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In the early '70s, Sun Tour freewheels were a revolutionary development, markedly superior to their European competition (Atom, Cyclo, Everest, Regina etc.)
Sun Tour freewheels provided much better shifting than older designs due to the superior design of the sprocket teeth. The tops of the teeth were not squared flat or grooved, as with older designs, but were asymmetrical, with a slant inward. This provided a sharper outside corner of each tooth for better chain pickup, and the slant helped the chain slide down sideways into good engagement if it was tending to run along the tops of the teeth. European freewheels with grooves running along the tops of the teeth were prone to a semi-freewheeling mode, as the side plates of the chain would skate along the grooves. The large sprockets of some Sun Tour freewheels also sometimes had teeth alternately bent slightly toward the left and right, to aid in chain pickup.
It was possible (and not unheard-of) to assemble Sun Tour freewheels with some of the sprockets backwards, markedly degrading shifting performance.
I used to regularly modify Regina and Atom freewheels by re-grinding the teeth of the sprockets so that they somewhat resembled those of Sun Tour or Shimano sprockets...a treatment later known as "Sheldo-Glide." [And I found that this only worsened the tendency of a 7- or 8-speed chain without protruding rivets to slide along. This is now the widely available chain that engages well with the sprockets of these freewheels. Uaing an indexed shifter avoids this problem; modern 5- and 6-speed index shifters are still compatible with old wide-spaced freewheels, or you could use an alternate cable routing or JTek adapter with a different indexed shifter-- John Allen.]
Another advance pioneered by Sun Tour was in freewheel removal. Sun Tour still stuck with the traditional two-prong remover design, but provided much deeper notches and a matching tool with a considerably better fit. The result was a much lower incidence of damaging tools or freewheels.
|French freewheel with weak notches||Sun Tour Perfect freewheel with stronger notches.|
Sun Tour also popularized the use of splined sprockets. Previously, the vast majority of freewheels used all threaded sprockets. Typically, the two largest would have left-hand threads and screw on from the back side of the body, while the smaller sprockets would screw on from the right. A freewheel would typically have 3 different threadings for sprockets in the different positions. The largest sprockets were the most difficult to unscrew, because they would get screwed on the tightest during hill climbing.
Sun Tour replaced the left-threaded large sprockets with a spline design using 4 splines. This made it possible to replace all of the sprockets without removing the freewheel from the hub.
Sun Tour did not invent splined freewheels. Cyclo previously offered a deluxe model called the "Pans" that worked the same way, but this was mainly offered to racers to facilitate gear changes to fit the requirements of specific courses. Normandy freewheels, a brand of the French company Maillard (later absorbed by Sachs and in turn by SRAM) used splines too. Sun Tour brought this design to the mass market, and made the all-threaded systems obsolete.
[Bruce Dance reports: All SunTour freewheels are date coded using the two digit date code system as described on the Trek vintage and velobase sites. The oldest 'Perfect' I have is a 'Q' so probably 1974; it is also marked '8.8.8' and 'Maeda Industries' but not marked 'Sun Tour'.]
First SunTour freewheel to hit the US market was was the "Perfect", mainly a 5-speed system, though 6-speed versions are not rare. The Perfect used 2 or 3 splined sprockets, and 3 or 4 threaded ones.
Most Perfects are limited to a 14 tooth minimum. The threaded sprockets were available in sizes up to 21 teeth. Some later 6-speed Perfect bodies in both normal and Ultra spacing had an extra smaller diameter thread that would fit a 13. Splined sprockets were available in all sizes from 16 through 28 teeth, plus 30, 32, 34 and in the uncommon "Alpine Gear" (AG) version, 38 teeth.
Sun Tour Perfect freewheel with the rare 13T sprocket.
There is a Shimano twist-tooth 13T sprocket with the same threading...
Sun Tour also marketed the "Pro Compe", which was essentially the same as the Perfect, but with a fancier appearance.
[Bruce Dance reports that Perfect bodies have a 16T ratchet and opposed pawls that engage simultaneously, giving 16 clicks. The Pro Compe bodies he has seen have the same pawl arrangement but fitted to a 15T ratchet, giving a 30-click freewheel body of about half the strength. Quite a few 'racing' and other freewheels were made in a similar way at one time, including Maillard Course, Maillard Normandy, various Regina, Everest models etc. This reduces lash when switching from coasting to pedaling, and tilts the freewheel outer body at one fixed angle to the inner body when under power, so loose bearings don't make the body tilt back and forth with a "click" twice per revolution.]
There were 3 different 6-speed spacings used on Perfect and Pro Compe freewheels:
See the spacing cribsheet on this site for more detail on this topic.
Perfects usually have a bronze or gold finish on the sprockets; Pro Compe, a silver finish, but the sprockets otherwise are interchangeable. Sun Tour 8.8.8. Gold 5 speed freewheels were Perfect variants. The gold-finished sprockets were a cosmetic touch. There also was a Pro Compe tandem version with a black body, wider pawls, a 16-tooth ratchet and better-finished bearing races. This was only ever sold in a 5-speed version.
[A note from John Allen -- This new section may be of practical interest if you are still are using a Sun Tour Perfect or Pro Compe freewheel. I still have a couple of bicycles with these freewheels. I have reground sprocket teeth at times to make them work with replacement chains. Read this section in connection with Sheldon's article on freewheels.]
Because of the different spacings and numbers of sprockets, Perfect and Pro Compe freewheels came in a variety of widths of the splined vs. threaded part of the body, and iotal widths.
Spacers for the Perfect and Pro Compe make for a complicated story. The 13- and 14-tooth threaded sprockets had integral full-width spacers, of different widths for normal and Ultra spacing. The larger threaded sprockets had integral, narrower spacers. Spacing washers were used for the remainder of the width to the next sprocket. Only the washers had to be of different widths. Similarly, the 16-tooth splined sprocket had a full-width spacer and was available in two widths, normal and Ultra. Splined sprockets with 17 or more teeth were flat and used separate full-width spacers. Beveled spacer washers were needed at the transition from threaded to splined sprockets, and behind a 15T threaded sprocket where the chain might bottom out on a regular spacer.
A Sun Tour Pro-Compe 6-speed Ultra-spaced freewheel with the usual 14T minimum threaded cog.
The same freewheel disassembled. Note thin shims next to spacers, and 4 splined positions. 5-speed versions had 3 splined positions.
Thin shims were often needed in addition to the regular, thicker spacers. Sutherland's Handbook for Bicycle Mechanics, 6th Edition -- still available as a CD-ROM -- includes a complete listing of the different sprockets and spacers. When building up a Sun Tour freewheel, it is helpful to have an ample collection of spacers salvaged from discarded freewheels.
The Perfect and Pro Compe tandem version had two ratchet pawls opposite one another, and an even number of ratchet teeth. If the freewheel's bearings were loose, the freewheel body would tilt slightly one way and then the other with each turn of the rear wheel, making a noticeable click-click, click-click noise. The freewheel's cover plate had a tendency to unscrew, probably worsened by this excess motion. Twice I (John Allen) had a cover plate come off completely, dumping all the bearing balls out of the freewheel. In both cases, I managed to ride home after screwing the cover plate back on, taking care not to coast.
Preventive medicine for both problems was to unscrew the cover plate (clockwise, using a hammer and punch and easiest with the freewheel mounted on a wheel), remove one of the thin shim washers underneath, and then replace the cover plate, securing it with threadlock compound. (Also see Sheldon's instructions on rebuilding freewheels.) Usually with one shim removed, bearing adjustment would be, well, perfect.
Sun Tour Winner, New Winner and Winner Pro freewheels usually came with silver-colored sprockets, like the Pro Compe.
The Winner (first version) was a short-lived, high-end version of the Pro Compe. I don't know too much about this model.
Then came the New Winner: the same body could build 5- 6- or 7-speed clusters. The New Winner used the same threaded sprockets as the Perfect and Pro Compe, except for the outermost one or two sprockets, which attached at a new and different, smaller threading. In the wide 6-speed version and the 7-speed version, the outermost sprocket was threaded to the next sprocket, rather than to the body.
A 7-speed Ultra-spaced Sun Tour New Winner freewheel, with a Perfect gold bottom cog
The New Winner had adjustable bearings, using a special pair of pin wrenches; there was a cone and a locknut, basically as with a bicycle hub bearing. The New Winner would go to a 12 tooth sprocket in 7-speed or wide 6 versions. The splined sprockets for the New Winner had shallower splines than those for the Pro Compe and Perfect, and were not available in the largest sizes -- but it was easily possible to adapt Pro Compe and Perfect sprockets by filing or grinding the splines. One unfortunate limitation was a result of the New Winner's being marketed as a racing freewheel. The largest threaded sprocket had only 21 teeth. while there were only two splined-sprocket positions. For this reason, it was hard to build up a freewheel with a reasonable progression and a wide range. There were a couple of ways around this problem. An aftermarket threaded-to-splined adapter was available for a while -- and also the integral spacer of a 15T threaded sprocket would pop neatly into place inside a splined sprocket. Spot-welding the two together made a large threaded sprocket..
Sprockets for normal-spaced 6-speed New Winner freewheels were identified as E-X-T-R-A-A from outside to inside, and for ultra-spaced, as U-L-T-R-A-A. As the letters suggest, all but the two outer sprockets were the same in both series; only the spacers were different.
The New Winner lent itself to customization, as shown in the two images below.
SunTour New Winner in a 12-15-19-24-30-38 half-step configuration
with normal (5.5 mm) cog spacing. The challenge: find a derailer that will shift this!
The same freewheel disassembled. The New Winner had only two splined positions.
A threaded adapter is used here for the splined 24T sprocket.
The Winner Pro went back to conventional shim-adjusted bearings, but was better sealed than previous models. The Winner Pro also had more splined sprockets and fewer threaded sprockets. The Winner Pro briefly offered an 11 tooth option in the wide six format. The Winner Pro also introduced the 4-prong extractor (previous models used 2 prongs.) There was also the Alpha series, basically a cheaper version of the Winner Pro.
Bruce Dance offers the following observations:
When the 'Winner Pro' and 'Alpha' series were launched they also (confusingly) launched a middle model which they called the 'Winner'. So there are two SunTour freewheels called the 'Winner', separated by about ten years.
The 'Winner Pro' has labyrinth seals and post-hardening-ground bearing races. The 1985 (newer) 'Winner' does not. They are otherwise identical, apart from the color of the lock-ring. The seals do not deter the ingress of the British weather completely, and must be regarded as as mixed blessing; once water gets inside, the seal ridges do seem to help water stay inside the freewheel body, where it would surely come out in use otherwise. [See Jobst Brandt's comments on sealed bearings -- John Allen] The only other benefit of the seals is that they make it less likely that a ball will be dislodged when rebuilding a freewheel body.
The Winner Pro/Winner body has a lubrication port set into the mounting screw threads. The idea is that the body can be removed from the hub, then purged with oil. It isn't a really 100% great idea; the hole is invariably blocked with a mixture of dried grease and aluminium particles from the hub threads.
Cleverly, the Winner Pro/Winner body had both splines and threads in the middle positions, so that the new bodies would accept all the older 'New-Winner' sprockets, as well as the new splined middle sprockets. The smallest middle-splined sprocket in most sizes is actually a unique fitting and cannot be interchanged with the others; the spline 'fingers' are longer in the inside diameter so that the threaded sprocket next to it bears against the tips and retains the sprocket correctly. The bevelled spacer between the #2 and #3 sprockets (for use with the smallest #3 sprocket) is an improved design that also bottoms against the body so that the #2 and #1 sprockets are clamped, but do not see the full force of the neighbouring sprockets, even if they are screw-threaded. (I have 'dished' many #2 sprockets with excessive force when using the older bevelled spacer on New Winner bodies).
The Winner Pro/Winner body (and the Alpha one, too) has a 15T ratchet and two pawls set at nominally 144 degrees. This gives 15 clicks and is meant to prevent the 'death rattle' which accompanies the older opposed pawl designs when there is play in the bearings.
The pawls inside WinnerPro/Winner/Alpha bodies are slightly wider and set on a smaller diameter than in the 'New Winner' and 'Perfect' bodies. I do not think they are quite as strong, not least because the nominal 144 degree pawl angle seems to be more like 143 or 145 degrees in reality, and typically the pawls clearly do not share the load properly when the bodies are new. By contrast New Winner bodies have pawls that share the load almost from new; at times I have used these for racing tandems without problems. [Indeed, Sun Tour specified the New Winner for tandem use, superseding the tandem version of the Pro Compe. -- John Allen]
The Alpha freewheel accepts all the splined Winner Pro sprockets, but is not threaded except for the the top sprocket, which is unlike most other SunTour freewheels, with a different thread. It is small enough to allow a 13T top sprocket, but not as small as the NWN/WP/W top sprocket thread. I think that the thread is the same size as that used on some Shimano freewheels, so could be the same as the thread on the 13T-top 6s 'Perfect' bodies (with which I am not so familiar). Otherwise, only the four-spline #1, #2 sprockets from other older Sun Tour freewheels can be made to fit these bodies.
WP/W/Alpha bottom sprocket body splines were intended to accept an 8-spline version of the bottom cog. However none of the freewheels I have from this period have anything other than the original 4-spline sprockets as per the 'New Winner' freewheel fitted. I don't know if they ever made 8-spline cogs in any numbers.
Sun Tour's innovations in shifters paralleled those in freewheels and derailers.
Derailer-equipped bicycles in the 1960s and early 1970s usually had downtube shifters, which required removing one hand from the handlebar. Some low-end bicycles had handlebar-stem mounted shifters, which looked good to newbies but which offered no way to stabilize the hand against vibration. They also posed the risk of injury to sensitive pars of the body. Sun Tour had answers to these problems.
Sun Tour Barcons (handlebar-end shifters) were the favored shifters for use with drop handlebars from the mid-1970s until the advent of index shifting in the late 1980s. These shifters allow precise control by wrapping the thumb and index finger around the handlebar end, operating the lever with the palm of the hand and the other fingers.
Traditional shift levers held their position against the cable pull by friction of the cover plate against the lever body. Friction was controlled by screw, sometimes with a D-ring handle so it could be adjusted during riding. Tightening required a hard pull against both the friction and the cable's tension. The Barcons had a patented feature, a ratcheted assembly so the friction only counteracted loosening of the cable.
What Barcons did for bicycles with drop bars, the Sun Tour thumb shifter, which mounted just inboard of the handlebar grips, did with flat bars. It conquered the mountain-bike market in the early 1980s.
I've become kind of a Sun Tour aficionado and therefore have spent some time researching the various road components that the company produced. It's difficult to locate comprehensive information, so I am putting some of it down here. I'll focus on the higher-end road groups and also some of the interesting and esoteric parts I've come across. I'll try to do it chronologically. A useful source for me has been the article "Sunset for Sun Tour," [Cited earlier in this article] although it is more of a historical overview.
Also see the 1980, 1989 and 1992 Sun Tour component listings, which are online.
The invention of the slant-parallelogram rear derailleur seems like a good place to start. Nobuo Ozaki of Maeda (Sun Tour's parent company) invented the design in 1964, and it was soon patented. The patent would expire in 1984, and Sun Tour's competitors would adopt the design immediately after. In the twenty-year interim, Sun Tour's derailleurs were typically superior to their counterparts. The primary benefit of the slant parallelogram design is that the distance between the jockey wheels and rear cogs varies less as the derailleur is moved. The first slant parallelogram derailleur was Sun Tour's Grand Turismo model.
Another interesting part came in 1966, Sun Tour's Spirt (not Sprint, or Spirit) front derailleur. It was a "top normal" derailleur, in that you move the lever opposite the usual direction to shift up or down. Thus both shift levers move the chain to a higher gear when pressed forward. Apparently the Spirt was produced for some time.
Not much information is around from the late 60s or early 70s. I think the top model from around that time period was the Sun Tour V. [The V series rear derailers were sold with different cage lengths. The preferred model for wide-range systems was the long-cage VGT. -- John Allen]
In 1975 Sun Tour introduced Cyclone derailleurs, the new top model. They were quite a bit cheaper than Campagnolo Nuovo Record and shifted much better.
In 1977 the new top group was Superbe. This year also saw Ultra-6 spaced freewheels, which allowed a rider to run a 6-speed freewheel with 120mm dropout spacing. In 1979 Ultra-7 allowed 7 speeds with 126mm. Superbe remained top of the line until 1981.
Sun Tour Symmetric shifters were an esoteric piece of early 1980s Japanese engineering. They could be mounted on frames with a single downtube shifter braze-on (like some of the Shimano AX components took) or with a supplied clamp-on belt. They are unique because shifting the rear derailleur automatically trims the front via a cam mechanism.[Sheldon regarded the design as flawed, but opinions differ -- John Allen] The video below, from N. Keith Duncan, shows the operation of this shift lever.
In 1981 Superbe Pro was introduced. Good stuff, the early to mid 80s Superbe Pro friction group is probably my favorite. Commands a premium price on eBay (I would know, I'm selling a group on there right now). Superbe was now second-best, with Cyclone below that. ARx, AR and BL (Blue Line, which featured interesting blue details on the components) were also introduced. Brakes and brake levers were rebadged Dia-Compes and I think the cranks and BBs were made by Sugino (all the ones I've seen come with a Sugino marked grease condom, in any case). Pictures of the 1979 Superbe group, 1985 Superbe Pro group and Blue Line are here.
A note on Superbe Pro BBs: Sun Tour used an unusual taper for Superbe Pro BBs of the time. The closest match other than a Superbe Pro BB would be Campagnolo square taper, from what I understand. I think this is the approach that Phil Wood recommends. [The taper was smaller than on most other BB axles. Other cranks would bottom out at the inside of the taper; SunTour and Campagnolo cranks would not engage fully with axles of other brands. -- John Allen]
In 1985 Shimano introduced indexed SIS shifting. Sun Tour underestimated the need for a competing product and postponed development of an indexed system until 1986, at which point SIS had become quite popular.
In 1986, the Sprint group appeared, a friction group placed in between Cyclone and Superbe (Superbe Pro was dropped for a year). The Sprint shifters included a ratchet mechanism (Sun Tour Power Shift) that disengaged the friction mechanism as you pull back. A lot of people like this design, and it is often compared to Simplex retrofrictions. There are Sun Tour Barcons that use the same design. There had been ratcheting models on lower end Sun Tour groups previously, and future Accushift models would also have ratchet modes.
In 1987, Sun Tour's Accushift index shifting was introduced. There were technical problems. Further market share was lost to Shimano. Accushift groups included Superbe Pro, Sprint 9000, Cyclone 7000, α-5000, and α-3000. Non-indexed versions of the second- and third-best groups' RD and levers were referred to simply as Sprint and Cyclone. Superbe was dropped. The easiest way to tell the difference between the newer and the older Superbe Pro groups is the logo font. Newer cranksets used a 130 mm bolt circle diameter instead of the old Campagnolo standard, 144 mm. Aero brake levers were introduced. 1987 Sun Tour Dealer Catalog. 1988 Catalog.
In 1989 the lineup was changed again. From top to bottom: Superbe Pro, Sprint, GPX, Olé, and Blaze. Olé was a response to Shimano Santé and featured white details. Didn't really take off. 1989 Catalog and additional scans from around the same time.
Most of the problems with Accushift had been cleaned up by 1990. Superbe Pro was still top-quality componentry, but Shimano had taken over the market. Superbe Pro sealed hubs were of course excellent. There was the famous hidden-spring brakeset which functioned well and is now collectible. Sun Tour SL replaced Sprint in 1991. A bit from the 1992 catalog:
One last unusual piece of engineering was the Sun Tour Command Shifter. They were something like STI or Ergo and mounted just inside the brake levers on the handlebars. The front shifter had the ratchet system, the rear could do either indexed or friction modes. They worked well, save for the fact that you couldn't shift from the smaller to the larger chainring from the drops (which is when you would want to do so). If you were clever, though, you could solve this by using the Sun Tour Spirt derailleur mentioned earlier. A picture of command shifters.
Sun Tour stopped producing components in March of 1995. The name was bought by SR, but the component designs did not survive.
|Sun Tour Freewheels article on Yellow Jersey site|
|Frank Berto: Sunset for Sun Tour|
|Many catalog scans (Scroll down to Sun Tour listings.)|
|Many more scans of catalogs, articles, brochures and advertisements|
|MOMBAT SunTour history|
|Phil Wood description of axle tapers|
Last Updated: by Harriet Fell