Legend Bike Co. — Founders & Builders of BMX

Linn Kastan

Co-founder of Redline Engineering. Builder of the first tubular chromoly BMX fork. USA BMX Hall of Fame, 1985.

Linn Kastan wasn't trying to change bicycles. He was trying to build his kid a Christmas present. The bike he welded together in late 1973, out of the same 4130 chromoly tubing his Chatsworth, California shop was already using for flat-track motorcycle frames, turned into one of the most consequential machines in the whole sport. Chromoly forks. Double-clamp stems. Three-piece tubular cranks. Race frames built for racing and nothing else. Trace any of it back far enough and you land on him.

Before BMX: Redline Racing Frames, 1970

Redline Racing Frames started in November 1970 in Chatsworth, California. Kastan and motorcycle racer Mike Konle built it. Kastan ran the heli-arc and drew the frames; Konle was the speedway and flat-track rider who brought the machining know-how. None of the first work was bicycles. They built lightweight 4130 chromoly motorcycle frames and swingarms for TT and flat-track racers, and inside a few years they were doing prototype motocross jobs for Honda R&D and Kawasaki out of that San Fernando Valley shop. By the early 1970s Redline had maybe six people on the floor and a name as the custom shop the ambitious riders came to.

That motorcycle background is the whole point. It's why the first Redline BMX parts looked the way they looked, got welded the way they got welded, and stayed together. Kastan wasn't figuring out frame craft on kids' bikes. He was carrying motorcycle-grade craft over to them.

The Christmas bicycle, 1973

Late in 1973 Kastan welded up a small chromoly frame for his son Curt, a Christmas gift, using leftover motorcycle tubing. He stashed it in the back of his pickup so the kid wouldn't find it. After Christmas, word made its way to Bob Hansing, the president of Shimano USA, who wanted to see it. One day Kastan happened to drive past Shimano's Sun Valley office, walked in, and showed Hansing the bike. Hansing pointed him up the valley to Jim Emerson at Pedalers West in Northridge — the shop where the early San Fernando Valley BMX kids hung around.

Emerson liked the frame. What he told Kastan was that the real trouble was the forks. The forged Ashtabula-style forks on every BMX bike of that era kept breaking. Kastan drove home turning it over in his head. By the end of that same day he'd welded up the first prototype Redline tubular chromoly BMX fork. He brought it back the next morning. Emerson bolted it onto a bike, a kid jumped it off roofs and starter shacks that night, and the fork held.

"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."
— Linn Kastan, VintageBMX interview

February 1974: the chromoly fork

The first production pairs of Redline tubular chromoly forks were leaving the Chatsworth shop in February 1974. Frank Numeroski, a parts distributor out of the Bay Area, walked in and offered to buy every fork Kastan could build. Then Joel Davis at West Coast Cycle came in with a thousand-piece order — the biggest Redline had ever taken. Bob Osborn, writing in the debut issue of Bicycle Motocross Action in December 1976, called them simply "the Daddy of them all."

1974: the Squareback frame

Late in 1974 Redline started building its first complete BMX frame — the Squareback, named for the rectangular-section lower chainstay with the dropout cut right into the tip. The frame numbers started at 100. Kastan kept the ledgers himself. He told VintageBMX that from November 1974 to March 1978 Redline built 10,500 frames. The Squareback was the first production all-chromoly BMX frame to ship in any kind of volume.

And it's the Squareback — not the MX-II — that the record points to as Redline's true 1974 first frame. The MX-II and the ProLine showed up a few years later, in the 1978 Redline catalog. That often-repeated line about "the 1974 Redline MX-II is the first purpose-built BMX bike" squeezes the timeline a little. Closer to the truth: Redline shipped the first chromoly BMX fork in February 1974 and the first chromoly BMX frame, the Squareback, later the same year.

Before the Squareback settled into that familiar shape, Redline actually built a pair of loop-tail frames in 1975 — one of which went out with the Rick's Bike Shop team and made the front cover of Bicycle Motocross News. Kastan swapped that looped rear end for the rectangular lower chainstay with the dropout cut into the tip, and that's the shape the Squareback is remembered for. Worth flagging on the record: USA BMX's own 2025 Hall of Fame profile dates the finished Squareback to 1975, while Kastan's own sales ledger — the source behind the "November 1974 to March 1978, 10,500 frames" count above — puts the frame numbering starting in November 1974. We're going with Kastan's own ledger as the more precise record here, but the discrepancy is on the record rather than smoothed over.

Small-batch specials: the 16-inch Squareback and the Monoshock

Not everything out of the Chatsworth shop in the 1970s was a mainline race product. By Kastan's own count, Redline built 637 of the original rigid Squareback frames before switching to the one-piece dropout redesign, a run of 150 sixteen-inch Squarebacks starting in June 1975 for a proposed 16-inch BMX class that never really took hold, and 35 Monoshock frames — banana-seat bikes built around the same chromoly tubing and fork, of which Kastan says he kept exactly one for himself.

The Konle split and full ownership, 1977-1978

By the mid-1970s two different futures were pulling at the partnership. Konle wanted to stay in motorcycles. Kastan was getting pulled deeper into bicycles. In 1977 the two agreed to part ways. Kastan took full ownership of Redline. Konle kept Champion Racing and the motorcycle side.

The ProLine series and Byron Friday

From 1976 on, Kastan had a teenage BMX racer from Van Nuys named Byron Friday riding his bike fifteen miles each way to the Northridge shop, working the tube bender and the chop saw, and breaking parts. Friday was Redline's in-house test rider — the rider Kastan handed every new fork, stem, bar, and crank to first.

"A young kid from the local area named Byron Friday came to work for me. 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

Out of that loop came the parts that ran BMX for a decade. The double-clamp stem, around 1975-76, born straight out of Friday snapping Ashtabula stems. The V Bars — a chromoly handlebar with a bent crossbar that Kastan said gave the bar enough spring to quit snapping at the weld. The ProLine frame and fork, with their five-inch head tube; the first ProLine got built in March 1978. The MX-II frame. The Microline mini-class frame. By the back half of the 1970s, every red-blooded BMX kid in America wanted Redline V Bars and a ProLine stem hanging off the front of whatever he raced.

The Flight Cranks, 1980

Kastan started chewing on a three-piece chromoly BMX crank in late 1976. Getting the geometry, the tubing, the spindle splines, and the bearing setup right took him roughly three years. The first arms were teardrop aero tubing; the next were rectangular 1" x 1/2" tube; then a heat-expanded rectangular tube. By the time the Redline 401 Series Flight Cranks went into production in January 1980 — tapered tubular arms, splined two-piece chromoly spindle, packaged with their own T-handle Allen wrenches — Kastan had killed off the one-piece BMX crank.

The Flight Cranks became, in his own words, Redline's best product ever. The current Flight Crank platform is licensed to Supercross BMX by Regent today.

Going overseas, 1979

In April 1979 Kastan flew to Kobe, Japan, and stayed two months, teaching six young welders at Kawamura Cycles how to TIG-weld. There were no machines waiting for him there. He shipped six welders over and set them up in a room about the size of a double garage inside Kawamura's office building. That tiny room turned out Redline complete bicycles for years.

The race team and the freestyle turn

The first real Redline factory team came together around 1978, and went out on tour with the ABA in 1979. Kastan later recalled that first tour roster as including Jeff Ruminer, Mike Bush, and David Clinton, though he wasn't sure whether Greg Hill made that very first trip or joined on a later one. The line-up that made Redline a household name on a race track — Stu Thomsen, Greg Hill, David Clinton, and the riders who followed. Thomsen and Hill won everything. In Kastan's own understated phrasing they were also "a couple of brats" to work with — though Hill ran into him at a Phoenix race years later and apologized.

In 1983 Bob Osborn handed off his magazine-affiliated freestyle team — R.L. Osborn and Bob Haro had been riding it — and Kastan picked it up. The RL-20 Prostyler frameset, then the RL-20 II in 1985, made Redline a freestyle brand on top of a race brand.

1985: USA BMX Hall of Fame

The American Bicycle Association inducted Linn Kastan into what is now the USA BMX Hall of Fame in 1985, in the Industry category. The HOF citation names him plainly as the founder of Redline Bicycles and walks through the fork, the double-clamp stem, the V Bars, the Squareback, the Flight Cranks, and the RL-20 II — and credits Kastan with wiping out heavy steel BMX parts pretty much on his own.

Kastan's spot in that class matters beyond the plaque. When ABA owner Bernie Anderson created the BMX Hall of Fame in 1985, Kastan was one of only three inaugural inductees, alongside racers Dave Clinton and Stu Thomsen — the only Industry name in that first group. Redline also sold a cheaper, painted-steel version of the tubular fork for racers who couldn't stretch to the nickel-plated chromoly original.

The sale, Kastan Engineering, and after

Redline went to its top distributor, Seattle Bike Supply, in 1988, and moved north to Kent, Washington. (Seattle Bike Supply was later bought by Accell in 2006; Accell sold Redline on to Regent in 2019.) Kastan waited out the non-compete and, in 1989, launched Kastan Engineering. The company built alloy Kastan frames and the single-bladed Strut fork.

More recently, Kastan has gone back to the part of his work that earned him the Hall of Fame plaque. Through Redline Vintage BMX and a licensing arrangement that lets him use the Redline mark, he has reissued the Flight Cranks, the V Bars, the seats, the stems, and — in batches — the RL-20 II Prostyler frameset itself. He still keeps the original Chatsworth ledgers, every Squareback frame number and the bike shop it shipped to. Per USA BMX's own 2025 update to his Hall of Fame profile, Kastan's day-to-day business today is Redline Aviation — a separate venture from the reproduction-bike licensing work.

Why he matters

Plenty of brands in this history can point to a single first. Redline, under Kastan, can point to a whole stack: the first production tubular chromoly BMX fork (1974), the first production chromoly BMX frame (Squareback, 1974), one of the first double-clamp BMX stems (mid-1970s), the V Bars, the ProLine series, and the first tubular three-piece chromoly BMX cranks (Flight Cranks, 1980). He pulled it off out of a motorcycle shop, with motorcycle tooling, motorcycle welding, and one teenager from Van Nuys breaking everything until it stopped breaking. The rest of the industry spent the next ten years catching up.

What we don't know about Linn Kastan

Kastan's own ledgers pin the Squareback's frame numbers to November 1974. USA BMX's own 2025 Hall of Fame profile dates the finished Squareback to 1975 and describes an earlier loop-tail version tested that year by the Rick's Bike Shop team. We haven't found a source that reconciles the two dates, so we've flagged it above rather than pick one.

The full roster of Redline's first ABA factory tour in 1979 isn't nailed down. Kastan's own recollection names Jeff Ruminer, Mike Bush, and David Clinton, with Greg Hill possibly on a later tour rather than the first one — his words, not ours.

We don't have a sourced account of exactly when "Kastan Engineering" became "Redline Vintage BMX" / "Redline by Kastan," or how the current Redline-name licensing arrangement is structured against Kastan's separate Redline Aviation business. If you have paperwork or a dated interview that fills that in, we'd like to see it.

Sources

USA BMX Hall of Fame — Linn Kastan (1985, Industry) at usabmx.com/about/hall-of-fame/868. Linn Kastan interview, originally conducted by Bill Curtin for VintageBMX (2002), republished at BMX Products USA (bmxproducts.com/pages/kastan-interview). USA BMX / Bicycle Retailer and Industry News — "USA BMX Announces Inductees For Their 40th Anniversary BMX Hall Of Fame" (June 11, 2025), for the 1985 founding-class detail. Redline Vintage BMX — Redline History (run by Linn Kastan). Wikipedia — Redline (bicycle brand). BMX Society community threads on the Redline ledger and the modern Redline by Kastan licensing arrangement. oldschoolmags.com — Kastan frame & fork bike test, BMX Plus! March 1989. BMX Museum reference — Kastan Interview. FatBMX — Preserving BMX History Episode 61, Byron 'TGI' Friday.