Hi ajita,
satara is anytime better option. It will take you around 1 hr or so to reach Mahabaleshwar.
if you dont have better connectivity from Banglore to Satara, try to reach Pune first...
From here you can either rent private vehicle or go with package travellers.
Reaching satara from pune doesn't have much frequency. happy travelling...
happy exploring....
You should travel to Pune from Bangalore by any means, either by train or bus and then travel to Mahabaleshwar on a bus or Taxi. (It’s a 3-3:30hour ride)
Hope this was helpful, Happy travelling.
Board a bus from Banglore to Satara; from where you can get many option to travel to Mahableshwar.
Don't board a bus to Nipani; you'll again need to change the bus there and alight at Satara and from there you'll get bus/ cab to Mahableshwar.
Best luck for your travel!