THE ORIGIN STORY OF BMX INNOVATION
Early days
Redline Racing Frames was founded in November 1970 when Linn Kastan, a motorcycle frame builder, partnered with professional flat-track racer Mike Konle. The two began designing and manufacturing swing arms and lightweight motorcycle frames in a single-car garage in Northridge, California. Kastan's unique skill in heli-arc welding, combined with Konle's expertise in machining, positioned Redline as the go-to custom shop for ambitious and talented TT and flat-track racers. The business quickly gained a reputation as an innovative entity led by two mechanical visionaries.
Throughout the early 1970s, Redline equipped numerous professional motorcycle racers with custom, lightweight frames made from 4130 chromoly steel. Within months, the company moved to commercial premises and began a journey of rapid growth and success, promoting and supporting its own professional factory racing team, and collaborating wth numerous industry leading companies.
Linn Kastan's initial venture into functional product design emerged by chance within the growing BMX scene. In 1973, he designed and fabricated a bicycle frame as a Christmas gift for his son. This frame was built from Chromoly, the same material that Redline used for its motorcycle frames, ensuring it was both strong and lightweight. For months, it lay hidden in the backseat of Kastan's truck, carefully stowed away to prevent his son from discovering it before Christmas Day. After a chance conversation with a friend, Kastan was encouraged to present his frame to Bob Hansing, the President of Shimano USA. Then, one morning while running an errand locally in the San Fernando Valley, Kastan drove past the Shimano HQ in Sun Valley and decided to seek out Hansing for his feedback. Immediately impressed, Hansing referred Kastan to Jim Emerson, owner of Pedalars West, a bicycle shop in Northridge, and an epicenter for the local "BX" community. That same afternoon, an informative discussion with Emerson inspired the design of a Chromoly tubular bicycle fork - a first in the bicycle industry. Kastan conceived the fork's design during his drive back to Redline and presented the finished fork to Emerson just a day later.
“As much as he liked the frame, what they really needed was a better fork because the forged fork that was on all of the early bikes was not strong enough for what these kids were doing. As I was driving back to my shop, I came up with an idea; I decided to make the fork from Chromoly tubing, and I actually made a couple that same afternoon. I went back to show him the next morning, and at first glance, he thought they were built from solid bar and would be way too heavy. But, he fitted them to a bike, and they put them to the test, and I guess it went pretty well because he called me and told me that I would be making a lot more. He also said to me that the bike was stolen at the track, and could I make another fork.I said, “I happen to have made another one already.”
- Linn Kastan
“ BMX forks were constantly breaking and Linn was the guy that essentially solved that problem. In the early 1970s, BMX was about jumping and racing on downhill tracks up in the mountains and the Redline chromoly fork was a game-changing invention because it was both strong and light. And Linn applied the same high standards to the design and production of everything he produced. The Squareback frames, the Redline V- Handlebars, the Proline stem, and the Chromoly Flight Cranks, were all became best in class products. Redline set the standard for reliability and functionality, and the industry followed their lead.”
- David Clinton
From Bicycle Motocross Action Magazine “New Products” section - debut edition - December 1976.
“Here they are folks, the Daddy of them all; Red Line Chromoly, tubular forks. What can I say about them that you don’t already know..? They’re expensive, (a shade over 30 bucks), and they’re tough (4130 tubing, heat-treated stem). They’re beautiful, and they work.”
- Editor and Publisher, Bob Osborn
Always thinking like an engineer, Kastan assessed the next point of potential failure, knowing that a reliable fork would transfer the same stress to the next weakest point; in the case, the frame. The connection to a ready-made R and D group at Pedelars West started a chain of events that led back to the bicycle he had built for his son Curt. Made from 4130 Chromoly steel, it was lightweight and strong but also relatively expensive. Compared to the Schwinn Stingray, the frame and fork were essentially the same cost as a complete bike.
“ In late 1974, we built Redline Squareback frames in small quantities. We were selling one or two at a time, while also making some modifications to the gussets and tube specifications throughout the year. Then in 1976, we ramped up production, and they became very popular. We made around 10,800 "Squareback" frames in our Chatsworth facility over a three-and-a-half year period.”
- Linn Kastan
The arrival of a new publication, *Bicycle Motocross Action*, in the mid-1970s became a catalyst for growth and an epicenter for the emerging BMX industry. Bob Osborn's vision for BMX presented the sport with a curated and artistic theme, creating a glossy newsstand publication aimed at kids but using language and an approach that didn’t talk down to them. Its content, art direction, and narrative crystallized and energized the new movement that was rapidly spreading beyond California and across the United States. In the Midwest and on the East Coast, local entrepreneurs began breaking new ground in dirt lots, building tracks, and forming local racing communities. This surge in participation created a gold rush moment for bicycle and component brands.
Sales of the Squareback established Redline as more than just an innovative problem solver, and by 1978, Linn Kastan was well on the way to producing a complete range of industry-leading BMX products. Along with the existing Chromoly fork and a |'V" Handlebar, the 1978 Redline product catalog introduced a built-for-purpose handlebar stem, seat clamp, and seat post. But the significant new introductions were two new Chromoly race frames, the MX-II and the Proline.
“ A young kid from the local area named Byron Friday came to work for me. He was becoming a pretty well known BMX racer, and he used to ride his bicycle from his home in Van Nuys to our shop in Northridge. It was about 15 miles door-to-door, and he would go through all of these back alleys and backyards on his way over. It was Byron that kept us aware of what was happening in the BMX scene because he was riding on these makeshift tracks they were building out in the San Fernando mountains. He became our chief product tester through the years when we were developing some of the first Redline products. The process was quite basic - we would make a part, or improve on one we had already developed, fit it onto Byron’s bike and see how long it would take for him to break it.”
- Linn Kastan
“I was talented on a bike, and very capable mechanically - my dad never touched my bike, I did all my own wrenching.Jim Emerson at Pedelars West bike shop suggested to Linn Kastan that I might be a good fit for Redline as their product tester. I lived quite close to the Redline factory in Northridge, so I rode my bike there every day, and Linn put me to work. My role was mainly to give Linn advice on where the opportunities for new products were and to test them. I also ended up working the tube bender, chop saw and helping out with anything else that was happening in production. Linn found it useful to have a BMX racer showing up every day - someone who was passionate about product development - and I was at least partially the catalyst and motivation for Linn to spend time drafting blueprints and designing the Redline Pro-Line series of products.”
- Byron Friday
By the early 1970s, Linn Kastan's focus on BMX product innovation had brought his partnership with Konle to an end. The two men had recently acquired an established motorcycle brand, Champion Racing. While Konle pursued a new direction with Champion as a solo venture, Kastan leanded into the bicycle industry with Redline.
As BMX participation grew exponentially, the demand for more reliable products became increasingly evident. Motorcycle race promoter Ernie Alexander organized a series of races under the banner of the National Bicycle Association (NBA), and a new generation of teenage bike racers was pushing their skills and competitiveness to unprecedented levels on demanding, chaotic, downhill tracks in the Santa Monica Mountains. Frequent equipment failures led to the rise of a cottage industry, with machine shops and custom racing car builders entering the BMX market, and new brands emerging regularly in BMX media. However, Redline's early success established the brand as a leading innovator in the industry, and the company gained significant momentum and a reputation for excellence. Linn Kastans next challenge was to scale up and find the production resources to deliver a complete bicycle in a box—ready to assemble and race.
In the late 1970s, Linn Kastan was introduced to Taka Nieda and his manufacturing agency, TEEL. Nieda's strong connections in the Japanese and early Taiwanese bicycle manufacturing industries opened the door to a world of mass production and opportunities to innovate and develop cutting-edge BMX products without relying on a highly trained workforce in the U.S. Redline's position as a leading brand in the emerging BMX market challenged Kastan to take a literal hands-on approach to developing overseas manufacturing resources.
In 1978, he traveled to Kobe, Japan, to meet with bike manufacturer Kawamura Sangyo and assess allocation options. While Kawamura had excellent resources, skilled staff, and a degree of automation that allowed them to efficiently produce high quantities of bicycles, they primarily built adult bicycles using the tube and lug system and were not experienced in the emerging TIG welding methodology.
While Redline maintained manufacturing resources in the United States for certain high-end models, its overseas partnerships allowed the company to access the entry-level market within the national bicycle dealer network. Throughout the early to mid-1980s, under Kastan's leadership, the brand continued to produce best-in-class products for the pro-level BMX racing and freestyle scenes, sponsoring iconic athletes such as Stu Thomsen, Greg Hill, and RL Osborn, among others. To this day, Redline products remain legendary and highly collectible among BMX enthusiasts and collectors.
Debut Issue Bicycle Motocross Action Cover star, Brian Lewis, aboard a first generation Redline Squareback, The Pipeline Skatepark, Upland, CA., 1980. Photography courtesy of Dean Bradley.
THE LEGENDARY REDLINE 401 SERIES FLIGHT CRANK
The following is an article featured in BMX Plus concerning the development of the Redline 401 Series Flight Crank.
The initial prototype of the Red Line Flight Crank was made in late 1975. It was developed because of problems test rider Byron Friday was having with available components. The owner of Red Line, Linn Kastan, felt there were three basic things wrong with BMX cranks at that time. The first was the aesthetics of the one-piece crank. Both the finish and overall appearance were so crude that they detracted from the look of a sophisticated race bike. The three-piece alloy sets looked great but were ruined by the time it took Byron to get out of sight. The second problem was the so-called quick-change sprocket. Trying to remove five Allen bolts, half of which usually were stripped out by the rider using the wrong Allen wrench, was not Linn's idea of the ideal setup. The third problem was rigidity. Linn wanted something reasonably light that wouldn’t flex like its alloy counterparts.
Since chrome-moly was working well in other areas of BMX, it seemed like a likely candidate for a BMX crank arm. The first arms were made out of teardrop aero tubing. The spindle was a splined piece of Inch-diameter chrome-moly tubing. The whole setup rolled on Timkin sealed bearings. The tubing proved to be inadequate for crank arms, mostly because of its inability to handle side loads.
The next arm was made from a length of rectangular 1" x 1/2 tube. It worked quite well, but its main shortcomings were Its lack of taper, which would have made it more attractive, and a lack of width on the end connecting to the larger boss. Because of the tremendous leverage or twisting movement on the arm, there needed to be more surface area in the joint connecting the arm to the spindle boss. An Increased offset (angling the arms out from the spindle) was necessary to keep the spindle as short as possible.
The spindle was changed to a two-piece model that would accept a standard big bottom-bracket bearing set. The splines were redesigned because the ends or the smaller splines were so easily damaged. The two pieces were welded in place and then brass-soldered to make them act as one unit. Although the original spindle worked, Linn felt it was too radical for BMX in 1975.
Then Linn had an idea for adding width to the rectangular arms. The arms were cut to length, caps were welded on both ends, and they were sent to the heat treaters to be annealed heat tempered. The tubes were heated to 1600 degrees F. They became soft, and the air in the tubes expanded, giving them a slightly rounded shape on both sides. This gave Linn the extra width he needed, and Red Line had its first successful crank arm.
At this time, the pinch bolt was replaced by two bolts that threaded into the spindle, similar to those found on three-piece alloy cranks.
Unfortunately, consistent results could not be achieved during the expansion process, so it was back to the drawing board. It took two years to find someone who could make the tapered arms used today. Their shape, roughly rectangular with slightly bulged sides and a slight taper from end to end, is nearly perfect for the stress involved, according to Linn.
The first cranks sold seemed to hold up well under 95% of the riders. After about a year, Linn changed to a large-diameter sprocket-drive boss. He also decided to go back to the pinch bolt along the end bolt as an extra safety feature.
Linn admits there is still room for improvement in the bearing area. He just hasn't found a satisfactory way to make a high-quality bearing that will fit the wide variety of frames on the market. Not everyone makes their bottom bracket shells with the same precision as Red Line.
The final package that is available in stores comes complete with arms, a spindle, and a standard big bottom bracket set /the crank arms accept a 9/16" pedal). The package also includes two "T'-handle Allen wrenches needed for gear changes. You can use Red Lines with their own special one-piece sprockets sized 40 through 46, or you can use a standard spider and sprocket setup. Red Line cranks are available in 170, 175, 180, and 185mm lengths. A complete Red Line Flight Crankset (two 175mm arms, loose-ball bracket set including spindle, one 44T alloy sprocket, one shoulder bolt, and two end bolts) weighs in at 1274 grams. The approximate retail cost is $160.00 for the cranks and $21.00 for a sprocket.
