Just Riding Along Crash Testing in the Cycling Industry

by Seth Lightcap

ODGee testing the flight controls.

Photo: www.olivierguincetre.com

Imagine this:

You’re blazing down a favorite trail on a new full-suspension mountain bike. Your brakes are buttery smooth, your suspension is dialed. The rocky trail melts under your wheels. Feathering the brakes you prepare to hit a small jump that drops off into a creek. The line for the jump is tattooed on your brain. You stand up on the pedals and pull up slightly as you hit the lip.

Whoa! The lip has more pop than expected. Someone manicured the takeoff. You’re floating balanced, but way over the front wheel. You aren’t worried yet. After all, your hard-earned dollars bought you a beefy suspension fork. You prepare for the blow of a nosedive landing.

The front wheel hits. Suspension fork bottoms out: Crack! Your virgin bike frame buckles directly behind the fork on the down tube. The front wheel folds left. You torpedo over the bars like a lawn dart. You’re headed for a rocky kiss. Your helmet is on, but is your chin-strap tight?

Is such a nightmare possible? Could a bike frame really just crumple landing a jump? Riding your average cruiser frame—absolutely. But if you were riding a frame built for such abuse? Not likely.

An airborne mountain biker amounts to a tremendous ball of energy. When a sudden impact redirects that energy into a rigid object like your frame or your helmet, there is a finite amount of force it will withstand before giving way. Cross that threshold and products will fail.

Whether it’s a bike or a baby crib, manufacturers are responsible for determining when a product will routinely fail. Once a product’s limitations are known, the company may label the product with explicit recommendations as to its intended use. If a product shows that it is prone to failing when used as intended it may be recalled. But if a failure occurs during improper operation, it is the responsibility of the user.

ODGee up the wall. www.olivierguincetre.com

In most cases, manufacturers must meet certain testing standards for products before they are deemed acceptable for sale. Depending on the product, standards may be voluntary or government mandated. Where public safety is a concern, standards are mandatory and governed by the Consumer Product Safety Commission. Voluntary standards are usually created by private organizations concerned about efficiency, compatibility, and safety.

The bicycle industry is regulated by both voluntary and mandatory standards. Basic frame strength standards are mandatory but most manufacturers surpass these. Bicycle helmet standards are mandatory, having been signed into law by Congress.

When developing new bike products designers must first assemble prototypes. As a design evolves, each successive version must be tested to meet the standards. Many cycling companies invest substantial resources into developing in-house testing facilities. Two California cycling companies known for their extensive test laboratories are Bell Sports and Santa Cruz Bicycles.

Bell is an industry leader in the manufacture of helmets. Starting with auto racing, Bell has gone on to produce helmets for just about every sport. With its purchase of Giro helmets in 1996, Bell Sports adopted a home in Santa Cruz and added the industry-leading designs of Giro to its own line of bike helmets. The merger also made possible a cutting-edge testing facility.

Santa Cruz Bicycles is an independent bike manufacturer that has helped pioneer the art of full suspension. Their frames are coveted worldwide for their superior ride and durability. Dedicated to producing only frames that meet strict self-imposed standards, Santa Cruz has created a custom test facility to assure that new frame designs meet their lofty standards.

Let’s take a peek behind the dead-bolted test lab doors of these two companies.

Tighten your chin strap!

Photo: Seth Lightcap

Bell Sports

A man of many helmets, I had a stack of questions when I arrived at Bell. Glimpsing the historical helmet display in the lobby, it seemed promising that I would leave with some answers. My docent was Bell’s Test Lab Manager, Brian Sidwell. Brian has run the test lab for several years and is an industry authority on testing methods and standards.

“What can I expect from my helmet?” I inquired before he even opened the test lab doors. “Will I walk away smiling from a massive head blow if my helmet hits first?”

“It’s not quite so simple,” he replied.

“The responsibility of a helmet is to provide an environment that will decrease the force of acceleration on the brain upon impact. The force of your brain slamming against your skull is what causes brain damage. Your safety will depend on how hard you hit.”

Certain variables not withstanding, a helmet that meets mandatory standards should protect you when the intensity of the collision is equal to or less than the test threshold.

“So what’s the test?” I asked as Brian led me into the lab.

Towering test machines were arranged to one side while helmets of every design were organized in surrounding racks. Brian loaded up for an impact test. A helmet weighted down with a head form was suspended two meters above a blunt steel anvil. With the flick of a switch, the helmet plummeted and struck the anvil, landing dead on its temple.

The blow barely fractured the hard plastic coating and left but a 1/8 inch depression in the helmet. Glancing at the monitor, Brian verified that the helmet had passed the standard.

I was impressed. You never know how hard your head will hit in a crash but the anvil blow looked rough. Witnessing the helmet survive with only minor damage, made one thing obvious Å0å2 a helmet can save your life.

But to be most effective, it’s imperative that the helmet fit properly, Brian stressed. A helmet should be comfortably snug. The ear adjustments should be just under your earlobes and your chin strap should be snug against your chin.

In the next test a helmet was strapped on a fake head. A weighted bar was then suspended from the back of the helmet. To meet the standard the helmet must stay on after the weight is dropped. As the bar fell, the helmet winced slightly but barely shifted.

I thought about how I flip my helmet back and scratch my head without undoing the chin strap. Would my helmet pass this test? Not how I’ve been wearing it. After countless bike rides, skate sessions and snowboard descents, I realized how foolish I had been parading around with a loose chin strap.

Blam! Another helmet hit the anvil.

“Every sport seems to have its own specific helmet,” I said to Brian. “Am I compromising my safety by mismatching a helmet with a sport it wasn’t intended for?”

“Not necessarily,” he replied. “The main difference between helmets is the amount of head coverage and the number and type of impacts they are rated for. A helmet can be worn in multiple activities, but if the accident is abnormal to the sport the helmet was designed for it may not perform adequately.”

I recalled how I had once lent a friend my rock climbing helmet for snowboarding. Obviously, my climbing helmet was not intended for the high-speed impacts of snowboarding. Nonetheless, it was still better than no helmet at all.

Finishing up the tour, I thanked Brian and the crew and headed out. Arriving home I remembered what I needed to do right away: Tighten the chin straps on all my helmets!

How would your body feel after 300,000 bad landings? Photo: Seth Lightcap

Santa Cruz Bicycles

Have you been mountain biking recently? If not, you may be surprised at the terrain even occasional riders attempt to negotiate. Singletrack trails aren’t just rocky hardpack anymore. On new trails you may ride off a four-foot log drop or launch a six-foot gap jump. It’s all part of the fun as confident riders trust that the bikes can handle such big hits.

The current crop of high-end trail bikes are the most forgiving and maneuverable ever produced. Engineers like those at Santa Cruz have spent more than a decade tweaking suspension and frame designs so that the bike doesn’t spit you off when you barrel into a garden of boulders. Your ability to keep control through massive bumps is due to the suspension absorbing the energy that’s created when your wheels spontaneously change position over an obstacle.

A bike frame with rear suspension is designed so that the metal tubes rigidly resist flexing while the shock absorbs all that it can handle. But like a boxer, metal will start to fatigue after repeated hits. When the metal components on a bike frame reach their fatigue limit they will crack or bend.

The test lab at Santa Cruz is dedicated to researching the fatigue limits of frame designs. Durability is incredibly important to Santa Cruz because they tune the ride quality to handle the roughest terrain around. Great handling means nothing if the frame cracks after a hundred bad landings. A hardcore rider expects a bike to suck up around half a million landings!

The first time I saw the test machines at Santa Cruz I was a little confused as to how a few clamps and hoses could simulate years of rider abuse in a single day. But the pile of broken frames in the corner had clearly been worked.

To better understand the torture tactics I talked with the designer of the machines, Eric Lindsley. He explained that the machines use hydraulic pistons to simulate the forces that an aggressive rider on tough terrain applies to a bike. One simulates standing and cranking hard on the pedals while another mimics landing a big jump. Programmed to apply the force of such landings in repeated succession, the bike absorbs the equivalent of a year’s worth of hard riding in a couple hours.

New designs also undergo tests designed to mimic catastrophic accidents. One of these is the JRA test, short for “just riding along.” The JRA test simulates running into a brick wall at faster and faster speeds. By compressing a hydraulic piston attached to the wheel mounts the frame comes under increasing stress. The test is over when a tube buckles or a weld cracks.

There are mandatory standards for frame strength but those standards are so low even toy-store bikes pass. The standards that Santa Cruz adheres to are purely self imposed. Rider owned and operated, they refuse to sell a bike they wouldn’t ride themselves.

Hanging throughout the test lab there are frames of every model with the number of test repetitions it took to crush them written on the tubes. Compiling all this information in a database, the engineers are able to compare frame strengths by model and judge new prototypes against proven successes. When a prototype fails prematurely they revisit the design and examine how to strengthen the area that failed.

The next time you are “just riding along” consider the forces pounding away on your frame. Don’t dwell on the image of your bike frame folding like origami, though. Frames rarely break catastrophically. But if you are still nervous about your old bike, buy a new one.