Front derailers that won't friction shift

[Joe Bernard]

Here's a weird thing I didn't know about. Will wrote this up in an email newsletter, I have just the one screenshot and don't even know if it's ok to quote the whole thing. But basically these "long arm" Shimano FDs are designed for brifters and don't work well with friction. That's really weird! 

Joe Bernard

[RichS]

Hi Joe,

That was a good post; great timing when there has been much discussion as of late concerning front derailer design. 

Thank you to Andy for his highly informative analysis!

Couple things in Will's post that stood out for me:

1. Will said he wasn't happy with the way a Claris front derailer friction shifted. I've used the Claris in double and triple configurations, friction shifted (bar ends), 8 speed 

without any problems. Maybe I missing out on something by not using a different der? I have a Suntour ARX on the way so. . .

2. Wonder what the forthcoming "good" friction shifting derailers will be?

Best,

Rich in ATL

[Benz Ouyang, Sunnyvale, CA]

On Saturday, May 29, 2021 at 8:33:18 AM UTC-7 RichS wrote:

Couple things in Will's post that stood out for me:

1. Will said he wasn't happy with the way a Claris front derailer friction shifted. I've used the Claris in double and triple configurations, friction shifted (bar ends), 8 speed without any problems. Maybe I missing out on something by not using a different der? I have a Suntour ARX on the way so. . .

Do you have the same version? Shimano reuses the same model name to differentiate their lineup, even if the actual derailleurs themselves have changed quite a bit throughout the years. For example, the 8-speed XTR from the 90s is a completely different beast than the Di2 XTR of today.

From visually examining the Claris called out in Will's email, it appears the incompatibility is due to cable pull. A longer arm will require more cable to move the cage the same distance, all things being equal. This won't matter at all for dedicated shifters (regardless of whether they're indexed), but friction shifters are generally designed for compatibility with older derailleurs, meaning they won't pull as much total cable as is required for the most current derailleurs.

Examples of these are the 11 and 12-speed derailleurs, or SRAM's 1:1 actuation ratio derailleurs. Traditional friction shifters either can't pull enough, or pull barely enough cable to run the modern rear derailleurs. The same logic applies to front derailleurs with longer cable pull requirements.

 

2. Wonder what the forthcoming "good" friction shifting derailers will be?

For me, ironically, good friction derailleurs will need to be matched to the cable pull capacity of the friction shifter. Yes, I understand the match doesn't need to be exact, like for indexed shifting; but one still needs to get the match close for best effect. For the rear, that means a 120° swing of the (downtube) friction shift lever should result in a 41mm lateral displacement of the guide pulley on the rear derailleur (41mm is about the width of a 11-speed cassette). For the front, the same 120° swing of the shift lever should result in about a 16mm lateral displacement of the front derailleur cage, to accommodate a typical triple crank.

Why limit the effective swing of the friction shifter to 120°, and not, let's say 150° or even 180°? Read on.

I want to put in a plug for optionally setting the travel stop of downtube shifters about 30° from parallel with the downtube. In other words, I'll like the shifter's "home position" to be just slightly raised from being parallel with the downtube. Using this design for the left shifter will enable easy actuation of both levers with just the right hand for right-handed cyclists, and using this design for the right shifter will do the same for left-handed cyclists. To enable such a design means ensuring the shifter pulls enough cable within a narrow angle of travel, so the proposed 120°.

Interestingly, I haven't tried this yet, but it appears that getting a second set of downtube stop washer from Rivbike and using the "opposite" one will allow this 30° offset, so we may not even need any extra SKUs.

[Matthew P]

Neat. 

But Benz,

 
How does the stop help? By the time the lever reaches the position, either it has pulled enough cable for the desired shift or not. Just because I stop it doesn't mean I've achieved my shift. I write this being well sure you are right and I am missing something.

180 degrees shouldn't affect the home position, right, because where the lever centers is separate from how much throw it needs to shift through the whole casette, or no? Ah, but the stop you linked to sets the home position?
But/also if you are saying 120 degrees is what you find comfortable, then I get that. Although I am confused as to why it is desirable to shift both downtube levers with the same hand. Ah, I get it; its because I'm holding my burrito in my other hand :-D

The 120 degrees calls to mind a hack from someone on this list to and a strip of brass on the shifter, thereby increasing its diameter and cable pull (pull ratio = linear cable moved per degrees moved of the lever, no?). I think I prefer more throw/degrees, bc it means wider degree ranges for each cog/shift/sweetspot. But the idea is a good one. If the "spool" the cable wraps onto could be adjustable or swappable, and there were no stops or adjustable stops, then we could set our desired pull/-ratio and total degree throw, no? Forget about indexing though I assume. 

Anyways, I'm complicating things. But nice to discuss and understand and fiddle.

Thanks
-Matthew
San Diego

[Garth]

The Claris you have Rich is the 2400, yes ? That's a "normal arm", while the long arm wonky pull version is the 2000. At least they're easy to spot visually.

Microshit makes a nice looking 9-speed normal short cage FD, it's in their catalog, the R52S.  I'm sure Grant @ Riv knows about it as it was pictured in one the email/blugs last year. Only he knows why they don't offer it , maybe they can't get them as I've found but few traces of it being sold.

https://www.microshift.com/models/fd-r52s/

[R Shannon]

Hey Garth,

You’re absolutely right. Checked mine a little bit ago and it is the 2400. I think it’s two or three years old.

Looked at the current design and it is distinctly different.

Thanks very much!

Best,

Rich in ATL

Sent from my iPhone

On May 29, 2021, at 5:23 PM, Garth <gart...@gmail.com> wrote:



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[Peter Adler]

"(P)ulled enough cable" - you're all overthinking this. 

https://www.rivbike.com/blogs/grant-petersens-blog/no-10-april-28-or-so-rughut

Not that I think this is going to happen, but I feel I must note that GP and I have been discussing rod-lever (AKA "suicide") front derailleurs for several months, ever since I raised the subject with him at RivHQ and he told me that he'd sent the 50s Huret one posted in the Blahg to some dude in Australia for possible cloning. It came back assembled in the wrong order, and no longer worked. I told him that I had one (currently installed on an early 50s French racer), and took it home to reassemble it correctly.

Aside from the economic practicalities of the expense of tooling, Grant's theory seems to be that the big problem with lever derailleurs is the "suicide" branding. He also complained again about the lower toothcount limitations of the cage, until I demonstrated to him that the flat mounting piece attaching the rod to the frame clamp (visible only in the first take-apart photo) allows the cage to pivot the angle to reach smaller chainrings (Huret's 1956 catalog: "Front derailleurs, cable control or rigid control, are used for competition and touring and allow the use of double chainrings."). My bigger issue is that the levers aren't long enough to reach on bigger frames, but Simplex had a competing rod-lever shifter called the Randonneur whose lever arm was detachable, so you could at least theoretically switch to a longer arm.

Grant's further theorized that if you changed the angle of the track on the central rod, you could get a longer travel range with the same amount of lever movement. Maybe!

I'm just saying. The amount of cable pull is only a problem if there's a cable. There are other ways of addressing the issue.

Peter "let's drag everybody back to the early 50s kicking and screaming; RH is about to release their Nivex RD clone" Adler

Berkeley, CA/USA

[Benz Ouyang, Sunnyvale, CA]

Matthew, the stop is to prevent the lever from running parallel to the downtube in its “released” position, meaning it has already reeled out all the cable. Not having the levers parallel to the downtube means one can shift both levers with one hand, which is faster and more convenient. This is especially nice if one needs to shift the front up, and the rear down, to maintain the same ratio, when switching chainrings; certainly, one wouldn’t want too much lag between the front and rear shifts.

I understand your desire for more angle per shift, to provide more granularity and buffer space between each gear. However, that angle per shift is entirely decided by how far you can accept your shift lever to rotate, and the number of speeds you’re covering. Holding those two constant, you merely adjust the lever cable spool diameter and the rear derailleur’s geometry to match. Whatever it is, I would say practically, I wouldn’t want the lever to move beyond 180 degrees as it appears to me like an ergo disaster. So if your lever and derailleur are matched, you’ll have 18 degrees per shift for a Bob-max 10-speed cassette. That’s quite a nice cushy buffer if you ask me.

On Saturday, May 29, 2021 at 12:28:28 PM UTC-7 Matthew P wrote:

[Benz Ouyang, Sunnyvale, CA]

You guys are overthinking the suicide rod shifter for front derailleurs. Just go 1X! :)

[ascpgh]

Don't need scary nomenclature, "suicide" derailleur, to ruffle the masses.

I actually had a guy (on a CFRP bike obviously with integrated shifters and under 30 spokes total holding his 6" section rims to his hubs) look at my bike with bar end shifters and proclaim them unsafe and that ride rules should prevent such dangerous things from being operated amongst all the "safe" riders and their equipment. "He has to move his hands away from the brakes to change gears". No shift, Sherlock. 

Andy Cheatham 

(Look, Ma...!)

Pittsburgh

[ascpgh]

Benz, "1X" is funny to me, one of my favorite FDs for $15 or less is a SunTour X-1.

Andy Cheatham

Pittsburgh

[Benz Ouyang, Sunnyvale, CA]

On Tuesday, June 1, 2021 at 4:08:01 AM UTC-7 ascpgh wrote:

…

I actually had a guy (on a CFRP bike obviously with integrated shifters and under 30 spokes total holding his 6" section rims to his hubs) look at my bike with bar end shifters and proclaim them unsafe and that ride rules should prevent such dangerous things from being operated amongst all the "safe" riders and their equipment. "He has to move his hands away from the brakes to change gears". No shift, Sherlock.

Wow! Wait until he gets a look at my Atlantis. Not only do I have to move my hands way, way over to the downtube to manipulate the shift levers, I also don't have any retention devices on my pedals and shoes! OMG! And my saddle…it's shiny leather! How do I do it? Well, at least I compromised with index shifters (switchable to friction).

[Nick Payne]

I can't see what the problem is. I have modern (10s, 11s) SLX, XT, and XTR front derailleurs operated by either barend or DT shifters, on both of which the front is a friction shifter, and the shifting is fine.

Nick