May 3rd, 2012
For the last several months there has been lots of anticipation about the Smart Enve System (SES) clincher rims. Now that we have them in stock we have had a chance to play with them and form an opinion. In short they’ve surpassed my expectations, which honestly were quite high.
Since the tubular versions of 3.4 and 6.7 have been out for almost a year and a lot of people are familiar with what makes the SES rims special, so there’s no need to go into great detail. We will, however, touch on some aspects that I find interesting as well as some which maybe just haven’t been much talked about. All of the Smart Enve System rims are designed to be used in matched pairs to produce the best results. All the rims are wider than standard Enve rims, but the front SES is wider and shallower than the rear (26mm wide front and 24mm wide rear), this is said to reduce drag and improve handling and the results are really noticeable. All SES wheels feel super fast, and wind tunnel data that I’ve seen backs this up. Perhaps even more importantly, handling is insanely predictable/stable.
Clinchers and Heat
To date the biggest problem with carbon clinchers has been heat buildup, so a lot of focus needed to be in that area. I knew Enve had been working to improve on this, but really didn’t know much about the testing. I spent some time chatting with them about the testing and found it to be pretty interesting. The testing machine runs a 600 watt brake load for 3 minutes. Why chose those numbers? Because virtually every other carbon clincher tested failed well before completing that test. Of course not everything was shared with us, but we do know that during the testing temperature both internal and external is recorded. We also know that they use lasers to measure changes in the sidewalls from heat and pressure. One thing I found interesting was that air pressure changes from temperature increases are also measured. I found this interesting because over the last couple of years, I’ve seen an argument raised that as heat increases and resins soften air pressure increases dramatically and this increase plays a large role in the deformation of the brake track. The numbers I’ve seen tossed around range anywhere from a few psi to an increase as much as 80 or 90 psi. I had never seen actual test data to show the increase in air pressure. Well now there is an answer and it is up to 12 psi. That is the highest increase they have recorded since testing began. Not nearly as significant as I had expected and says a lot about the advancements of dealing with heat in a carbon clincher.
Braking Surface, Spoke Holes and Warranty
Continuing on with the brake track, on the SES rims the transition from sidewall to braking surface is perfectly smooth, no raised lip as on other models. This was intentional as the lipped transition could not create the aero effect that was being sought. Carrying on the with idea of molded in spoke holes, Enve molds in the brake track and spoke bed on the SES. It comes out of the mold finished and does not require any grinding, smoothing, or texturing of the brake track. The method for this molding process is not something they were willing to talk about.
Another nice thing about the rims is that the warranty has been expanded from the industry standard of 2 years, all the way out to 5 years. One of my favorite things about Enve is their customer service. They are one of the few companies that are actually a pleasure to deal with if you have a problem. So when they say a 5 year warranty I have full trust that they’ll honor it.
The Smart System and Handling
One place where the SES rims really shine is in handling. Enve has created a steering metric which they call the stability index and at first seems a bit complicated and maybe beyond my ability to explain. Simply put, it measures steering torque at the front wheel in a changing wind. When the 6.7 tubular came out, I had spent a little time looking at this index and trying to relate to it, but then after having ridden the wheels realized that perhaps it wasn’t something to quantify and explain. It’s not only easier but more impactful to just experience. I have yet to ride a 60 or 70mm deep wheel set which handles this well. Being in the 130 pound range, I am pretty sensitive to buffeting from wind and gusty conditions. It’s not that the SES wheels eliminate this because they don’t, it’s that they change the way you interact with it. In theory a linear response to changes in wind makes them super predictable and that in turn leads to more stability . In reality it does 2 things. First it reduces fatigue in gusty or changing conditions, both mental and physical fatigue. This change is even more noticeable as the speed increases, such as on a high speed mountain descent with gusts that change direction. The second thing it does is restore confidence. Most of us tend to ride slower when we’re being blown unpredictably around the road on a high speed descent. The SES wheels return that descending confidence in a big way and feel more connected to the road in such conditions leading to simply faster riding.
My original plan was to use some 3.4 clinchers as my daily riders, but now I see no reason why not to use the 6.7, which to me seem to handle as well as my standard 45mm Enve set. So needless to say I’m impressed, the rims are more than I had expected. I do think I should note that while aero numbers for the clinchers have not yet been publicly released, they are coming. However I can say that they tested as being more aero than their equivalent tubular SES rims.
A comparison of Enve Smart Rim Weight
I was also impressed with the weight of them in relation to the tubular as well as their weight in relation to other clinchers. When you compare the tubular 3.4 to the tubular 45 set, you see a significant jump in weight to the SES version. A pair of Enve 45 Tubular rims weighs 590 grams and a pair of Tubular 3.4 weighs 735 grams, a jump of 145 grams over the standard Enve. When you look at the clinchers though a set of 45 are 900 grams and a set of 3.4 clinchers are 890 grams. So for all intensive purposes there is no weight gain. Which makes me ask, what will become of the 45 clincher. For an extra $100 per rim, no weight penalty, improved aerodynamics and better handling, why would anyone not choose the SES version over the standard?
For the weights we measured and averaged quite a few sets, and found that there was very little variation in weights, seeing that consistency says a lot about the manufacturing. Averaged clincher weights are as follows:
Enve’s Smart vs Zipp’s Firecrest
While lots of people have been talking about the SES rims, many publications seem to be avoiding the fact that Enve is definitely taking a shot directly at Zipp’s Firecrest line. Putting together an Enve set equivalently priced to 303 firecrest (3.4 clinchers, Tune 45/170 hubs and CxRay spokes) you can end up with a wheel set that is virtually identical in terms of aerodynamics across the board, but handles better and saves more than 200 grams of weight. Comparing the same build with 6.7 clinchers to the 404 set you have the same handling advantage, 180 grams of weight savings, and arguably an even more aero wheel than the 404. So it looks like that shot was well placed.
Aero data can be found here please note that the data is for the 3.4 and 6.7 tubular, the clincher data will be coming soon.
We also have some 8.9 tubulars to cover, but we’ll save that for next week.