I have read from several different sources on to determine the chain length: Put the open chain on the largest cogs front and back, without the derailleurs, without slack, and add a link.
I'm having trouble wrapping my mind around this concept--how would the chain be long enough using this method? After the derailleurs are added, how would the chain be long enough if/when one chooses to put the chain on the biggest cogs front and back?
Also, presuming the above method is correct, does "no slack" mean pull the chain taut?
The "definition" of a link is both pieces.....the space between 3 rivets. Always has been.
That advice is standard and it works. It's based on road bikes and hardtails, however. Most suspension designs are fine with it, too, but some want an extra link in order to prevent ghost shifting or wrapping up the rear derailleur and ripping it off the knuckle. Depends on the rear wheel path....if it grows a little bit then you need an extra link in there. VPP is a good example of this.
The derailleur's "other" job is to take up slack in the chain with the cage length via spring tension. When you cut your chain to length this way, you're allowing just enough to cover the big-big combination....the derailleur will do the rest. Since you should never really be riding your gears in that combo, the chain won't be too short in normal gearing combos and you've allowed for the worst case scenario. If you're in the big-big, the derailleur will be stretched out to the max and maybe get a little noisy, but it won't harm anything. Make sense?
Thank you guys. I appreciate all the information. I do need to remember to fully compress the suspension when measuring. While recognizing that big-big is not a typical nor recommended combination, I was having troble seeing how having "just long enough" plus the "space of 3 rivets" gives one enough length to run the chain through the rear derailleur (with the big-big).
I believe that it works, but I'm just having trouble visualizing it.
i guess it seems like an extra inch of chain/2 links won't be enough length to get it through the derailleur when i'm in the 34 tooth cog and still have a nice S shape http://www.parktool.com/repair/readhowto.asp?id=26. when you have the big-big measurement i assumed that nobody is using the big-big combination while riding giving them enough chain length to avoid killing their rear derailleur. anyway i'll give it a try.