# Question on Shimano Front Deraulleur Indexing, pull ratios and compatibility



## Lombard (May 8, 2014)

Is a "9-speed" Shimano mountain (Deore M590) front triple derailleur compatible with a "10-speed" Shimano road (Tiagra 4600) front triple STI shifter?

Thanks!


----------



## Kontact (Apr 1, 2011)

It should be, because Shimano road and mountain used the same actuation until 10 speed mountain.

The "should" is a little CYA because there are other things going on besides actuation - like the chainline differences between road and mountain. But I would buy these parts for my own bike with the assumption they would work properly.


----------



## MMsRepBike (Apr 1, 2014)

I think so? 4600 is the older one, 4700 is the new one right?

When they released the 4700 10 speed Tiagra, they changed it to the 11 speed pull ratios.


----------



## Kontact (Apr 1, 2011)

According to this chart, 4700 is the same as 4600 for the front:

2017-2018 SHIMANO Product Information Web

And the rear:
2017-2018 SHIMANO Product Information Web


----------



## MMsRepBike (Apr 1, 2014)

Kontact said:


> According to this chart, 4700 is the same as 4600 for the front:
> 
> 2017-2018 SHIMANO Product Information Web
> 
> ...



Not what I'm seeing on that chart.

I'm seeing that 4700 levers can NOT go to the 4600 mech.


----------



## Kontact (Apr 1, 2011)

MMsRepBike said:


> Not what I'm seeing on that chart.
> 
> I'm seeing that 4700 levers can NOT go to the 4600 mech.


Oops, you are correct! I was looking at the text on the left and not the actual boxes.

Yup, 4700 does appear to be different than 4600 and 9 speed mountain. So the OP will need to either use 4600 shifters or a 4703 FD.


----------



## Lombard (May 8, 2014)

Thanks Kontact and MMsRep!

The shifters I have are 4600. I knew the rear actuation ratios were all the same for 8 and 9 speed mountain and 8, 9, 10 speed road. Wasn't absolutely sure about front actuation ratios.

Sheldon Brown's page is vague and says road and mountain aren't compatible without stating which generations. I was skeptical about this info:

https://www.sheldonbrown.com/front-derailers.html 

To be more clear, I am taking an older touring bike and changing the old road triple 30/42/53 to a touring triple 26/36/48. It appears shifting would be OK with the original Tiagra triple FD, but because of the larger arc, would be doing a lot of trimming to prevent the chain from scraping the end of the FD. So I wanted to know if the Deore M590 is a viable solution.


----------



## Kontact (Apr 1, 2011)

Lombard said:


> Thanks Kontact and MMsRep!
> 
> The shifters I have are 4600. I knew the rear actuation ratios were all the same for 8 and 9 speed mountain and 8, 9, 10 speed road. Wasn't absolutely sure about front actuation ratios.
> 
> ...


Sheldon died several years ago, so things are getting outdated on his site.

What do you mean by "larger arc"? Spacing is the same, so the derailleur isn't moving in a larger arc than a road derailleur.


----------



## Lombard (May 8, 2014)

Kontact said:


> Sheldon died several years ago, so things are getting outdated on his site.
> 
> What do you mean by "larger arc"? Spacing is the same, so the derailleur isn't moving in a larger arc than a road derailleur.


Yes, I realize Sheldon died about a decade ago. It appears Harris Cyclery is updating the site to a degree.

When I say larger arc, I am talking about the curvature of the FD. Ideally, the FD should have a curve (or arc) that matches the largest chain ring. This curve will be sharper with a smaller ring. So naturally, mountain FDs have a shaper arc than road FDs. Correct?


----------



## Kontact (Apr 1, 2011)

Lombard said:


> Yes, I realize Sheldon died about a decade ago. It appears Harris Cyclery is updating the site to a degree.
> 
> When I say larger arc, I am talking about the curvature of the FD. Ideally, the FD should have a curve (or arc) that matches the largest chain ring. This curve will be sharper with a smaller ring. So naturally, mountain FDs have a shaper arc than road FDs. Correct?


It's correct, but in practice derailleurs frequently fail to match the curvature of the chainrings because of seat tube angle. I have a SRAM road derailleur that hangs well off the back instead of following the 53t ring on one bike.

48t use to be the large MTB ring, so it will depend on how flexible Shimano intended the FD to be. Even if the curve is tight, the nose would still probably get pretty close to the ring.


----------



## cxwrench (Nov 9, 2004)

Lombard said:


> Yes, I realize Sheldon died about a decade ago. It appears Harris Cyclery is updating the site to a degree.
> 
> When I say larger arc, I am talking about the curvature of the FD. Ideally, the FD should have a curve (or arc) that matches the largest chain ring. This curve will be sharper with a smaller ring. So naturally, mountain FDs have a shaper arc than road FDs. Correct?


Yes. It's even noticeable on road front derailleur cages. They're designed to work w/ up 55t or so chainrings so when they're used w/ 50t or smaller there is generally a bigger gap at the tail of the cage than the front. Which can sometimes lead to thrown chains and is exactly why SRAM make the 3* shim for the braze-on mount.


----------



## Kontact (Apr 1, 2011)

The SRAM shim is only really needed with Q-rings. You have to have a huge gap in the back before the chain could get under the derailleur on the outside.

Sometimes stuff doesn't work well together, but chances are the 590 will be fine. But if there are doubts, why not order a more appropriate derailleur, like one for a hybrid? But if you have the FD already, give it a go.


----------



## Lombard (May 8, 2014)

Kontact said:


> Sometimes stuff doesn't work well together, but chances are the 590 will be fine. But if there are doubts, why not order a more appropriate derailleur,* like one for a hybrid*? But if you have the FD already, give it a go.


Huh? Don't most hybrids use mountain components? I know my old 2002 Cannondale Silk Adventure 400 does.

I do have the Deore M590 FD, so I'll let you all know how it goes once it's all together.


----------



## Kontact (Apr 1, 2011)

Lombard said:


> Huh? Don't most hybrids use mountain components? I know my old 2002 Cannondale Silk Adventure 400 does.
> 
> I do have the Deore M590 FD, so I'll let you all know how it goes once it's all together.


There have been hybrid groups, designed with medium ratio gearing instead of the tiny cranks for MTBs. They were also used on touring bikes. I've used front derailleurs from such groups before because they are top pull - if that's what you need.


----------



## Lombard (May 8, 2014)

Kontact said:


> There have been hybrid groups, designed with medium ratio gearing instead of the tiny cranks for MTBs. They were also used on touring bikes. I've used front derailleurs from such groups before because* they are top pull *- if that's what you need.


My FD is bottom pull. Cable comes up from the BB.

Description of M590 is it can be used with crank up to 48T and it can be either top or bottom pull:

Shimano Deore M590 9SP Front Derailleur | Jenson USA


----------



## Kontact (Apr 1, 2011)

Lombard said:


> My FD is bottom pull. Cable comes up from the BB.
> 
> Description of M590 is it can be used with crank up to 48T and it can be either top or bottom pull:
> 
> Shimano Deore M590 9SP Front Derailleur | Jenson USA


What is the real issue? Have you mounted the FD on the bike yet or not?


----------



## Lombard (May 8, 2014)

Kontact said:


> What is the real issue? Have you mounted the FD on the bike yet or not?


Not yet. Work has been getting in the way. 

I don't think there is a real issue. You answered my question about compatibility which apparently is not an issue. So thanks.


----------



## cxwrench (Nov 9, 2004)

Kontact said:


> The SRAM shim is only really needed with Q-rings. You have to have a huge gap in the back before the chain could get under the derailleur on the outside.
> 
> Sometimes stuff doesn't work well together, but chances are the 590 will be fine. But if there are doubts, why not order a more appropriate derailleur, like one for a hybrid? But if you have the FD already, give it a go.


If you had the first gen Ti cage Red front derailleur combined w/ a compact you probably needed it...if the bike had a steep-ish seat tube angle you really needed it. They originally came up w/ the shim for those godforsaken piece of **** derailleurs.


----------



## Kontact (Apr 1, 2011)

cxwrench said:


> If you had the first gen Ti cage Red front derailleur combined w/ a compact you probably needed it...if the bike had a steep-ish seat tube angle you really needed it. They originally came up w/ the shim for those godforsaken piece of **** derailleurs.


Considering that the seat tube and cranks have the same center point, I doubt the steepness has anything to do with it.

But it is a poor derailleur. It works okay on friction, though.


----------



## jeffj (Nov 25, 2004)

Front road derailleurs are not the same pull ratio as MTB derailleurs. You can't reliably expect to use a road STI shifter with a MTB front derailleur.

The 4700 STI rear shifter has a different pull ratio than the 4600 and all other 10 speed rear derailleurs. In other words, you can't use a 4700 Tiagra RD with 10 speed 105 shifters.

4600 is 10 speed, and you can use a 4600 RD with 10 speed 105 shifters.

4700 is kind of in a stand-alone position with regards to rear derailleurs, but 10 speed front road derailleurs will work with either 4600 or 4700.

I found out the above by trying to use a 4700 Tiagra 10 speed RD with 10 speed 105 shifters. The RD would not adjust properly across the range. I message Shimano tech support, and they informed me about the uniqueness of the 4700 shifter/RD.

MTB front derailleurs don't work right with any road shifters as the pull ratio is different. 

Touring bike riders that want use MTB derailleurs with drop bar shifters have some unique challenges. The pull ratios are different for the front derailleurs, and the chainlines are different as well. There also can be issues with the arc and size of the FD cage.

If you want to use MTB cranks (because of the lower gearing) with road shifters, it can get really tricky. Road FD's have pretty long cages, and they are arc'd for larger chainrings. Getting the FD low enough to just clear the top of the outer (large) chainring can be difficult because the lower part of the cage may hit the chainstay before it gets low enough to keep the chain from overshifting. 

On my touring rig (Specialized AWOL), I ended up using SRAM Apex 10 speed brifters with a Shimano CX70 FD (think smaller/shorter cage) and a White Industries VBC square taper crankset. The VBC crankset was set up with 42t and 26t chainrings (a 16t difference). I took advantage of the square taper interface and found a spindle length that gave me a roughly 45mm chainline. Paired that with a SRAM 10 speed long cage MTB RD, and an 11-36 cassette, and I have decently low gearing on my drop bar touring rig. 

Drop bar touring rigs that want low gearing for carrying heavy loads up steep hills don't have a lot of choices, but there are work-arounds.

J-Tek makes some pull-ratio adapters that might help, and you might find direct mount FD mounts that are made to put your road FD out to a 50mm chainline that will line up to your MTB crankset, but it doesn't guarantee that it will shift well with whatever chainring combo you have.

Also, Gevenelle takes MTB thumb shifters and mates them to road brake hoods to make a semi-custom brifter that will shift MTB derailleurs front and rear.


----------



## Kontact (Apr 1, 2011)

jeffj said:


> MTB front derailleurs don't work right with any road shifters as the pull ratio is different.


Do your comments account for the fact that the OP is using a 9 speed generation MTB derailleur before the pull ratios were changed between road and MTB?


----------



## jeffj (Nov 25, 2004)

Kontact said:


> Do your comments account for the fact that the OP is using a 9 speed generation MTB derailleur before the pull ratios were changed between road and MTB?


I did skim the thread a bit, so I may have missed that 

Damn thread skimmers. . . .


----------



## headloss (Mar 3, 2013)

Kontact said:


> Do your comments account for the fact that the OP is using a 9 speed generation MTB derailleur before the pull ratios were changed between road and MTB?


I'm sorry to resurrect this zombie thread (tis Halloween time though, so why not!) but what??

The *REAR *pull ratios for Road and MTB were the same up to and including 9 speed and then with 10 speed and MTB-Dynasys they went their separate ways. However the OP is asking about *Front Derailleurs *. Road and Mountain bike front derailleurs were never the same pull as far as I know... you might have been able to get them to work, but the arm length between the pivot and the cable anchor are measurably different between road and MTB for any speed, but most certainly 9 speed as I just measured two front derailleurs, a road and a mtb, to make sure I wasn't going crazy. 

Anyway, the OP had three years to test this out. Hope it all worked in the end!


----------

