Seven Cycles – Page 61 – U.S. Built Custom Bicycles in Titanium and Titanium-Carbon Mix

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.

How a Bike Gets Born

To make a bike, a Seven anyway, you need a rider, a hammer, an anvil, a set of number and letter stamps, a wax pad, and a pair of drop outs. Here at our shop, there is no bike without a rider, and every rider gets their own serial number.

You load a unique code, four numbers, a letter, two more numbers into the stamper, and press it into the wax pad to check that it reads correctly. You pull a pair of raw dropouts from the bin and lay the drive side one on the anvil. You raise the hammer, not too high. Accuracy is important.

Then you pound the stamper with the hammer and that, THAT, is how a bike gets born.

The Big Ideas – Just-In-Time Manufacturing

The Big Ideas, as a series, is about this whole bike building project we embarked on in 1997 and the foundational ideas that make what we do possible. The first installment was about Single-Piece Flow (SPF).

This week we’ll talk about Just-in-Time manufacturing (JIT).

JIT is the idea that our own manufacturing inventory only arrives exactly when we need it to, that a rider ordering a bike actually triggers the process of the bike’s component parts beginning to move toward the bike builder’s work space. This is the method that supports the madness of Single-Piece Flow, and the myriad complications of building fully custom bikes on a short timeline.

We make it work by doing a lot of forecasting. After crafting 30,000 bikes, one-at-a-time, by-hand, we have a lot of data to crunch, so we do our best to see the future, the materials we’ll need to build the bikes our riders will want.

Another thing we do is keep all of our materials in their rawest form. All of our titanium tube stock, for example, is straight-gauge. If we need to build a butted frame, we butt the raw tubes to suit the order. We achieve three things this way. First, we reduce the amount of inventory we need to keep on hand. Second, we maintain control over the refinement of the materials, so that we’re refining them for their specific rider, rather than just turning out generic tubesets. And third, we maintain a tighter control over the quality of our materials. Smaller lots of tubing are easier to inspect. The best materials make the best bikes. This turns out to be a big deal.

Less inventory also narrows our focus on process and adds a sense of urgency to every build. To succeed with JIT, we need to clearly define each design before we start to build. We need to solve the design challenges in advance, because our system depends on having a very low amount of material waste. Our ability to build the next bike literally depends on getting the bike in front of us right. That’s good pressure, and it produces great bikes.

Streamlining processes and tightening inventory makes US, craft manufacturing possible. This is how you can get a fully-custom, US-made bike for the same price as a high-end, Asian-made production bike (where labor and materials costs are a fraction of our costs). In a world filled with batch-made products, Just-in-Time manufacturing as a way to bring craft-made bikes to market is, for us, a very big idea.

Trail, Rake and Bikes That Handle Well

Our friend Phil tests the 622 SLX (and its handling) on the cobbles of Northern France.

For a simple machine, it can be hard to understand how to make a bike handle the way you want it to. While a lot goes into how a bike feels on the road, the basic mechanisms of good handling are trail and rake. Trail is the distance between the axis of the headtube, where it intersects the ground, and where the tire actually contacts the ground behind it. Rake, or offset, is the distance between the axis of the headtube and the axis of the front axle, usually between 4 and 6cm.

Our approach, here at Seven, is whenever possible to keep trail constant. The trail sweet spot is just under 6.0 cm. “Sweet spot,” in this case, simply means consistent and predictable handling at any and all speeds.

For example, if a rider is looking for a criterium bike (think: quicker, more agile steering), we keep the trail fixed, and adjust the head tube angle. Steeper is quicker. Of course we’ll change a lot of other geometry elements, too: drop, chainstay length, front center, ride position, tubeset, etc. Conversely, if the rider is looking for a century bike (think: stability), we keep the trail fixed and make the head tube angle slacker. And all the other geometry elements change, too.

Altering trail to affect handling seems like a logical move, but the result is handling that changes throughout the speed range. A high-trail bike will be super stable at high speeds and pretty squirrely at low speeds. High speed stability might sound good but it also means that when getting in and out of corners the bike will fight you. Messing with trail basically means the bike behaves poorly.

Unlike a Seven, plenty of stock bikes don’t have trail in the sweet spot. Riders get used to bad trail. This is particularly noticeable on really small production bikes. Small stock bikes are trying to avoid toe overlap by using a slack head tube angle without an appropriate fork rake; most companies use one or two fork rakes across the size range, so the trail is terrible on bikes with top tubes shorter than about 53 cm. Otherwise, they’re doing something goofy with the geometry somewhere else – seat tube angle, drop, etc., always making compromises because they don’t have the fork rake options to get them back to a reasonable trail.

It’s really interesting when that same, smaller rider gets on a Seven with the right trail; the feedback is that the bike handles amazingly. “It’s on rails,” “telepathic,” and “I descended faster than ever,” are common phrases we’ll here.

Of course there are exceptions to every rule. A few examples of rare instances when we’ll change trail from the sweet spot are:

We have no option: For example, the rider wants to use a non-Seven fork that only comes in one rake.
Some specialty bikes: Sometimes on heavy duty randonneuring bikes we’ll do low-trail because this makes the bike more stable at low speeds – and it can help with handlebar bag weight on the front end. On some triathlon bikes we’ll break the trail rule and increase it to make the bike more stable at high speeds. And on most mountain bikes the trail standard gets ditched – in part because of fork rake limitations.

At its most simple: Handling is dictated by head tube angle. Predictability of the handling is determined by fork offset.

The Cycling Media Reacts to Mo Bruno Roy’s Retirement

It’s been a happy/sad week for Mo Bruno Roy, since she announced her retirement from Elite Cyclocross racing. New beginnings are like that. It’s a testament to all the things we said about her just a few days ago, that the cycling press has covered her retirement in a way they don’t usually mention other riders moving on.

There were kind words on VeloNews, a nice interview on Bicycling, and a photo series on The Radavist, showcasing Mo’s Mudhoney PRO race bike, all-in-all the nicest way to sign off from elite racing that we can imagine.

Stay-tuned for our own interview with Mo, and don’t think you’ll stop seeing her on her Seven or in these digital pages. She’s not racing elites next season, but, in literal terms, she can’t stop/won’t stop.