re the Alan/Vitus frames:

As mentioned above, it is due to the small diameter alu tubing. While it did flex quite a lot, with a smooth steady cadence, and as long as I stayed seated it was really a nice lively ride. That said, pedaling while standing brought on flex at the BB more than I wanted to feel, especially considering it was a 30+ year old frame and I was intent babying it. So, a wet noodle, but a comfortable and manageable dish once you are used to it.

.....but after getting used to the Alan, when I went back to a steel track bike at first it felt dead in comparison. And then I remembered how much fun sprinting could be