I thought it might be fun to dive into another area that is sure to generate some lively discussions.
another area? Its not like this hasn’t been covered (no pun intended) 25 times before…
IIRC Tom A. said a good set of tube/tires will save you a minute or two over a half, but I could have misinterpreted.
doesn’t dr tommy use a disc cover?
he has the record at IM florida
johnnyo recently beat him in a half IM, he uses a disc cover
theres really no reason not to use a disc cover unless money is no object and you want to save a few grams
In reno a TT course record was just set on a disc cover. I know it’s the rider and not the wheel, but I think that’s pretty sweet :). Many others had zipp discs.
Like someone else said, get the disc cover then spend the money on something else to make u faster or just save it.
IIRC Tom A. said a good set of tube/tires will save you a minute or two over a half, but I could have misinterpreted.
It all depends on the tires/tubes you are on now and what you are comfortable with using in the future 
Have a disc cover cut by wheelbuilder on a fp60 and fits great. Had my fastest bike time ever at devilman going till i flatted the rear tire. I was averaging around 23 - 23.5 mph. Tried to make up but it was in vain. Toasted my legs for run!!! but it was sure worth it. Caught a guy who came out of water 4 minute ahead of me then flatted. It Had to take at least 10 minute to change. Plus I derailed coming out of t1 when time was going!!! Hey if you have money to burn then a disc is worth it. If not get a cover.
I have an Open Pro Powertap with covers and a Corima disc, used the wheelcovers for the 1st time last November at IMAZ was very impresed with the fit, it was no surprise that posted my fastest IM time due to me not pushing too hard on the bike. But nothing beats the sound of the disc tho, if I’m racing a short TT or tri then its the disc just for the sound.
I have a cover on a Mavic CXP33 rim with Chris King hubs. The fit is not great-the rim is not deep enough to tape the perimeter and the chain rubs on the innermost cog. However those are minor issues and the cover works great. I’ve paired it with both a used HED CX (60mm) front and a Gigantex 85mm front and it makes for a fast wheelset. If the sound of a disc is that important, just make the humming whoosh sound as you pass people.
Mine didn’t fit well untill I cut to fit as close to the spokes as possible. My hub is kind of a star shape and the cover buldged a lot. Now it fits great and the only down side is that you can feel the weight on a hill. Still works great.
Disc cover works really well with 404s. Definitely get them to cut is.
Even pro’s use covers… the $$$ don’t make sense to me for a true disc wheel, but to each their own
Actually, i found with mine that it actually DID make a whump sound when I taped the cover to the rim using electric tape, especially when hammering hard or climbing agressively. I did not do this with just the screws. I’m thinking maybe the tape seals in air and it vibrates or something.
“Trust me, I know that sound. There is nothing more frustrating than knowing you are about to be passed without even turning your head.”
I would think being passed by a guy with a $70 cover while rocking along on your $2000 disc would be more frustrating than that.
Last weekend I was at a race with around 500 participants. I counted only three disc wheels in the bunch and only one disc cover (mine). The nice thing is that I can literally throw the bike in the back and not worry about the wheel. If I had a $1000 wheel back there I think I would be so anal about protecting it I would never have any fun.
sigh… I miss that sound. seriously, it’s almost worth the $$$ just for the sound. Fortunately, not that many people pass me and my wheelcovers, so I am coping.
I really miss the expression on people’s faces when you down shift a gear under load while passing them up an incline. whup-whup-whup-BAM-whupwhupwhupwhup.
Dude, I feel like I stole one of your children.
always amaze at that comment about feeling the extra weight of a cover… it s about 1-200gram more than the lightest disc…
your bike, 20lbs… you,.,maybe 150lbs total 170lbs and you can feel a difference of 1-200 gram in your rear wheel? that is 0.00294% of the total weight of the equation…
you must be so in tune with your body to be able to feel this. You must be a highly train machine like no one else. or perhaps…your head is playing tricks with you and you fall for it. I think that is the case…
I cant feel the difference in weight…
Sunday at the PERSONA HALF IRON in canada… the top 5 guys of the bike with the the fastest rides on the course and also a new course record were all on disc cover
Tom evans
Me
MarkyV
Ian
Kyle Marcotte…
no one mentionned weight ever… other than our anorexia weight issu eating burgers!!!
my children wouldnt make such cool sounds, or go as fast.
I am happy it’s found a good home.
http://www.ted.com/talks/dan_ariely_asks_are_we_in_control_of_our_own_decisions.html
Mine didn’t fit well untill I cut to fit as close to the spokes as possible. My hub is kind of a star shape and the cover buldged a lot. Now it fits great and the only down side is that you can feel the weight on a hill. Still works great.
Get the cover. Save the $ for something else that will improve your bike split even more:
PM
aerohelmet
proper fitting
fast tires and tubes
I concur with this suggestion.
To the OP:
I have used a wheel cover and a disc. I only use the disc now. When I used the cover it was on an 808 tubular so it was a very light, stiff and aero wheel. I was very happy with this setup, but your results may differ depending on what wheel you will use the cover on. If it is a Mavic Open Pro it will obviously be heavier and a little more flexy. I would most likely still be on this setup had I not started working at a bike shop. It got a little out of control. It all started with me getting a PT and lacing it up in my training wheel then I thought it would be a good idea to get the Zipp 900 disc with PT. Of course from a racing/feedback standpoint it was a great idea, but from a financial standpoint… maybe not.
The following depends on what wheel you would put a cover on.
Is a Zipp disc more aero? Yes
Lighter? Probably not
Stiffer? Yes
Louder? Yes
I am inclined to say that the Zipp disc would be faster than a wheel cover. Are we talking significant differences? Most likely not.
and this is why we have wind tunnels
so we can actually know rather than guess
perhaps the new sub 9 disc is faster than a wheel cover (though, maybe not if the cover is on an 808)
but, the data tells an interesting story on disc covers vs ‘real’ discs. biketechreview.com has it for a fee.
I am inclined to say that the Zipp disc would be faster than a wheel cover. Are we talking significant differences? Most likely not.
A disc is a disc is a disc. I used to run a homemade disc cover, very fast and added a handful of grams to my velocity deep Vs. Cost me three hours of time getting it right and $16 dollars. For those on a budget that is kinda hard to beat.
I am running a regular wheel with my cover so I have to use more of the cover than if it was on a 404 or 808. It probably adds about a pound to the wheel. I agree that it isn’t much of a difference and it is probably more mental than anything else. I make no claim to be in touch with my body. There is the thought that the rotational mass of the wheels makes the weight issue more important. Does anybody remember that issue of Triathlete that had the weights that you put on your wheels. They had a spring so that at high speeds the weights would move towards the rim creating more rotational mass. But then as the wheels slowed down they would move back to the hub to decrease the rotational mass. They were supposed to be best on a rolling course and save a small amount of time.