TVS Ntorq an aesthetic marvel but has lot of flaws. I still think, TVS did great in all scooters except Ntorq ( All generations).
Coming to bikes for Bangalore city ride of 40kms considering your back ache issue, I honestly suggest Honda SP125. Its a solution for your problem.
If you are riding below 65kmph speeds.
This holds good even if u r commuting 40kms one way X 2.
But only good for single ride.
I suggest xpulse 200, if u r going above 65kmph speeds and the roads that you are using are extremely bad.

