I don't remember seeing a big boy with the gears, but still I think you shouldn't need any mods as such. However, there are a couple of things you would have to let go off and they are the "chain cover" and the "center stand" to be able to accomodate the system. There is one thing to keep in mind though - the gears system uses a thin chain, which I am not sure how well they could cope up with this heavy big brother.

The off terrain bike of your friend might have had 26" wheels compared to the 28" on your Big Brother so the same gearing on the smaller wheels will give us a lighter ratio.

@Ashwin Prakash : Hero to Herculas ?

good man , hope you will lose some weight riding the bi cycle

You got me there at the chain guard and main stand part, guess its better to keep her stock, else will loose the main factors which makes her special.

Yeah, Hero giving me headaches. This is more reliable and in a way maintenance free.

About the loosing weight part, I'm the type who believe obesity is royalty in disguise.

Thanks bro.

Very nice bike ashwin'jee .. I just saw the post .. you are making me feel sad for selling off my old Raleigh roadster (was made in asansol here) .