Platy front derailleur with Riv wide-low double (39x28)?

[Tom Wyland]

OK, I'm still struggling to find a FD.  I tried a Microsoft R9 and that didn't seem to work.  The local bike shop said 10 speed won't work with 9 speed (which is all they had).  I'm running friction. 

Leah was nice enough to show how her older Deore (9 speed triple mountain?) was set up. Has anyone purchased a FD that works for them?  I'm having a hard time with all of the different variations (on ebay) or the myriad of 10-speed triples new.

Thanks!

Tom

[Pam Bikes]

I have an older derailleur I got from the used bin at our Recyclery bike shop.  Most old school derailleurs will work for friction.  I don't even know the name of it.  It's all metal.  The newer derailleurs are sized for different tubing and it had a plastic shim that did not hold.  Where are you located?  You need a mechanic who is used to older bikes.

[Tom Wyland]

Thanks, Pam.  I'm in the DC area (Herndon, VA) but it's spring and all mechanics are booked.  I'll ask Tim/Daniel at Bikes at Vienna when I can get there.  I'm trying to do this build all by myself as a project.  I would rather not order and return 5 FD if possible.

Tom

[Garth]

Tom it helps us readers to know what "doesn't seem to work", as in how ? The road FD's that I've set up with 24/26 low rings have all shifted brilliantly.

If the FD is hitting the frame raise it until it does clear, then test it by riding around wherever you are. The FD doesn't need to be as close to the big ring as "suggested". Everything of the manual drivetrain lends itself to endless creativity.

This will help you understand all the various FD designs. 

https://bike.bikegremlin.com/1297/bicycle-front-derailleur-compatibility/

[RichS]

Tom,

Have you tried a Shimano 9 speed Sora? Available as a double or triple. I have one of these (double) on a frame and it works fine. Friction shifting 7 cogs with a 46x34 in the front. Mine is shimmed but so far no issues. The number of front and rear derailers on the market today is indeed staggering.

To Pam's point I'm sure others on the list can point you to some vintage derailers that will work for you.

Best,

Rich in ATL

[Patrick Moore]

Garth is right, you can use a road derailleur (or any other) and simply raise it high enough to clear the stay. I've done than many times with no shifting problems.

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Patrick Moore

Alburquerque, Nuevo Mexico, Etats Unis d'Amerique, Orbis Terrarum

[Jon Dukeman]

Tom

Google

IRD sub compact fr derailleur .Numerous bike shops sell them.

I love mine.

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[lconley]

What is the external diameter of the Platypus seat tube that the front derailleur clamps to?

Laing

Delray Beach FL

On Tuesday, May 25, 2021 at 9:27:10 AM UTC-4 Tom Wyland wrote:

[Tom Wyland]

Its 28.6? It can be shimmed from a larger sized clamp.

Tom

Sent from my iPad

> On May 26, 2021, at 7:30 AM, lconley <lco...@brph.com> wrote:
>
> What is the external diameter of the Platypus seat tube that the front derailleur clamps to?
>
> Laing
> Delray Beach FL

[lconley]

The Roadini had the "baseball bat" seat tube that flared at the bottom and took a large diameter FD (same as an early Clem), and I was just wondering if the Platypus was the same, which would eliminate a lot of 28.6 FDs. You can shim a large diameter FD down, but you cannot shim a small diameter FD "up."

Laing

[ascpgh]

My SunTour Superbe Pro answer for the 46/30 nine speed drivetrain on my 650B rando:

The Mavic 860 FD answer for my 46/34 eight speed drivetrain on my Rambouillet:

What makes these work for compact ring sizes and combinations is a lack of sideplate sculpting which only serves to improve the function of particular drivetrains in very limited chainring tooth counts by simultaneously being near or clearing the chain when in particular cog/ring combinations so as to have snappy shifts but reduce the need for trimming across the cogs in a particular ring. 

I'm all friction/manual on my FDs so I don't care about avoiding trimming the cage when it drags a bit, that's my job. These old parallel plate FDs will perform well across a greater range of ring sizes and differences than modern sculpted ones, we tried a bunch to see what fit and functioned best when building this bike last spring. If you're using integrated shifters and need a FD to both function across your two chainrings quietly I suppose you are turtled by all the new stuff that demands your chainrings be of limited options and differences.

Andy Cheatham

Pittsburgh

[Joe Bernard]

Tom, what exactly is/was the problem with the Microshift you tried? 

Joe Bernard

[Tom Wyland]

Um, it seemed like the cage wouldn't clear the stay?  Also it didn't appear to move far enough for the "low" gear when I pushed it all the way in. Maybe it could be modified.  I could re-purchase it (LBS) and try again, I supposed.  Seems like you're all saying that most of them should work.  So user error on my part, maybe?

Here's the model:  Microshift 539 Triple 9-speed:  https://www.jensonusa.com/Microshift-R539-Triple-Front-Derailleur

Tom

[Joe Bernard]

Two potential issues I see here: 

1. That's a triple fd and your cranks are triple, they just have a trouser guard instead of a chainring in the 'big ring' position. The problem people are encountering with this setup is the guard isn't much bigger than the middle ring and they think the derailer should drop down to meet it. Nope! Leave that gap so the cage still hits the middle/small rings in the right spots and clears the chainstay. Here's a pic of my Campy fd on a triple for an example: If I want to replace that big ring with a smaller diameter trouser guard, the derailer would stay in the same spot. 

2. If you've backed the Low limit screw all the way out and the derailer still won't drop the chain to the small ring, your bottom bracket spindle may be too long. Check if you have massive clearance between the rings and the chainstay. 

And a possible solution: I have another one of those Campagnolo derailers and the shim I bought to make it work on my Susie with a 28.6 tube. But now I'm doing 1x and don't need them so I'll cut you a crazy deal if you want to try it. Holler at me for pics, text 415 786 4623. 

Joe Bernard

[lconley]

Did you mean to say that the spindle may be too short? If the derailleur cage cannot move far enough inward, shortening the spindle will only make the situation worse. Agree with the rest.

Laing

[Joe Bernard]

I meant too long, but I see what you're getting at here: The chainstay clearance might be what's preventing the small ring shift. SO..let's get a derailer mounted properly first, then we can see if the problem is solved before moving to spindle length 👍

[ascpgh]

Real world gearing has lower tooth count/smaller circumference than big brand OEM spec. The profile of front derailleurs caters to precisely what they choose as your gearing, even MicroShift:

That derailleur expects to be at a 52t chainring's radius (plus 1/8"for tooth clearance) above the BB. Don't have to see it with those specs to know there's a lot of cage tail to cope with possibly meeting the chainstay when lowering it on your seat tube. 

When you choose smaller chainring combos it requires moving the FD down the seat tube to the right proximity of your big ring and if you've gone below manufacturer's recommendations (or have a low BB) the tail of a triple may hit the chainstay. 

As viewed from above, larger rings intersect the out angling stays if not on longer spindles. Reduce those rings' toothcount and you just bought clearance from the stay and you can lower your Q with a shorter spindle. Max outward reach issue negated. 

This is how i've come to use old road double FDs on my compact drivetrains. 

Andy Cheatham

Pittsburgh

[Joe Bernard]

Andy, I think you're onto something with the long tail of that particular mech. It appears to be a clone of the "9-speed" Shimano 105 that Riv used to spec on their triples 15-20 years ago, and they had a problem with them landing on the chainstay because of a combination of low BB (creating a steaper stay angle) and 46t big rings (instead of 52). Which is to say I'll bet most mountain triples would work better on that frame. 

Joe Bernard

[lconley]

Here are 3 front derailleurs - left to right: Shimano FD-2300 w/integral 31.8 clamp (2x8); Microshift FD-712FS w/Origin8 28.6 clamp (2x10); IRD Sub-C w/IRD 28.6 clamp (2x10).

Note the length of the cages gets shorter from left to right - the IRD is specifically meant for subcompact gearing - its cage also has more curve. If you are going to use one of these (a 2x FD) with an outer chain guard on a triple crank, you may want to get some chainring shims (there are such things) for the chain guard to space it out as the 2x FDs are meant to sit closer to the largest chainring and may crowd the chain guard. As pointed out by others, 3x FDs have more shape to the cages and can sit higher to clear the chainguard.

Laing

Delray Beach FL

[Tom Wyland]

I'm going to try one of Joe's vintage derailleurs next.  Stay tuned. Thanks, Joe for the parts connection and the offer to help!  

Tom

[Matthew P]

I'm finding this thread more helpful than expected.

I wanted to add this in order to simplify:

"Front derailers don't generally care how many gears you have in back, though models designated for higher numbers of speeds may have slightly narrower cages , so they might be a bit more fussy in adjustment/trim when used with wider chains."
- sheldonbrown.com/speeds.html

If people have found exceptions to that rule I would be happy to hear them - would be good to know.

Double or triple cranks/rings vs. double or triple FD simplifies when you're friction shifting up front, which is even easier than in the back.
Then you just gotta see about the reach/throw of the FD.
Good catch on spindle length part of this equation! And I see how the bash guard kind of confuses things with setting the FD height.

I'm setting up a FD on a Toyo Atlantis. Of course all 3 FDs I have are all 31.8 mm clamps. I'll shim.
Thinking about puttin a lever right on the FD.
Back end of the cage was looking close to hitting the chainstay on first mock-up. Might need a shorter cage. Nicely shown by Laing.

Joe that is awesome you offered up a FD, a campy at that. If it doesn't work for Tom, I'd gladly buy it off you for a campy build in the q. Or feel free to tell me to stop swooping on parts :)

Nice work group.
-Matthew
San Diego

[ascpgh]

Long cage designs are trying to make initial contact with the chain by the side plates at a place where the most effective use of lateral movement is.  FD design to accommodate more gears on triples and integrated brake/shifters has to deal with both trim and rapid contact with the chain at a point that is most likely to initiate the chain being dropped to a smaller or letting go of a ring's teeth and climbing onto a bigger. 

Ramps and pins handle the work once the chain contacts a bigger ring. Abrupt movement initiates shifts to smaller rings. I think in some of the designs the longer tail of the FDs came from the contouring of the side plates reducing trim needs as you shift across the cassette while on a specific ring. When in larger rings the chainline is proximate to the front or middle of the cage but plate shaping to reduce trim requirements in that area of the FD might create some long movement before contacting the chain for an up shift from the smallest ring. 

I suspect that the answer was harmonics and the abruptness of the trigger release nature of most integrated shifter actions, that the long tail placed the initial contact at a place (when using the brand's specified chain) creates a wave complimentary to the pretty specific chainring reccos (limitations) of the package inserts. That's a brittle system if it's true but after looking at how deep Shimano goes in this sort of secondary or tertiary physical function in other cycling and fishing gear, I think it's for real. 

Not interested in click shifting? FD cages don't have to be such elaborate origami or '60s Cadillac long. Look at this one. Not only friction but no cable either. Again why I ended up with what seem like obscure antiques to move my chain between the rings...because I am doing it, not the snap of a spring loaded device on my handlebar. Modern cycling is trying so hard to remove cycling as a barrier to cycling that it gets tangled up in its own line like a fly fisher trying to cast too far. Sometimes a learned skill will be required. 

Andy Cheatham

Pittsburgh

[ascpgh]

As soon as I posted that last item I opened this gem that substantiates some of my suspicions about Shimano's intents.

Lordy. I just want to ride my bike as an escape from other complexities. They are going to force me to call it something else that more accurately reflects what it is if they are going to use their industrial might to drift the concept their way. Soon nothing they produce will have applicability to me except maybe a fishing reel. 

Andy Cheatham

Pittsburgh