Making a Cannondale BadBoy ride softer I have a Cannondale BadBoy with slick tyres, no suspension etc. On roads the ride is fine, but I do less of that these days and more along tracks (e.g. unmaintained paths, towpaths etc.). On non-metalled surfaces the ride is incredibly hard and I get incredible vibration through the forks and frames. What are my options for modifying the bike so I can mitigate this? Will suspension forks soften the whole ride or just the vibration through the handlebars. My local bike shop recommended knobbly tires, a suspension-fitted seatpost and/or front suspension forks. Or should I just keep the bike for road use and get something more appropriate ?

I would start with the biggest knobbly tires the frame and wheel will take. It came with a 28 mm. I doubt there is enough clearance to put a mtn 2.2 on it but even a 35 mm or 38 mm is big step. In knobby a 35 mm will be sold as a CX. Run the tires at less than maximum pressure unless you are over like 180 lbs. Those slicks are not the correct tires anyway. For a fairly small cost you are going in the right direction.

A suspension fork will change the geometry and is expensive.

As for a suspension seatpost you are probably riding the ruff stuff out of the seat already.

If you are going with a separate set of wheels then tubeless to run at a lower pressure. But now you are starting to spend some money. Depending on how big of tire the frame will take pick the proper rim width.

I would just start with some tires.