Helen: I do not believe that you can race someone you cannot see - you can only race yourself against the course, unless you have on-board telephony of some sort telling you where the others are in comparison to your self? Events like the TT are, and always have been, more akin to rallying - do the very best you can, and see where you stand afterwards. It is part of the fascination and difference, not a criticism. The Mountain Course needs to be ridden intelligently, taking loads of factors into account - the weather, how your bike is performing, how the tyres feel, even how you as a rider are feeling, and the advice always was to ride at nine-tenths, because on proper roads no-one can ride all the time precisely - the other tenth is what keeps you alive! In the middle of all that, if you can calculate how fast all the others are going and adjust your pace to be that little bit faster than them, then you deserve sainthood, the Nobel Prize, and an honourary world championship!
That sort of "racing" is not for everyone - the late great Barry Sheene hated it straight away, and said to me "how do I know how fast I have to go if I can't even see who is racing?". He never "got it", and in no way did this detract from his standing as the top rider of his era, it just meant he was not a TT rider.
To see Ralph Bryans, Luigi Taveri, Jim Redman, Phil Read, Mike Hailwood, Giacomo Agostini, Kel Carruthers, Tommy Robb, Chas Mortimer.....all of whom were as brilliant at Spa, Brands Hatch, Barcelona as they were at the TT, jumping from a single-cylinder 4-speed right-hand change, to a five or six-cylinder six-speed left-hand change, with their choice of tyres restricted to 'black and round, or black and round, all with knobbles on' demonstrated the wide scope of just how good they were on the rough, the smooth, the wet and the dry -and they had to push-start every time!