Suspension 101: Get Some?

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Nov 102011
 

Freakishly wonderful weather meant I put some time in on my Jones again today, and I had to chance to ride one of my favorite trails.

I’m aware of the irony of writing about designing a new full-suspension frame while spending time riding a rigid bike, but my trails are so perfectly smooth and obstacle-free that all those fancy pistons and ball bearings and such seem like decadent opulence. Why, once you’re out of the quarter mile rock garden on this section, you have only nine or so logs to hop before things mellow out onto a logging road. (“Logging road” is a local term, referring to rock gardens wide enough to try to drive a quad at least into if not necessarily out of.)

No, in all honestly, I was feeling pretty tired today and had planned on going with the Pivot 429, only to discover it had a flat front tire. I no longer work at a bike shop, which means every time I encounter even a small “mechanical,” I immediately give up and start looking for a different bike. So the Jones 1×10 got the call, and a damn good thing, too. Having rolled up on a 10-point buck entertaining his lady friend, I emerged unscathed and unintimidated, thanks to this.

Only four points, but they're titanium, so step off, Bambi.

While gently coursing along, having the shit only lightly kicked out of me, I had time to contemplate the point of “full-suspension.” A friend following the suspension design stuff I’m working on recently asked me to write more about the basics of suspension–set up, how suspension is supposed to work on a mountain bike, that sort of thing. I’d been wondering where one begins something like that, and suddenly I had my answer.

The first step in understanding the basics of bicycle suspension is to ask yourself if you need it.

I don’t know a single hunter who uses an automatic weapon to bring home the venison. Assault rifles might be able to fire a hell of a lot more bullets at something, but that doesn’t make them “better.” Trying to use one would completely miss the point. But from what I can tell about preferred firearms for violent revolutions and zombie apocalypses, the more bullets, the better. Different strokes, you know. Consider, too, that I was living in Atlanta during the height of the SUV craze, and many of the vehicles being sold there were actually two-wheel-drive. As a guy who had to haul three dogs home to a particularly vertical part of Pennsylvania every winter and planned to move back there soon, I was looking for something a bit more four-wheel-drive, but the salesmen kept acting like I was requesting the humidor custom fitted to fit my favorite cigars option. He didn’t get why I would pay extra for powered front wheels. (In the end, we could only afford the powered front wheels of a comically small Saturn anyway.)

So my first piece of advice about owning a mountain bike with suspension is to ask yourself if you want it. Even the best full-suspension frames out there are more complicated than a rigid bike, and ask more of their owners. Maybe your trails are perfectly smooth (like mine), and you accidentally started a fire the last time you tried to change a lightbulb–in which case, the more enjoyable long term decision might be a bike with less going on.

There certainly seems to be a lot of simplicity going on these days. If you just dabble in the whole “mountain biking” thing, no doubt you’ve noticed that a lot of the cool guys have switched to brightly colored, really simple bikes and micro-brews with more complicated label graphics, instead of the previous vice versa.

This is because everyone else found out about full-suspension bikes, and owning one no longer says, “I’m deadly serious about this shit,” the way it used to.

"You aren't stupid passionate like I'm stupid passionate" circa 1999.

They were riding full-suspension bikes when you were roller-blading, pal. Green Day isn’t a punk band. Welders’ hats are the new trucker hats. Marilyn Manson was just Skinny Puppy for slow kids. Handlebar mustaches are the new sideburns. Etc.

So maybe you don’t need a full-suspension frame for your riding, and you can get much nicer components for less money on a bike without suspension. With less to fiddle with, you might even ride more. It could be awesome.

But probably not.

For a lot of trails that aren’t as smooth and boring as mine, even a pretty compliant steel, titanium, or carbon frame that doesn’t have wheels that go up and down when they hit something is going to kick the living shit out of you every once in a while. Most owners of ultra-minimalist single-speeds also own suspension bikes, and the trade-off of lugging around the added weight and complexity sometimes means being able to walk the next day. It’s good to understand that–particularly with the rise of very slightly smoother-rolling 29ers–full-suspension bikes are no longer quite as aspirational–a marketing term that means “shit you want without knowing why,” but they still make a hell of a lot of sense.

So the first step to buying a full-suspension bike isn’t a technical detail or consumer check list: it’s asking yourself if you need one. You’re the expert there, and your favorite trails are your resource. They’ll tell you what type of bike to own, and whether you need a Jones H-bar, or an automatic weapon.

The Details

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Nov 082011
 

I’m sure there’s confusing and intentionally misleading information about playing the stock market or home dentistry here on the Internet, but I have a hard time believing any information out there is as screwed up as what I see about shock rates on mountain bikes. What we hear from a lot of manufacturers comes to us as filtered through the Marketing department, and for all we know originated as much in Accounting as in Engineering (“Say, we got a great deal on a thousand rockers so-and-so couldn’t use. How ’bout you design a frame that uses them?”), so bullshit is rampant. Often, getting information about how suspension systems actually work in this business is like listening to a drunk friend describe a movie you’ve never seen.

I’m certainly no engineering expert myself, though as English Majors go, I think I’m passable, and I do have that level of respect for simple machines that gets earned somewhere in the four thousandth hour of staring at a design and trying to figure out why it keeps laughing and kicking you in the nuts instead of “working.” The key to making something decent is knowing what you want, and what I want out of my design is the Holy Grail of shock rates: the highly variable one.

In an earlier post, I’d mentioned the advantages of using short rockers to give yourself maximum shock rate tuning options. My thinking there–and it could be flawed, but I don’t think so–is that shorter rockers have the ability to rotate more throughout the movement of a suspension system (as opposed to something like a Horst-link bike, in which the whole chainstay is effectively a slower rotating link), and that two substantially rotating little rockers open a lot of tuning doors.

Why? In the illustration below, I’ve colored my rockers orange.

Consider the rotation of each of the orange rockers in the image above. Now imagine each of those orange lines connected to the main frame and spinning in a circle, what you effectively have are two gears. Their movement can be very finely tuned, and that means so can your shock rate.

So now’s the time in the course of development when I throw out all previous shock rates I’d created and look to come up with one, final, “perfect” set of shock and leverage rates I can graph like these examples. Ideally, you want your suspension to be as supple as possible up to the sag point–the point to which the suspension should compress with a rider on the bike–then firm up at and just past that point for pedaling, then drop away some for smooth bump absorption during that middle range of travel, before finally firming up again as the frame begins to run out of travel.

That might seem like total gobbledygook to some of you, but hardcore nerds out there, I welcome your feedback: please send your thoughts as to the ultimate shock rates throughout a bicycle’s rear wheel travel. I’ll keep tuning that shock position and those rates in the meantime, and will try to go into greater detail right here. There’s still a particular type of ride that I’ve just never gotten from any other frame, and that’s what I’m after.

That, and a name for this thing. Suggestions welcome there, too.

Made in the U.S.A.?

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Nov 072011
 

One of the criticisms I often hear of high-end bike companies is that all of their frames are made in Taiwan (or, increasingly, China). The assumption here is that production costs in developing countries are so low that brands are outsourcing to drive up their profits and make more money–and that’s usually a pretty good assumption. But as a guy trying to get a prototype frame built, so far it’s been my impression that Taiwan is not the cheapest, but rather the only place to do it.

I hope I’ll be proven wrong, but so far companies in Taiwan, and their trading agents, have proven to be drastically more responsive and interested in building the frame. Stateside builders I’ve talked with either lack resources and need a year or more to get something built, or don’t seem interested in getting back to me. And that sucks. I’d rather build this prototype here. In an ideal world, I’d even like to have options in a fabricator, and get this single frame built in six months.

But what’s become pretty obvious to me is that there’s just not much small-scale manufacturing going on here. That isn’t to say we can’t make things. In a backyard DIY sort of way, we’re still the top of the food chain. We still have enough of a middle class that once upon a time had disposable income for some of us to have small machine shops and painting booths in our garages, and we know how to genuinely create something. But we seem to go straight from “I have a friend who can MIG weld” to “Alcoa,” without all that much in between.

No, we’re more of a “Service Economy,” which means we better hope they keep opening new Starbucks.

At least BikeRumour was showing off some serious hardware that’s U.S. made.

Speaking of the prototype I’ve looking to create, most of the questions I’ve been getting revolve around (pun intended) the lower rocker. Here’s a detail shot:

One of the patented aspects of the design is the position of that lower rocker. Unlike a lot of short lower rocker orientations, this design lets the swingarm attach at the front of the rocker–ahead of where the rocker attaches to the frame. This allows for several things I believe to be very good, but one key characteristic of the design is a 29’er-friendly axle path.

Most people can understand that the larger diameter rear wheel causes clearance issues with the frame–in particular, once a bump force acts on the suspension and moves the rear wheel upward, it doesn’t take long for that arcing big wheel to get really close to the bike’s seat tube. That part’s pretty straightforward. But a 29er’s bottom bracket also sits lower relative to a bike with 26″ wheels. Because of that lower bottom bracket (aka “increased bottom bracket drop”), a totally unladen 29er is a little like a 26″ wheeled bike that’s already partway into its rear travel.

Center of the bottom bracket sits significantly below the axle.

This all means that axle path relative to that bottom bracket shell is critical on a 29er. (In the process of working this out, I looked at Niner’s CVA system, which is a pretty brilliant way to deal with the challenges of the added bottom bracket drop on a 29er.) Getting sufficient travel without having to shove the seat tube forward (shortening the effective length of the rider’s compartment) or pushing wheel out behind the rider with longer chainstays (which can decrease maneuverability and make the bike ride “flat footed”), is a challenge.

After a whole lot of hours testing rocker widths, angles, and orientations, I believe I’ve found an axle path that will let a 29er be as agile as most 26″ wheeled bikes. There was also a very specific effect I wanted to see happen with the swingarm, and I’ll have some more on that later.

Looks Like Death

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Nov 032011
 

Nigel Tufnel Day is fast approaching, and that means spending quality time with the family, singing along to “War Pigs,” and trying to explain a Maiden show to the kids.

I’m not sure what it says about me that I let my six-year-olds watch GWAR on Jimmy Fallon (don’t worry, I DVR’d it–I’m a stickler for bed times), but I’m pretty sure that when you tell them you once almost managed to rip the giant rubber hammer Oderus was using to bash members of the audience on the head right out of his claws, you’re not supposed to beam with crazy pride when one of the kids looks up at you and says, “I want my life to be just like yours.” (If there hadn’t been so much fake blood, I’d’ve had that hammer, too.)

Balsac is the intellectual one.

At any rate, the ultimate “going to 11” day is nearly upon us, and it has me all philosophical and pondering the current place of the not-so-heaviest of metals in the world of bicycles: aluminum. (“Aluminium” for those of you who feel the need to add still more vowels to perfectly good words.) As a guy thinking more and more about designing a bicycle, what I’m wondering is, will there be any high-end aluminum bike frames ten years from now? Five?

Don’t get me wrong: steel isn’t going anywhere, and if Moots were a publicly traded stock, I’d be in that, but one has to wonder whether carbon fiber is slowly becoming the only game in town for fancy-pants, high-tech frames. When it comes for ultimate frame materials–particularly for full-suspension frame–there’s just none more black than carbon fiber.

So what would you do?

This isn’t a bridge I have to cross right away, and I don’t think I’ve ever known anyone crazy enough to use carbon fiber for prototypes (well, OK, there was at least one), but, if you wanted to try to impress the world with what you suspect might just be a decently badass suspension design, would you produce the frames from aluminum, or is the bar so high these days that you have to go straight to carbon to even be competitive?

That’s what I’m wondering tonight.

That, and, “Why don’t more vocalists use analog profanity editing techniques during live performances like Maynard?”

The American Dream*

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Nov 012011
 

(*Made in Taiwan?)

Just when I think I’m down to only snarky rants, something important to me and maybe even interesting to others comes along. In this case, my search for someone to build me a frame has become the sort of thing worth mentioning here, because it’s decision time.

I’ve been hoping to find someone capable of fabricating a frame for me. Before anyone suggests I go to Portland, where custom frame builders cluster around the pedi-cabs of tourists, jostling for attention and occasionally locking handlebar mustaches in terrifying displays of territorial competition, I’m not looking for an “artisinal” frame builder capable of airbrushing The Last Supper on a steel hardtail with six top tubes (though that would be pretty cool). I’m looking for more of machine shop this time around. This is the contraption what I’m fixing to see made:

In 2007 I came up with a different take on a suspension system for a bike frame, then forgot about it until the patent was approved last year. I’m a fan of crowdsourcing ideas, and previously mentioned that I’m open to any ideas for the design and for partnerships, but, unless you’ve read the patent in detail, chances are you don’t know much about the design. I’m going to try to provide as many details about the design as possible here at canootervalve.com, and, as always, I’m easy to find at chris@canootervalve.com and would love to talk suspension systems.

Here’s some things I’m up to with the design:

  • Conceived from the ground up as a 29er–rear tire clearance and the relationship of the bottom-bracket to the wheel’s axles require a unique design
  • Predominantly vertical axle path
  • Short, dual-links allow a huge tuning range for bike rate
  • Designed around simplicity and frame fabrication versatility–I wanted to keep the suspension system from compromising the basic front triangle design
  • Everything low–the position of the shock shouldn’t ruin the bike’s standover
  • Maximum tire and chainring clearance
  • The shortest rockers that would still allow a range of quality ball bearings
  • Very little chainstay growth under compression–it’s not a World Cup DH frame, and I want the chainstays to be short all the time, not just when the bike’s sitting still
  • Yep, short chainstays–more importantly, a suspension and frame design that allows them to be as short as possible, and likely into hardtail range
  • Simple swingarm that can be built of larger diameter shapes
  • Light by design

Here’s a quick animated GIF to help illustrate the motion of the swingarm, which is the unique part.

Those of you who really geek out on suspension systems will pretty quickly notice what’s so different about the design. What Sotto has developed for Yeti is the only other thing I’ve seen that orients the rockers in this position, and the designs seem very similar, though they’re doing something different from me. More on the actual swingarm motion later, or if anyone wants to contact me privately.

Anyway, I don’t have a welder or a machine shop, and I need to build a proof of concept to go test this thing. I’ve already been in touch with multiple builders to get an idea of time frame and cost of the project. Given all my recent rants about U.S. innovation and such, I naturally was trying to have the prototype built here in the States, so, as a kind of practical experiment, I contacted two different parties about building the proof of concept frame today: both are companies–not individuals–and one was in the U.S., while the other was in Taiwan. Both have already gotten back to me.

Decisions.

I’ve never been in the position of a manufacturer, paying for fabrication of a product. In both cases, I’m in the “about to sign a non-disclosure agreement” phase, but it will be really interesting to see how the two scenarios play out, and what the actual, landed, price difference will be. More than anything, it will just be tremendous learning experience to go through this process, and my goal is to document as much of it here as possible.

Though I’m not looking to launch a bike company right now, I think I might also need a name for a new company I need to create as the owner of this design. I named the last thing I did “Speedgoat,” so tough to say where I’d go with this.

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