An IFR general aviation departure from BUF on Runway 14 was required to take evasive action to avoid traffic conducting a low approach on Runway 23.

Narrative

I was departing BUF on an IFR flight plan from Runway 14. I was cleared for take off by the Tower as another single engine aircraft looked as he was making a low approach and on the go to intersecting Runway 23. I had the other aircraft in sight and I hesitated until it looked like he would pass by the intersection so I would be behind him on departure. As I lifted off; he made a left turn to crosswind at the intersection of the two runways at an altitude I would estimate to be four to five hundred feet; putting me below and directly behind him on the same course. I had good visual contact at all times with the other plane until I overtook him as I was the faster plane. I adjusted my climb to stay well clear underneath him until he was behind my aircraft. As I was concentrating on staying clear of the other aircraft; the only thing I thought I heard from the Tower was for the other plane to make a left turn which is what put him in my path. In thinking back to the sequence of events; the other plane was too close to my departure flight path for the Tower to have cleared me for take off; and I misjudged his speed in clearing my departure path and should have told the Tower I was waiting a few more seconds to start my takeoff roll; making sure the other plane was clear of my departure path.