^^ The top whack varies considerably (only in case of normal bikes)...Mostly according to tradition if you see, then 125cc bikes have lower HP than 150cc bikes. On the other hand tweaked/tunned bikes like R15 are designed to get more out of 150cc, same is done with a duke 125cc....
Anyways 17bhp is by no means much for a beginner, as such in India we can say bike till Pulsar 200 are also beginners bikes... But considering that its India, its unfair to call bikes like unicorn,pulsar,Fz,fazer,apache etc as beginners bikes, pulsar 135, twister,stunner, passion, splendor, slingshot etc can be termed as beginners bikes for India ... Its just my opinion, may differ.