2:45 marathon target with 1:17 half?

It's a tough one to answer without more information.

As a stand alone time, a 1:17 says you're certainly capable of running sub-2:45.

However, the marathon is a very different beast from the half. It's far less predictable (a lot more can go wrong), and higher mileage is going to be far more critical. Some people are just better suited to the half than the full.

Also, I think it's a mistake to readjust your goals 6 weeks out from a marathon. Everyone gets faster in their marathon block - that's why you do it.

I'd stick with the sub-2:50 goal, go out at 4:00/km (6:25/mile), and then see what you can do after 30k. You may crank it down to a 2:46 off that pace - and are you really going to be disappointed if you run 2:46-low, as opposed to 2:44-high? I'd say not, especially if there's a real possibility of going out at 2:44 pace, only to blow up and run 3:01.

I think you definitely have the talent to break 2:45. Whether or not you do so this block will depend on your training. As folks have said - and it can't be said enough - the marathon is a completely different beast from the half. Part of me thinks you'll be more pleased with your race if you shoot for an 8-min PR and run 2:50, as opposed to going after 2:45 and blowing up.

You've already done 13 miles at half marathon pace this cycle. As your last or second to last long run before the taper, think about a 20-mile long run with the last 14 at marathon pace. Do yourself a favor and run it in trainers, not super shoes. See how it feels at 6:25 per mile. If you nail it, maybe 2:45 is in the cards.

I want to make sure I have this clear -- you like to run a 24 mile run at your goal marathon pace in training, 6 weeks before the race? It would seem that you are basically just running a marathon before your marathon to check if you can maintain your pace in the upcoming marathon.

I interpreted it more as if your goal for the marathon is 2:45 (6:18/mile), you run 24 miles in 2:45 (6:53/mile) 6 weeks out

My bad, I misread his comment -- makes sense now.

We have similar PRs (though like everyone I firmly believe I underachieved at the 5 and 10K distances). No reason you shouldn't target lower 2:40s. Go out at 1:22 and bring it home.

Also known as a time trial.

Back in my early/mid 20s, I could regularly run about 1:17 (PR 1:16 flat), but I never made it happen properly in the Marathon (2:49). My best effort came during a season where I was probably running 70-80 miles per week for about 4 1/2 to 5 months, with weekly intervals and tempos, and lots of 18-20 mile long runs but way too fast. We would probably do them at 6:10 pace with the last few miles under 6, this was pre-GPS so the only way to know was to use whatever mile markers there were in the forest. A week before the M, I did my PR for 5KM on the track 16:08, then went out in 6 flat pace and maintained it until 20, then crashed and burned, running 2:49. That was a very painful way to run 2:49. People have mentioned the importance of fuelling and I can't agree more. this was all back in the 90s, when gels were just starting to become edible. That M probably had Gatorade and water, with maybe some Powerbars and I hadn't really started to experiment much with stuff. We never brought fuel with on long runs. After that 'thon, I never trained properly again. Good luck OP, pacing and fuelling are key.

Many do this then wonder why they’re flat on race day. It’s about having the confidence and patience to “Save it for the race.’”

That's a good point. I'd already be super happy with anything under 2:50. I'm still young and will run more marathons in the future so I'm confident I'll run under 2:45 soon.

Depending on the weather and course very doable. We always used the formula, double your half time and add ten minutes to get a prediction of a marathon finish time. Go out easy thinking to run 30 seconds per mile slower than goal pace for the first couple of miles….In actuality if you think slower by 30 seconds, you will hit your goal pace for the first couple of miles instead of getting hyped up and go out too fast by 30 seconds under goal pace. Take what the course gives you but plan on feeling goo by 18 miles so you can cruise those last miles and negative split.

2:45 is spot on. A good estimate if you put in the mileage is add 5 minutes to your half and double it, that is almost exactly 2:45 for you

I think the differing feedback you are getting from people is not surprising, since people have different aptitudes re: shorter vs longer distance races. I did 1:17:48 as a solid but not all out half while in training for a full, and only did a 2:48:34. But that marathon was unfortunately NYC which, unless one starts in the elite group, is a poor choice. What I think goes in your favor is that, compared to me, you are more gifted at longer distances (I ran a 15:51 5k the same year I only did 2:48). For one who is more talented at longer distances, as you are, I would think good tapering, good choice of marathon, good nutrition and hydration, and good pacing all give you a solid shot at 2:45. If you can slightly negatively split from each 10k to the next and really put it all out there going fast in the last 10k (when so many are falling apart), I think you may be able to do it!

I mean this is how you crash and burn if you haven't put in the right kind of marathon training but use a race equivalency calculators to determine your marathon pace.

100% doable in my opinion, but I very much agree with the poster who suggested going out in 4 min/k and seeing what you can do after 30k.
I had an identical goal last year at Boston (2:45) with slightly slower prs than you in shorter distances (actually I hadn’t ever broken 1:20 in a half, though I reckon at the time it wouldn’t have been a problem).
I went out in 1:21 high and ended up on pace until about 30k then slowed quite a bit (didn’t bonk, legs just didn’t have any pop) and ran 2:49 low. I reckon I could have ran 2:45 with proper pacing. Frankly I only didn’t bonk because I’m quite used to 3+ hour races on the bike.
Point being, based strictly off the 1:17, of course you can run 2:45. That said, would you be happy running 2:50? What about 3:10?
I think going out at 4 min ks (6:26 if you use miles) is the most sensible, as it would take you out on pace to run 2:48:47 and it would mitigate the possibility of hitting a wall and struggling to break 3.
I vote with the poster who said go through 30k at 2 hours even (4 min/k) then if you feel good start to ramp it up and actually “race”. A fast last 10k will put you close to 2:45 and if you just hold steady you’ll break 2:50.
Just my two cents as someone who was in a similar situation (though again, slower prs but perhaps more accustomed to racing longer distances). Best of luck!

Based on your training and past races, I'd say 2:45 is realistic on a good course, good weather, and proper pacing. I would recommend you do at least one 20+ mile training run at or near race pace to make sure it's comfortable.

My one tip is trying to pick it up is ok in the last mile or 2 try to do it further out and its asking for trouble. I found even on halves that I/ would feel great at 8 or 9 miles pick it up then blow up still with a couple of miles to go. The marathon will accentuate that. I would aim for sub 2:50 and keep the pace steady all the way. Not all runners are the same at each distance I would have struggled to convert my half time to a marathon. Those tables assume equal ability at all the distance you may be better at the marathon or worse. Go for a nice pb then you have a great target for next time

Update: Ran the London Marathon today in just under 2:42. Was quite surprised to be honest. Ran the first half in 1:21, which was a lot faster than expected but it felt very relaxed. It was a great race