We will be visiting Sorrento, Pompei and Capri for a couple of days and then need to meet up with a bicycle tour in Bari. What is the best way to get from Sorrento to Bari?

At Trenitalia.it you can find the train schedules. You would need to get to Naples Centrale station, change in Caserta and arrive in Bari about four hours later.

The local Circumvesuviana train runs about every half hour from Sorrento to Napoli Garibaldi, the penultimate station on the line (www.vesuviana.it). Trenitalia has connections from Napoli Centrale which adjoins the Circumvesuviana's Garibaldi station. Trenitalia's web site (www.trenitalia.com) does not show the Sorrento line.
Train connections from Napoli to Bari are not very frequent. If there isn't a train at a suitable time, an alternative is the hourly bus from outside Napoli Centrale station to Foggia. These take about two hours, and there are lots of trains onward from Foggia to Bari.

Thank you for your train recommendations. Is it difficult to drive from Sorrento to Bari? By driving, we could pack our luggage in the car and visit Pompei along the way.
How long would it take to drive from Naples to Bari?

Hello tyacko, I have driven by car from Naples to Bari but I don't remember exactly how long it took but I know it was not to long. We had taken the hydrofoil from Capri back to Naples in the morning. Got our extra luggage from the hotel we had stayed at in Naples, retrieved our rental car, drove to Bari and arrived in Bari at the end of the afternoon so I would say around 4 hours or so? A good way to see a part of Italy that a lot of people don't see. Enjoy!