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M781 Front Derailleur on 48/36/26 Deore Crank

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M781 Front Derailleur on 48/36/26 Deore Crank

Old 04-28-15, 08:36 PM
  #1  
OrangeSoma
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M781 Front Derailleur on 48/36/26 Deore Crank

I'm trying to get an XT Triple Front derailleur to work on 48/36/26 triple crank (Deore M610), but I can't get it to hop on the 48 tooth chain ring for the life of me. Even with the Hight limit screw all the way out.

Shimano XT M781 Conventional 3x10 Front Mech | Chain Reaction Cycles

According to Chain Reaction cycles it can only fit a 42 tooth large chain ring. I'm confused because dude at a bike shop told me it will work.

Anyone have an idea?
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Old 04-28-15, 10:09 PM
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bring it back if you havent scratched it up or destroyed the box. just tell them hey the specs only allow for a 42t ring, i was told it would work with 48t, can i exchange it for something that will of equivalent performance level or close to it?
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Old 04-28-15, 10:50 PM
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The M781 is a 40 to 42 tooth large chainring.

There isn't any Shimano 3x10 MTB front derailleurs that are made for a 48 tooth large chainring.

http://productinfo.shimano.com/#/spe...t%20Derailleur



There is Shimano 3x10 Trekking front derailleurs that are made for a 48 tooth large chainring.

http://productinfo.shimano.com/#/spe...t%20Derailleur

Last edited by cobba; 04-29-15 at 04:59 AM.
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Old 04-29-15, 07:32 AM
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Originally Posted by cobba View Post
The M781 is a 40 to 42 tooth large chainring.

There isn't any Shimano 3x10 MTB front derailleurs that are made for a 48 tooth large chainring.

2015-2016 SHIMANO Product Information Web



There is Shimano 3x10 Trekking front derailleurs that are made for a 48 tooth large chainring.

2015-2016 SHIMANO Product Information Web

What is a trekking derailleur? I've never heard of it before. The drivetrain that I'm building is actually 3x10 with 11-36 in the back with XT dynasys RD. Then I have the deore M610 crank.

Gevenalle GX shifters...
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Old 04-29-15, 08:56 AM
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Originally Posted by OrangeSoma View Post
What is a trekking derailleur?
It's what you need.

I've never heard of it before.
Put 'trekking bike' into google and hit search.

The drivetrain that I'm building is actually 3x10 with 11-36 in the back with XT dynasys RD. Then I have the deore M610 crank.
If have a look at the models and specs in the Trekking series, you'll see the same model names that are in the MTB series, you'll also see that the 10 speed shifters and derailleurs are Dynasys too.
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Old 04-29-15, 10:35 AM
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If have a look at the models and specs in the Trekking series, you'll see the same model names that are in the MTB series, you'll also see that the 10 speed shifters and derailleurs are Dynasys too.
It would have helped knowing this since this is the second derailleur I've had to order.


This is what I'm gonna get here:

Shimano XT FD-M780 Top-Swing Front Derailleur

It doesn't say whether it's a dual pull or not though. I'm gonna need bottom pull that's a top swing.


It also seems like there is the same models that only go to a 42 tooth outer ring. See here:

Shimano XT M780 Top Swing 3x10 Front Mech | Chain Reaction Cycles


Other option I was thinking was going with Shimano Sora (this is for a touring bike), but this M780 derailleur seems like it's the way to go. Also I looked up the stats on these and they have an M780-3 and M780-6 model with no apparent differences in the link you sent me. Did Shimano make a typo for the max ring that one of these can fit?

or are the retailers (Chain Reaction Cycles) mistaken about the max ring size?


Maybe we'll never know.....
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Old 04-29-15, 11:18 AM
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try a Shimano road triple FD.
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Old 04-29-15, 11:21 AM
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Originally Posted by OrangeSoma View Post
Gevenalle GX shifters...
Don't like Shimano brifters?

Do you know that 9 speed Shimano MTB rear derailleurs will work with 10 speed Shimano road brifters and a 10 speed cassette?

A Tiagra FD-4603 front derailleur will work with your 48-36-26 crankset.

Thorne Cycles uses the combos above on their touring bikes.
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Old 04-29-15, 11:31 AM
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Don't like Shimano brifters?

Do you know that 9 speed Shimano MTB rear derailleurs will work with 10 speed Shimano road brifters and a 10 speed cassette?

No I was not aware actually. Had I known I probably would have considered that option. I like my current setup, except for my front derailleur not working.

A Tiagra FD-4603 front derailleur will work with your 48-36-26 crankset.

Thorne Cycles uses the combos above on their touring bikes.
Would you recommend a Tiagra FD over the M780. I like the M780 Top Swing because it seems it wouldn't get in the way of my water-bottle mounts...
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Old 04-29-15, 11:40 AM
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Originally Posted by OrangeSoma View Post
Would you recommend a Tiagra FD over the M780. I like the M780 Top Swing because it seems it wouldn't get in the way of my water-bottle mounts...
On the following 2 bikes you can see what the Tiagra derailleurs look like.

http://www.sjscycles.co.uk/thorn-clu...ed-prod37049/?
http://www.sjscycles.co.uk/thorn-clu...ew-prod35868/?
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Old 04-29-15, 11:51 AM
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Originally Posted by cobba View Post
On the following 2 bikes you can see what the Tiagra derailleurs look like.

Thorn Club Tour - 520S - Red/Blue Touring Bike - 1,603.79
Thorn Club Tour Mk4 610S - 1,499.99

Nice I see that they were able to use the water bottle cage mounts still by using washers to clear the derailleur clamp. Sounds like you're recommending the Tiagra??
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Old 04-29-15, 11:58 AM
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Originally Posted by OrangeSoma View Post
Sounds like you're recommending the Tiagra??
Just showing you what it looks like and letting you know there's other options.
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Old 04-29-15, 12:03 PM
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Plenty of info on touring bike setups: http://www.bikeforums.net/touring/
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Old 04-29-15, 03:06 PM
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Originally Posted by cobba View Post
Plenty of info on touring bike setups: Touring

Thanks for all your help. You were awesome. I decided to go with the M780. The guy I chatted with from the online store said it would only work with Dynasys shifters though I don't believe him.


From what I've read it's only the rear's that have different cable pull ratios thus requiring the Dynasys shifters. I think the the Gevenalle front shifter should work fine with it.
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Old 09-26-16, 06:08 PM
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Trekking parts

Orangesoma, don't know if you found your front derailleur solution, but the trekking drive trains are a middle of the road cross in gearing between a mountain bikes low gearing and a road bikes taller gearing. Mountain bike front derailleurs from Shimano will start with an M before the number, like M780, M781 etc.The trekking derailleur you need will start with a T, such as T780 and T781. These have a larger capacity for the wider gearing jumps on your front crankset. Just make sure you get the correct number for your set up. 2x or 3x front chainrings.
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