HOT: Active* forum members generally gain 5% discount at starbike.com store!
Weight Weenies
* FAQ    * Search    * Trending Topics
* Login   * Register
HOME Listings Articles FAQ Contact About




Post new topic Reply to topic  [ 22 posts ] 
Go to page 1, 2  Next
Author Message
PostPosted: Tue Feb 11, 2014 9:33 pm 
Offline

Joined: Tue Sep 11, 2012 6:07 pm
Posts: 574
We all know that Shimano did not make a mid/long cage rear derailleur for the DA9000 level. However, I recently acquired an Ultegra 6800 GS rear derailleur, and I don't see why the long cage wouldn't work on my DA derailleur, other than the weight penalty.

With that in mind, does anyone know anywhere that makes, or would be willing to make, a longer RD cage? I contacted Fibre-Lyte, and they have no plans to make such a beast, and none of my searches have provided me with an answer.

Thanks.

_________________
2013 Madone 5
2012 SpeedConcept 7
2013 Superfly


Top
 Profile  
 
PostPosted: Tue Feb 11, 2014 10:18 pm 
Offline

Joined: Thu Mar 26, 2009 11:06 pm
Posts: 170
Haven't you effectively answered your own questions: use a 6800 cage?


Top
 Profile  
 
Posted: Tue Feb 11, 2014 10:18 pm 
  • 14.90 € (including 19% VAT)
  • 61 components


Top
  
 
PostPosted: Tue Feb 11, 2014 11:45 pm 
Offline

Joined: Tue Sep 11, 2012 6:07 pm
Posts: 574
I wouldn't want to for the reason I stated in my post, the weight penalty.


Sent from my iPhone using Tapatalk

_________________
2013 Madone 5
2012 SpeedConcept 7
2013 Superfly


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 12:13 am 
Offline

Joined: Mon Aug 20, 2012 12:12 pm
Posts: 126
Location: Bristol
199g vs. 158g? Really? I know this is WW, but this is a bit much considering the variables. If you need a GS rear mech then you're running a big ass cassette (32?) which is already quite a bit heaver than the DA 11-28 equivalent. This leads me to believe that you're not running a compact (in which case you should) or you absolutely need a 32 to climb (in which case 30g makes no discernible difference until you shift some weight off yourself).


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 1:01 am 
Offline
User avatar

Joined: Wed Mar 06, 2013 4:23 pm
Posts: 289
Location: Austin, TX
I think 41g is significant given it's WW. More importantly, and I may be completely off base here, but even though the longer cage will give you more chain wrap capacity, I thought I read somewhere that the knuckle on the DA derailleur is different such that you won't have enough "B-tension room" to accommodate an X-large cassette.

_________________
My Cervelo R5
My Cervelo S3
My MTB


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 1:02 am 
Offline

Joined: Fri Mar 09, 2007 1:26 am
Posts: 408
Location: USA
+1000 :noidea: :noidea: :noidea: :noidea: :noidea: :noidea: :noidea: :noidea: :noidea:


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 1:35 am 
Offline

Joined: Tue Nov 11, 2003 9:47 pm
Posts: 1689
Location: Santa Cruz, California, USA
Grill wrote:
or you absolutely need a 32 to climb (in which case 30g makes no discernible difference until you shift some weight off yourself).


Some people actually race their light bikes in difficult climbing races where low gearing is a benefit even for very fit riders.

I know someone who used a 32t cog with 7900 DI2 derailleur for one of those climbing races. With 7900 Shimano moved the pivot a little to make room for larger cogs. While the spec is 28t, 30t is easily doable and 32t with the right combination of getting lucky on your frame's derailleur hanger and twiddling the B screw.

Can you swap the 6800's cage onto the DA derailleur? While the longer cage surely accounts for some of the weight difference it wouldn't be all of it. The DA body will be lighter than the Ultegra one.


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 1:47 am 
Offline

Joined: Thu Jan 02, 2014 2:27 am
Posts: 1
I have the new Dura Ace 11 speed and I just put a 11/32 on with the reg derailleur. I had to adjust the B screw but it works just fine. I can post pic if you need.


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 4:19 am 
Offline

Joined: Tue Sep 11, 2012 6:07 pm
Posts: 574
If push comes to shove, I will swap the Ultegra cage over. That being said, cdenloe, can you post the photo? I'm ordering my wife's 32T soon, and if it works on my bike, then it's all academic, otherwise, it's time to mod the RD with the Ultegra parts (which I'd rather avoid).


Sent from my iPad using Tapatalk

_________________
2013 Madone 5
2012 SpeedConcept 7
2013 Superfly


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 7:54 am 
Offline
User avatar

Joined: Sat Dec 06, 2008 10:14 am
Posts: 957
Location: Sweden
As the length of the cage really doesn't play a very big part in how large a cog you can run with the derailleur, that comes down more to where the upper jockey wheel is placed in relation to the cassette. This is the main difference between a road and a mtb RD.

So, if you just move your RD a little further away from the cassette, you will be able to use larger cogs. If the B-tension doesn't do it for you, you could just have a new derailleur hanger custom made that does the trick.

If you're already researching custom made carbon fibre cages, this seems like a viable option.

Longer cages will most of all just let you chain cross more. If you're climbing 20% gradients I suspect you're an advanced enough rider never to venture into full chain cross big/big.

_________________
Roadbike
Planet X Stealth w/ drop bars

Mountainbike
Van Nicholas Zion Ti


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 10:07 pm 
Offline

Joined: Mon Oct 15, 2007 9:28 pm
Posts: 904
K-Edge will modify a 9000 derailleur and install a mid-cage.
I already checked into it as I am considering doing the same.


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 10:18 pm 
Offline
Formerly known as wassertreter

Joined: Tue Apr 12, 2011 8:08 am
Posts: 1916
Location: Pedal Square
What DMF says.
Unless you want to run a triple front, you don't need a long cage (to take up the slack chain), and it will not help you running a bigger cassette.
If you want to squeeze out the last bit of clearance after giving lots of B-screw, swap in a 10t top pulley cog.

Edit: Some clarification: the DA 9000 RD has a capacity of 33t. Take away 16t for the 50/34 compact front, and you have 17t capacity left for the rear. That is exactly what's needed to handle an 11-28 cassette. However, the capacity typically specs err on the conservative side, so you can usually handle a bit more. For a 32t bottom gear cassette, to be on the safe side with regard to chain tension, use a chain length as you would for 28t. That means you can not cross chain big-big, but who in their right mind would do that with a big cassette anyway.

If you run a standard 39/53 front you don't have those issues at all, because the smaller 14t front capacity leaves 2t extra for the rear, so you'll probably get away without running a short chain.

_________________
Bikes: Raw Ti, 650b flatbar CX


Last edited by HillRPete on Thu Feb 13, 2014 12:02 am, edited 1 time in total.

Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 10:37 pm 
Offline

Joined: Tue Sep 11, 2012 6:07 pm
Posts: 574
Makes sense. I'll see what's out there. Thanks.

_________________
2013 Madone 5
2012 SpeedConcept 7
2013 Superfly


Top
 Profile  
 
PostPosted: Wed Feb 12, 2014 11:43 pm 
Offline

Joined: Sun Mar 27, 2011 8:16 pm
Posts: 425
Maybe I'm a thicko, but I got the GS version of the 6870 to run with an 11-32 cassette and a 52/36 chainset.

Largely because I wanted "just works", I admit.


Top
 Profile  
 
Posted: Wed Feb 12, 2014 11:43 pm 
  • 14.90 € (including 19% VAT)
  • 61 components


Top
  
 
PostPosted: Thu Feb 13, 2014 12:32 am 
Offline

Joined: Mon Oct 15, 2007 9:28 pm
Posts: 904
The other benefit to the mid-cage (other than running the 32 tooth cog) is that with more chain the bike works better while in the big ring.
This is important on bikes with 52/36 or 50/34.
When you race you end up going back and forth on a compact chainring set more than you do on a 53/39. The mid cage and longer chain allows to to cross-chain better.
I have set up a few wi-fli and 6800 bikes with mid-cage derailleurs.
I am considering going mid cage myself. I will probably get a 9000 derailleur and
have K-edge turn it into a mid-cage.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 22 posts ] 
Go to page 1, 2  Next


Who is online

Users browsing this forum: Bing [Bot], Google [Bot], Jman, splat and 54 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

   Similar Topics   Author   Replies   Views   Last post 
There are no new unread posts for this topic. DURA ACE 9000 OR ROTOR

in Road

treetrees

10

2472

Tue Dec 10, 2013 11:10 am

maquisard View the latest post

There are no new unread posts for this topic. Dura Ace 9000 changes to 9001

[ Go to page: 1, 2, 3, 4, 5 ]

in Road

NYCPrynne

65

18818

Fri Mar 14, 2014 5:58 pm

Grill View the latest post

There are no new unread posts for this topic. Dura Ace 9000 Chainring Sizes

in Road

JimmyRingo

12

953

Wed Jul 30, 2014 5:29 pm

06SpiceRed View the latest post

There are no new unread posts for this topic. Dura-Ace 9000 FD shifting pattern

in Road

wca9922

5

977

Thu Jan 30, 2014 9:28 am

TheDarkInstall View the latest post

There are no new unread posts for this topic. Dura-Ace 9000 Hoods problem. Slippery

in Road

ToffieBoi

9

915

Sun Jun 08, 2014 1:01 am

BRM View the latest post


It is currently Fri Aug 22, 2014 9:11 am

All times are UTC + 1 hour




Advertising   –  FAQ   –  Contact   –  Convert   –  About

© Weight Weenies 2000-2013
hosted by starbike.com


How to get rid of these ads? Just register!


Powered by phpBB