Whether posted times are BS or not is very dependent on the actual route and terrain, which we don’t know. Any fittish cyclist could equal my speed on the way into work – it’s a very fast route, lots of downhill and flat, only two tiny climbs, excellent visibility if it’s not foggy. Could I average 25-30mph over the same distance on the flat? No. Or through town? Unlikely. My return time back up the hill is much slower, but it’s more fun to post the silly-high one-way speed, with the return time as disclaimer 🙂
TBH, my average speed into work is more governed by risk management (aka balls) than strength. There are bits where it’s possible to be touching 50mph, but if there’s any sort of side wind or gusts, or animals near the road then that sort of speed is extremely unwise… The times I’ve done silly near-30mph averages have been perfectly dry, clear days with no sheep within ambush distance and a light, non-gusty tailwind. It’s then possible to use the speed off the steep downhills to maintain high speed on the flatter sections, but it’s all generally down hill (about 900ft drop I think). So not BS, but not exactly a normal commute.
When I used to ride TTs regularly (quite a time ago now…) I used to do 27ish munutes on my road/audax bike on the old Bristol loop from the rugby club on Cribbs Causway (before they cocked it all up with lights everywhere), so I’m not any sort of super-hero.