FLO Cycling unveils all-new Carbon Clinchers
article & images by Nick Salazar
Mar 1, 2016  hits 88,236

Before any design work, FLO collected a ton of data on wind angles

Perhaps the coolest part of these new wheels is the design process that was used to create them. As a fellow designer, this is what interests me the most. The FLO guys feel the same way. Co-founder Jon Thornham told me that "To us, the design process is almost more important than the product itself. It tells our story, and will be our image for the next few years." And what a story they are telling with these wheels. The design process was, as far as I can see, the most comprehensive and advanced this industry has ever seen, bar none. Yes, I'm saying that the development process of these wheels by the industry's beloved "bargain brand" has now jumped to the very front of the pack, and is pushing the boundaries of what makes for good design. The story FLO has to tell about these wheels is simply staggering.

Watching the Wind

FLO's yaw frequency statistic, showing a prevalence of low-yaw conditions

The tale begins with a question that has been hotly debated in recent years: what yaw angles should triathletes be worried about if they want to go fast? Are low-yaw scenarios only applicable to the ultra-fast athlete on a near-windless day? Or do we all see 20-degree angles for a significant part of our daily rides? FLO set out to answer that question in a more thorough way than I've seen done to date by any manufacturer, anywhere in the cycling industry. The data they have gathered is of industry-wide significance, and pertinent to every component manufacturer. That's not to say FLO has the final word on this subject, but right now, they are one of only a couple brands to do this kind of work. Trek is the other notable brand having published a comprehensive study of this kind, and their results very much corroborate those that FLO achieved.

The upshot of these tests is that, contrary to the story we've heard from many other brands recently, it's the low-to-moderate yaw angles that triathletes see most often. In FLO's data, athletes see yaw angles at or below 10 degrees almost 80% of the time! Yaw angles below 5 account for a whopping 50 percent! FLO noted that while some courses (like Hawaii) can produce slightly higher yaw angles, most courses are similar in what the statistical curve looks like. Trek found the same result. It's starting to look like all athletes (even the slower ones) want to be concerned with what happens from 0-10 degrees much much more than what happens between 12.5 to 20 degrees of yaw. Simply put, yaw angles of 0-12.5 degrees are nearly 9 times more likely than yaw angles above 12.5. This is just the opposite of what some brands have been touting in the last few years. Yes, it's true that on a very windy day, fast and slow athletes alike may experience unusually high yaw angles. And there are courses like Ironman Hawaii, where the section from Kawaihae to Hawi and back exposes athletes to notoriously-strong crosswinds. But the story FLO tells (and Trek collaborated in their detailed Speed Concept '13 White paper) is that those winds aren't enough to dethrone the low-yaw conditions as those of greatest importance. Not even close. The 9-times-more-important figure I quoted above actually includes data from the Hawaii course, in both FLO and Trek's data!

Algorithmic Design

CFD mesh of one design iteration

FLO's next step, having a statistic of frequency over yaw, was to set out designing new rim profiles that would be the fastest wheels overall. Or in layman's terms, they optimized for the yaw angles that athletes see the most. But they did one step further, and this is the step that is an absolute industry-first, as far as I know. FLO was able to set up an iterative process controlled entirely by computer. They told the computer what their constraints were, and let the computer generate a rim profile based on those constraints. The computer would do a CFD analysis for a given shape and calculate the aerodynamic drag for that rim across all given yaw angles. Then it would make a revision to the shape, retest, and compare the new shape to previous results, using a weighted average of yaw angles based on the real-world statistic FLO had calculated. Then it would repeat. And repeat. And repeat. In total, the algorithm ran through a hundred and fifty iterations or more for each of the wheel shapes (FLO's 45, 60, 90), before arriving at the optimal design. The FLO Disc design started with the FLO 90, and optimized from there. If I have one complaint with the design process, it's here. I'd prefer to see a disc designed independently of another rim profile. Doubtless the FLO Disc is incredibly fast, but could it be faster if designed as an independent structure with its own set of constraints? Possibly.

In all, FLO's approach is a staggering advance in the development of bike parts, and one I can only imagine working for rims at this point. Why? Because compared to other components, a rim is relatively simpler in shape. That is, a rim consists of a single profile, which is the same everywhere on the wheel. Just three constraints - rim depth, rim width, and brake track angle - mean the domain is relatively small, as the algorithm has a nice boundary on all sides. And yet, even with that near-ideal case for optimization, the process FLO used in its algorithmic design would have been completely impossible with the resources used to design and create their initial batch of wheels. They rented out the supercluster of processers from CFD industry leader CD-adapco, in order to get results in a reasonable amount of time. On the computers used to design their original rims, this new optimization algorithm would have taken more than 4.5 years to solve.

So how did all this design work translate into aero performance? Hit the jump and let's take a look.


Tags » flocycling,  wheels

The Dream Team 

I was fortunate to review a whole collection of the new wheels, including a FLO 45 front, 60 front, 60 rear, 90 rear, and Disc. This dream team of five wheels clocks in at the price of one pair of wheels from a competitor, and covers virtually every imaginable training and racing situation.

  • The Dream Team
  • The Dream Team
  • The Dream Team
  • The Dream Team
  • The Dream Team
  • The Dream Team
  • The Dream Team
  • The Dream Team
  • The Dream Team
  • The Dream Team

The Disc 

The FLO Disc is based off of the design of the FLO 90, with the remainder of the wheel (the spoke fairing) optimized independently. This results in some strange-looking shapes, but an undeniably fast wheel.

  • The Disc
  • The Disc
  • The Disc
  • The Disc
  • The Disc

The Details 

FLO makes their own hubs, compatible with 10 and 11-speed cassettes. These are user serviceable, even on the disc, and are all laced with Sapim CX-ray spokes (except the discs, which get Sapim Laser spokes).

  • The Details
  • The Details
  • The Details
  • The Details
  • The Details
  • The Details

Design + Development 

An exemplary and innovative design process led FLO on an incredible journey resulting in the wheels you see in this review. All images in this section courtesy FLO Cycling.

  • Rim profiles for the Flo 45, 60, and 90.
  • FLO collected a wealth of data about the actual yaw angles riders most often see.
  • FLO collected a wealth of data about the actual yaw angles riders most often see.
  • FLO collected a wealth of data about the actual yaw angles riders most often see.
  • FLO collected a wealth of data about the actual yaw angles riders most often see.
  • FLO's yaw frequency statistic showed a prevalence of low-yaw conditions, even in courses like Ironman Hawaii.
  • Molding the tire/rim interface with a Continental GP4000S II tire, an aero and CRR leader.
  • Tracing the interior cavity of the mold and translating into 3D data.
  • The ultra-fine CFD mesh FLO used for its analysis and design.
  • Testing aero drag for a rim shape.
  • The Thornham brothers conducted extensive aero testing at the A2 facility.
  • Jon Thornham celebrates some good results in the tunnel.
  • Chris Thornham ensures accurate tire pressures during the tunnel tests.
  • Chris Thornham checks wheel alignment during the tunnel tests.

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