The bike industry has traditionally worked backwards from race bikes to fill shop floors with race look-alikes for everyday riders who will never turn a crank in anger. What is good for the pros, so the logic goes, must be good for you, too, and for some very small number of non-pro riders, that could be true.
As with all our bikes, we start with the purpose of the bike and work forward. Going fast requires being able to sit in a comfortable, aerodynamic position, to be able to handle your bike in tight spaces, and to get good power transfer through the rear triangle.
As custom builders, getting to that perfect position is a given. We can replicate exact saddle and grip positions from a bike fitting. We can dial in handling by adjusting headtube angle and fork rake to produce the exact characteristics the rider wants. We can adjust the stiffness of the rear triangle by selecting specific diameter chainstays, up to and including the 1″ stays we call “race stays.”
Our 622 SLX rivals all of today’s carbon race machines for weight and stiffness, but it incorporates more road feel and better comfort than those bike through its unique combination of laser-cut titanium lugs and filament-wound carbon tubing. Our all-Ti Axioms make great criterium bikes for their ability to absorb the heavy impacts of racing on imperfect pavement and the way they come through the occasional crash.
The technology of race bikes evolves quickly, and adapting to new component standards can be a challenge, but with a custom bike these things can be considered during the design phase to leave you with as many upgrade options as possible.
The thing is, bikes aren’t fast. Riders are fast. The best way for the rider to Go Fast is to design a bike around them that fits them perfectly, handles the way they want it to and transfers as much of their power as possible.
Here’s a 622 SLX we built with our friends at Bean’s Bikes in Berwyn, PA. This Ti/carbon machine is finished with our Lug Deluxe paint scheme with a special “rattlesnake” finish on the carbon that shows a different color depending on the light and the angle you’re looking from. The decals are a custom Glitter Gold outline.
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. Titanium can be lighter still, and just as comfortable. It won’t corrode, will survive better in a crash, can be repaired. In a word, it is durable. And finally 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 SLX. 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 SLX 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.
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.