I would like to have a disc wheel on the back of my tri bike. The cheapest one I have seen is the Renn 575. But I just can’t justify spending $600+ for one. But I stumbled on an alternative. A few companies make aero wheel covers. They are made of plastic, and fit over the spokes on the rear wheel to give disc wheel like aerodynamics.
I have found a few different versions of aero disc wheel covers. The first one I found was on eBay named Uni Titanium, that is made of vinyl sewn around a titanium frame. It is apparently held to the wheel by clips.
The next one I found is theCH Aero Wheel Cover. These are kind of a one size fits all lens shaped pair of plastic discs. I have read about problems with these that if you have an unsual number of spokes, that things may not line up correctly. My rear wheel has only 20 spaced bladed spokes. But at $60, they are the cheapest.
Then I found some aero disc wheel covers on Wheelbuilder.com. They start at $65. But the cool thing about these is that you can have then custom cut for your wheel for an extra $15-$25. They ask you on the website how many spokes you have, wheel dimensions, etc. They also come in both 700c and 650c size! I was the most impressed with these.
The Wheelbuilder.com and the CH Aero wheel covers consist of two lens shaped plastic discs that fit on either side of the wheel and are held together by bolts.
Now are they any good? I have been reading various reviews. Some people point to studies that disc wheels only save a minute or two of 40 kilometers. But other reviews, where people have actually used them, seem to suggest that they increase speed maybe up to 1 mph. That that seem to work best on flats and downhills, but that uphills are a littel slower due to the weight. Though from what I can see, the weight added is only like a pound.
Many things I have read are that an aero helmet is more benefit than a disc wheel. But I think that is when cost is being factored. An aero disc wheel cover costs $100 or less. So that is probably less than a good aero helmet. So I think that the benefit might be worthwhile. It doesn’t have the coolness factor of a true disc wheel like a Zipp or a HED. But I think they still look pretty cool!