Predict my London Marathon time please

Off the 1/2 maybe a 2:48 ?

2:01:08 - No human is limited.

I'd say sub 2:50 is realistic based on the 1/2. You haven't done a lot of mileage but those long runs are pretty good. It might feel a bit different doing a long run outside though so keep that in mind

Man these treadmill only training sessions are tough. It really depends on how well calibrated your treadmill is. I have send way too many stories of monster treadmill work that simply didn’t translate to the real work. That said, based on that half and the volume/long runs you have been putting in maybe 2:55? It’s hard to say given the lack of marathon specific workouts embedded in the long runs.

Should be able to go 2:50-2:55 off of the half. Would be more ambitious (sub-2:50) but the treadmill training & mileage have me a little more cautious.

What's your history with the half & full? Is the 1:18:45 a PB for you or did you run faster than that before the 2:58? Something feels a touch off. The 1:18 suggests that you're ready to take a good amount of time off of the 2:58. What were the splits in that race like?

Yeah, so I agree… I don’t trust the 1:18 because it was on a tread so not sure how indicative it is of a ‘real’ 1/2 marathon on the roads. But I suspect it’s probably more like a 1:22, and that’s the kind of shape I feel like. So I’m basically going to target a 2:54 (which if I can pull off would be a nice 4 minute PB), and if I’m feeling good at 30k I’ll try to run a negative split. I’d be thrilled with a sub 2:50 but if I commit myself to that, I risk blowing up and running a 3:05, which would just piss me off.

That sounds perfect. When I went sub-3 for the first time my half was 1:20-mid. I ran 2:53 after being on sub-2:50 for for most of it (I ended up running 2:47 in my next marathon without improving my half). I think you can run closer to 2:50 but you have the right mindset. Ease into it. Hold 2:54 pace through 30k. Still gives you a shot at low-2:50s if you can pick it up whereas starting too fast might put you back around your PB.

Out of curiosity, what would you consider to be marathon-specific training embedded in the long runs.

I neglected to mention that the reason I didn't do anything fast in my long runs was that I had a strain (or maybe a micro tear) in my quad in the middle of one of my "fast tempo" runs (which happily coincided with an 'off week' where I didn't have to do a long run. I found that I was able to train through the injury but only at a slow pace of like 5:00/km... so hence why in the long runs, I didn't run faster than 5:00/km, but instead did the up-hill 1k repeats at 6% incline.

I had actually started doing those because I was signed up for both Boston and London and undecided which to do, and wanted to be prepared for the hills in Boston. Boston has a 150m elevation gain at heartbreak hill, so I figured if I could do 700m of elevation gain over the course of a 35k run, then I'd be prepared.

But in the end I decided to skip Boston, and miraculously my quad is at 100% now and I was able to crank out that 1:18:45 (3:45/km) so I feel I'm ready to go.

I will say that I found running 12 x 1k @ 5:00/km @ 6% incline was much harder (more depleting) than running 12 x 1k @ 3:45/km @ 0% incline... especially embedded in a 45k run. That's why I feel optimistic I won't bonk at 35k like I've done in every other marathon.