Best way to determine chain length

[LiveFreeOrDie]

Hey all. Going to install a couple of chains today and I was curious to know how everyone does it? Some measure on the small cogs, others on the large. I've always done it on the large. Thanks! :)

[Cicli]

I always go small-small. That assures the longest chain possible. It has always worked for me.

[teleguy57]

Yes, small-small works has worked the best for me.

[R3awak3n]

I always do big-big minus couple of links .

Always worked perfect for me. I guess it doesn't really matter, seems like both ways work just fine.

[carpediemracing]

+1 small small

[LiveFreeOrDie]

I always go small-small. That assures the longest chain possible. It has always worked for me.

While the chain is through the rear derailleur correct?

[katematt]

small small with a little tension on the rear der.

[rePhil]

See if this linky works.....Park Tool.

https://www.facebook.com/video.php?v=882770191764268&set=vb.131408076900487&type=2&theater

[brockd15]

While the chain is through the rear derailleur correct?

Yeah, through the rear derailleur.

This write-up is pretty good:
http://www.slowtwitch.com/Tech/Chain_How-To_-_Part_1_3279.html

[Mark McM]

It depends on the riding environment.

For road bikes, small-small is usually best. It gives the longest usable chain, allowing the greatest opportunity for swapping between different cogset/chainring combinations, as well as increasing the life of the chain (since it cycles through the drivetrain less frequently). The reduced tension in the bottom run of the chain also decreases parasitic energy losses in the chain.

For off-road use, large-large can sometimes be better. Large-large results in the shortest usable chain length and increases tension on the derailleur cage spring, reducing the potential for chain-slap and chain-drop when riding over rough terrain, and may also decrease the potential for chain suck.

[AngryScientist]

well,

if you have a drivetrain that works now, the easiest way is to use the old chain for the measurement.

but yea, if it's a new build, i go big-big, then verify enough chain tension small-small.

[Ralph]

I always use small to small (for road bike) for reasons mentioned above. Then if I decide it's too long (not nenough tension....tossing chains, chain not pulling upper pulley back enough to clear largest rear cog after using B screw, etc), can always take more links out.

[Mark McM]

I always use small to small (for road bike) for reasons mentioned above. Then if I decide it's too long (not nenough tension....tossing chains, chain not pulling upper pulley back enough to clear largest rear cog after using B screw, etc), can always take more links out.

That's a good point - even if the chain is partially worn, you can always remove links, but it is never a good idea to add links to a partially worn chain.

[tumbler]

Another vote for small-small w/ a tiny bit of tension. I was getting mixed results (in between sizes) the last time with Shimano's recommended methods. Switched to small-small and everything is running perfectly. It's also simple and more intuitivive than the other methods of overlap+2, etc.

[marciero]

Years ago I did big-small with rear pulleys aligned vertically. Was quick-and-dirty rule of thumb that was fine for 53/39 12-23. These days, on wider range gear configurations with short cage derauleurs I typically do big-big with rear deraileur stretched out, plus a link or two, to access big-big gear combo, which I use often enough.

[regularguy412]

I've always used big chainring/smallest rear cog and the rear der pulleys vertical. I also like to try and run the B-tension screw all the way out (top wheel closest to the cogs), if i can without it hitting. Additional note: I typically don't use a lot of variation in cog sets. Biggest cog normally use is 25 and smallest is 11. Right now, I'm using a 12-25 10-speed set. New chain and cogs. on my new ride just purchased from a forumite. I got the Ti/Enve fork Serotta Fondo that was previously in the classifieds. Had to check the chain length for new, since I suspected the chain length that was in use on the CSI was not gonna be just right.

Mike in AR:beer:

[pinkshogun]

Didn't Sheldon recommend big/big/add a link b4 cutting not routed through derailer? has this method fallen out of favor?

[LiveFreeOrDie]

Ended up doing the short/short method with a slight tension. There is about a centimeter of clearance from the derailleur cage. Seems to work okay.