Chain length for 1 x ? setups

[IDB1]

Using 1 x 7 as example. .

Would a 1 x 7 setup run on a 7-speed chain or, because of the single front ring, would it benefit from being slightly shorter?

Also. . do new chains always come with a bit extra?
What's the method for getting the correct length?

 

[one-eyed_jim]

Would a 1 x 7 setup run on a 7-speed chain or, because of the single front ring, would it benefit from being slightly shorter?

When you talk about "n-speed" chain you're referring to the chain's width. Narrow-spaced cassettes need narrower chain links.

For the length, I usually run the shortest chain I can get away with. It reduces chain slap, and there's no need to carry the extra weight of chain around if it's not needed. I also prefer a short-chage mech.

Also. . do new chains always come with a bit extra?

Chains sold for mtb use will be long enough for a wide-range triple. 116 links seems to be a common standard. All derailleur chains on the market will be long enough for a wide-range 1x9 with plenty to spare, assuming you're not running some crazy huge chainring or yard-long chainstays.

What's the method for getting the correct length?

Loop the chain over the biggest sprocket and biggest chainring without passing through the derailleur. Note the chain length and add an inch.

 

[IDB1]

When you talk about "n-speed" chain you're referring to the chain's width. Narrow-spaced cassettes need narrower chain links..

what a dork (me) . . only chain I've ever bought was a singlespeed one..

Loop the chain over the biggest sprocket and biggest chainring without passing through the derailleur. Note the chain length and add an inch.

thanks . .

I'm shocked (mildly) that the mech makes that little difference to the required length . .

 

[one-eyed_jim]

I'm shocked (mildly) that the mech makes that little difference to the required length . .

Well, that's working to minimum length. In big-big the derailleur will be stretched forward almost in a straight line with the chain. It looks extreme, but it works fine - better than with excess chain, in my view.

You can leave it longer if you like. It'll still work fine, and nothing's to stop you shortening it later.

 

[FluffyChicken]

I would get the short cage mech of a road mech or if you want transplant the cage of a road mech and put it on your MTB mech for the look MTB's shortest is usually a medium cage (though we call it short)
You'll need a similar era mech to do this.

I would personally put it through the mech and top top and add your two links as normal (see shimano's tech docs for drive systems).

or you can sit it in the middle sprocket and make the length so the jockies hang vertically down. this will put less stress through the mechs tensioning springs.

Depending on the mech you may want to play around with it's spring positions in the cage arm to either tension it more or not.

Have fun and play around and see what happens and works for you.

BUT as long as it long enough to go in top cog and short enough to go in bottom cog... without snapping the chain or locking it into the top cog or having it dangling around in bottom cog it'll be the correct length.

 

[IDB1]

I would get the short cage mech of a road mech or if you want transplant the cage of a road mech and put it on your MTB mech for the look MTB's shortest is usually a medium cage (though we call it short)
You'll need a similar era mech to do this..

Why be that?? Because of the single ring up front??

Hadn't planned on messing about much (the current 1x7 we have uses a long cage M739), the 1x9 I am putting together will be built with a Sachs Plasma to start with. . see how I get on with that

 

[FluffyChicken]

For the same reason roadies use them really. Not essential of course.

 

[dyna-ti]

Err.........I think its ,largest sprocket to largest chainring then add 2 links :?