of beating.

Keep this thing updated so I can track your progress yo.

I ran 2:29 a few years ago on 25 MPW. I did 3 runs during the week of 5 miles and a 10 miler on Sunday. I did two 13 mile runs leading up to the race and had a goal of 2:35 but felt so goo after getting out too fast that I just kept going at that pace.

No.

I know a triathlete that was able to do something similar to what you're attempting. The vast majority of his training is bike/swim focused because he's very injury prone.

His first attempt at the marathon off of roughly 30 mpw with a lot of bike and some swim training was a miserable failure. He completely blew up at 18 miles.

During the next marathon attempt he supplemented tri training and running (still roughly 30 mpw) with a TON of lower impact time on his feet (a lot of hiking hills, walking, working from a standing desk, basically anything to get time on his feet). It apparently worked as he was able to run a 2:34.

I think you can do it, but I suspect you'd benefit from trading one day of cycling for another day of running 10+ miles for the last 8-10 weeks of your build (so like 40mi/wk+12 hrs cycling instead of 30 + 15). FWIW, I had similar/equivalentish college PRs to you (1:55/3:59 800/1500; 25:40 XC 8k) and did a fair amount of cycling and not very much running in my 20s/early 30s (though not nearly at your level -- like cat 4/5 racing). I ended up running a 2:33 marathon at age 40 on 45mi/wk + another 2-4 hrs cycling. I'd previously run a 1:14 half/2:48 full off of about 25-30mi/wk + the same amount of cycling and I think those extra 15-20mi/wk running were huge for making the jump.

I think you will have to put in at least some 20 miler long runs.

I think you can get there with your background OP. I would train more like a triathlete than full blown cyclist if you want to race the marathon closer to potential. Instead of 15-25mpw, bump to 30-40 (or closer to 45-50) if you can. The demands for the marathon are different. If you're doing a ton of biking then 30 miles/week of running is worth a lot more. It's the back end of the race where the volume might make a difference. You already ran times that predict faster than 2:37 on limited mileage.

just posting an update here, marathon is next sunday.

i've averaged 30mpw for the last 20 weeks, but at various points i had to basically take a full week off running for injuries so it has been more like 4 weeks @ 40//1 week off. have sustained a steady diet of 300-450mpw cycling throughout.

key workouts within the last 3 weeks:

- 21 miler avg 7:00 with the last 8 miles at 5:50

- 16 miler avg 5:55 pace, HR maxed at 160

- 10 mile tempo run after a 4h bike ride avg 5:42

- progressive half marathon starting at 6:00 and finishing hard with an average pace of 5:45

- 3x3 mile (3:00 rest) avg 5:23 pace for the repeats

because i was so injury-prone, my training over the last month has been basically 3-4 runs per week of only quality: ~8/10/14 miles tempo. i kept getting injured doing slow junk runs so i cut out all the fat, dropped my mileage and had basically everything i ran be at marathon pace or faster with 1-2 days off in between workouts. gonna shoot for 2:37 and see what happens. lets get weird.

feel free to follow my attempt on strava

Check out JJ on Strava

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Strava Cyclist Profile | John Jantz

John Jantz is a cyclist from Arlington, Massachusetts. Join Strava to track your activities, analyze your performance, and follow friends. Strava members can plan routes, participate in motivating challenges, and join clubs....

Link:www.strava.com/athletes/9293005

Lance Armstrong tried that at the NYC marathon in 2005 and ran a 2:46. He even came from a triathlon background so had done some running earlier.

Interesting experiment if nothing else, and looking forward to seeing how this goes!

Good luck for the race!

marathon was today: 2:35:34. paced it well, but i knew the last 10k would be a struggle with my lack of mileage. cardio was fine but my legs started dying at mile 22 but limited my "death" to running like 6:05's. let me tell you friends, it took absolutely every ounce of my focus to fight the lockup and keep moving even at that pace - literally cracked at the finish line. am beyond smashed now. thanks for following along <3