So besides the $1800, what are the biggest differences between the two? Is the disk wheel significantly more aerodynamic than the cover? Obviously weight is a concern, so what are the weight differences between a plain disk and a wheel with a cover (say a zipp 606 wheel with a cover and a zipp disk). And after reading several threads on the issue I have heard that both that disk covers don’t make the whooshing sound of a disk, AND that they do. So whats the real story here, and what does cause the whooshing sound on the disk wheel that doenst on the cover? Is it the dimples perhaps?
Weight is irrelevant.
There might be some weight savings from a disc wheel, but for me it’s just less hassle than putting on/taking off a cover. Buy a Renn 575 for $500 and you’re set.
Ditto to Sailinfast’s comments.
I think you’ll be hard pressed to find scientific data that says a disk is significantly more aero than a cover, except for maybe the new Zipp with negative drag.
I’ve always read that disks are lighter.
My cover makes some noise but not nearly as pronounced as a disk, nor as cool…IMO.
Another possible consideration is comfort and handling. I’ve heard that disks are much stiffer than a cover over spokes and not as compliant. No experience though since I’ve never ridden a disk.
The weight difference between the Pro Lite disc that I used to own and my 808 clincher/cover combo is 150 grams.
My times are about the same but I haven’t done anything very scientific or repeatable to compare the two.
It takes 5 minutes to install so I don’t see the point of spending an extra $400 for a renn disk to make things “easier”.
My training partner says that it makes a noise like an attack helicopter. Whump Whump, instead of Whoosh Whoosh.
I love the disk sound! If money is an issue go with the cover, otherwise Disk are Coooool!
I run a disk cover and actually like that it’s heavier than a disk, given a flat course → flywheel effect.
Aero wise a disc is a disc, cover or not. That extra $1800 won’t buy you any extra performance. For that kind of a savings I can live without the whoosh sound.
Well, yeah of course I asked about the sound because disk sound awesome!! Whether that sound is worth 1800, i’m not sure. For that money I could by some speakers, mount them on my bike, and blast out racecar sounds as I zip along.
In that case, why not run with an even heavier wheel? Or is it the perfect amount of heaviness? 
Aero wise a disc is a disc, cover or not. That extra $1800 won’t buy you any extra performance. For that kind of a savings I can live without the whoosh sound.
A disc is not a disc aero wise. There are differences between the different models. A Renn disc does not has the same performance as a Zipp clincher or Hed disc and definitely not the same performance as a Zipp Sub 9 disc.
In Reply To The weight difference between the Pro Lite disc that I used to own and my 808 clincher/cover combo is 150 grams.
My times are about the same but I haven’t done anything very scientific or repeatable to compare the two. ----------------------------------------------------------------------------------
The 808 is pretty aero in it’s own right. I know that aero trumps weight, but this is rotating weight, and we’re already pretty aero. So I’m still a bit unsure of the benefit.
I have an 808 tubular with a PowerTap SL and am considering a wheelcover. So, who has an 808 and puts a wheelcover on it? Clincher or tubular (and does that matter)? CH Aero, Wheelbuilder, or what? Happy with it? And yes, I gotta ask…how does it look?
Head on over to Tri-zone.com, join the Tri-zone team (it’s Free), and get a Zipp disc shipped for $1327.46. Just my opinion, and that’s all it is, but I’d run a simple deep rim in the back before I’d cover it with a cover. It just looks wrong. Kind of like a Bento box.
out of curiosity, why do you need to remove the cover for training? i assume people don’t train on their zipp discs because they don’t want to ruin it, but why not train with a $75 dollar wheel cover?
For one thing, you would need to carry a disk wheel adapter chuck in case you got a flat and it’s a pain to use one of those with a floor pump, much less a hand pump.
Head on over to Tri-zone.com, join the Tri-zone team (it’s Free), and get a Zipp disc shipped for $1327.46. Just my opinion, and that’s all it is, but I’d run a simple deep rim in the back before I’d cover it with a cover. It just looks wrong. Kind of like a Bento box.
You do realize that a bento box has very favorable aerodynamic properties.
I’m able to use my floor pump with the cover on and no adaptor. The chuck opening is a good size.
“There are differences between the different models.”
Aw c’mon, let’s get real. Let me repeat - a disc is a disc is a disc.
You’re talking a few seconds or so over 40 kms between the different models. It’s not like you’re comparing any given model disc against a 32 box spoke.
Sure a few seconds is very important to a pro TT rider, but to the average recreational triathlete?
BTW - show us the evidence that any disc is faster than a disc cover.
“I’m able to use my floor pump with the cover on and no adaptor. The chuck opening is a good size.”
Same here. I also cover the chuck opening with a cut piece of thin black plastic held with electric tape.