Update.
It did hurt, but some interesting stats.
Slowest, going over a flyover bridge @ 12 mph, cadence 43 rpm
Maxed out at 30.2 mph, cadence about 108 rpm
Average for the 10 miles just a bit slower than 21mph or 76 rpm
Did some long stretches on the return at 26mph or 94rpm, which was reasonably comfortable. Slightly down hill, with side wind.
Don't have a cadence reader, but as fixed all the time, have used one of the online calculators.
Overall time still a bit slower than my age standard @ 28:36
But this gear (95") definitely not an everyday gear.
Cheers Keith