carbon fiber – Seven Cycles

The Numbers

As you can imagine, at a company whose name is Seven, numbers play an immeasurable part in everything we do. The name Seven, just to get this out of the way first, is a product of our desire to build bikes to be ridden on the seven continents, a lucky number, a prime number, and even as a word, a symmetrical combination of letters that looks good on a down tube.

Taking a step backwards to six, the first number in the name of our category defining 622 SLX, we find carbon, the sixth element in the periodic table. Carbon fiber is the defining element of the 622 line of bikes. It brings elemental lightness to those bikes. High frequency vibration, radiating up from the road or trail, disappear between the fibers.

Now jump forward to twenty-two in that same table, titanium, the metal that launched our bike building careers. Five times the strength of steel at the same weight, titanium moves with a rider like nothing else. It flexes and returns microscopically, soaking up the lower frequency jolts that push beyond carbon fibers range. Titanium smooths the ride, keeps your tires connected, spares your muscles. It won’t rust. It holds a shine like little else.

a wall of photos — A Long History of Photo-Taking

Nineteen is another prime number. Nineteen is the number of years Seven has been building and delivering bikes. Our second full decade is there on the horizon. And, with apologies, we are primed to do our best work. This year’s R&D effort will produce a slew of new products, new bikes, new forks, new frame components. We have already begun planning limited editions for our anniversary, already begun gathering the ideas that have been developing over those decades.

There are so many more numbers, too. Too many to call out, the lengths and angles of every rider-specific frame we’ve designed, more than 30,000 of them, the number of bike and component companies we’ve partnered with, the hundreds of bike builders we’ve been fortunate enough to train and learn from in return, and of course, all the riders, many of them with two, three and more bikes they asked us to build for them, maybe the most important number of all.

When We Ride Roubaix

The Queen of the Classics, the Hell of the North, the Paris-Roubaix “road” race from the suburbs north of Paris over the famed cobbles of northern France and into the velodrome at Roubaix takes place this Sunday, and we can’t help but think (mostly because our own Rob Vandermark is there riding the course on Saturday) that titanium makes a lot more sense for a cobbles bike than carbon fiber.

Carbon fiber is great at being light and stiff, but it’s no mystery why many of the big bike companies put elastomers or pivots in their rough road bikes, because carbon fiber doesn’t absorb the bigger impacts as well as a more compliant material, like titanium.

Here’s Rob’s bike with Paris in the background. Look for more photos from his trip over the pavÃ© in the weeks ahead.

A Holistic Approach

Every new bike purchase is, in a very real way, a design challenge, engineering the best possible solution for the type of riding you want to do. How you address that challenge can vary wildly, from choosing an off-the-shelf bike that already does most of what you want it to do, to building a fully custom bike.

When we think of a new bike at Seven, we start our own design process with material choice. What frame material makes the most sense? Steel has a unique ride feel, bright and lively, comfortable. In the hands of a good builder, steel can be light, too. But titanium can be light and just as comfortable. It won’t corrode, will survive better in a crash, can be repaired. In a word, it is durable. And carbon fiber, which is even lighter (in most cases) and stiffer. It dampens vibration well, but is not generally as durable as titanium or steel, nor as naturally comfortable.

We think it’s important to start at the beginning, with frame material, rather than jump forward to decisions based on component spec or features. The riders we talk with every day know what they want their bike to do. Why not choose the material that does those things best, rather than settling for a bike retro-fitted to do them.

As an example, many carbon fiber road bikes have some sort of impact dampening system built in, something to take the edge off, either an elastomer insert or a suspension pivot. What this suggests is that the base frame material wasn’t the best choice for the purpose, a more compliant material like steel or titanium made more sense.

We also know that it is possible to get benefit from multiple frame materials, which is why we build mixed material bikes like our 622 XX. Here again, we try to take a holistic approach, matching the materials to the purpose from the beginning of the design, instead of engineering ways to overcome a material’s weaknesses. The 622 XX uses frame material to incorporate the stiffness and lightness of carbon fiber with the compliance and structural strength of titanium. It looks pretty good, too.

When you take a holistic approach to bike design, you work forward from the frame material’s capabilities, rather than working backwards from its limitations. This is what we try to do, with every bike.

Titanium/Carbon Mixes – The Best of Both Worlds

If you were to take a carbon fiber tube and wrap it against the wall, then hold your ear to it, there would be little if any sound emanating from the tube. If you did the same test with metal, it would sing like a tuning fork. The same holds true for frames, metal sings and carbon whispers. These two qualities make for very different experiences on the road. Carbon bikes, like our Diamas line, make pitted and potholed roads feel like you are pedaling over wall to wall carpeting; smooth, with very little feedback. Metal bikes, like the Axiom, Resolute, Sola, and Mudhoney, on the other hand, provide constant feedback keeping you in tune with the surface of the road. Once we start customizing and manipulating tube sets, we can alter how compliant or how stout the frames will be, but the material dictates how the road’s vibrations will be relayed to the rider.

There is a gap between whispering and singing, and to some, that’s where the perfect bike resides. By adding carbon tubes to a titanium frame, or vice versa, we can fabricate a bike that hums, bridging the gap between the two materials.

The idea of a titanium frame paired with carbon seat stays for the intended purpose of soaking up road vibrations was a notion that Seven pioneered and first implemented with the Odonata back in 1997, and though there have been some updates and improvements the same basic model exists today, now known as the Elium SL.

The ride of a ti/carbon bike is so pleasant, that we offer them in road, cross, and mountain bike disciplines.

Crafting Carbon

We have covered steel and titanium in recent posts. Now it’s time to talk carbon fiber.

Our approach to carbon fiber is fundamentally different than the one taken by most production bike builders, who focus primarily on the lightness and stiffness of carbon. While those are both positive characteristics of the material, we believe, in any rider-specific bike, they have to be balanced against the needs for the bike to fit properly, handle well and last a lifetime.

Though we are sometimes perceived as exclusively a Ti frame builder, we are working with carbon fiber every single day and have been for many years. We have, at this point, built thousands of custom carbon and Ti/carbon mix frames. Carbon fiber is a material we value highly for its aforementioned lightness and stiffness, but also for its natural vibration dampening characteristics. So whether we’re building an all carbon Diamas, or a mixed material machine like the 622 SLX, we always focus on why carbon belongs in the design, and then work to maximize its benefits.

There are two basic types of carbon tubing that we work with. One is round carbon tubes, like the ones we use in our Elium line, the 622 SLX and the Mudhoney PRO. These tubes are built to our specifications for diameter and wall thickness. By mixing and matching a wide array of round carbon tubes, and mating them to titanium lugs, we can tune the stiffness and handling characteristics of mixed material bikes in much the same way we do with our all Ti frames.

The other type of carbon tubing in heavy use at Seven is shaped. Just as we have an array of round carbon tubing, we also keep a significant selection of shaped tubes on hand for use in our A6 carbon line. While the outside diameter and appearance of the tubes remains constant from model to model, the wall thickness varies, altering the performance characteristics of each tube. Cut, mitered, wrapped and bonded in house, our shaped A6 tubes give us complete customizability of fit, handling, and road feel (within the range of possibility for carbon).