3-D motion censors help pair body to bike
By ALLEN GEMAEHLICH
Eric Lusby plans on road biking for a long time.
So to him, it only makes sense to make sure his bicycle fits the best it can.
Most people usually test ride a bicycle and get the opinion of the bicycle salesman, but Lusby is one of a growing crowd of bicyclists who is taking it a big step further.
He recently met with certified physical therapist and The Bicycle Studio of Western Colorado owner, John Weirath, to get fitted with a 3-D motion sensor that only came out a year and a half ago.
“I love biking,” Lusby said. “This is something I plan on doing for a long time. Meeting with John gives me peace of mind that what I’m doing is correct and safe. If I do something, I want to do it right and it’s his job to make sure I’m doing it right.”
The Retül 3-D Motion Capture Technology system uses infrared LEDs (light emitting diodes) to provide several measurements of the body at its joints throughout the movement.
The infrared LEDs are in a harness strapped to a person. The LEDs are placed at the person’s joints (hip, knee, ankle, heel, metatarsal, shoulder, elbow and wrist). One side of the body is measured at a time.
The infrared light shoots in one direction to the receiver and gives an accurate measurement to less than one millimeter, Weirath said. The margin of error is 0.2 millimeters.
The receiver has three slits for eyes that read the sensors.
“It is not a fitting protocol,” Weirath cautioned. “All it does it provide information and a lot of it. I get asked quite often, ‘does this make fitting easier?’ But by doing this, it makes fitting a bike more accurate and better.
“If a person has knee problems, it can track so many different measurements with the knee, we can test if its moving admirably. We can make adjustments and retest and make improvements.
“It doesn’t tell you what to do. You need a really strong background in bio-mechanics to read it.
You need to deal with the human body on a daily basis. Otherwise, there is too much stuff there.”
The system can measure a person’s knee angles, hip angles, hip to wrist, elbow angle, ankle range and the knee lateral travel distance.
Once Weirath takes a couple of tests, he can adjust a bike and provide bicycle measurements to fit the bicycle specifically to an individual from saddle height to frame reach and handlebar reach.
“With this, you don’t have to eyeball bike fitting anymore,” he said. “It tells you down to the millimeter whether you knee is tracking down a little bit. It takes the guesswork out of it.
“Having the expertise to not only work with peoples bodies, but I’ve done bike fittings for almost 10 years now. There are times, where I might leave something unfixed. If I change that, it might cause a problem elsewhere. You’ve got to know when to stop.”
Once the test is completed, a bicyclist can take a copy of his measurements and purchase a bike to fit his needs or the bicyclist can simple order a bike through Weirath. He can design the frame then have the frame built by Seven (based out of Boston) or Guru (out of Montreal).
A cyclist can come for one fitting for $125 or come back for a couple of followups for $250.
“Once you do a test, most go ahead and do the full-fitting,” Weirath said. “I’ve had people go through four saddles and spend 300 to 400 dollars on saddles.”
One bicyclist in the valley, Tim Sewell, has used Weirath’s services to fit three of his bikes.
“I wanted to make sure if I was going to sit on a bike that long, it would fit well,” said 44-year-old Sewell, who competes in road races. “One reasons I got fit was because I had knee and back
pain that stopped me from running. If I was not on a bike that fit well, the pain would flare up a bit.
“Anybody who has a little pain on the bike, it’s worth it. The bikes been almost therapeutic.
Getting on the bike helps.”