Superbe Pro FD question
 

Maybe a dumb question, but will a Superbe Pro FD handle a triple? The shifter is likely to be a Superbe downtube shifter, if that makes any difference.

Just wondering what the chances are of assembling a Superbe Pro 3x7 drivetrain, even if the crankset isn't Superbe.

Generally the problem with road derailleurs is that they don't drop down enough at the back end to allow the chain to get to the granny gear without dragging on the bottom of the cage.

So it depends on the chainwheels, and luck.

Since the bike isn't going to have a Superbe crank, why not sell this nice derailleur to someone who will make correct use of it and buy a decent triple derailleur?

I don't have any Superbe components now, but the frame they would go on is a 1989 C'dale ST. Just about the correct time period for Superbe Pro, I'm thinking. Haven't decided which way to go with this one yet, just fairly sure I don't want to leave the shimano components on it.

That generally precludes using the granny chainring with the smaller two or three cogs but if you stay in the larger cogs, the chain usually clears the FD's cage tail.

I've used both Shimano and Campy road front derailleurs with 52/42/26 and 53/42/26 chainring combinations and dragging the chain on the FD's cage wasn't a problem.

Which is why I said it will depend on the chainwheels. It can work, but when it doesn't it is usually for the reasons I stated.

Up until about a month ago I was using a Suntour Cyclone FD on a '84 Cannondale ST with 30-40-50 chainrings. I had used that setup for years. I then swapped around parts and now have on the same bike a Suntour Lepree FD with 30-49-52 chainrings. It also is working beautifully. (That Lepree may very well be the original derailluer that came on the bike in 1984.) So, I just went to my bike/parts stash and held up a Superbe FD against that Lepree - the end of the cage on the Superbe is about 1/4 - 1/2 inch higher than on the Lepree, so you may not be able to use quite as wide of a range, but try it and see. I'd think the Superbe could still handle a fairly wide range between the chainrings. I then went and compared the horizontal range of the Superbe with the Cyclone. Mechanically (the moving parts and the set screws) are identical between them. It appears Suntour used the same "molds" on those two derailleurs, but the Superbe is just a bit shinier - better finish - and seems to have some of the extra metal "pared down" (I assume for lighter weight) compared to the Cyclone. But since the mechanical parts seem to be identical I'd think the Superbe would be able to handle the width of a triple - the Cyclone did. Sorry, I forgot to hold the Superbe up against the Cyclone to compare cage lengths, and now everything's put away and I'm too lazy to dig it all out again to check that measurement. Edit - just for comparison to your proposed setup, I have used both Suntour Accushift indexed barend shifters with a 7 spd. freewheel and Shimano 7 speed indexed bar end shifters with a 7 speed Shimano casette.

@tcarl, thank you for taking the time to compare the FDs you have and for relating your experience with Suntour triples. That is a big help to determine if this is a feasible upgrade.

That's what I was thinking too. It's another version of the chain slack take up non-issue with triple cranksets.

In real life, you only ever use the granny chainring with the largest 2 or 3 rear cogs. Consequently you don't need a front derailleur that hangs way down in back and you don't need a rear derailleur that can take up all of the slack in the little/little. Your friction downtime shifter is also a significant problem solver with a wide range crankset.

Your welcome. You mentioned that you don't have a Superbe FD yet. If you go shopping for one somewhere (like Ebay) be aware that the Cannondale ST have a 1 1/4 inch seat tube, vs. the standard 1 1/8 which was common on the steel bikes of the era. I guess in today's terminology those would be the 28.6 mm and 31.? mm diameters. Since Suntour was specked as original equipment on many bikes of the day those larger diameter band clamps were common (at the time). But in looking for and buying a derailleur be sure to check the band/clamp diameter.

Will it work? Sure. With down tube shifters virtually anything can be made to work.

Will it shift smoothly and consistently? Probably not. FD's designed for triples have cages and geometry meant to do a better job moving the chain from the middle to and from the inner chainring. This is exacerbated with 6-7-8 speed setups that have graduated tooth height as the ring entry/exit method instead of the later 9-10-11 speed systems that utilize tooth profiles and indents to assist with shifting.

In other words, you may be better off with a Deore FD to shift your triple. They are also relatively inexpensive and easy to find in the 31.8 clamp size required by Cannondale seat tubes.

just the difference between smallest & largest wont be large, but the stroke can be wide enough.

half step 4 or 5t difference between middle and largest will be using a road FD as the shallower back plate allows that ,

52,45, 36 perhaps... deeper one on a Triple FD wont clear the bigger middle, then you have to raise the FD higher, to reach the outer chainring.







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speedevil - the Superbe FD's shift doubles only. If you google SheldonBrown you can access some of the old Suntour brochures and this will give you more info to what FD's you could use if you wanted to use a triple. Off the top of my head, I think you'll have to go to a mountain bike style suntour FD.