I tried crazies once this year , got dropped , i was doing 350W ++ and got dropped from the front , i think the front is doing 400-500 w.
in general , all the faster group has huge group size, here is a sample, from one of my rides last week with a "fast" group. 36 kph average for 1 hour , really good workout.
Jezuz....these guys really so fast.
But of coz to be very fair, Ben is like specializing/training in full Ironman distance, maciam like 2X that of a full marathon. A parkrun or even 10k kinda effort with repeated surges with national level people in it would be somewhat out of place.
I running shorter / middle distance i find still ok for one reason or another..... But i think ~ 400 watts and beyond sustained for like over 5km solo (WCH or TMCR straight 1 way)....maybe, just maybe attainable on a very good day with all the aero "hacks" i chut . But more sustained like 15 to even 30-40 mins, i think just forget it, impossible in my lifetime even if i retire now and train full time.

I "heard" the really strong guys do 45-48kmh (at the front of pack) and with none of my aero "hacks" employed, just body positioning nia....but of coz a great determinant is mainly the presence of any tailwind/crosswind via the rear.
Note, i no power meter, srsly. I only base it on 42kmh. + hopefully little to no wind.
Like recently past 10 days the SE wind quite shiok, riding on WCH towards Clementi super shiok but clementi to city sucks.
