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

New: Take Part in the new April's Giveaway for a Chance to Win the Euybike S4 Pro Max ebike worth $1299


Derailleur cable adjustment
#1
Adjusting derailleur cable tension, I am curious why compressing the housing tightens the cable and therefore moves the derailleur. Please explain the mechanics.
  Reply
#2
The term "adjusting the cable tension" isn't really accurate. When you turn the adjuster barrels, you're actually making the housing longer or shorter (not by compressing the housing, but by making the adj barrel itself longer or shorter). In effect, you're making the path that the cable has to follow to get to the derailleur longer or shorter. The length of the path of the cable will change where the derailleur sits for a given shifter position. The actual tension on the cable is just a function of the strength of the spring in the derailleur. I'm not sure why this became the conventional term for the adjustment.
  Reply
#3
(09-24-2012, 12:11 PM)DaveM Wrote:  The term "adjusting the cable tension" isn't really accurate. When you turn the adjuster barrels, you're actually making the housing longer or shorter (not by compressing the housing, but by making the adj barrel itself longer or shorter). In effect, you're making the path that the cable has to follow to get to the derailleur longer or shorter. The length of the path of the cable will change where the derailleur sits for a given shifter position. The actual tension on the cable is just a function of the strength of the spring in the derailleur. I'm not sure why this became the conventional term for the adjustment.

Thank you. Please clear it up a little more. I understand you are saying when the barrel adjuster is turned counterclockwise it lengthens the barrel, so the cable has further to travel. But how does it travel further and tension more, when it seems as though the cable is just passing through the barrel? Does the shape of the housing stay the same?
Sorry for all of the questions, just trying to understand.
  Reply
#4
The housing itself does not change. On most adjusting barrels, there are two parts with one threaded inside the other. When you turn it, the inner part threads out of the outer part making the part's overall length longer. Look closely as you turn it, you should be able to see what changes.
  Reply
#5
(09-24-2012, 01:15 PM)DaveM Wrote:  The housing itself does not change. On most adjusting barrels, there are two parts with one threaded inside the other. When you turn it, the inner part threads out of the outer part making the part's overall length longer. Look closely as you turn it, you should be able to see what changes.

So the housing does not change, the cable tension does not change, but making the barrel longer, the cable pulls on the derailleur, making it move. Do I have it, and thank you?
  Reply
#6
(09-24-2012, 02:09 PM)Bob K Denver Wrote:  So the housing does not change, the cable tension does not change, but making the barrel longer, the cable pulls on the derailleur, making it move. Do I have it, and thank you?

Yes
Nigel
  Reply


Possibly Related Threads...
Thread
Author
Replies
Views
Last Post
 
1,323
05-14-2020, 08:14 AM
Last Post: Dany6
 
12,298
07-26-2015, 12:38 PM
Last Post: Painkiller
 
14,728
02-16-2015, 09:41 PM
Last Post: budstutor
 
7,858
09-15-2013, 03:34 PM
Last Post: Joe_W

Forum Jump:

[-]
10 Latest Posts
Food after late training ride
Today 02:48 PM
1987 Tommaso Alloy lugged frame
Today 11:18 AM
Injury Recovery
Today 08:20 AM
RECOMMENDATION
Yesterday 04:24 PM
New Member
Yesterday 03:31 PM
2011 GT Tachyon upgrade/mod
Yesterday 08:45 AM
Doctors are Prescribing Cycling
04-23-2025 09:50 PM
What was your first bicycle?
04-23-2025 09:17 PM
New Rider Here — Momo + Viribus = Ready ...
04-23-2025 09:15 PM
The great thing about trikes
04-23-2025 03:47 AM

[-]
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. GirishH
24 posts
no avatar 2. SPINMAN
14 posts
no avatar 3. meamoantonio
13 posts
no avatar 4. Flowrider
12 posts
no avatar 5. Painkiller
11 posts