May 9, 2012 at 6:31 pm #93329Keymaster
For the last several months there has been lots of anticipation about more Smart Enve System (SES) rims coming from Enve. Last week we wrote about the new 6.7 and 3.4 clinchers and shortly after the new SES 8.9 tubulars showed up. We’ve now gotten them in stock and had a chance to play with them and form an opinion. In short the 8.9s are another well-targeted rim with a chance to replace discs in most Time Trial and Triathlon setups.
SES 8.9 Rim Dimensions
Like all the SES rims the 8.9 is designed as a matched set front and rear with varying dimensions. An 85mm deep 26mm wide front and 95mm deep 24mm wide rear optimizes each wheel for its role in the complete aerodynamic profile of a bike. The rims are designed primarily with aerodynamics in mind, but also with an eye on keeping them stable in changing conditions. Claimed weight is listed at 500 grams front and 545 grams rear. The sets we weighed were all virtually identical with each other at 500 grams front and 566 grams rear.
This wheel is definitely geared more for triathletes and TT riders than for training and racing on the road, although some may find these wheels suit many courses well since handling stability is on par with the standard Enve 65mm wheels.
A look at SES 8.9 Aerodynamics
One question I asked Enve last year when they announced the SES wheels was if they had plans to make a disc version, and the answer was a simple “no.” There was no more info given than that, but now I understand their logic. They claim that in the wind tunnel the rear of the 8.9 tested within 5% of the most aero discs on the market. The general idea is that the 8.9 gives up a little in aerodynamics over the best disc but takes an advantage in weight/moment of inertia, as well as in handling/stability. All while being safer and less taxing physically to ride. The idea seems to be a rear wheel that overall is as fast as a disc but doesn’t have drawbacks to the same degree as a disc. Looking at weights, Zipp discs come in at about 950-1000 grams and Hed at 1200 grams. A .9 rear laced to a Tune 170 with CX-Ray spokes would come in at 760 grams. Certainly a noticeable difference, and this could be an advantage on technical courses with braking and acceleration to deal with, not to mention if it’s on a windy day. Looking at Tour magazine’s aero tests of different discs, if the 8.9 rear is within 5% of the best disc, then the 8.9 is actually more aero than many standard discs on the market, while at the same time it is easier to handle and works on a much wider range of courses and in a wider range of conditions.
Enve 8.9 Rims vs Zipp Firecrest Wheelsets
The 8.9 doesn’t stand alone, there is another wheelset out there that exhibits these same behaviors, the 808 Firecrest. Again the 808 is faster than many standard discs and easier to handle. So perhaps the real comparison should be the 8.9 to the 808. Aerodynamically they are pretty evenly matched and both are amazingly fast. Both have some of the best braking surfaces in the industry. Both use similarly shaped profiles and depth to achieve their goals. Both do very well at handling changing wind and both are quite stable. So the differences start to seem quite small. Both are proven to be pretty durable, though I’d give the reliability edge to Enve for their molded (instead of drilled) spoke holes. Note that having your choice of hubs to build with the Enve rims opens up a wide range of hubs to best suit the rider’s needs. Customer service at Enve is stellar to say the least, while for Zipp it’s improving but perhaps may leave something to be desired. If the goal with this wheelset is to improve over a set with a disc rear by having similar aerodynamics but a lighter setup, then it seems the weight could matter quite a bit. The 808 is claimed to weigh 1520 grams but in reality is closer to 1530 grams. Taking into account the actual weight of 8.9 and not the claimed weight, an equivalently priced wheelset to the 808 ($2500) would weigh 1435 grams. The Enve 8.9s are almost 100 grams lighter, with about 50 of those grams being a difference in rim weights and not hub weights. It seems it would be hard to go wrong with either set, but perhaps a few advantages point towards the 8.9s.
When all the attributes are averaged will the 8.9s be faster than a disc setup? In many cases it looks to be the case. Perhaps the bigger question though is: will the development of wheels like the 8.9 and 808 kill the disc?May 9, 2012 at 7:01 pm #93330sami srour
Good write up of the state of the art for TT wheels. The problem however, is that there has not been any new designs for disc wheels in a while. I have to think that if the industry paid more attention to producing state of the art disc wheels, they have got to be more aerodynamic in zero wind conditions.July 16, 2012 at 1:26 am #93331KP
Thanks for the article. I ordered the Enve 8.9s and will get them soon. While getting a wheel design as aero as possible in a wind tunnel is a good start, we all know racing and training conditions are very different. I live and train in Asia so there are ‘strength’ issues with wheels as the road conditions are very different from Country to Country plus another huge issue is cross wind stability. Some of my best bike splits were done in windy conditions on reasonable road surfaces with a disc wheel, however I really am looking for something close to a disc but more forgiving in cross winds and changing conditions (real race conditions). If I can be counted in any stats it is that I chose the 8.9s over the Zipp Firecrest 808s and a Disc after a lot of research and the ‘Smart’ relationship with Enve. This article just confirms my correct decision. My other wheels are MadFiber. Thanks KPDecember 15, 2012 at 4:55 pm #93332Francisco de Almeida
Perhaps the ability of a full rear disc to ‘sail’ better in crosswinds, adding that tiny bit of forward trust, may help them retain a slight margin in windy time trials e.g. along coastlines. This may be more relevant to triatlon than stage racing.