Members who are interested in cycling will be familiar with the way in which bicycle gearing is expressed, even nowadays, in figures that tell you what the equivalent size of wheel would be if it was the main wheel of an "ordinary" ( penny farthing ).
A big chap like the one seen on the road could probably ride a 60 something inch diameter wheel, of course you only have the one gear for up and down hills and on the flat! But on a modern derailleur racing bike, a 60" gear is quite a lowish / medium gear, a fit rider would go up a modest incline in 60", so to get up towards 20 mph with that gear on an ordinary one's legs would be whirling. A racing cyclist on a modern bike would usually be using 85" to 100" for riding at a similar decent speed, a sprinter in the Tour de France might be shoving 120" for all he ( maybe she! ) was worth, and doing over 40 mph .. Dave
