Here are some insights from a top (perhaps, the top) BMX frame builder about titanium and even steel frames. He talks about the forces in BMX. We also have to keep in mind that even road bikes experience potholes, and getting torqued by the rider when sprinting or climbing. This part of the discussion starts at the 20 minute mark, however, the whole video is interesting, at least to me, as it establishes who Mike Laird is (I had no idea), how he came into frame building and how he became one of the top BMX custom frame builders. In case you skip the first 20 minutes, he built frames for Olympic Champion BMX riders.