Front derailleur options for 38/24 front, 11-36 rear?

[Robert Calton]

Good afternoon group! :) Hoping to tap into the collective wisdom here to pick a front derailleur for my Homer build, it's the last piece! 

I'll be using the Silver 38/24 crankset, 11-36 cassette with the Shimano Deore XT M761 rear derailleur. I saw that the matching XT front says it's for a triple chainring, so I need to find something that's for a double. 

What would folks recommend? 

[Patrick Moore]

Robert: About 10 years ago I swapped out a 3X7 drivetrain on my 2010 Fargo for a 2X9. The 3X7 consisted of 46/36/24 rings pulling (iirc) a 15-24 7sp cassette, and I swapped that out for a 38/24 X something-like 13-26 9 speed (29 1/2" Schwalbe Big Apples, then ditto Big Ones).

The derailleurs were both LX of the period. When I converted the chainrings I simply swapped the 46 outer for a (BBG) bashguard, swapped the 36 for a 38, and adjusted the FD throw limit screw. I did not change the position of the FD on the seat tube. After all, the FD shifted the 36/24 properly in that position, and it's not surprising that it shifted the 38/24 properly in the same position.

Later I swapped the LX FD for an ancient Dura Ace FD which I did mount a bit lower, but for the bottom of the cage to clear the chainstay as well as for the lower edge of the cage to clear the (IIRC, 48 t-size) bash guard, the FD had to be placed much where it would have been placed for a 46/36/24. The DA FD worked just as well as the LX. Again, 38/24 X 15-24 (or close) drivetrain.

Nowadays, I have a 44/28 wide-range "subcompact" setup and the same DA FD positioned high enough above the 44 to clear the 48-t-equivalent bashguard; here too front shifts are just fine.

FWIW.

Matthews "road bike for dirt" with 42/28 (before I installed the 44) and Dura Ace 740-something FD. There must be close to an inch of gap between the bottom of the outer FD cage plate and the top of the teeth of the 42 t ring:

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Patrick Moore

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[Robert Calton]

Thanks Patrick! I saw a really nice bottom pull DA front mech used on eBay, first gen, and it says it has a 16T capacity. Since I'm at 14T differential on my front chainrings (38-24),  would this work? Does me running 11-36 cassette have anything to do with the front derailleur choice? 

[Bernard Duhon]

I m running a Campy Athena FD of unknow vintage but I guess its 10 years old.

Paired with a 42-26 & 11-36,  9 Speed

It works very well

 

Bernard

 

From: rbw-owne...@googlegroups.com <rbw-owne...@googlegroups.com> On Behalf Of Robert Calton
Sent: Saturday, May 11, 2024 2:16 PM
To: RBW Owners Bunch <rbw-owne...@googlegroups.com>
Subject: Re: [RBW] Front derailleur options for 38/24 front, 11-36 rear?

 

Thanks Patrick! I saw a really nice bottom pull DA front mech used on eBay, first gen, and it says it has a 16T capacity. Since I'm at 14T differential on my front chainrings (38-24),  would this work? Does me running 11-36 cassette have anything to do with the front derailleur choice? 

On Saturday, May 11, 2024 at 2:54:01 PM UTC-4 Patrick Moore wrote:

Robert: About 10 years ago I swapped out a 3X7 drivetrain on my 2010 Fargo for a 2X9. The 3X7 consisted of 46/36/24 rings pulling (iirc) a 15-24 7sp cassette, and I swapped that out for a 38/24 X something-like 13-26 9 speed (29 1/2" Schwalbe Big Apples, then ditto Big Ones).

 

The derailleurs were both LX of the period. When I converted the chainrings I simply swapped the 46 outer for a (BBG) bashguard, swapped the 36 for a 38, and adjusted the FD throw limit screw. I did not change the position of the FD on the seat tube. After all, the FD shifted the 36/24 properly in that position, and it's not surprising that it shifted the 38/24 properly in the same position.

 

Later I swapped the LX FD for an ancient Dura Ace FD which I did mount a bit lower, but for the bottom of the cage to clear the chainstay as well as for the lower edge of the cage to clear the (IIRC, 48 t-size) bash guard, the FD had to be placed much where it would have been placed for a 46/36/24. The DA FD worked just as well as the LX. Again, 38/24 X 15-24 (or close) drivetrain.

 

Nowadays, I have a 44/28 wide-range "subcompact" setup and the same DA FD positioned high enough above the 44 to clear the 48-t-equivalent bashguard; here too front shifts are just fine.

 

FWIW.

 

Matthews "road bike for dirt" with 42/28 (before I installed the 44) and Dura Ace 740-something FD. There must be close to an inch of gap between the bottom of the outer FD cage plate and the top of the teeth of the 42 t ring:

 

 

On Sat, May 11, 2024 at 12:35 PM Robert Calton <nca...@gmail.com> wrote:

Good afternoon group! :) Hoping to tap into the collective wisdom here to pick a front derailleur for my Homer build, it's the last piece! 

I'll be using the Silver 38/24 crankset, 11-36 cassette with the Shimano Deore XT M761 rear derailleur. I saw that the matching XT front says it's for a triple chainring, so I need to find something that's for a double. 

What would folks recommend? 

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Patrick Moore

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

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[Patrick Moore]

I've not used a first-gen DA FD, but I have used a 7400 and a 740n -- either 01 or 02; I think it's the latter. Again, it shifts very well over a 44/28 and also did so ove a 38/24.

Now, I may simply be less demanding about FD performance; and I don't shift the front a great deal (my setups since the 2X9 on the Fargo are 1X + granny) but when I do shift the front, I don't have any more problems than I had with more typical road doubles or old-time mtb tripls.

I do have a chain catcher mounted to the chainstay just aft of the bb to prevent chain suck, but I first installed that on the Fargo with the 46/36/24 triple when I was having chainsuck problems; I've not had that problem with the 2Xs.

To sum up and answer your question directly re the 1st-gen DA FD: I guess it will work fine. But if you ask me in court, I'll deny everything.

Good luck! And keep us informed.

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[Patrick Moore]

Forgot to address one of your questions:  Does me running 11-36 cassette have anything to do with the front derailleur choice?

It might, since with such a small outer cog the chain will be closer to the chainstay and bottom of the FD cage than with a bigger outer like a 13 or 14. Whether this makes a difference in your case, I cannot say for sure, but again I'd guess that, since you will be using the 11 only with the 38, this won't matter.

There's also the matter of a wider cassette and chain rub on the derailleur cage. Is your cassette 11 speed or more? If so, I can't speak to that, but the wider the change in chain angle and the narrower the FD cage (as, for a 1st-gen DA road FD for 5 o 6 speed freewheels) the more chance of chain rub on the extreme outside and inside cogs unless you trim the FD. For me, I use my DA 7402 (I am pretty sure) FD with a 10 sp cassette and when I set the FD "in the middle" of its range there is no chain rub either in small or big cogs, and I think there's still futher leeway for chain angle without rubbing.

Also affecting chain angle is chainstay length, but as this the RBW list and not rec.bicycles.tech or Cat.6.fredlist, I'd guess that will not be a problem for you.

[Robert Calton]

Thanks for the wealth of information Patrick :) I am excited to learn more about bicycles in general and thrilled to build this Homer over the next month. I will be running a 9-speed cassette, so I don't think that I'll be trying to find a super narrow FD cage. I'll look into the DA 7402 and similar derailleurs. I like the all-silver look. 

[Patrick Moore]

Robert: If you will be using a 9 speed cassette, I'll go out on a limb and predict that the first-gen DA will work fine. I'll go so far as to offer: If after trying it and getting expert advice if it  does not work, and as long as the FD is in the same condition as when you bought it, I'll buy the 1st gen DA from you for your full purchase price minus your shipping expense from the seller. (I'll pay your shipping cost to me, of course.)

To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/6cab37ed-55cd-4dd4-a4d9-b71b4564689cn%40googlegroups.com.

[Robert Calton]

That is extremely generous of you, Patrick, wow! I will then order this derailleur with delight (it's a little nicer condition than the other one). I plan to have my local, independent bike shop assemble the bike when all the parts arrive -- just waiting on this then and the wheels. They've got the right ethos for this community (they only sell steel, normal folk's bikes and mostly older "rescue" bikes they recondition), so I trust that they are experts on installation. I'll keep in touch after the build, hopefully with a successful report and some glamor shots :) 

[Patrick Moore]

I don't see the latter listing (auction had closed when I looked) but I'll honor my commitment; the various other DA FDs that popped up were in tht $40 to $60 range, which I don't mind paying. And I'm 9/10 convinced that yours will work fine.

To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/33eba3fc-6f22-4beb-bab0-707d274f829fn%40googlegroups.com.

[Patrick Moore]

It just occurred to me that I can use a good FD that still has the outer throw limit arm -- the extension of the parallelogram that contacts the bottom of the outer limit screw; I cut off that on my 7400 when using it with a Silver triple -- the throw was just right sans stop to get the chain onto the 46 t ring -- and ditto for the 7402, to get that one to work with a wide-Q (172 mm IIRC) Bontrager Race Lite pipe spindle external bearing triple. That too serendipitously worked perfectly without any except design limit to its outer throw. But I should replace the 7402 with the 7400 on the Matthews because with 158 mm Logic (triple converted to double) there is far more throw on the 7402 than needed -- whence a "manual" stop when I shift -- while the design limit on the 7400 ought to be just right for this Logic.

[Nick Payne]

My suggestion would be one of the Shimano MTB FDs intended for two chainring setups, as they are designed to be used with that size of chainring. Here's a Deore XT M786 2x10 FD on my Appaloosa with 38/26 chainrings. The Shimano specs for that FD say that it's designed to be used with chainrings from 38t to 44t - I've used it with a 36t chainring without problem - the bottom of the FD cage still cleared the chainstay OK.

Nick Payne

[Dan]

To add another data point:

I've been using the Shimano Sora FD on my Appaloosa.

It shifts a 42-24 front mated to a 12-36 rear flawlessly. In friction, of course.

Really, the shifting is amazing coming from the indexed FD on my other bike.

[Stephen Durfee]

Hi Robert,  just wondering if you have considered a 42/28, or other options for the front?

I have been running a Silver 38/24 with a chainguard on my All-Rounder for the past year or so, and I'm planning on converting to a triple, swapping out the guard for a third, 46T ring. I found the smaller design of the crank to be frustrating ...even on level ground, I'll be pushing the limit. Downhills are only for coasting. That said, the smallest ring of the freewheel has 13T.

When I built my Homer, I went with a VO 46/30 compact double. So far, so good!

[Robert Calton]

Good question, chef. I did consider other options, including a 42T 1x setup like I had on my previous bicycle. When I looked at Rivendell's build options and other writings, they suggested the 38/24 for all-around riding on a variety of surfaces and if you didn't have a preference, go with that. My riding generally involves city pavement, slow roll group rides, rail trails, and only light groomed wooded trails all at party pace. I generally didn't pedal much downhill anyway on the last bike I had, so I figured this would be a good starting point. 

Good thing is, these Silver cranksets hold their value well and if I feel like I need something a little bigger, I can always switch down the road at a minimal cost :)