Have questions or want to discuss cycling? Join Now or Sign In to participate in the BikeRide community.

New: Take Part in the October Giveaway to Win the Qiolor TIGER Retro Electric Bike


Dura Ace RD7900 with 11-28T (7900)
#1
To measure the proper chain length i have to pass the chain from the biggest front chain ring and the biggest rear cassette ring (28), without passing through the derailleur pulleys. So, after the chain front and rear meets, and if i am correct, i have to add two more links.
Ok?
But....the problem is that shimano in the service instructions of rd 7900 says that i have to add , especially for the 11-28t sprocket, two more links. Is it correct? Pls help. Thanks

  Reply
#2
It should just be 2 links no matter which derailleur you use.<br />
Big chainring to biggest rear cog + 2 links.
See :- http://bikeride.com/calculate-chain-length/
If you are unsure then add the extra links (4 links?) but I think you'll find they are not needed. You can always take them out after. If the chain is too long then the derailleur will rotate right back (small ring to small cog) and allow the chain to rub on the bottom of the cage. If the chain is to short then you won't get the big to big without straining something.
There is another way shown in this tech' document. It involves big chainring to small cog and getting the derailleur 90 degrees to the ground.<br />
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/DA_Di2/RD7970/SI-5X20A-002-ENG_v1_m56577569830673791.pdf

Ride hard or ride home alone!
  Reply


Possibly Related Threads...
Thread
Author
Replies
Views
Last Post
 
29,677
03-23-2011, 11:00 AM
Last Post: dave_sd
 
13,457
03-03-2011, 04:03 PM
Last Post: colcazal
 
8,636
04-07-2009, 08:34 PM
Last Post: DaveM
 
12,861
04-07-2009, 08:15 PM
Last Post: DaveM

Forum Jump:

[-]
10 Latest Posts
Moving in Style: Beyond Regular Transpor...
Yesterday 09:11 PM
Great UK Cycle Camping Map, For E-Bikes,...
11-10-2024 06:55 AM
Cycling is Anti-Aging, But There's a Cat...
11-10-2024 06:48 AM
BAGGI 1936(?)
11-09-2024 10:24 AM
Do you have a four foot rule?
11-09-2024 10:10 AM
Trek domane tyre
11-08-2024 05:07 PM
Greetings!
11-08-2024 04:39 PM
Peugeot Nouveau Folder
11-08-2024 04:34 PM
Community Discussion Cycling Myths
11-07-2024 09:05 PM
Tasmania! Anyone ridden here?
11-07-2024 05:15 PM

[-]
Join BikeRide on Strava
Feel free to join if you are on Strava: www.strava.com/clubs/bikeridecom

[-]
Top 5 Posters This Month
no avatar 1. enkei
22 posts
no avatar 2. GirishH
17 posts
no avatar 3. Jesper
16 posts
no avatar 4. Flowrider
14 posts
no avatar 5. Talha
10 posts