You still need to look down to see if you're in top gear - but look down for a longer time to note the engine revs and then look across at the speed.
As I see it, there are basically three conditions on the road: urban when the limit is 20mph or 30mph, extra-urban when the limit is 40mph or 50mph, and fast, when the limit is 60mph or 70mph. An experienced driver or rider should certainly be able to know what 20mph and 30mph feel like, simply by the passing of street lights and road markings and general street furniture. What gear I'm in is somewhat academic at lower speeds because the engine has so much flexibility, but I used to get all worked up about it when I was new to the ST because I couldn't tell the difference between 2nd and 3rd gear.
I know what 60mph or 70mph feels like anyway by wind noise and because I'll usually be riding at a fairly constant speed, and thus will already have a working knowledge of what my speed is. So my rule of thumb for whether I'm in 4th gear or 5th gear is: ~4000rpm and 60mph means 4th; 70mph means 5th. And even more rule of thumby: if the speedometer needle's position is way up relative to the rev counter needle, I'm satisfied I'm in 5th. It's bizarre but I actually prefer to use the rev counter as my speedometer because if I know what gear I'm in I know what my speed must be - and the graduations on the rev counter scale are larger and easier to see. But then, I always had an uncanny ability to make complicated things simple, and simple things complicated.
There are times when I don't believe it all and I try to change into 6th. I mean, heck, even my 1987 VFR had a 6th gear.
