Front Derailleurs / Derailers / Whatever

[Erik]

I'm working on putting together my shiny new gold Sam H that I picked up from the Rivendell shop today.  Everything was coming together beautifully, until I went to install the front derailleur. It's a Shimano 105-5700 for a 2x set up.  I'm running a Silver Wide/Low double with a 38 / 24.  The cage on the derailed is too long to set it up with the correct spacing between the large chainring / guard and the cage.  It ends up hitting the chain stay when I shift.  

Does anyone else on here have a similar set up with a wide / low double?  If so, what front derailleur do you use?  For the life of me, I can't figure out a suitable replacement for the 105 and am dreading trying to find one for sale anywhere.

Any thoughts or advice?    

[Patrick Moore]

Erik: Before you swap, try simply raising the derailleur so the cage barely clears the stay. I had no problem using my circa 2011 LX fd with a 38 t ring in 2nd "big" position after I removed the 46 t outer ring in 3d position (replaced latter with guard); I didn't even lower the fd, simply screwed in the travel stop. It shifted just fine.

I've shifted small outer rings with all sorts of front derailleurs; currently I shift a 42 outer with an 8-speed era Dura Ace front derailleur sitting high above the ring, and it shifts to the 28 ring just fine. Earlier I used a different, perhaps 9-sp Dura Ace fd to shift a 46/36/24 Bontrager Race Lite triple; it shifted just fine after I performed delicate surgery on the cage's throw limiter.

Lastly, used this same 9-speed DA fd both with a 44/30 and a 52/38 ring combination on the same Ram; couldn't tell any difference in performance.

IME, tho' I may be very tolerante, if you can properly adjust throw and keep the cage from hitting the crank arm, front derailleurs are very, very forgiving.

Of course, friction; can't speak to indexing.

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Patrick Moore

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

[Joe Bernard]

What Patrick said because this is a common weirdness encountered with that chainring setup. The original plan when Grant said goodbye to the big ring on a triple was to run 24-38 without a derailer, you would put a stick down there to move the chain or kick it or hop off and make the "shift". Well the pantguard is roughly the same size as the formerly-middle ring, and what happens when you introduce a derailer on what is nominally still a triple crankset is it wants to sit at the height of the now missing big ring. Raise that derailer, son! 

[Erik]

I'll give this a shot tomorrow with the 105 and see what happens!  The gap between the cage on the derailer and the pantguard is about an inch, maybe slightly more.  I'm shifting with DuraAce bar ends, so it's friction.   I also have an ugly, ugly XT front derailer that would need some shims for the seat tube.  The cage is slightly shorter but it's so ugly and bulky that I'm not certain I could stomach having it on this bike.  I'll post up some photos once its all set up.  Now, I just need to remember how to set up cantilever brakes... 

[Joe Bernard]

I'll just tell you the unfortunate truth now: I had that horrendous XT on something (it may be on the Bombadil I sold Jason Fuller) and it's magic. I remember sending a pic of it to Grant after he had said something about ugly/perfect Shimano parts and said, "It's almost alarming something this ugly can work so well."

[Philip Barrett]

My boss said that about me once.

[Paul Richardson]

i can't locate it right now, but somewhere in a blahg grant wrote in reference to the ugliness of a front derailler, (probably the same XT you're referring to), 

"forgive it and move on."  

i have a shim'd XT front on my suzie and try to remember this advice whenever i idly find myself wishing it was vintage XTR.

paul

takoma park, md.

[Jon B]

If you are really stuck, IRD makes a "Sub-C" front derailleur designed for subcompact setups.  From the picture, it appears to have a shorter cage than usual.  I cannot attest to its function or whether you need it, just alerting you to its existence.

Jon Blum

[Brian Campbell]

Save yourself the time and aggravation of trying to find the correct rd. This one will.

https://www.interlocracing.com/shop/product/60110-ird-front-derailleur-sub-c-braze-on-2351?search=derailleur

Buy the bolt on mount and your done. Its not the cheapest option but it works really well. Also for Shimano drive trains the gap between the front derailleur and the the large ring should only be a few millimeters. Yes you can make other derailleurs  work and it might be fine.

[Tom Wyland]

I had the same question about the front derailleur and the silver low-high 38-24 crank.  It's my first build with a FD.  The gist is to get a road double and mess around until it works?  I have no intention of spending $80 if a cheap one will work.

Tom

[Patrick Moore]

That's what I've done, with success. Again, I've only used friction setups, so can't speak to indexing.

And again, and btw, I've also used another strategy: a mtb fd mounted really high above the ring (ie, high enough to clear the stay). Seems to work fine, perhaps because mtb fds have large inner plates. Example: LX fd and 38 t "outer" ring in middle position (38/24, guard in place of original 46 t ring). IME, the bigger hassle is getting the best lateral angle for the cage.

On Mon, Apr 5, 2021 at 10:01 AM Tom Wyland <tomw...@gmail.com> wrote:

I had the same question about the front derailleur and the silver low-high 38-24 crank.  It's my first build with a FD.  The gist is to get a road double and mess around until it works?  I have no intention of spending $80 if a cheap one will work.

Tom

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[Patrick Moore]

Photo of current Dura Ace 740? and Logic 42/28 with BB Bash Guard. Fun fact: I hacked off the outer throw stop to get this der to work with a very wide-stance, pipe-bb Bontrager RL triple, and now I can shift the cage about 1 cm beyond the bash guard. No probs, just shift carefully.

[Bill Lindsay]

I have a 650B MIT Atlantis with a Rivendell Silver 38/24 crankset.  I'm running a Shimano CX70 front derailleur and it works perfectly well.  I'm using Rivendell XO friction shifters mounted on the stem on an IRD stem shifter perch.  

Bill Lindsay

El Cerrito, CA

[Joe Bernard]

Yes, or as Patrick mentioned you can use any old (and cheap) Shimano mtb triple. The 24-38 Silver cranks are a triple with the big ring replaced by a smaller pant guard; if you mount the derailer in its normal position the cage contours will hit the middle and granny rings in the right spot. The only "problem" is the big gap over the pant guard looks a little funky. 

Joe "funky is good" Bernard

On Monday, April 5, 2021 at 9:01:43 AM UTC-7 Tom Wyland wrote:

[Matthew P]

Patrick that looks great.
Nice coupling of the two arcs of the toothless outer ring/guard and the fd cage.
Did you really have to hack off the stop, as in, backing out or removing altogether the limit screw wasn't enough? I believe you regardless.

I'm slowly grasping a few things:
1. the fd has to clear the toothless outer ring, which probably places it a little high with respect to the outermost ring that has teeth
      1.a. when people say "mount the FD high" is it high with respect to that ring (middle in the triple) or high wrt the toothless outer (aka really high for the middle ring)?
2. I bet that guard/toothless-ring also works great as a chain stop. pretty hard to throw the chain off your biggest ring when you have one of those, no?
But if the chain never comes off I don't get to do my current favorite bike trick: put the chain back on just using the fd (and pedalling, of course)

- Matthew
"I passed on the bash guard triple but am liking them more" and
"i can always throw it off the inner ring for fun" and
"but I can barely get the chain there in the first place right now" and
"would like to see this ugly-functional fd" and
"doesn't yet comprehend long (road?) vs. short (mtb?) fd's"
P
in San Diego / Kumeyaay Land

[Joe Bernard]

When people (me) say "mount it high", it means high over the small pant guard which would be a bigger chainring if that triple crank still had that ring. But it seems to matter a lot which fd you use because they don't all need that trick. Here's a pic I stole from Leah's (Bicycle Belle Ding Ding) Instagram after remembering she uses the Silver 24-38-guard crank setup on her (extremely rad) Platy. I don't know what derailer that is but it's sitting right over the guard with barely a gap and still clears the chainstay. Buy whatever is on her bike! 

[Philip Barrett]

Oh man, when you said "mount it high" I tried to, but sort of lost interest half way through the project & called out for pizza.

I'll be here all week, try the veal.

[Joe Bernard]

I'm just talking about derailers, mate. Or derailleurs, your choice. 

[Patrick Moore]

I had to cut off the stop only because I perversely insisted on using an 8 or 9 speed-era road front der with a much later and 2-piece mountain bike triple.

Without the stop, the derailleur will kick the chain over the bash guard and off the crank entirely; the reason is that the derailleur has to be positioned high enough (just high enough) for the outer cage to clear the bash guard, otherwise it won't move outward enough to shift the chain onto the "middle" ring. Note that my bash guard is the equivalent of a 44 t ring, IIRC; ie, not much bigger that the 42 now in "middle" position.

The matching curves is purely fortuitous.

[Ben Miller]

I have a converted Sugino hi/low a la Grant-style with a bash-guard in place of the outer ring. I briefly had it on one of my bikes, where it worked fine, but just recently took it off and replaced my GF's triple with it. On that drive train, it will frequently get stuck between the hi-low chainrings while she is downshifting. The chainrings are very new. The chain on GF's bike isn't new, but checking for stretch with a chain tool, it isn't overly worn. I think (?) i've installed the chainrings correctly, but maybe not?? Any thoughts, as I'm confused by what's happening. My first thought is just to replace the chain (even though it appears to have some life left). Oh and on the original bike (mine) it was a 9 spd with a 10 spd chain. This bike (GF's) is a 9 spd with a 9 spd chain. Curious that it would work better with a 10 spd chain?

On a related note, Patrick Moore said: "IME, the bigger hassle is getting the best lateral angle for the cage." Totally agree. Any shortcuts/tips to this?

Ben

[Joe Bernard]

Have you ridden the GF's bike to see what's going on with the shifting? Is she using a friction shifter or index? If index, it may not work with what crank. 

[Ben Miller]

I've not ridden it, just shifted it in the bike stand, where it seems to shift fine. On the bike stand it is obviously not under load, which is an important point since it seems the chain is always getting stuck when she is shifting under power. 

The shifter is a Microshift R9, which is indexed. But the downshift simply releases all the tension, (returning the FD to the lowest possible position). I guess maybe that could be an issue since maybe the abrupt action is too violent compared to a smooth human actuated downshift?

[Joe Bernard]

That could be the problem, or the chain is indeed too old. I think you would need to ride it yourself to sort it out, but any indexing not specifically designed for its groups chainrings is always a struggle. She'd probably be better off with a friction thumbshifter or bar-end (depending on bars) so she has all the control of the shift. 

[Ed Carolipio]

I suggest using an FD for a road triple or a mountain triple (instead of a road double) with the 38-24 cranks as those are just the middle and inner chainrings the FD expects in a triple. The 105 is designed for a very large outer ring (around 50-ish) in a compact double crankset (43.5mm chainline).

Shimano CX-70 is a popular choice - as Bill points out - and it's designed around a 46-30 compact crankset. The new GRX FD would probably work as well since that is designed for a 46-29 compact crankset, though I don't have direct experience with it.

I like to run a mountain triple (the venerable Shimano Deore M-591) with the 38-24 as well the 34-24 (low-low) and the 42-26 (Sugino XD600 with a chainguard as outer ring) from Riv. I have also used a Shimano Sora FD-3030 with good success:

https://bike.shimano.com/en-EU/product/component/sora-r3000/FD-R3030-B.html

 

--Ed C.

On Wednesday, March 31, 2021 at 9:26:47 PM UTC-7 Erik wrote:

[Ben Miller]

Thanks Joe, 

I think I'll try the chain first and see if that fixes it. Hopefully it will, since my GF is not terribly interested in barcons or DT shifters (it actually had barcons originally and I replaced those at her request with the R9).

Ben

[Joe Bernard]

Ben, when you say "stuck" is the chain jamming and stopping the cranks, or is it falling between the rings? If it's just a problem of the chain not moving over far enough to hit the granny, you may be able to adjust the indexing (or reposition the cable in the fixing bolt) to make that shift more solid against the chain. This is hard to explain in word pictures but imagine a friction shift where you kept pushing down on the left bar-end until the chain made it over to the small ring. Her shifter needs to slap that fd cage over hard/far enough to complete the shift. 

[RichS]

This thread has been of particular interest and help as I have never performed a triple to a double with guard conversion. Currently putting the finishing touches on a homemade chain guard (a rewarding effort so far). The shared experiences here on derailer setup will be invaluable as I work through this installation. 

Thank you to all!

Best,

Rich in ATL

[Matthew P]

Neat Rich! Same here. I'm giving the triple to double conversion a second thought. I didn't like them before because I thought of them as a crippled triple. But this thread has changed my mind. The toothless outer ring has been referred to by multiple names with associated functions: bash guard and a term implying saves the cuff of your pants. These appeal to me more than ever, and I  like the idea of the toothless outer ring theoretically making it near impossible to throw the chain over/off the outermost toothed ring.

So, Rich, a question: did you grind the teeth off a chaniring? Wouldn't that leave it very short? The one Riv sells seem to be as tall  as the toothed version. Whats the best DIY?

-Matthew

[R Shannon]

Hello Matthew,

Not sure if this is the most efficient method to create a DIY guard but so far I'm happy with the effort. Here is a work in progress picture  of the guard. It started life as a 50 tooth Shimano 110bcd ring. My big (now middle) ring has 46 teeth. Following is how the modification went:

1. Used a hacksaw to remove the teeth without getting too close to the line which would become the outer edge of the guard. This went pretty quickly.

2. Next, used an oscillating tool for careful removal of the remaining material while avoiding cutting into the new edge and maintaining an even circumference. Slow process!

3. Using fine and coarse files along with coarse emery cloth I was able to achieve a smooth edge. 

4. Last step: Steel wool and wet sanding with various grades of emery cloth to get a decent finish.

I don't have a bench grinder or dremel but those would certainly be helpful. If you're game I'd say give it a try. I'll post a picture when I reach the finish line.

Best,

Rich in ATL

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[Ian A]

Hacksawing off the teeth and then filing is best. You can always remount it on the crank to the bike and have someone turn the crank while you hold the file to the ring, creating a makeshift lathe. Using a dremel or benchgrinder means potentially breathing in fine aluminum dust, which is not a healthy option.

IanA Alberta Canada

[Patrick Moore]

It's fun to make your own bike parts, but just FYI: BB Bash Guard offers nice looking guards in all sizes and shapes and colors for very little money. I saw one just now for $12; I think mine is like that.

https://bbgbashguard.com

My brother has made his own from discarded rings, but he starts by snapping the teeth off with a vise grip or something like that. I should think that easier than sawing.

[Matthew P]

Neat Rich. Thanks all for sharing.
Perhaps a good use for old sharktoothed outer rings.
Yes I think I've heard of a "ring-in-vise, snap teeth with vise grips, file finish" approach.
Not a bad plan B(BG) Patrick
-Matthew

[Brian Campbell]

Where are the cheap ones?