Disk wheel question

Looking for information from some of you techies on aerodynamics of disk wheels. Specifically the flat disks vs. the more “rounded” style ??

Which are better and the reasons behind it ?? One style more suited to a particular situation ??

Rounded. Almost always will be faster. same type of thing as firecrest. ill let someone else explain exactly why so i dont mess it up

Check these:
http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Lenticular_VS_Flat_Disk_P23087/
http://archive.roadbikereview.com/04/0EFD04D5.php

Wind tunnel studies have also shown that flat discs do better on bikes that shield the rear wheel with a cutout in the seat tube, while lenticular (curved) discs do better on more “standard” frames.

Interesting comments so far. In my case I have an opportunity to buy at a crazy low price a new Cormia flat disk that I would like to use on the track for some workouts. I thought about using it to race on the track also but was told about the differences between flat and lenticular disks. Looks like it is minimal and may be non existiant in an indoor track setting. So getting a flat disk vs no disk is an easy decision.

For track racing a disc is pretty critical (and there are no crosswinds, so a flat disc is slightly faster).

Discs are used in almost every track event, from sprints, to pursuits, to pack-type events (points race, miss&out, etc.).

http://www3.pictures.zimbio.com/gi/Olympics+Day+8+Cycling+Track+ZHGk6aAuSlil.jpg

http://www1.pictures.zimbio.com/gi/Njisane+Nicholas+Phillip+Olympics+Day+9+Cycling+NRyBmEfhnzhl.jpg

http://cyclingweekly.media.ipcdigital.co.uk/11141/000008167/036e_orh100000w575/london12-track-aj-Van-Hoecke-4.jpg