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Delving into the archives, we came across this ‘Retro Review’ of a Koga Miyata bike with Shimano’s famous AX groupset from 1982.
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“It still amazes me how many different technical issues Shimano tackled in one go… indeed a very brave effort.”
Experimental Aerodynamics
Koga Miyata Fullpro-A
– By Warren Meade
(Originally published in #RIDE60, May 2013)
Before it had become a major player in the road cycling market, Shimano was prepared to think outside convention. The first generation aero revolution with Dura-Ace AX was impressive but ultimately too far ahead of the times…
The current trend towards aerodynamic road frames is blurring the line between purpose-built time trial bikes and road bikes. And while weight reduction, exotic materials, aerodynamic wheels and the aerodynamics of the rider have seen significant advances over the last three decades, it’s not new.
Improving the aerodynamics of the rest of the bike has been the last frontier over the last couple of years.
Every time I see one of the “new” crop of aero road frames tested or written about, I can’t help but look at the old Koga Miyata sitting idle in the corner of my storeroom and think, ‘Hang on, haven’t we seen this before?’
Concealed cables, special brake calipers that reduce the bike’s frontal area, teardrop frame tubing with matching seat pillar, airfoil shape bottom bracket shell, wing-shaped drink bottle, aerodynamic shrouds on the head fittings and hub cones and special spoking patterns.
All this may sound like the list of features from the latest Giant, Felt or BMC, but is in fact a list of attributes of the 31-year-old road bike you see here.
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Top mount gear levers were found on many AX-equipped bikes (above). Claimed reduction in air resistance: “0.73 per cent”.
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In 1972, Shimano had borrowed the best technology from the likes of Campagnolo, Suntour, Stronglight and Simplex in the design of their brand new Dura-Ace range, and gradually built up market share and credibility in the top end of the market during the following decade.
In 1980, borrowing ideas from no one, the Japanese company presented the completely new AX aerodynamic range to the public.
The flagship was Dura-Ace AX, to be marketed alongside their ‘traditional’ parts, Dura-Ace EX.
The AX groupsets were available in four levels, the lowest level called AX, followed by Adamas AX, then 600AX, and finally, the top-of-the-line Dura-Ace AX. The upmarket 600AX and Dura-Ace AX ensembles looked very similar to one another and, in hindsight, were design masterpieces.
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The Para-Pull mechanism (above) allowed the caliper profile to be contained within the frontal area of the fork. Aero? Yes. Stopping power? Not really. Claimed decrease in air resistance: “1.96 per cent”.
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If you can locate a 1980s bike equipped with the lower level AX, or Adamas AX parts, you will be struck by the clunkiness – bordering, quite frankly, on ugliness – of these components. This may explain why very few were sold in Australia, and hardly any seem to have survived.
Shimano went out on a limb when it conceived the new AX Aero series. Designed and tested with the aid of the company’s own purpose-built wind tunnel, these parts were revolutionary.
Up until that time, the development of bicycle components had been evolutionary, with parts getting stronger, lighter and more efficient in very small increments over a 100-year period. Steeped in tradition, it was very difficult to get cyclists, particularly racing cyclists, to embrace new technology.
Going through the AX features one by one, it still amazes me how many different technical issues Shimano tackled in one go; it was indeed a very brave effort from the interloper of the times. They had progressed from being an unashamed (but quality) copier of the established players, to turning the whole component game on its head, in under 10 years.
The many features introduced are explained fully in the captions on these pages but, apart from the improved aerodynamics underpinning the designs, they included a pioneering form of indexed shifting, ‘compact’ chainwheels, brake cables hidden underneath the handlebar tape, a front derailleur that ‘trimmed’ itself, a seven-speed cassette that would accept an 11-tooth cog, and a crank and pedal interface that gave a lower overall centre of gravity.
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Dyna Drive pedals (above) lowered the rider’s foot by 15mm compared to a normal pedal. This gave an effective crank length at the bottom of the stroke of 174mm for a 170mm crank. A normal pedal had an effective equivalent length of 159mm. Claimed decrease in air resistance: “4.9 per cent”.
The DD cranks were introduced as an optional part of the Dura-Ace EX line in 1980, and then made available as standard with Dura-Ace AX in 1981. Adapters were available (later) to reduce the one inch threading down to 9/16”, so you could use these cranks with a ‘normal’ pedal.
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It was a revolution in equipment at a time when cycling was still taking innovations in product very cautiously.
For the 1981 model year, the list of technical innovations was so long that Shimano printed a special 38-page brochure just for the AX groups; this came in addition to the 68-page ‘normal’ brochure devoted to all the other groupsets they produced at the time.
Our feature bike is a Koga Miyata Fullpro-A from 1982, a rare beast even when new, sitting at the top of the brand’s price list. This was 40 per cent more expensive than the next model, the Team Miyata – a Dura-Ace EX-equipped pro level bike, featuring normal (ie. round) frame tubing.
I have been enthusiastic about the ‘AX aero’ range since it was considered “current issue” in 1981 and 1982 and, over the years, I’ve managed to acquire three interesting variations of the second-tier 600 AX bikes with “semi-aero” tubing. But I had not been able to find a “full aero” frame, nor a Dura-Ace AX-equipped machine, with or without the full aero frame tubing.
The semi-aero frames, with Tange tubing, are quite common in Australia. These have a normal lugset, and the three main tubes are simply ‘squashed’ into an oval shape in the middle.
Locally, the various levels of AX-equipped bikes were marketed extensively under the National and Standish brands.
My 20-year search for a full aero Dura-Ace bike had been fruitless until recently. I had bought a ‘new old stock’ teardrop-shaped Dura-Ace seatpost about 10 years ago, just in case I eventually located a suitable frame, and this rare-as-hens-teeth, uniquely shaped seatpost was missing. I do this with many of my projects, putting together the pieces of the veritable jigsaw over a long period of time, hoping the puzzle will be complete one day.
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The rear derailleur (above) dispensed with the top pivot spring, making for a lower-profile design. This was good for aerodynamics but bad for functionality. The outer cable was dispensed with, reducing resistance and cable friction. Claimed reduction in air resistance: “0.82 per cent”.
This is Shimano’s earliest seven-speed cassette hub, only available initially as part of the Dura-Ace AX group, with its matching ‘indexed’ rear derailleur. Just to confuse the issue, 600AX, Dura-Ace EX, and 600EX were only available in six-speed.
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Around 2007, I saw a bike advertised simply as a ‘Koga Miyata racing bike’. Little was known of the brand in Australia and the reason this advert piqued my interest was that I’d ridden one during a trip to Holland in the 1980s. The ad for the second-hand bike had a poor quality photo, but I thought I could make out the Dyna Drive cranks, and Koga Miyata’s signature ‘team’ colour was obvious.
The mid-blue was usually only applied to the brand’s top level bikes, as it was the colour used by the Belgium-based Capri Sonne pro team (managed by Walter Godefroot and Patrick Lefevere) in 1981, when it used Koga bikes.
On the strength of this, and given the price was reasonable, I decided to take a punt and buy it, regardless of the bad photo and what appeared to be the poor condition of the bike.
You can guess what’s coming next. When the “Koga Miyata racing bike” eventually arrived, poorly packed and treated shabbily by the courier, the contents of the box proved to be very satisfying.
Beneath at least 20 years’ worth of grime lay mismatched and buckled rims, worn out tyres, torn handlebar tape, cut-off handlebars, broken spokes, seized cables and a flogged out left crank arm hanging from the bottom bracket axle.
The list of minor things that were wrong got longer and longer as I disassembled the bike, but any faults were mitigated by the fact that it had started life as arguably the most exotic and expensive example of a Shimano AX-equipped bike produced anywhere in the world, by any manufacturer. It was a diamond in the rough.
And yes, I was delighted to find it had the elusive full aero teardrop tubing and the full complement of Dura-Ace AX components were present and correct, if a little unloved.
Even the special Dura-Ace teardrop-shaped seatpost was intact, so the one I had salted away years before could be consigned to the display case or sold off.
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The elusive seatpost, made specially to match the aero tubing (above), branded ‘Miyata aero’ on our bike, but almost certainly made by Tange. The teardrop profile is obvious in this photo and matches up perfectly with the special Shimano post. Nearly all AX-equipped bikes come with a seat tube that is round at the top that takes a normal seat post. Claimed reduction in air resistance (post only) “1.55 per cent”.
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Despite the scratches and dirt, once stripped down, the frame and fork turned out to be in excellent structural condition with no evidence of internal rust and no dents or bends. Furthermore, despite its state on delivery the frame polished up too well to contemplate a repaint.
The restoration of bikes (and other things) is trending towards preservation rather than restoration and these days I only consider repainting or re-chroming if the original finishes are in very poor condition, or major repairs have been carried out that make re-finishing essential.
The reason this particular Koga Miyata model was so much more expensive than the ‘standard’ Dura-Ace bike in 1982 became increasingly obvious as I inspected it closely.
No lugs were available to suit the teardrop-shaped tubing, so the entire frame had to be fillet brazed.
Every frame was handmade, with each tube junction being a time consuming task performed by a highly skilled tradesman.
The bottom bracket shell alone is a work of industrial art.
The Koga Miyata company has an interesting history. Miyata had existed in Japan for some 85 years by the time that Koga was established in the Netherlands in 1974. Miyata began to make frames and bikes in its Japanese factory for Koga and, around the same time, Koga became the Shimano importer for Holland.
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The bottom bracket shell (above) is a work of art: a complex casting, fillet-brazed into the aero main tubes.
The frame is designated ‘DD-560’, Koga’s way of stating that a frame was made specifically for the DD cranks and pedals. This is actually a 54cm frame, but it is called a 560 as it was meant for a rider who would ride a 56cm frame, if ‘normal’ cranks and pedals were fitted.
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In 1976, in a sensible collaboration, Koga formalised its close relationship with Miyata, by branding their bikes ‘Koga Miyata’. And due to both companies’ very close association with Shimano, almost the entire range of Koga Miyatas were equipped with the very latest components from the Shimano catalogue.
Koga and Miyata now exist as separate brands, with the Koga name appearing on a range of modern carbon-fibre bikes and Miyata returning to its roots, offering high-end traditional steel frames, made to measure, with chrome lugs and perfect paint.
Koga Miyata was one of the first, and certainly the most enthusiastic, adopters of the new Shimano aerodynamic technologies, jumping in head first for the 1981 model year, with a full range of bikes equipped with the four different levels of AX. Koga Miyata catalogues from the early 1980s read like a resounding endorsement for Shimano products. And it turned out they had backed the right horse, as they rode the Shimano rise to dominance of the market right through the 1980s and 1990s.
This rise by Shimano to market domination was only interrupted once, and strangely enough, by the failure of the revolutionary AX aerodynamic product line.
Being ahead of its time, too quirky for most, and some minor faults all meant that the range lasted barely two years, with AX-equipped bikes appearing in catalogues for a further year or two, in a vain attempt to get rid of unsold stock.
The saving grace was that Shimano’s design and production facilities were improved dramatically to deliver the AX line so, despite the failure of the product, the bad memory was quickly erased with the introduction and overwhelming success of SIS (Shimano Index System) gear shifting in the mid-1980s, and the marketing of the hugely successful mountain bike groupsets (with indexing) around the same time.
Shimano has been flying high since then, without aerodynamics, and 25 years elapsed before the words ‘wind tunnel’ were dared uttered again.
– By Warren Meade
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The 130 BCD spider (above) allowed the use of smaller chainwheels (this bike came with a 40/48 combination). The 48 set-up was lighter and gave a smaller frontal area. Claimed decrease in air resistance “0.9 per cent”.
The front derailleur had a lateral linkage, presenting less frontal area, and also incorporated a ‘yaw’ function, providing an automatic trim adjustment as it moved across the chainrings… with shades of current thinking from SRAM. Claimed reduction in air resistance: “0.65 per cent”.
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‘Retro Reviews’ were a regular element of RIDE Cycling Review magazine (1998-2017). The original author of the series is Warren Meade, a passionate cyclist and bike historian who lives in Lakes Entrance, Victoria.
We have published numerous Retro Reviews online. Click here for a full list of the series. (If you cannot find a bike that you’re interested in reading about, send us a message and we will see what we can do about putting it on ridemedia.com.au.)
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