How's 108kmh (67.5mph)?? Drafting a flat bed truck, but for the ~3-4k's I was drafting I didn't go under 80kmh. I promptly collapsed when I got home and didn't (couldn't) do anything for hours. I was about the same age when I did this (I'm now almost 33 and nowhere near as fit). It was mostly flat, but there were a few short, easyish hills on this section, I assume the 108 was done coming down the other side of one of them. The truck driver was watching me in his mirrors and dodging potholes (and cutting off other cars) to give me a good run
Some time before that my bro reckons I was pulling away (with 2 other riders in tow) when he was doing an indicated 110kmh in his car (didn't have a cycle computer then), but I'm sure there was a fair bit of speedo error. This was on a big downhill. I never believed him until I did that 108 drafting the truck and saw it on my cycle computer with my own eyes
I used to regularly do 85-90kmh coming down Mt Cootha in Brisbane. It wasn't terribly steep, but it was long enough to get the legs really pumping
52.4 on a screaming down the wall at Altoona this past summer. 1st time pulling 50+ in a pack. Funny thing was, it felt like no big deal as I was with nine strong riders. 50+ solo causes a lot of shaking and uncertainty. Under race conditions, you barely notice it as you're just trying to hold your position. This was in the Cat 4 race. Rumor has it that the pros were pulling 60+ on the same hill. Yikes!
76 km/h, which I think is around 47 in your speak.
That of course was down hill. Fastest on the flat was 51 km/h, but I had a good lead out to get me up there, and I managed to keep the rate up for around 20 seconds, and I suspect a bit of a tail wind.
I suppose to make any speed claims on the flat, it really should be on your own, and followed by an attempt in the opposite direction and then take an average of the two. I wonder if I could beat 45 km/h in those conditions...
I feel an experiment comming on....