The Bike
Rob Foster’s hands are full.
The 34-year-old Ҵýƽ senior ismarried with four children, all daughters.He’s loaded up on physiology, biomechanicsand anthropology courses andknee-deep in medical school applications.
He’s also leading a small research teamin the development of a bicycle for a potentiallyvast ridership — obese peopleof up to 450 pounds.
Foster (IntPhys’16) used to beone of them.
“I have a lot of empathy for peoplewho are in that position,” the now-slenderformer banker said in a springinterview at the Locomotion Lab in theClare Small Arts & Sciences building.
Hard at work for more than a yearnow, Foster’s team aims to produce a finalprototype by the end of 2016 and makethe design publicly available at no charge.
“Take it. Apply it. Use it,” he said,emphasizing that the group has nocommercial intentions. “Help some folks drop some pounds.”
Foster, 5’11”, knows the burdens of obesity.Four years ago he weighed 327 pounds.
“My earliest memories are of beingpicked on,” he said.
But in early 2012 Foster and his wife,Jessica, decided to slim down. They’dseen obesity’s toll on others, and theirweight was keeping them from fullyenjoying life with their girls, includingtwins Autumn and Abigail, now 9.
“We couldn’t go out to the playground,”he said.
Jessica did Zumba; Foster took uptennis, then started jogging and cycling.
Using Google Scholar, Foster, thenworking as a bank manager, dug into theacademic literature about obesity, lookingfor guidance and understanding. He andJessica set what felt like reasonable goals(lose two pounds a week) and let themselvescontinue eating foods they liked,but at far smaller portions. Their successlanded them on Good Morning, America.
Today Foster is a trim 172 pounds.He wears eyeglasses with rectangularlenses, a close-cropped, neatly trimmedbeard and often a baseball cap. He’sfinished two marathons and theBolderBOULDER 10K three times.He gets around town on an off-the rackFuji. You’d never know hewas once seriously overweight.
But millions of Americans are— about 80 million, according tothe Centers for Disease Control,or 35 percent of the adult population.Foster wants to improvethe odds they’ll slim down, andhe and his academic adviser,Rodger Kram, think a customizedbicycle could help.
“For very heavy people, evenwalking, let alone jogging, impartshigh forces on the hip, knee and anklejoints,” said Kram, a CU integrativephysiology professor. “Swimming is anotherform of aerobic exercise, but manypeople are not comfortable wearingbathing suits in public. Bicycling is a fun,social and low-impact way to get aerobicexercise and hence burn calories.”
Foster grew up in Westminster, Colo.,a strong high school student keenon science. He briefly attended theUniversity of Northern Colorado, butdropped out. He married, had kids andspent nearly a decade in retail banking.Occasionally he rued quitting school;he’d seen himself as a medical doctor.
Emboldened by his successful weightloss and encouraged by Jessica, Fosterdecided in 2012 that it wasn’t too late.A year later he enrolled at CU anddove headfirst into the study of integrativephysiology.
Last fall he approached Kram aboutdoing original research. Kram suggestedthe bike project, attempted once beforeand suspended after a previous teamfailed to connect with obese people.After hearing Foster’s story, Kramknew he’d found the right guy.
“‘You have what we would call ‘obeseexperience,’” Foster recalled Kram saying.
Take it. Use it. Apply it. Help some folks lose some pounds.
So Foster and a fellow undergraduate,an engineer, began working on a bikethat’s more comfortable and safer forthe obese than off-the-rack bikes, seekinginput from heavy riders, including aBoston blogger who writes as “TheFat Cyclist.” The team is developinga bike obese people could ride on Boulder’s bike paths, uphill or down, atgreater than walking speed.
Bicycle manufacturershavepreviously producedbikes for heavy riders,but Foster has foundthem lacking, especiallywhen it comes to thebraking systems, whichhe called “in no way adequate.”
After testing all available types ofbike braking systems, the researchersfound the best ones required at least 43feet and 4 seconds to stop a 450-poundperson traveling at 15 mph. The teamwants brakes that stop the same rider in1.5 seconds and no more than 15 feet, inline with existing federal standards for a170-pound person.
The researchers are not trying toreinvent the bicycle — they’re tryingto adapt it, mainly by identifying anoptimal combination and configurationof existing parts. The bike willlook more or less like regular bicycles,an important point for obese peoplethey interviewed.
“They didn’t want anything that wasgoofy looking,” Foster said. “They don’twant to be the bear on a bicycle.”
Beyond the brakes, the team is rethinkingthe wheels and gears, seat post(solid rather than hollow), aspects offrame design (optimal height for the tophorizontal crossbar and handlebars) andsaddle (a tractor-style seat, perhaps).
The braking system will be the mostcomplex new element, andthe challenge is to generategreater braking force withoutwarping any parts.The tentative solutioncalls for a hydraulicsystem with two front rotors(as in a motorcycle)and two sets of calipers,effectively doubling thefriction on the front tirewhen the brakes are applied.It also calls for doubling the forceapplied to the rear wheel.
By spring Foster and team had producedan initial prototype and were raising moneythrough a CU-sponsored to finish the project.
Ultimately they want a bike that appealsto obese riders — but still requiresthem to work.
“If it’s too easy,” said Foster, “we’redefeating our purpose.”
Photo by Patrick Campbell