Tech question on MTB derailleur

amirm said:

Hi all:
I need some education on front derailleurs. In particular, I want to
know about the swing mechanism. What's the difference between top and
bottom swing? What difference does it make? How can I work out mine is
top or bottom swing?
I have a Deore derailleur, and as part of upgrading the drivetrain, I
want to put a new XT. The seller asks me to specify the swing type.
Obviously, I'm not buying the part at my LBS. Can someone help?
Cheers, Amir.

Never mind, I worked it out. Mine is a top swing

Cheers

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amirm said:

Never mind, I worked it out. Mine is a top swing.
Cheers.

shouldnt it be 'top-pull' or bottom-pull' ??

ie which orientation the cable pulls on the mech fro

From my (albeit totally un-researched and off the cuff) memory it woul
seem that the majority of mtb front mechs are top-pull to keep the cabl
protected from mud/road-grime if it were going round under the B

anyone wanna clarify that

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Nope. Bottom-pull derailleurs can be either top swing or bottom swing.
eg the Deore XT FD-M750 and FD-M751.

Nick

flyingdutch said:

amirm said:

Never mind, I worked it out. Mine is a top swing.
Cheers.

shouldnt it be 'top-pull' or bottom-pull' ???

flyingdutch said:

shouldnt it be 'top-pull' or bottom-pull' ???
ie which orientation the cable pulls on the mech from
From my (albeit totally un-researched and off the cuff) memory it would
seem that the majority of mtb front mechs are top-pull to keep the cable
protected from mud/road-grime if it were going round under the BB
anyone wanna clarify that?

You're right about the routing. However, some manufacturers still prefe
routing through the down tube and under BB (including mine). Shimano ha
recently moved to make dual pull structure which one mech can be used i
either way

However, top and bottom swing refers to the position of the swing ar
in refernce to the clamp. Due to space restriction, eg in duallies an
some compact frames, top swing mech has become popular as the clam
can sit really close to BB. Shimano manufacture two versions of eac
front derailleurs which are both dual pull and multi-clamp. That is
they can fit any of the three mainstream seat tube sizes and they ca
use either routing direction. The difference is only in the swin
geometry. A traditional hard-tail should be able to use eithe
version. In my case, I am going with the M760 derailleur which is to
swing. M761 is bottom swing

It seems swing geometry has not been an issue on roadies, and they al
seem to use the bottom-pull bottom-swing set up

Hope this clarifies a little

Cheers, Amir

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"amirm" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

However, top and bottom swing refers to the position of the swing arm
in refernce to the clamp. Due to space restriction, eg in duallies and
some compact frames, top swing mech has become popular as the clamp
can sit really close to BB.

<snip>

Quoted message said:

The difference is only in the swing geometry.

There's more to it than that, as some derailleurs are BB mounted with no
clamp, bottom swing and cable routing under the BB. These are used for
dualies with an interupted/minimal seat tube where a clamp-mount cannot be
used.

Cheers
Peter

Peter Signorini said:

"amirm" <[email hidden]> wrote in message news:OgJcc.12-
[email hidden]:[email hidden]-
etserver.com...

Quoted message said:

However, top and bottom swing refers to the position of the swing arm
in refernce to the clamp. Due to space restriction, eg in duallies and
some compact frames, top swing mech has become popular as the clamp
can sit really close to BB.

<snip>

Quoted message said:

The difference is only in the swing geometry.

There's more to it than that, as some derailleurs are BB mounted with
no clamp, bottom swing and cable routing under the BB. These are used
for dualies with an interupted/minimal seat tube where a clamp-mount
cannot be used.
Cheers Peter

Peter

It's interesting you said that. Someone also said that in general botto
swing shifts better than top swing. So when this third group of BB
mounted derailleurs came around, they went for bottom swing and not to
swing. This is consistent with road bikes using bottom swing. So one ca
conclude that top swing is a solution to address restricted requirement
of specific set-ups, eg duallies, and it's not necessarily as good

Cheers, Amir

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Boy, that Singlespeed is lookin' good 😄 😄 :

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