Being confident with speed means being confident you can stop. This comes down to your field of vision. The further ahead you look, the more confidence you have in your speed. Looking 200 meters ahead is all very well at 50km/h, but as you go faster your brain will be happier scanning for hazards way down the road. In bad weather, when you can't see far, speeds drop dramatically but confidence needn't.
How well you brake is also critical to confident speed. Combine looking well ahead with the ability to use everything your brakes have to offer, learning how much road you need to stop, and you'll be happy going pretty damn quickly where the view allows. Practice applying the brakes in a rapid yet smooth manner, transferring the weight smoothly onto the front tire. And practice again, because you will never be a fast, confident rider if you can't stop the motorcycle in a hurry.
Nowhere does confidence – or lack of it – show itself more than when cornering and no area of motorcycle riding benefits more from additional training or track riding. There is virtually nothing by way of cornering training in a motorcycle test and the paltry advice provided is completely useless. If you're happy that your motorcycle and tires are in good functional order, then whether you've good reason to be confident is mainly down to understanding and, again, experience. As with any speed-related facet of motorcycle riding, how far you can see and stop is critical. Doing 100km/h when you're leant over and can see only 30 meters ahead is just plain stupid.
Being confident doesn't necessarily mean being fast. Open corners tend to engender more confidence simply because you can see where you're going. But now can you really be sure you're not going to overcook it? You can't. Your level of confidence relates directly to experience. In the dry just about any motorcycle will scrape something before it slides if – and it's a very big “if” - it's being ridden smoothly on a good, clean road surface.
When you're going harder than you're used to, stepping outside your comfort zone puts doubt in the mind that upset concentration and clear thinking: tension creeps in and inhibits control. If you want to learn pain-free, only small graduations in corner speeds over a number of kilometers will take you there. You can follow another rider into a corner and get around at the same speed, right? To an extent, yes, but you have to know you can trust them. You may never know that the unknown ultra-fast motorcycle rider you've latched onto isn't a grown-up idiot boy on a stolen motorcycle – or a suicidal maniac. Reckon you can stick with either one? Or want to?