Please help! **Shimano XT Rear Der, M780 Info**

[wayno]

Hello Hubbers

 

Any Idea if this der, is compatible to 9 speed using XT SL-M770 shifters??

Edited July 18, 2013 by wayno

[Johan Bornman]

If it says DYNASIS anywhere on the derailer, it is not compatible with 9spd.

[wayno]

Thank you for help. It does have dynasys....

[Bobbo_SA]

If it says DYNASIS anywhere on the derailer, it is not compatible with 9spd.

 

Mind my ignorance...

 

Hear me out for a second, a derailleur works on a spring mechanism and only moves the distance governed by the click / pull in the shifter, thus a 10spd derailleur would only move as far as the 9spd shifter moves it (presumably the correct distance for the cassette). The only thing I could see would be the width of the cages not allowing the 9spd chain to feed smoothly through the "jockey wheels" but this is mm and I doubt the "jockey wheels" in a 10spd RD are any different to the 9spd ones.

 

As long as the H limit is set not to allow it to go past the 9th ring (shifter wouldn't allow it anyway but still) then why wouldn't it work?

 

Edit: corrected terminology

Edited July 19, 2013 by Bobbo_SA

[Bobbo_SA]

And in reverse, what stops a 9spd RD being adjusted (H screw) to allow it to travel further to the 10th ring

[Flowta]

Mind my ignorance...

 

Hear me out for a second, a derailleur works on a spring mechanism and only moves the distance governed by the click / pull in the shifter, thus a 10spd derailleur would only move as far as the 9spd shifter moves it (presumably the correct distance for the cassette). The only thing I could see would be the width of the cages not allowing the 9spd chain to feed smoothly through the "jockey wheels" but this is mm and I doubt the "jockey wheels" in a 10spd RD are any different to the 9spd ones.

 

As long as the H limit is set not to allow it to go past the 9th ring (shifter wouldn't allow it anyway but still) then why wouldn't it work?

 

Edit: corrected terminology

 

The width of the cassette is no different.

 

The rear derailleur works on a parallelogram/4 bar linkage to convert the pull of the derailleur cable to the sideways movement of the derailleur (the spring only brings it back to it's starting position)

 

The difference between 7, 8, 9 speed system is that the shifters pull in more or less per click.

Shimano has always used a pull ratio of 2:1 (i.e. the amount of cable pulled vs. the sideways movement of the derailleur) till now, they have changed the ratio to almost 1:1

 

SRAM has used 1:1 till now, (I stand corrected but I think the pull ratio of the 10 speed stuff is different)

[Bobbo_SA]

The width of the cassette is no different.

 

The rear derailleur works on a parallelogram/4 bar linkage to convert the pull of the derailleur cable to the sideways movement of the derailleur (the spring only brings it back to it's starting position)

 

The difference between 7, 8, 9 speed system is that the shifters pull in more or less per click.

Shimano has always used a pull ratio of 2:1 (i.e. the amount of cable pulled vs. the sideways movement of the derailleur) till now, they have changed the ratio to almost 1:1

 

SRAM has used 1:1 till now, (I stand corrected but I think the pull ratio of the 10 speed stuff is different)

 

Ahhh, now you see there is some logic and not only good marketing, :-) I never took into account that the change in "parallelogram" geometry may affect the way the RD actually moves across the gears.

[wayno]

Thank you so much Hubbers!

 

Thanks Flowta, makes alot more sense now.

[_freak_]

I would like to re-visit Dynasys

If my RD has a little lever on it, that can be adjusted by moving it back and forward by hand, what does this do?

Its on a XT 2/10 setup bike...

Please educate me

[Meezo]

I would like to re-visit Dynasys

If my RD has a little lever on it, that can be adjusted by moving it back and forward by hand, what does this do?

Its on a XT 2/10 setup bike...

Please educate me

 

its a clutch system, it should say "on" and "off"

 

The device practically eliminates slap and, because it keeps the chain under tension, it also limits the chance of a chain dropping off the chainrings.

 

http://www.bicycling.com/mountainbikecom/bikes-gear/tested-shimano-xtr-shadow-plus-rear-derailleur

[Guest Karma]

its a clutch system, it should say "on" and "off"

 

 

 

http://www.bicycling...rear-derailleur

 

if it lasts for more than 500km.

Know too many people who had theirs, including my own sent back because of failure on the clutch.

[Hennie VR]

if it lasts for more than 500km.

Know too many people who had theirs, including my own sent back because of failure on the clutch.

 

And I just converted to 1 x 10 and need my clutch to work.

[Guest Karma]

And I just converted to 1 x 10 and need my clutch to work.

 

luckily they warranty replace without any issues.