(09-11-2009, 04:08 PM)NickJ Wrote: There has been much discussion on this subject over the years. Nobody can convince me that the course is the same length as it was when first used in its present form in 1920. As I see it there are four different ways of measuring the course.
a) Round the outside of the course.
b) Round the inside of the course.
c) Round the centre line of the course.
d) Round the racing line.
My opinion would be round the centre line of the course. It beats me with all the fancy gadgets around these days that someone can't establish EXACTLY how far round it is.
There is another side of me that romantically wants to see the 37.73 distance remain unaltered, and used as THE standard against which we measure lap times.
When I raced there I used to laugh when asking another rider what they got round at, they would reply, "just short of 114", or "just short of (say) 117". What mattered to me was what TIME did you go round in. 19minutes and 10 seconds is faster than 19m 15s, but they both might be 117mph.
Five more laps at five seconds slower and you're HALF A MINUTE behind.
So, to me it's an irrevelance. The man (or woman) who completes the course in the least TIME will be the winner, and who gives a stuff about the average speed?
And another thing. It must be a mystery to the non British anyway, as everyone else except America/Canada uses Kilometers. Yes?
However, in hindsight, obviously there has been the romance of the first, 60,70,80,90,100,110,120,130 etc, and I'm one to speak as I can name them all! Only one date mattered to me when I was growing up, and I could name the day far more easily than I could remember the Kings and Queens of England. June 7th 1957. Bob Mac sets first 100mph lap, Gilera 4 riding number 78, second lap, 101.12.
So, back to course distance. Leave it as it is!!
And DON'T let anyone else mess with the course as they have at Windy and Brandish.

Hi Nick! You're right: what is important is the TIME as it's the MEASURED physical quantity; infact the value of the average speed is calculated. But the comparison between the different editions needs a permanet basis. Of course the comparison is olny a calculation: it's not the "realty".
About the romance of the first "x mph lap", it's of course part of the cultural area that makes use of the "mile" as lenght unit of measure: it has a cultural value but a very special one (i.e. the TT races were born in that same cultural area). If we use the metrical unit of measure:
first 100 km/h lap: Jimmy Simpson, lap 1 1924 Junior race (also first 60 mph lap).
first 150 km/h lap: Geoffry Duke, lap 5 1950 Senior race.
first 200 km/h lap: Steve Hislop (unofficial) 1991 TT practice; Jim Moodie lap 1 1999 Senior race.
first 210 km/h lap: John McGuinness lap 2 2009 Senior race.

P.S.
About first 100 mph. It was the second lap of the 1957 Senior TT as you say, but the average speed was 101.03 mph. 101.12 was the average speed of the fourth lap (the fastest of that TT edition);-).