How fast can I run a 5k?

Idk, run one and find out

18:59?

assuming this is just a small local race, your goal should be to beat all the women. sub 20 should do it.

When cyclists list a w/kg number, they are usually referring to their FTP or 1 hr power.

A FTP of 5 w/kg is a US national team level pro. Most of the high level crit riders that have those type of numbers only weigh 60-65 kg.

5w/kg at 83kg and a raw power of 415 watt average over an hour is not believable for someone who rides 3 hrs a week. That is Fabian Cancellara, Miguel Induran type numbers.

I ran faster than you in HS, biked somewhat seriously in my 20s and 30s, weigh less, and have a off the couch FTP of around 3.5 and trained in the 4.2-4.5 range depending on test method when riding 10 hrs a week.

In any case, sub 18 maybe low 17 should be doable in 4-6 weeks off of 20 miles a week.

After that, there's no reason you can't approach your hs times if you get down to HS weight and put in the miles.

I was (recently) able to sustain 420 watts for 30 minutes. Im 6 ft 4 and range from 180 to 185lbs. Not sure exactly where that puts my ftp at or what my watt/kg would be but I think its close to 5.0.

Im planning on converting my normal rides to runs as much as my body can tolerate without injury. Maybe 3 runs for a couple of weeks and then 4 up to the race, cross train on the bike on the days off. Im thinking about sub 18 but am curious to see if improvements come quick due to the cycling fitness.

That's some serious power. W/kg would be ~5.0 if you could hold that for an hour. Most would say to multiply the power by .95. That would give you something like 4.75. Still really good. The watts would put you in the top .5%. The w/kg more like 90th percentile. That's pretty wild on 3 hours/week, unless you have years of cycling experience. Could be possible that the stationary bike's power meter isn't 100% accurate. This reads as you not riding a real bike on a trainer with power pedals and/or calibrated smart trainer.

End of the month 5k just go out and have fun. Don't be tempted to go too hard in training. If you want to get back into running look past the race at the end of the month. Check the race off with something under 20:00 & then keep training. Could probably run something reasonably quick within a year or two. My vote is to get on a real bike & see what you can do there with some more training. Maybe a duathlon or triathlon would be a fun challenge for you.

No idea. Just go and run one.

Maybe aim for 20 minutes but kick the last mile if you’re feeling good. Sounds like you’ll improve quickly. You’re still young.

What's the difference? If you just started running training for a race in 26 days, you're not serious about it anyway. If you really ran 4:30 12 years ago, you should have a better idea what you can do right now than anyone else would.

If someone on here told you sub-18, would that give you some kind of special motivation that you otherwise couldn't access? If you were a 9:45 guy, you could do 15:45r at your best. It will take a year of running training, at the level you reached in HS, to just approach your potential.

As others have said, run this one at the end of April and you will have a baseline. Once you are fit enough for intervals, you will be able to estimate your current ability more easily, without running an actual race, or coming on here and asking HFCIR like a middle schooler.

red flag, describe this bike. Most people with a bike on a trainer would say that, soooo peloton? which gen would say a lot about possible accuracy. Non-peloton stationary bike wattage number is random enough to be useless.

Delusional

Given that information it is certain you can run 17:48.9.