Interesting topic. I can't match the Herculean exploits of some posters but the theme seems to be that most have got something life enhancing out of their rides. The most I have managed in a day was waaay back at Easter 1981 when I did an Audax event as part of an Easter tour of Wales and the borders using YHAs. It was grandly titled "Across the Desert of Wales", the premise being that the route of the Audax was very sparsely populated. The distance was nominally 200km/125 miles and the hills, the hills, my God, the hills. There were an awful lot of them. The base was Staunton on Wye YHA, sadly long closed like many others particularly the simple ones. I was a YHA Youth Group leader then though on this occasion I was on my own. I remember it being a blisteringly hot weekend, not raining as I would have expected in Wales.
The route was Staunton-Kington-Rhayader-Abergwesyn-Beulah-Builth Wells-Glascwm-Michaelchurch on Arrow -Staunton. However by the time I had reached Builth Wells I had decided to take the longer but less hilly route via Glasbury and Hay on Wye as my legs were giving me some concern and I couldn't face any more major climbs. I had impressed myself by out twiddling some serious looking racing types earlier purely because they didn't have the gearing to climb some of the pitches on the mountain roads and were walking, but most of them had sailed past me once the roads became less extreme. By the time I got to Staunton my cyclometer was reading 145 miles and lying in bed that night I could still feel the road vibrating beneath me. My heart rate remained high until I fell asleep, completely wrung out.
The next day I could barely move but motivated myself to cycle stiffly to Hereford to do the touristy things -about 20 miles round trip. I had booked to stay the night at Staunton before continuing with my Easter tour on the following day.
Although I did another Audax at a later date, they were not really my thing. I did some 100 mile days, some of them back to back and felt fine after them while doing tours and YHA weekends over the years. It's a while since I've done 70 miles in a day, more usually 20-40 but I have been stretching the distance more this year with lockdown etc.
