which bike?

[informashun]

i request any info on most suitable bike for me.
i am 71 and want to start local cycling, had a knee repeplacement and need some exercise.
the criteria therefore is something lightweight , not expensive am told a hybrid type would be ideal.
i reckon im asking a lot but there are loads of you out there knowledgeable.
any assistance most welcome.
thanks in anticipation.

[henrymullen]

Take the front wheel off an ordinary bike and chock up the back wheel and away you go