Go Back  Bike Forums > Bike Forums > Tandem Cycling
Reload this Page >

Eccentric Adjustment question

Notices
Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

Eccentric Adjustment question

Old 02-26-14, 02:16 PM
  #1  
LastKraftWagen
Senior Member
Thread Starter
 
Join Date: Feb 2014
Location: Wind Tunnels of Cheyenne
Posts: 361

Bikes: Burley Duet [of some unknown year] (the guinea pig); 2001 Ventana ECDM (the project); And always one less than I think I really need.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Eccentric Adjustment question

Not a tandem mechanic, and having an issue adjusting the timing chain tension on my Burley Duet (2000ish I think). I've found and loosened the two allen bolts on the front BB shell, and I've tried tightening the chain tension using a Park Tool pin spanner (the green-handled one I think) inserted in the pinholes on the right side of the BB, but this does not seem to be tightening the chain tension...Am I doing this wrong? I can press on the chain to increase slack (once released), and I can rotate/push the crankarms forward to take some of the play out of the chain, but there still seems to be more than 2" of play in the chain at it's tightest through a rotation of the cranks (i.e. this is the best it gets).

Thanks,
LKW
LastKraftWagen is offline  
Old 02-26-14, 02:32 PM
  #2  
merlinextraligh
pan y agua
 
merlinextraligh's Avatar
 
Join Date: Aug 2005
Location: Jacksonville
Posts: 30,555

Bikes: Wilier Zero 7; Merlin Extralight; Co-Motion Robusta; Schwinn Paramount; Motobecane Phantom Cross; Cervelo P2; Motebecane Ti Fly 29er; Calfee Dragonfly Tandem

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1000 Post(s)
Liked 130 Times in 73 Posts
If you've got the fat part of the eccentric spun all the way to the back of the bb shell (i.e. the bb spindle is as far forward as it can go) and you're still have 2" of slack, your chain is too long.

Are you actually spinning the eccentric in the shell?
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
merlinextraligh is offline  
Old 02-26-14, 11:22 PM
  #3  
LastKraftWagen
Senior Member
Thread Starter
 
Join Date: Feb 2014
Location: Wind Tunnels of Cheyenne
Posts: 361

Bikes: Burley Duet [of some unknown year] (the guinea pig); 2001 Ventana ECDM (the project); And always one less than I think I really need.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I will need to get someone sighted to let me know... Blind and can't feel if the eccentric is as you describe. I can feel the BB move backwards when loosened and by pushing/rotating the cranks I can achieve the original 2"+ slack. I honestly didn't try to slacken the chain with the pin spanner, are these pinholes on the side (located between the shell and the BB axle) the proper location to move the eccentric and remove the slack?

Thanks,
LKW
LastKraftWagen is offline  
Old 02-26-14, 11:31 PM
  #4  
chojn1
Senior Member
 
chojn1's Avatar
 
Join Date: Jun 2009
Location: Sugar Land, TX
Posts: 288

Bikes: Eriksen Tandem, DIY CF Tandem, Aluminum Tandem, Lightspeed, Cervelo, Specialized, Trek

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Try removing a few links from your chain.
CJ
chojn1 is offline  
Old 02-27-14, 01:35 AM
  #5  
Bezalel
Senior Member
 
Join Date: Mar 2010
Location: City of Brotherly Love
Posts: 1,561

Bikes: Raleigh Companion, Nashbar Touring, Novara DiVano, Trek FX 7.1, Giant Upland

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
If when your BB is fully forward you still have too much slack, your chain is too long. Put the BB in the rearmost position and remove as many links as possible, then move the BB forward.

If you are having trouble getting the eccentric to rotate, try a stronger pin spanner.
Attached Images
File Type: jpg
image_17531.jpg (57.1 KB, 8 views)
Bezalel is offline  
Old 02-27-14, 06:08 PM
  #6  
zonatandem
Senior Member
 
zonatandem's Avatar
 
Join Date: Dec 2003
Location: Tucson, AZ
Posts: 11,017

Bikes: Custom Zona c/f tandem + Scott Plasma single

Mentioned: 3 Post(s)
Tagged: 1 Thread(s)
Quoted: 74 Post(s)
Likes: 0
Liked 7 Times in 5 Posts
Another way to tighten the crossover chain is to 'float' as chainring dead center between top and bottom of chain. Chainring needs to be one or 2 teeth larger than the cross over rings are. Yes, the chainring will 'float' and stay in place. Tightens the chain and makes for a great conversation starter!
Just an alternative . .
zonatandem is offline  
Old 02-27-14, 06:51 PM
  #7  
LastKraftWagen
Senior Member
Thread Starter
 
Join Date: Feb 2014
Location: Wind Tunnels of Cheyenne
Posts: 361

Bikes: Burley Duet [of some unknown year] (the guinea pig); 2001 Ventana ECDM (the project); And always one less than I think I really need.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
While I will probably go with removing a link or two, I honestly haven't checked/noticed the tension problem since the last replacement and it cold have been measured wrong...I'm hyped about that floating ring thing! I'm thinking some sort of flourecent or obnoxiously bright paint or perhaps rigging a battery and some LEDs...
LastKraftWagen is offline  
Old 02-27-14, 07:50 PM
  #8  
JanMM
rebmeM roineS
 
JanMM's Avatar
 
Join Date: Jan 2006
Location: Metro Indy, IN
Posts: 15,868

Bikes: RANS V3 ti, RANS V-Rex, RANS Screamer

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 562 Post(s)
Liked 177 Times in 117 Posts
Originally Posted by zonatandem View Post
Another way to tighten the crossover chain is to 'float' as chainring dead center between top and bottom of chain. Chainring needs to be one or 2 teeth larger than the cross over rings are. Yes, the chainring will 'float' and stay in place. Tightens the chain and makes for a great conversation starter!
Just an alternative . .
Sometimes referred to as a 'ghost ring'.
__________________
RANS V3 Ti, RANS V-Rex, RANS Screamer
JanMM is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Tandem Tom
Bicycle Mechanics
10
03-02-17 11:41 AM
frantik
Bicycle Mechanics
7
06-30-13 08:09 PM
johnnyboy1
Bicycle Mechanics
8
04-07-13 11:40 AM
GriddleCakes
Singlespeed & Fixed Gear
4
11-11-11 01:31 AM
GriddleCakes
Bicycle Mechanics
3
11-10-11 12:20 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.