Why? I'll give several reasons.
A wheel with freewheel threading may still be serviceable, and you may wish to keep it in service.
Today's derailer-equipped bicycles have a 130mm or 135mm rear overlocknut distance, to accommodate an 8-9-10 (I'm getting dizzy)- 11-12-sprocket cluster. Most 1980s and earlier derailer-equipped bicycles have 120mm overlocknut distance. Most also have steel frames, and the dropouts can be respaced, but you may want to keep the spacing as is. Many 1980s and 1990s bicycles have 126mm spacing, and the frames are of aluminum, so the dropouts cannot be respaced.
SunTour Perfect, Pro Compe and New Winner series freewheels work with the 120mm and 126mm overlocknut distance. These freewheels were very common and are also very versatile. There are still enough of them -- and parts -- around to meet the needs of bicyclists who would like to keep an older frame and wheelset in service.
Unlike freewheels currently in production, the SunTour freewheels also allow almost any sprocket combination you might want. A SunTour narrow-spaced ("Ultra") freewheel will index with a Shimano derailer and 7-speed shifter -- or with an 8-speed shifter using a bit of alternate cable routing.
The one significant disadvantage of these freewheels over current ones is that the sprockets are not ramped, and so shifting is not as smooth. But, if you want to choose your own gear progression, or your bicycle has less than 130mm spacing, the tradeoff may make sense for you.
I still have, and ride, a couple of bicycles with these freewheels. I have even reground worn sprocket teeth at times to make them work with new replacement chains. (See information on regrinding sprockets in our article on freewheels.)
You also may be interested in these freewheels for historical reasons. We have another page about SunTour history, with more background information on these freewheels.
All Perfect, Pro-Compe and New Winner bodies can be identified by the stout two-notch freewheel-remover fitting, and by the flange at the back, with four notches corresponding to the four splines on the larger sprockets. The bodies also are labeled on the cover plate.
Perfect and Pro-Compe freewheel bodies are very similar, except for finish. Perfect bodies are bronze-colored, and Pro-Compe bodies are black. There are three general types:
SunTour Pro-Compe freewheel for Ultra spacing, with 2mm overhang
Pro Compe freewheel with the 13t sprocket
Classic European freewheels have an odd number of ratchet teeth and two pawls directly opposite one another, so only one pawl engages at a time. SunTour New Winner and Perfect bodies, and some Pro Compe bodies, have an even number of ratchet teeth and two pawls directly opposite one another. As you turn the freewheel slowly backwards, you can hear it go ttick-ttick-ttick as the two pawls engage at (nearly) the same time. Unless the freewheel's bearings are adjusted just short of binding, chain pull rocks the outer body one way, then the other as the wheel turns, making a light clunk-clunk noise. The cover plate of some of these freewheels has a tendency to unscrew, probably worsened by this excess motion. If the clunk-clunk noise starts or gets worse, check right away whether the cover plate is coming loose. Twice I have had a cover plate come off completely, dumping all the bearing balls out of the freewheel. Both times, I managed to ride home after screwing the cover plate back on, taking care not to coast.
The freewheel can be restored with about 100 new 1/8" bearing balls -- but as the saying goes, an ounce of prevention is worth a pound of cure. Disassembly of a freewheel usually makes no sense, but this is the exception. (See Sheldon's instructions on rebuilding freewheels.) Mount the freewheel on a wheel and tighten it with a freewheel remover or by riding. You can leave the sprockets in place. With the wheel off the bicycle and the freewheel facing up, unscrew the cover plate clockwise. If you don't have a pin tool that fits, you could use a hammer and a pointed punch, alternating between the two holes in the cover plate.
SunTour Pro-Compe freewheel with cover plate removed, revealing bearing balls and shims
With the cover plate off, you will see a circle of bearing balls, and inside that circle, shims (very thin washers). Usually, removing one or two shims will bring the bearings into good adjustment -- that is, just short of binding. Test the adjustment by replacing the cover plate, spinning the freewheel backward to check whether it binds, and trying to rock it. Then remove the cover plate again.
For final reassembly, clean the threads of the cover plate and the mating threads of the inner body. This is possible with Q-Tips and solvent without further disassembly, though you may find cleaning easier if you place a cup over the freewheel to catch the bearing balls you can see in the photo. Hold the freewheel in place on the wheel so the bearing balls at the back of the freewheel stay in place, and turn the wheel over so the visible bearing balls drop out. Then, still being careful to hold the freewheel in place, turn the wheel right-side-up again and clean the threads. After cleaning, pour the bearing balls in and distribute them. Don't relubricate yet. Apply a couple drops of blue threadlock compound to the cover-plate threads before reinstalling it -- only a couple of drops, and only to the cover plate, so you don't gum up the bearings or the pawls.
Screw the cover plate back on counterclockwise and tighten it. Tightening the cover plate turns the freewheel body the same way as to remove the freewheel, and that is why it must be tightened onto a wheel. Let the threadlock compound harden. Before riding the bicycle, drip oil into the mechanism as described in our article on freewheels.
The New Winner body is cleverly designed to take 5 or 6 sprockets in 5.5mm spacing; 6 or 7 sprockets in 5mm spacing. The outer sprocket can be as small as 13 teeth with 6 sprockets, or 12 teeth with 7 sprockets. New Winner bodies have an adjustable lockring rather than shims and generally were supplied in correct adjustment. Two of the special tools shown below, now rare, are needed to disassemble or adjust the New Winner body, but this work is very rarely necessary.
Not easily obtainable but usually unnecessary: SunTour New Winner tool
SunTour Perfect sprockets are bronze-colored, Pro-Compe sprockets are gold, and New Winner sprockets, silver. These freewheels use four-spline large sprockets, and threaded smaller ones. The teeth are 2mm thick. Exception: sprockets from the earlier-model Winner, are black or gold, some are slightly thinner, and some have eight splines rather than four. The photo below is of the sprockets and spacers for the common 5-speed Perfect freewheel.
Dimensions are as in the table below. The diameter given is for the freewheel body. The inside diameter of threaded sprockets is about 1/2 mm smaller than the outside diameter of the threads to which they attach..
| File splines of Perfect sprockets to use on
Pro-Compe or New Winner body.
|V||5.5mm spacing||52mm||16||3.5mm spacer for wide (5.5mm) spacing,
|5.0mm spacing||52mm||16||Includes 2.7mm spacer for Ultra (5.0mm) spacing. Not used on New Winner, so no code.|
|threaded||R||All||44mm||15||21||Has wide threading flange to secure splined sprockets on New Winner narrow-spaced 6 and 7-speed.|
|threaded||T||All||44mm||15||19||May not have wide threading flange to secure splined sprockets on New Winner narrow-spaced 6 and 7-speed.|
|N||5.5mm spacing||44mm||14||Includes 3.5mm spacer|
|P||5.0mm spacing||44mm||14||Includes 2.7mm spacer for Ultra spacing (but 3.5mm will work on Pro Compe)|
|threaded||Perfect||40mm||13||14||Used only on the rare Perfect body
with two threading diameters.
Shimano 600 or Dura-Ace sprocket will work.
|14||16||6-speed wide. Outer sprocket threads onto this one.|
||For 6-sp wide, threads onto X sprocket; For 5-sp, outer sprocket, attaches to body.|
|39mm||13||14||6-speed narrow outer sprocket, attaches to body|
|13||15||7-speed second-outermost sprocket. Outermost sprocket threads onto this one.|
|35mm||12||13||7-speed outer sprocket
attached to next sprocket.
Shimano Uniglide or track sprocket
threading is slightly smaller: won't work.
Except for the 16-tooth sprockets, in two widths with integral spacers, all four-spline sprockets are interchangeable, though Perfect sprockets have slightly deeper, rounded splines which may have to be filed before they will fit a Pro Compe or New Winner body. Most 44mm threaded sprockets are fully interchangeable too. 14-tooth sprockets came with two widths of integral spacers, as indicated in the table. Using an outermost 14-tooth 44mm-threaded sprocket for 5.5mm spacing on an Ultra-spaced freewheel works OK except on the New Winner 6- and 7-speeds, where it would reduce the spacing to the next outer sprocket.
The outer one or two New Winner sprockets use a threading different from other SunTour sprockets, and so sprocket availability may determine whether you will want to use a New Winner body. Only the New Winner's two innermost positions take splined sprockets, making a good sprocket progression with large sprockets hard to assemble -- but we have a workaround, keep reading.
The image below shows 5 kinds of special New Winner outer sprockets and gives their threading diameters. The E sprocket is attached to the X sprocket to make a 6-speed, and directly to the body to make a 5-speed.
The letter codes for the New Winner provide a nice mnemonic:
Let's look at the photo of sprockets and spacers of the common 5-speed Perfect freewheel again. Because of the different spacings and numbers of sprockets, Perfect and Pro Compe freewheel bodies were made in several splined, threaded and total widths. Spacers of different widths established the different sprocket spacings.
The spacer behind the outer, 15-tooth sprocket is beveled to avoid interfering with the chain.
The two leftmost spacers, between the splined sprockets, are 3.5mm thick and the sprockets are 2mm thick, for a combined spacing of 5.5mm. The outer spacers are only 1.9mm thick because the outer, threaded sprockets are thickened near the center hole for the threads. 14-tooth threaded sprockets and 16-tooth splined sprockets have integral full-width spacers. Splined sprockets with 17 or more teeth are flat and use separate spacers, as shown. Ultra spacing uses thinner spacers. The table below identifies the different spacers.
|52mm||57mm||3.5mm||Steel, split ring|
|52mm||57mm||2.7mm||Steel, split ring, or plastic, with 4 splines
|transition||New Winner||52mm||56mm or
|0.9mm||Used in Ultra new Winner where the second splined sprocket does not overhang the end of the splines.|
|All||44mm||54mm||1.9mm||For 5.5mm sprocket spacing. Beveled spacer must be used behind a 15T sprocket|
|All||44mm||52mm||1.1mm||For 5.0mm sprocket spacing. Beveled spacer must be used behind a 15T sprocket|
The next photo shows a Perfect body with three splined sprockets and two spacers in place. The red arrow points to one of the splines. The rightmost splined sprocket overhangs the larger-diameter section of the freewheel body, as shown, so that the spacer behind the next, threaded sprocket can secure the splined sprockets.
Perfect and Pro-Compe bodies designed for the narrower Ultra (5mm) spacing have a splined section to accommodate three or four sprockets and their narrower spacers. With some Ultra-spaced freewheels, paper-thin shims are needed in addition to the regular spacers so that the rightmost splined sprocket overhangs the splines and the threaded sprockets secure the splined ones.
With Ultra (5.0mm) spacing, the second-largest sprocket does not overhang the splines of the New Winner body, and so a special 0.9mm thick spacer allows the threaded sprockets to secure the splined ones, as shown in next photo. To engage this narrow spacer, the first threaded sprocket has to have a wide flange.
When building up a SunTour freewheel, it is helpful to have an ample collection of spacers salvaged from disassembled freewheels. Sutherland's Handbook for Bicycle Mechanics, 6th Edition -- still available as a CD-ROM -- includes a complete listing of the different sprockets and spacers.
The New Winner body takes only two splined sprockets, and threaded sprockets were sold only in sizes up to 21 teeth, requiring a big jump in size between sprockets if the splined sprockets are large. An aftermarket adapter to allow a splined sprocket in the third position was available once -- no longer -- but there is a workaround. The 15-tooth threaded sprocket's flange fits neatly into the opening in a splined sprocket with flat-top splines, and can be tack-welded onto the inside face of the larger sprocket (the side where the teeth are shorter), also serving as a spacer. The welds must not extend higher than the face of the smaller sprocket. Grind the welds down if necessary.
Splined sprocket modified into a threaded sprocket.
outside face of sprocket | inside face of sprocket
Freewheel and cassette bodies are designed so the rear derailer will clear the spokes with the smallest possible sprockets. With larger sprockets, the slant of the spokes allows an additional sprocket closer to the wheel. A dished sprocket, or one bolted onto the innermost splined sprocket, can be added without increasing wheel dishing or dropout spacing.
A dished sprocket will move the other sprockets 2 mm farther to the right, and can allow a body which was designed for 5.5 mm sprocket spacing to accommodate an additional sprocket in 5 mm (Ultra) spacing. Dishing a sprocket requires the use of a machinist's tool -- an arbor press -- and a forming template of 1/8" or 3 mm sheet metal with a round hole in the middle. The part of the sprocket which is to be bent should first be heated red hot to soften it and allowed to cool slowly, otherwise the hardened steel may crack. Avoid overheating the teeth.
On my Cannondale bicycle with 126 mm dropout spacing, I have a 7-speed Ultra-spaced freewheel with the largest sprocket dished, on a Pro-Compe 6-speed body. Because the sprocket is dished, the wheel dishing is more moderate than it would normally be, and so the wheel is stronger.
Thanks to Yellow Jersey bicycles for review of this article, and an article wth more information about these freewheels.
Last Updated: by John Allen