Having had a small heart procedure done last year and only being in my mid 40's i need to get fitter and remember enjoying bike riding from younger days so am on the verge of buying a bike.My question is does bike riding really help with cardio fitness as i only ever really remember my legs acheing riding a bike rather than actually getting out of breath.Im not sure my back and joints are up to pounding the streets running so a bike is what I fancy but does it really get the heart pumping so to speak ?