In my quest to customize my bike absolutely as much as I possibly can, I customized one of those great quality, but cheap $12 SIS compatible 7 speed freewheels. Thought someone might be interested that it can be done.

I wanted 'corncob' gearing so I can tool around and impress people, but I needed a bailout gear for those steep driveways you occasionally encounter.

I took a 13-15-17-19-21-24-28 and a 14-16-18-21-24-28 and managed to combine them into a 13-14-15-16-17-19-28. Works like a charm! Of course, I had to get a few extra cogs off loosescrews, and had to spend a little time with the dremel...

I couldn't find anything off the shelf, and the stuff out there that was closely spaced was without the ramps that make the Shimano freewheels work so well. I've got the thing shifting perfectly with 8-speed ergos.

As you can see, I still have to take a sharpie to that big cog...

Most of my freewheels are custom built using the Suntour Winner system, which allows building 5 or 6 speed freewheels for 120mm hubs and 6 or 7 speed freewheels for 126mm hubs. The system has different width spacers, permitting regular or narrow (ultra) cog spacing. I purchased a "shop board", which came with freewheel bodies, cogs and spacers that allow an almost unlimited variation in gearing setups. I recently even used this system to build a single speed freewheel for a restoration of a 1970s Mercier. The advantage of this method over just buying a single freewheel is that I could achieve a near perfect chainline to within +/- 0.5mm and could choose cogs from 15T to 21T.

What a cool set up! I don't suppose those boards come up on eBay too often...

I read about those boards when I was researching my options. After scouting out eBay, I figured I'd need to spend hundreds of dollars to get the materials for customizing a vintage freewheel, and then I'd have compatibility to worry about.

With the Shimano stuff, I counted on the various cogs and freewheels being compatible, and it mostly worked.

Yeah, that suntour board is very neat. I agree about the writing on the big cog, it's just a tad over the top!

I think I once saw an incomplete board on eBay for some exhorbitant amount. I bought mine over 30 years ago, and it came with at least 3 of every size cog, 6 of every size spacer and 4 bodies. I had the shop where I ordered it get me some additional parts, such as the smaller size cogs than wear out more frequently. I have since bought several complete freewheels to augment it. Also, most of the parts are interchangeable with other Suntour freewheels such as the Perfect and ProCompe. You could get the bodies with French threading by special order only. Shifting is on a par with Shimano Uniglide, but neither are a match for Superglide/Hyperglide.

sciencemonster that is an excellent setup! Which cogs did you end up having to grind down? I'll see if I can duplicate it here at the shop.

Yeah I this new stuff really get my blood boiling. Back in the 80's you could buy a freewheel, or body and customize it as you saw fit. it wasn't easy to get the spacers and cogs just right but the companies made them and it was possible. Then they went to cassettes, the perfect system to be able to pick your cogs and gearing and then only started selling complete ones, or not sell or make the cog you wanted, or worse they would rivet them together...

Now we make freewheels similar to cassettes and still make it difficult to customize... It would be so easy to make standard body and cogs.....

I know, I know... it isn't the big market share, it isn't racing, it isn't cost efficient. blah.blah.blah.. (pulls out old codger card)

Hey Sciencemonster,

Did you have to change or modify the cable attachment at the rear derailleur? I thought that there were issues using 8 speed shifters with current 9/10 speed derailleurs because of a different actuation ratio.

Please let me know because I have a set of Record 8 speed hubs and 8 speed downtube shifters but no 8 speed rear derailleur. If I can use a new derailleur then I have an idea for a great retro-rod.

thirst

I got the oversized 17 and 19. I had a 6 speed, and it took three big, three small. I guessed that the 7 speed would be 3 big, 4 small but I was wrong - it's the other way around. So I had to cut the 16 to fit on the larger splines. I also had to scavenge the 6 speed spacer that bridges the transition from big spline to small spline - it had an inset built in to take up slack taht I needed to use, and I had to trim it's width to fit the narrower 7 speed spacing. So all in all, I spend $30 ont he freewheels, and $20 on the extra cogs.

Also, the 14T and 13T cogs have built in spacers and they meshed up kinda sloppy - but when I tightened the nut down I kept them straight and it worked out great. This weekend I am going to take it apart for pictures and make a web page explaining what I did and how.

A little pricey, but a NOS Regina corncob is, like, $150 - and this shifts a heckava lot better. I also have a slew of extra cogs so I can change the gearing if I need to.

I'm not having any problems. It took me a couple trips to fine tune it, but it indexes fine.

Of course, the only other indexing bike I ever use has 3 speeds...so I'm not the greatest judge.

Higher up in this thread, I cite a link that quotes Campy itself saying it's close enough. If it wasn't, it would be trivial to adapt the freewheel - all the spacers are plastic. A couple passes with some emery cloth...there is your .22mm. The 13 and 14 are metal - but you could grind them down or not.

I am thrilled with the result, although I do miss my downtube shifters...

My bikes are nearly always a Frankenbike setup like that - very well done! It's amazing how well a good freewheel with a modern derailleur will shift, even with downtube friction levers! Makes me wonder why anyone needs indexing.

I needed indexing because I ran out of things to play with. I moved the downtube shifting set up to a new rain bike, which, when I get a frame more to my liking, will become my everyday bike, then I'll convert my Comp into a rain/around town bike...and then...

I just like to futz with things. I've still got tandems and folding bikes to go...so I won't be bored for a while.

The Zeus freewheel used all splined cogs except the outermost, which was threaded to hold the rest in place. All the splined cogs were completely interchangeable. No spacers were needed; the cogs themselves were shaped to provide the needed clearance. All the splined cogs were aluminum for light weight; the threaded cog was steel. The body featured two notches to fit a standard Regina 2-prong tool, but was also splined to use Zeus's own remover that eliminated the risk of damage to the body that pronged removers often cause. The splined remover proved so popular that the French freewheel manufacturer Atom/Maillard copied it, and later Italy's Regina also copied it so a single splined tool would fit freewheels from Zeus, Atom/Maillard, and Regina. Shimano eventually came out with their own incompatible splined freewheel tool, but unlike the Zeus tool it required removal of the axle locknut and spacers for the tool to get access to the freewheel body. This was eventually changed to another incompatible splined design with a thin wall remover (like Zeus had all along) so no disassembly was necessary.

I sense a few kindred spirits on this board! I don't have a SunTour board, but I do have a good assortment of SunTour cogs on the pegboard in my garage. I have been building custom freewheels since 1971, when I was trying to make do with 10 speeds and without replacing expensive aluminum chainrings. My first efforts were on my Nishiki Competition: 54-47 (stock chainrings) / 14-15-19-21-28, which gave me 8 tight ratios on top and a 45-inch granny. Stock Peugeot PX-10 gearing at that time was 52-45 (same gap) / 14-15-17-19-21, which provided a couple of redundant ratios and a knee-abusing 58-inch bottom end.

Next, I faced the challenge of building a bike for my wife with a 52-42 TA Professional crankset. I started with a very popular racing concept, 52-42 / 14-16-18-21-24, but sacrificed the top gear for a granny for the local hills in above Los Angeles, ending up with 52-42 / 16-18-21-24-32, which worked very nicely with my old SunTour V-GT derailleur.

Next I got into third-step 15-speed gearing, for which I recreated the stock 13-26 freewheel sequence of my very first road bike, which had been geared 52-47 / 13-16-19-23-26. My new system was 49-46-43 / 13-16-19-23-26, which gave me 14 very nicely spaced ratios and a redundant, and unused, large-large crosschain. I ran 50-47-44 / 14-16-19-23-26 on another bike, for a 13-speed setup with no cross-chaining.

I know......digging up an old thread, but....

I'd like to know if this type of modification can be done between the 13-28 FW722 and the 14-34 Mega FW723. ???? You know, set up like this: 13-15-17-20-24-28-34.

It'd be $40 to do it, but still less than the IRD 13-32!

I work on a great number of FWs and the challenge with the least expensive Shimanos is how they are assembled. The large cogs are held together with a spider and rivets, thus rendering customization next to, if not impossible.

Sunrace FWs are said to function just as well as the Shimano HG FWs. I've not tried them but do have a new one in my spares and looks great and does not have the big black cog with "Shimano" in the last position.

They run in $20-30 range shipped.

Thanks, Bob. Yeah, I don't mind that black, Shimano tagged cog so much. I never look at those things when riding....

But, I did read in another thread about Sunrace, yesterday, so looked them up. I found they had that wide range 8spd, but...oi!....I don't have any 8spd shifters. That being said, I have some 7spd Shimano thumbies with friction/indexing rear. I wonder, then, since I really prefer indexing offroad.....avoiding overshifting more.....if I could run the indexing option offroad limiting myself to only the gears I typically use offroad and, then, run friction on road allowing utilization of that 8th spd when desired. What do you think, Bob? I have read 7spd and 8spd were real close spacing.....close enough for "adequate" indexing.

Oh, btw, anyone have experience using the 8spd freewheels? I read where there's a strength issue concerning the axle using more than 7spds.......and, 7spd even being questionable. Compared to a freehub, that is.

You might look at this link about 1/2 down the page about Mega-

https://sheldonbrown.com/mega7/

I was able to mix cogs between Sunrace and Shimano, I believe I put a Shimano 30t UG cog in the biggest position, replacing the Sunrace's 34t Mega-sprocket.

I had to grind flats on the Sunrace retaining ring to twist it off, since the 2 tool notches are well-recessed with apparently no tool available (you could easily make your own from 1/4" flat stock though).

I don't recall if Shimano and Sunrace cogs could interchange on the small-diameter splines, but can on the 3 large-diameter spline positions, at least WRT Shimano cogs fitting on the Sunrace body.

The earlier MegaRange 6 and 7-speed freewheels did not have the large sprockets riveted together. That came later, presumeably to save weight.

Goint to 6, 7 or 8 speed freewheels puts ever more stress on the axle, so a solid axle is recomended as rider weight causes too-frequent axle failure. 8-sp freewheels did not last long in the high-end market for this reason.

I've built hundreds of freewheels, and some were a ridiculous amount of work to put together. Chalk it up to too much coffee and basic stubbornness.

Sunrace quality has improved a bit, I've not had a loosely-assembled one come in over the last a several years. I've seen a few with loosely adjusted bearings, enough to cause a tick-tock rocking sound in certain gears.

I didn't know that corn-cob freewheels were scarce, and would have thought they would still be available cheaply.
Smaller items on Ebay suffer substantial mark-up because of the shipping cost and effort in creating and managing the auction, not to mention Ebay's substantial fees.
Maybe corncob freewheels are becoming like vintage track parts(?), gobbled up by hipsters?

Yum, i happen to have two corn cobbs, one on my Bianchi SS (13x18) and one on my Torelli Super Strada. I might can put something on a little bit higher to get this old body up low hills.