Depending on how much you and your training favors the shorter stuff, I think your goal of 1:20 is selling yourself short. I could currently run about a 15:50 5k or a 33:40 10k, but would expect to run at least 1:14 or so in an open half. Given, I very specifically train for 13.1 off the bike, but still.

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Benjamin Deal - Professional - Instagram - TriRig - Lodi Cyclery
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What kind of mileage were you at for your 5k and 10k PRs? Specifically the length of your long run and any longer workouts you have under your belt such as long tempo runs

Times alone it could line up but its hard to say for sure

Thanks for taking the time to reply.

Oh wow okay, that's interesting.
I mean I always do 1 workout of intervals a week 8x1km or something, and 1 Long slow run up to about 28km. Recently during these long runs I've been doing 2x5km at 3:45/km- so I felt I was probably ready to do a half marathon.

I guess I'll head out at 3:45/km and try and keep it there as long as possible!

Probably in the region of about 4.5-5hours or 60-70kms per week. Which I'm sure isn't much for a lot of people, but adding in about 10 hours on the bike too, which I'm sure has some cross over benefit.

The long runs have been over 21km for a few months now

one staple workout I have done for solo half marathons is 3x2 mile at 13.1 race pace +5-10 seconds/mile with 2 minutes easy rest. Seems similar as your 2x5km workout in terms of overall affect.

Id say start the first bit slightly slower than that (maybe 3:50/km) and then after a little bit see how you feel and then pick it up

Based on the info provided, and Depending on the course and weather, I would shot for 1:17.

I agree with you. I ran 16:305k two weeks before a 1:16 open half. Just need to be strong late

Great, well this has definitely given me the confidence to just go for it.

Any nutrition tips people can share? 1 gel at about 12km is what I had planned.

Did you run in school? And what's your average weekly run volume for you?

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@floathammerholdon | @partners_in_tri

I am fairly fat adapted and it was 45* when I did mine so I had some water and a pack of fruit snacks that I stole from the kids haha. Dad nutrition for the win. I didn't run in high school or college but I have been consistent for 8 years now. I average 25-30 miles a week.

https://www.mcmillanrunning.com/

The free running calculator is very useful. Probably best i've found...

Your 5k projects to a 1:16:24
Your 10k projects to a 1:17:39

Seems that you should be able to comfortably break 1:20; taking it out at 1:18 pace is probably a safe bet

Based on your 10k, Daniels projects a 1:16:51.

Ok cheers, that's an interesting calculator!

Hopefully conditions will be good. It's a pretty flat course, so should be conducive to a big PB

Wow so I'm looking at my past few months and I have maybe 4-5 weeks that crest 30mi and likely average somewhere around 23. I've had periods where I'm probably averaging 30 with 40 mile weeks in there but that hasn't been the focus. Still this was lower than I would have thought.

And yeah I was a decent high school runner considering my injuries (~15:50 XC) and then ran for 3 semesters in college before stopping. Anytime I would hit 70mi a week my body would start to feel like shiiet.

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Benjamin Deal - Professional - Instagram - TriRig - Lodi Cyclery
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We have very similar 5k/10k PRs.

10k PR - 34:34
5k PR - 16:42 (was actually the first 5k of my 10k PR...went out a little hot)

My open half PR is 1:15:29 on a course w/ rolling hills but absolutely perfect weather and perfect race execution. The day I ran that time was the best race day I've probably had in any race in any discipline. I ran with a small group of 5-6 for pretty much the entire race and spent precisely zero time in the wind. Conditions were perfect - low 40s and no wind. As long as you have a good day/cooperating weather you should absolutely hit sub 1:20.

you could say that again

Haha it was a local race and I got a little too caught up in staying with the leaders who went out real fast. ~4k in they both completely exploded and I found myself with like a 40 second lead but already deep in the hurt locker. Those 6k were probably the most painful I've ever had...held on to win by 5s though!

Wow, well done- great when everything falls into place like that!

Unfortunately its a covid secure race, so everyone is going off at 15sec intervals- maybe I'll be able to find a few ppl to draft.

that could be a lot of fun - chasing people the whole way.

.....and yes, if you can do mid 16s and sub 35 you can go way under 1:20. Depends if you want to see how fast you can go or play it a little safe and make sure of the sub 1:20. i think i would be a little conservative and target 30:00 at 5, knowing that will lead me to doing 29 high.....all while staying comfortable. Then just take it from there. Get yourself a 1:18 something, then go for 1:16/1:17 range next time.

Turning this around to ask you what 5/10k times would "translate" into a sub 1h14 open half?

Thanks

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At 6' 1" and 200 lbs my half marathon PR right now is 1:19 a couple summers ago at age 38. (perfect execution with 40 min out and 39 on the return!)

I've done 5-6 since then and keep trying to break PR but keep getting around 1:21- 1:24. I keep going out too fast thinking I can hang on to the end.

In this last one went out too fast managed 5k adult PR of 17:00 and 10k lifetime PR of 37:00 within the race. Followed but 8 min positive split on the return LOL is right... 1:25 I think.

a) I think I can hit low 16min in 5k with proper focus (did a 16:20 back in HS on hilly course)
b) and maybe a 36 in a 10k

We all have out strengths and weakness, I think I have decent longer speed but lack in the outright leg speed for shorter stuff.
This is all on 20-30 mpw and smoking weed every day...

A 200 lbs pothead who can go sub-1:20? You defy physics.

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@floathammerholdon | @partners_in_tri

There are dozens of predictive race time models out there. The one that is most reliable for me is the Jeff Galloway Magic Mile model. It hits the 1-mile, 5K, 10K, 15K, Half Marathon PR's all with in 1-3 seconds of my actual race time. Everyone is different though so the numbers from that model don't work very well for your 5K to 10K results. I ran the numbers from your 5K and it says that you should be running your 10K 50 seconds faster that you are. It says that you should be able to run your half marathons at a 1:15. So....It appears you are what one of these predictive models call a speedster. That is someone who is more competitive at shorter distances. I am what that model calls a combo running being someone who is as competitive at an 800m run as I am at a full marathon and everything in between. There also are people that are more competitive at long races (i.e. 100 milers) than they are short races which is why there are dozens of predictive race time models out their and why some fit some type of runners well but not others. So...with your 10K being 50 seconds slower than the Galloway model I would put you at about 2 minutes over the half marathon time for about a 1:17 predicted time.

My worst half however is a 1:26 and my PR is a 1:23. There is no way I could ever get to a sub 1:20, but I am only a 17:45 5K type guy.

Thanks! That's really interesting. I had never thought of myself as a 'speedster', I definitely have a diesel engine on the bike- I have a very good hour power, but my 5 sec, 1 minute and 5 minute power is quite poor comparatively.

It'll be interesting to see what happens this weekend! I think I'll go out more conservatively than 1:17 pace- probably between 1:18-1:19 and then pick it up if I feel good at 15km