Vision Metron 55 & 81

December 19, 2013

When most people think of FSA and their Vision Tech sub-brand, they think of aerobars, not wheels. Their handlebars, brake levers, and cranks are a common sight on triathlon bikes all over the world, but I can count the number of FSA wheels I’ve ever seen on two hands. We recently reviewed on of their more popular products, the Metron aero crankset.

This is no secret to the folks at FSA, and they’re out to change the situation. For 2014, they’re rolling out a slew of new wheels, including clinchers tubulars, deep rims, shallow rims, and everything in-between. Today we are reviewing a mixed pair – the Metron 55 front and 81 rear, both in tubular version. How do they stack up against the established competition? Let’s take a look.

We’ll begin with an overview of the basic specs and measurements.

Vision Metron 55 and 81mm tubular specs:

MSRP: $960 front, $1,499 rear, $2,459 per pair
Weight: 1,455 grams per pair
Rim Depth: 55mm front, 81mm rear
Rim Width: 25.4mm front, 24.2mm rear
Spokes: 18 front, 21 rear, bladed stainless steel
Compatibility: Shimano/SRAM 9-10-11-speed; Campagnolo version also available
Rider Weight Limit: No official limit
Warranty: 2 years for manufacturer’s defects
Decal color options: White/Red or Black
Sizes: 700c only
Includes: Includes quick release skewers, valve extenders, Swiss Stop yellow brake pads, and 1.8mm spacer for <11-speed cassettes

These wheels are also available in carbon clincher versions:

Metron 55 Clincher set: $2,599, 1620 grams
Metron 81 Clincher set: $2,699, 1792 grams

The photo above shows the accessories that come with each pair of Metron wheels – Swiss Stop yellow carbon pads, quick release skewers, valve extenders, and a 1.8mm spacer for use with 9 and 10-speed cassettes. The extenders require removable core valves; my favorite type.

It’s standard practice to find warning labels all over modern wheels. Notice, however, that these tubular wheels do not feature a tire pressure limit (unlike carbon clinchers):

Also notice how the spoke nipples are exposed through the rim (also called ‘external’). I always prefer this style for ease-of-service – especially on tubular wheels. Internal spoke nipples require that you remove the tire to make adjustments to the wheel (requiring you to re-glue the tire).

The Metron 55 front hub features straight-pull spokes and an overall minimal design. Ceramic bearings come stock, but we’re unaware of the source or grade.

Both front and rear hubs also have an adjustment nut on them for adjusting bearing preload. We only had the wheels in our possession for a few weeks, so we weren’t able to see how this worked first-hand.

The rear wheel has the now-common 2:1 lacing pattern that we see on many rear carbon wheels. Traditionally-built wheels with a 1:1 lacing end up with much higher spoke tension on the drive side (right) than the non-drive side (left) due to the different spoke angles. Using 2:1 lacing effectively forces half as many spokes (on the left) to do the same amount of work, increasing their tension significantly. I think this makes a lot of sense, and we will continue to see other manufacturers follow suit.

Those unfamiliar with tubular wheels might not think of this detail, but it is important: Valve hole diameter. The hole drilled in the outer rim wall must be larger than the hole drilled in the inner rim wall. This allows the material built up around the tubular tire valve to sit down in the rim properly, thereby avoiding a bump in the tire. Vision got it right:

Rim Shape and Width

Rim shape and width are of key concern to wheel buyers today, so we had many questions for Vision. The front rim is 25.4mm wide at the braking surface, and the rear is 24.2. In my book, this puts them officially in the ‘wide’ category, but not ‘super-wide’. Some rims are venturing into 27 and 28mm waters, for better or worse.

What Vision has done is very reminiscent of ENVE’s Smart System wheels. The rim width and shape differ for each rim depth. For example, the front 55mm rim has a relatively wide inner edge:

…while the rear 81mm rim has a very sharp inner edge:

We asked Vision’s Ron Correa to weigh in on why they chose the rim shapes that they did.

He writes,

“Like a ‘quiver’ of surfboards for different waves or breaks, the approach for our Metron wheel line was similar, to offer a complete wheel line in different depths to match any condition the cyclist would encounter on the road in the real world.

We were able to achieve this by developing the profiles in CFD (Computational Fluid Dynamics) for the purpose they would likely be used for, which is why the 55mm (all around aero=wider range of yaw for general cyclist) has a wider taper to the ID of the wheel compared to the 81mm (TT=shallower range of yaw). Considering this, the user benefits further by using the wheels as a modular configuration (40/55, 55/81, 81/disc, 3 spoke/disc) for days the wind is fickle and the athlete needs increased stability as well as aerodynamics for their particular purpose.

Another reason the 55mm is wider at the ID is it was refined to also be used with a larger volume tire (25mm) which is becoming common for the general public and pro tour due to lower RR and increased traction and stability.”

In effect, they designed the 55mm wheel for use with larger tires and lower speeds, and the 81mm wheel for use with narrower tires and higher speeds. While I understand the thought process, I personally go back to the reality of modern triathlon bikes and their hidden brake setups. For the vast majority of triathlon customers, I think the simplicity of consistent rim width is more important than a small change in rim width for any sort of other benefit. The Metron tubular disc matches this 81mm rear at 24.2mm, but the 40mm and 55mm versions sit at 25.7 and 25.4mm, respectively. This isn’t something that is of huge concern for those that rarely switch wheels, but when companies seek to sell multiple wheel options to us for different weather conditions, it only makes sense to standardize.

Ride Notes

I used these wheels with Michelin’s new Pro 4 25mm tubular tire, which we will look at in a separate article. The completed setup looks very sharp.

Unfortunately, my rear wheel was out-of-true right out of the box. When I personally build wheels, I shoot for lateral trueness of about <0.5mm, or as perfect as possible with very even spoke tension. I estimate that the rear Metron 81 had 1.0 – 1.5mm lateral runout. It did not get any worse with riding.

Vision representatives tell me that this problem would have been covered under the 2-year warranty, and that they carry out repairs when necessary. Customers are instructed to visit their local dealer, or call FSA directly at 425-488-8653.

FSA also sent a pair of their SL-K brake calipers ($255, 307g).

Historically, I am a fan of Shimano brakes, and these FSA brakes impressed me with their solid feel and lack of flex. With the supplied Swiss Stop pads, and Dura Ace carbon brake levers, the stopping power and modulation were very good. I rode the wheels in both wet and dry conditions, and from temperature ranges of roughly 35 – 60 degrees Fahrenheit, with no apparent change in braking behavior.

My only complaint with the brakes is that the quick release lever does not open the pads up very far; figure about half of what a SRAM or Shimano caliper will do. Clearance to my front fork was very tight on the left pad – it just cleared:

Aero Performance

Vision representatives tell us that all of their aero testing was done at the San Diego Low Speed Wind Tunnel.

I found it interesting that they chose to test all tubular wheels with the 22mm Continental Sprinter tire. While I have heard praise for this tire’s durability and quality construction, almost every wheel company tells me that the aerodynamic performance leaves much to be desired. According to Correa, this tire was chosen for a specific set of reasons:

“The aero data we have at this time should be viewed with the understanding that it does not reflect the true aero benefit which can be had from our wheels. It is internal development data which is focused around comparing one profile to another, [is] only a honest comparison within our line. We should have more conclusive data next year that will include the tubular wheels tested with many other tires (and clinchers), but at the moment it is incomplete.

The reason being is that the Metron profiles were built from scratch using CFD, with a tire that had no tread, so we needed a similar tire for the [wind tunnel] that was neutral. The Sprinters are a consistent beta tire; we can send the same beta wheel/tire to the tunnel with the next batch of test wheels and get within 5-8 grams from the previous runs. Tubular tires with tread patterns can vary the result further from one tire to the next and are not as consistent in repetitive isolated testing.

Is the Sprinter the fastest tire we have used? No, but it isn’t the worst either. Again, [it is] very neutral and primarily chosen for development.

One thing we have noticed in tunnel tests with using the Sprinter is it tends to stall wheels early and climb as the YAW increases vs. other tires which delay the stall and buffer it further afterwards. Considering it does this for all wheels (competitors or ours), it has allowed us see the value of the rim profile over the benefit of the tire used.”

This graph compares the new Metron 55 and 81 tubulars to the older and narrower Trimax Carbon 50:

This expanded graph includes the Metron disc, 3-Spoke, Metron 40 tubular, and shallow Trimax Carbon 24:

Without competitors’ information or faster tire choices, it is difficult to say exactly where the Vision product fits in the marketplace. I can say with a high degree of confidence that they are a sound improvement over older Vision product, and narrow wheels in general, especially with modern 23 and 25mm tire choices.

Summary

Overall, I think FSA is making good progress in the world of wheels. They’re on the wide rim bandwagon, and make a very sharp-looking product. The braking quality with their calipers and Swiss Stop pads ranks among the best in the industry, and general ride quality is outstanding. Despite not truly knowing the aero benefit compared to other brands, I enjoyed my time spent with the Metron 55 and 81. The rear wheel truing issue was disappointing, but (unfortunately), it’s not the first time I’ve seen it in an expensive set of carbon wheels. Your mechanic is still a necessary and valuable resource, despite increases in technology.

Most triathletes will benefit from the carbon clincher version of these wheels. The price goes up, but so does the convenience factor and ability to change flat tires on-the-road.