Fitting a chain

[Alison]

Ive just opened a boxed NOS XT RD and it mentions the chain length. And I quote: Add 2 links (with the chain on both the largest sprocket and the largest chainring)

Yeah so did I!
But that's not what I'm used to fit chains, and Alison sure couldn't use that for her case.

I don't see why you think she couldn't use the big + big + two method for a double chainset?

Big + big + two is the standard recommendation and much the most straightforward and safest, compared to the alternative hit-and-miss methods suggested above, for the reason that Hamster describes so well.

You will only ever get a sagging chain in the small/small combination if you have the wrong rear mech for your chainrings and sprockets spec. And small/small is such a daft gear to use that it doesn't make any sense basing your chain length around it.

Aaarrgg Don't confuse me even more I was just settled on small/small

Alison could you just make it clear whats your set up (front & rear)?

t's an 2x8 set up, if that's what you mean.

Alison

 

[RobMac]

Thanks Ive got it now

 

[FluffyChicken]

Big, Big + ~2 as per shimano from the retro era. Instruction from them are in the Archive from the retro era.
Any other method allows the possibility of the chain to snap or get stuck in gear. I would rather have a saggy chain I could change out of than a snapped one.
It doesn't matter how many cogs you have.

Of course you could just ask SRAM. It just happens to be the same method, though as they use a power link it's
Wrap the chain around the largest front chainring and the
largest rear cog so that the ends of the chain meet below the
chainstay, bypassing both the front and rear derailleurs. Pull
the chain tight and note which rivet the end of the chain is
nearest. Add one inner link so that you have an inner link on
both ends of the chain, and a SRAM PowerLock

Rear suspension bikes should be deflated/fully compressed when you fit the chain to get it correct apparently, I assume the chain length might need to be longer in that position. Check you particular suspension setup to see if it does get longer, I'm sure some might be the other way around.

Anyways,
XX Tech docs
http://cdn.sram.com/cdn/farfuture/iYvoI ... manual.pdf
or Visually
http://www.youtube.com/watch?v=SBBPnOFgCRI&feature=plcp

Of course Park agree's and they even go all technical.
But they give pointers of what to look out for.
http://www.parktool.com/blog/repair-hel ... gth-sizing

 

[Whatleymeister]

Big, Big + ~2 as per shimano from the retro era. Instruction from them are in the Archive from the retro era.
Any other method allows the possibility of the chain to snap or get stuck in gear. I would rather have a saggy chain I could change out of than a snapped one.
It doesn't matter how many cogs you have.

Of course you could just ask SRAM. It just happens to be the same method, though as they use a power link it's
Wrap the chain around the largest front chainring and the
largest rear cog so that the ends of the chain meet below the
chainstay, bypassing both the front and rear derailleurs. Pull
the chain tight and note which rivet the end of the chain is
nearest. Add one inner link so that you have an inner link on
both ends of the chain, and a SRAM PowerLock

Rear suspension bikes should be deflated/fully compressed when you fit the chain to get it correct apparently, I assume the chain length might need to be longer in that position. Check you particular suspension setup to see if it does get longer, I'm sure some might be the other way around.

Anyways,
XX Tech docs
http://cdn.sram.com/cdn/farfuture/iYvoI ... manual.pdf
or Visually
http://www.youtube.com/watch?v=SBBPnOFgCRI&feature=plcp

Of course Park agree's and they even go all technical.
But they give pointers of what to look out for.
http://www.parktool.com/blog/repair-hel ... gth-sizing

^^This^^, which is what Anthony has said too. Worked a treat for me. Using the formula on the Park Tools website achieved the same chain length as using the Big+Big+2 method exactly. Remember when you do this to wrap the chain around the two big rings but not through the rear mech.

 

[Alison]

Just a thought, but, does it matter in the large/ large set up that the largest chainring is the middle one at 32 teeth, sorry for my ignorance

Alison

 

[joss]

Use largest to largest, threaded through the rear mech.
This will establish the maximum chain required.
Tension the chain by pulling both ends together, pull until the jockey wheel cage is set to represent 5 o'clock on a clock face.
That should do it.

 

[Anthony]

Just a thought, but, does it matter in the large/ large set up that the largest chainring is the middle one at 32 teeth, sorry for my ignorance
Alison

No, it doesn't matter - the chain will be long enough for your 32 ring and your biggest sprocket. Obviously if you later on fitted a triple chainset with a bigger ring, you would need to add links to your chain or buy a new chain.

Basically big + big + two means that your chain is long enough to deal with whatever mistake you might make in the heat of the moment, without damaging your rear mech or your frame. To cut the chain, you run it just around the rings, not the rear mech - the additional two links give you enough allowance for the rear mech when you finally come to join the chain up.

The one piece of advice that Shimano won't give you however is don't buy a Shimano chain! Buy an SRAM with the magic link and fitting will be so much easier. Remember that the magic link is one of the plus two. And if it so happens that it can't be plus two, go for plus three, not plus one.

 

[Loki]

I'm in the Large-Large + 1" camp, never thought a miss shift destroying a RD is a sound I ever wanted to hear.

 

[Alison]

Just a thought, but, does it matter in the large/ large set up that the largest chainring is the middle one at 32 teeth, sorry for my ignorance
Alison

No, it doesn't matter - the chain will be long enough for your 32 ring and your biggest sprocket. Obviously if you later on fitted a triple chainset with a bigger ring, you would need to add links to your chain or buy a new chain.

Basically big + big + two means that your chain is long enough to deal with whatever mistake you might make in the heat of the moment, without damaging your rear mech or your frame. To cut the chain, you run it just around the rings, not the rear mech - the additional two links give you enough allowance for the rear mech when you finally come to join the chain up.

The one piece of advice that Shimano won't give you however is don't buy a Shimano chain! Buy an SRAM with the magic link and fitting will be so much easier. Remember that the magic link is one of the plus two. And if it so happens that it can't be plus two, go for plus three, not plus one.

Thanks

Alison

 

[gtRTSdh]

Lets simplify this into 3 steps.

1) Big-Big + 2 links.

2) Rear independant suspension - suspension must be moved to the position that stretches the chain most, then step 1.

3) Before you cut the chain, thread it through smallest smallest and rear mech. If the rear mech has the capacity to keep a longer chain (than B2B + 2) tight then set your chain longer, you alos have this option if desired. I do this on my road bike where the deraileur is often stretched a long way being in the largest chainring most of the time.