I spent 12 years in the bike industry (mid 80’s to late 90’s), mostly working in R&D and design. I primarily designed and manufactured components but also designed and built frames, including road bikes, mountain bikes (rigid and suspension), time trial frames, and even a superlight lugless fillet brazed mini BMX frame. I raced road bikes while in college and worked in bike shops as a mechanic prior to working in R&D.
I didn’t drive a car during this 12 year span and averaged several thousand miles per year on a bike. This was a fantastic time to be in the industry as mountain bikes were very new and suspension was just coming into the market. Nobody really knew what they were doing and we had an absolute ball doing it. I probably have at least four different suspension bike designs I’d still like to build…
If I were to build frames today they would all be brazed steel artsy lugged road/gravel/touring frames that took advantage of the skills I’ve learned making jewelry. Lugged frames are just so darn pretty…
Custom road bike
I built this steel road racing frame back in 1995 and put a boatload of miles on it. This was my fourth handmade road racing frame (including two time trial frames.) A well taken care of steel frame can last decades (and I still believe they have the best overall ride quality.)
This frame was silver brazed using an oxy/acetylene torch and all the tubes were mitered by hand using a file and a hack saw. I made a simple jig to hold the tubes in place while the frame was tacked together. The frame is a mix of Reynolds 531 for the seatstays/chainstays, Reynolds 653 for the top tube and down tube and 731OS for the seat tube. The finished weight (not including fork) came in around 3.75 lbs.- not too shabby for a 56cm frame with an oversize top tube. The lugs came from Henry James and the dropouts came from a friend who is a frame builder. The dropouts are kind of neat as they have a deep socketed joint for the chainstays and seatstays. The fork is a carbon fiber Kestrel EMS Pro.
I tend to build my road bikes with pretty relaxed geometry since that’s always worked well for me. I have a long femur and I need the seat to sit far back so this bike has a relaxed seat tube angle- 72.5 degrees. The head tube angle is 73 degrees and with a 56cm top tube length I can get a really nice comfortable ride and still get a good handling bike. The oversize (1.125″ OD) top tube makes a big difference in handling- the old 1″ diameter top tubes made for a pretty flexy bike with this relaxed geometry.
Early road frames
Both of these brazed steel frames were built at home while I was in college in 1987. Both use tubular tires -back then, the ride quality difference between tubulars and clinchers was night and day. The time trial “funny bike” had a 700C Mavic aluminum disc wheel (which had a fantastic gyroscopic effect and was crazy loud) and a smaller 650C front wheel- this was pretty standard back then. I built two of these time trial frames. I believe the road racing frame was Vitus GTi tubing someone gave me and the time trial frame was Columbus SL with the special curved seat and top tubes. These are the only photos I have of my early frames. My first mountain bike frame was built in ’88 (lugged with Tange tubing) and was stolen while I was in college.
Tension Link suspension bike (1994)
(Note- this bike was designed ages ago and we’ve learned a LOT since then. The 90’s was a period of extreme experimentation when it came to suspension bikes. Quality of suspension dampers since then have increased greatly, and single ring drivetrains have made the packaging and overall design process much simpler.)
This was an early URT (unified rear triangle) suspension bike design of mine- the original prototype “proof of concept” version was built in 1994. A second version was built around 1999-2000. I did a final longer travel concept in 2008 and then officially put it to bed. URT designs really worked best as a short travel XC type bike.
The Tension Link is an open source suspension bike design- it is released under a Creative Commons Share Alike 3.0 license and it is free for anyone to use in any manner they wish as long as they credit the source of the design. I fully encourage people to modify it and improve upon it. My reason for creating this design was to build a suspension bike with good performance that features simple/very low cost construction, has minimal maintenance and can be easily customized in terms of sizing and geometry. There are several reasons for open sourcing the design but the main reason was to be able to make it available free of charge to all the small custom builders out there- the design is really well suited to the needs of the small custom builder that wants to offer a niche market suspension bike but maybe has been put off by the expense, complexity and patent infringement issues of other designs.
Pictures of the 2nd generation “proof of concept” prototype-
The 1st generation “proof of concept” prototype-
This bike was very, very light and was constructed from fillet brazed steel. It certainly wasn’t pretty but it worked really, really well as a short travel XC bike.
While this design is easily built from chromoly steel (allowing for easy customization) it can also be constructed from Aluminum or carbon fiber for much greater weight savings. The prototype has 3.5 inches of travel but it can also be built with increased travel with a longer stroke shock. The schematics below show the design for a 6 inch travel version. I built the first version of this bike in 1994 and later hacked together the second version shown here. The original prototype had 3″ of travel and a Noleen shock and it was a multi tube frame design instead of the simpler single torsion tube. Here are the drawings and leverage ratio plot for the 6 inch long travel version done in the program Linkage. It is interesting to note that the kinematics of this design (BB and pedal movement relative to rear axle position) are similar to that of the Mongoose Freedrive floating BB system (a design that gets consistently good reviews.) For comparison, the difference between the two designs regarding BB movement at maximum suspension compression is approximately .12 inches. Both designs have very little change in leverage ratios as the suspension compresses, with the Tension Link design being slightly more progressive.
The program Linkage is available here- http://www.bikechecker.com/home.phtml
The file for the Tension Link bike has been uploaded to the Linkage database so people can download it and modify it as they wish- all of the critical frame dimensions and suspension design parameters can be viewed in the Linkage program.
Here are the diagrams for the longer travel Tension Link bike-
And for comparison here are the diagrams for the Mongoose Freedrive bike (note that this diagram was not done by myself so I cannot 100% verify its accuracy but it should be close enough for the sake of comparison.)
In summary, the Tension Link design has some advantages:
*ease of construction/fixturing and minimal welds
*up and rearward axle path
*ability to construct small frame size- easily down to 14″ effective seat tube length
*low center of gravity/good mass centralization
*low stand over height
*direct load paths- can be constructed to be very light weight and have excellent torsional stiffness
*all loads are fed into the ends of frame members
*can be built with very short chainstays- prototype stays are 15.75″
*can be built with 26″ wheels or as a 29er/650B, geared bike or single speed
*simple/clean cable routing
*excellent tire clearance
*can be built with cantilever or disc brakes
*suspension is active whether you are sitting or standing
*linkage is easily modified to vary compression curve
*pull rod (tension link) is loaded primarily in tension so it can be very light weight
*frame members can be constructed from a wide variety of materials (4130 steel, carbon fiber, Titanium or Aluminum)
*frame size does not greatly affect suspension linkage geometry
Specs for the prototype are:
4″ front travel
3.5″ rear travel
15.75″ chainstays
12.75″ BB height
69 head angle
73 seat angle
23″ top tube
Here’s a video of how it works-
Real Design
After leaving Onza four of us former Onza employees started a company named Real Design. My job was design engineer/creative director- I designed components, built prototypes, sourced manufacturing and did art direction for advertising/packaging design.
Here are some of the projects I worked on including hubs, brake levers, bottom brackets, chainrings and cassette gears.
The 2nd gen brake lever (X-Lever) was probably my favorite product as it really fulfilled all of the design requirements quite splendidly. It was very light weight, incredibly durable, had excellent ergonomics, worked with a wide variety of brake systems, had almost no friction and it was simple to manufacture.
The hubsets were designed from the perspective of a bike shop mechanic/wheelbuilder ( I had built hundreds of wheels.) They had forged hub shells (which made them good for radial lacing), good quality seals/bearings, needle roller bearing supporting the drive hub and they were simple to take apart and service. They were pretty light too. These were my original design drawings before they went to our CAD engineer/designer.
The cassette gear cluster was an oddball product. The smaller cogs were steel while the larger cogs/body were machined from a single Aluminum forging (an industry first.) It was crazy light but the Aluminum cogs just didn’t hold up well to the rigors of mountain biking with mud and dirt. It was sold as a “race day only” product. It is interesting that now there are several one piece body designs on the market.
The first bottom bracket assemblies produced were a standard two bearing deisgn using steel and Titanium spindles. The 2nd generation design was interesting in that the bearing cups could accept up to four bearings and the spacer/wave washer assembly reduced side loading/binding as not two bikes ever had the exact same width BB shell.
The chainrings proved to be one of most popular products Real offered (I did not design these.) These were machined from solid Aluminum plate and received a very durable electroless nickel finish.
Onza
During my time at Onza in the early 90’s I worked in research and development and worked on cranksets (Titanium and Aluminum), tire designs, brakes, bar ends and clipless pedals.
The fabled Onza Titanium crankset. These were cast in 6Al/4V Ti. This was the stuff of legend and I still hear all kinds of stories about these to this day (most of it wrong.) This project was already underway when I began working at Onza. The 1st gen crankset is the one with the round holes- these cranks had several problems: the pedal hole was too shallow and the taper would bottom out on the BB spindle. These tended to fracture near the pedal spindle. The 2nd gen cranks had triangular windows- and these also fractured near the pedal spindle. This is where I came in. The first step was to verify the design loading using non destructive testing- this was done on a laser interferometric holography rig at AiResearch (thanks to a good friend of mine.) The problem turned out to be the casting process (not a surprise.) Even with chem milling and hot isostatic pressing they simply could not survive the stress. Since forging was out of the question due to cost I had two sample sets machined from solid (I got a deal on production material from Oremet). The plan was to test them to failure on a purpose built load test rig and compare the results to the leading market Shimano XT crankset at the time. If they passed I had a plan written up to produce a limited run of 1000 units. In the end the machined samples were produced ( I heard they were gorgeous) but never tested to my knowledge- I had already left to start Real Design. A total of around fifteen prototype cranksets were produced ( I broke two sets myself on my own bike.) They were never offered for sale. There was also one sample casting of the 2nd gen Ti crank made in Aluminum as a display piece (there was no finish machining on this casting and it was never shown in public.) There were two Aluminum cranksets as well, one early absolutely massive version which was extremely overbuilt and another that I did drawings for that was to be forged and produced in Taiwan but it never came to be.
The Chill Pill was a cable hanger I machined one afternoon as we needed a cable hangar for the new H.O brakes (which were a design purchased from Rich Williams of Boulder Bicycles.) I made several sets of these for pro riders to test out and production started very shortly afterward.
The H.O. clipless pedal. Some people thought these were the best thing ever and some people hated them. I had sold a clipless pedal design to Onza (how I got hired) but it was never used as the H.O. pedal was well under development in Taiwan. I was brought in to help troubleshoot and iron out production problems. The biggest problem was the tolerance on the height of the base plate relative the the elstomer/stainless cleat retention plates. If it was off by more than about .0025″ the pedal simply would not work. The other problem was the elastomers would turn rock hard in cold weather. The pedal body was structurally sound and they were very light weight, especially the Titanium spindle version. I had already begun a complete redesign of the pedal in ’94 using traditional wound springs but had already left the company before it went any further.
The Aggro (front) and Honch (rear) tires. This was the first project I worked on at Onza. I did about thirty drawings for these tires (at 10X actual size), showing individual knob designs as well as casing profiles. These tires were designed for hardpack conditions (they were terrible in mud) and they were very fast with excellent cornering grip due to the side knob design and consistent spacing. The rubber compound was fairly hard for the time (69 durometer.) The tires were designed by one of the owners of Onza, Dan Sotelo. Dan also designed the now very desirable Porcupine tire, as well as the extremely popular Smoke and Dart tires produced by Panaracer.
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