Front Derailleur Esoteric Quest
 

Let me describe the situation. I have a bicycle that is set up as an 81 speed. In order to keep gearing in the range of mere mortals, I went with a front triple with 34-36-40 gearing. In theory, it should be a breeze to find a front derailleur that can handle the massive 6-tooth gap, but I have an issue.


https://cimg6.ibsrv.net/gimg/bikefor...2773897e32.jpg

I can't lower the FD any further to get it any closer to the chainrings because it will hit the cable and chainstay.

https://cimg3.ibsrv.net/gimg/bikefor...c7aefb3792.jpg

This shows the chainline when at the limit. I have fiddled with angling the derailleur, but in order for it to reliably shift to the inner chain, it ends up hitting the tire.

https://cimg6.ibsrv.net/gimg/bikefor...bf964b0843.jpg

Does anyone know of a FD that can handle the triple that either has a shallower angle, or which has an adjustable angle (like the old Simplex FDs)? Hoping to find something that doesn't cost more than the frame did. ;)

Or, modify that one. My thought - drill for a #2 or #4 screw though the outside plate, run a nice neat SS pan head from the outside, through the outer plate, through a bushing made from aluminum or steel tubing, though a washer, through the cutout on the inner cage plate, through another washer and a lock washer and nut or just a red locktite'd nut. Cut off the bottom of the cage. Could look like it was made that way.

Ben, the guy who enjoys making bikes different. (I have three I could show you for inspiration.)

I would try a MTB triple type it may have a smaller arc, and double check your chainline. It takes one heck of a spindle to have the Maxi tripled from double.

Paging our resident constructeur @gugie.

Yes. That type of modification.

Alternatively, would anyone know the dimensions of the current Tiagra FD-4700? Looks pretty short.

https://cimg9.ibsrv.net/gimg/bikefor...452b35d40c.jpg


-Kurt

either an old shimano 60 or 600ex will do it and clear the stay. i have tried both in very similar circumstance. the 600ex is currently still in operation on a 39/36/24 half step on one of my gran turismos. the shimano 60 would work except the tail end is a bit too short and the chain rubs when down in the granny. iow's, it can clear the stay, handle the triple shift, but not the amount of drop

This is C&V, Campagnolo Gran Sport, cage is rotatable.

If the derailleur is hitting the tire, move the crankset out with a longer BB spindle? If you want to try a different rear derailleur, I've had success with Cyclone MkII's.

That's all I've got.

I may come back to ask for that visual.

The RD works like a charm. I am 99.99% certain that I'd have no issues shifting if I could bring the FD down farther (to within 3-5mm of the rings). The front only contacts the tire when I adjust the FD (looking from atop it down the seat tube) clockwise far enough to facilitate the shift to the inside ring.

Kurt,

That looks like it would be a viable answer - presuming it's a bottom pull and would come with an adapter for a 28.6 seat tube. I can look that up.

Other points about C&Vyness are taken, however this project has already strayed so far from purity, it is no longer really a concern of mine. :)

Oops, sorry, senior moment. I meant front derailleur, and I still recommend a Cyclone MkII

Having been through a similar situation, there is no easy solution. The problem with moving the lower cage bolt up is that the plates don't line up, as 2nd photo shows. The problem with using a MTB triple is the small difference in ring sizes. You would have to gap the inner plate to the middle ring, which would leave a large gap to the outer. That could work but the chain will overshift the big ring rather easily. Gevenalle makes a CX FD for slightly smaller rings but I don't know if it can handle a triple.

https://www.gevenalle.com/product/bu...nt-derailleur/

You might try to find a MTB triple FD with a large inner plate and then shave it down for better clearance.

3 front * 7 cogs * 3 IGH, I presume? Cool! This reminds me of Charlie Harding's 90-speed bike, on display in his Westwood (Los Angeles) shop in the 1970s. I think he went 3x6 derailleur gears with a 5-speed IGH.

Coincidental post
 

Newer old guy here so didn’t want to be laughed at when trying to get my Miyata 1000 from 48-38-28 to 42-34-24. My triple front wouldn’t get low enough for the 24 and looked bad. As you said a 600 from my local co-op did the trick. Might not translate to this situation, but shifted all 3 nicely.

What about one of the Suntour Microdrive FDs? Those were made for small chainrings. Suntour BL FDs have small cages also.

http://velobase.com/ViewComponent.as...=113&AbsPos=64

@USAZorro...
Eighty one speeds! Wow. I did see a guy, once outside of the liquor store, riding a home made 36 speed recimbent steed one day. I do wish that I had taken a picture but, alas, I did not.

Of course, you could adapt a larger fourth ring and use that as an excuse to raise the FD ;)

-Kurt

what model of the 600 series? the one i'm using is an early 80's arabesque friction only

nothing laughable about your change out, btw :)

3 x 9 x 3 IGH

600EX I think
 

600EX I think. Came from co-op but matches one from an 85 Centurion I have that is EX I think. Paid $5 so gave it an uneducated try with good results. With careful chain length tuning I get the 5 easiest gears on the 24T before the chain hits the Miyata chainstay protector hoop.

In the immortal words of Homer Simpson, "Doh!" My bad ...

What are you cog tooth counts in back?

0.75/1.00/1.33 IGH like a Sturmey AW, or other?

I presume you have already created a gear chart and shift diagram. :)

The closest I ever got was a 36-speed, with 3 in front and a 4-cog 14-16-18-20 block in back on an AW.

As suggested, maybe a BL or Cyclone.

This:

https://cimg4.ibsrv.net/gimg/bikefor...e88c2c57d8.jpg

What’s the length of the FD cage? I can route around in my deep FD bin to see if I have anything shorter.

I think the Shimano 600 FD in question is a FD-6207.

Some Suntour Mountech FD have a "step" or notch at the bottom of the cage to clear the cable and chainstay on touring bikes with lots of hanger drop.

Campagnolo 8/9 speed triple FD have short cages with inner plates that can clear half step chainring differences and smaller chainrings.

Shimano 9/10 speed trekking FD are available for the lesser angle between the seat tube-chainstay on frames with more hanger drop. The angle range is stamped on the back of the inner cage.

Tip to tip, 100mm even.

Center of seat tube to rear end 57mm (measured parallel to the ground - hoping this makes sense without resorting to drawings).

Haven't forgotten about the crankset, but I have practically every style besides cotterless road, and have been hoping to source one locally without success.