At what point does weight outweight aerodynamics?

[montage]

Not sure where to stick this...


But I am considering knocking up a TT bike on a very tight budget...which may mean home made handlebars etc .....anyway at what point does the heavy weight make aerodynamics pointless? As in where does the balance lie?


does that make sense?

 

[Bigtwin]

Weight only matters when you start/stop, and go up/down hill.

Most TTs are fairly flat, and once you've started, you're off.

Over 18-20 mph, form drag is the major factor, as a square mathematically. In other words, you have to put in a huge amount more power to overcome wind resistance and generate then hold more speed.

So, shape through the air wins hands down over weight with a TT bike every time.

 

[LeeW]

I mananaged a self-timed 10 mile TT in 18:59. This is about a minute faster than the course record. I did this on a bike weighing about 75lbs which is saying something. www.velomobiel.nl . However at low effort levels and low speeds under around 12mph the Quest seems slower than my Fujin SLII (which weighs 19lbs).