I am currently learning to ride motorcycles and my friend is using his gsxr1000 to teach me.I think the size is perfect and its comfortable for me to stand on.Other then power what is the downside of learning on a 1000cc bike? Should I get a 1000 if I'm used to them?
There's nothing written in stone that says you can't learn on a liter bike. It's just that when most people begin to learn, they make mistakes. A small mistake made on a Ninja 250, can be a huge mistake on a liter bike.
When you're learning throttle control and clutch control, braking, turning, counter steering, etc....it's easy to slip up. On a small bike, it's a pretty easy thing to recover from. But if you're sitting on a liter bike and pop the clutch too fast, it'll probably get away from you.
And then there is the speed. Things just happen faster on a liter bike. They're very unforgiving machines - it only takes a couple seconds and you're going 100+. It takes a lot of practice to handle a bike at those speeds.
You also need to build muscle memory so that you don't have to think about shifting, braking, turning, etc....so that when something goes wrong, you can concentrate on thinking yourself out of the situation, instead of thinking about which hand to use to engage the clutch.
It takes a lot of saddle time. It's better to learn on something that's more forgiving of your mistakes. I mean, think about it. These are basically race bikes with turn signals. Which do you think it would be easier and safer to learn in, a purpose built race car, or your Mom's Taurus?