So long since I fitted a new chain that I’ve forgotten all the rules of thumb! I think one was large ring at front, small at back then add two links…..??

Any others?

Thanks

Should be – Large at front and large at rear +2 links

…through the derailleur?

No.

I use big big and 1 link (1 full link being one narrow bit and one wide bit)

I do big-big plus two, to be on the safe side with modern clutch mechs, they seem to get really noisy with short chains. Don’t forget to cycle any suspension through its travel and measure at maximum extension.

You want it to not snap or damage anything should you use the worst case scenario. So big front, big back through the mech as normal + a link or two for luck.

Are we talking HT or FS? Those calculations are generally for hardtails.

If it’s FS compress the shock as much as possible while measuring the chain length as that can make a bit of a difference to the length required.

Thanks for replies, I’m glad I asked!!

Sorry, its for a HT

Is there a rule of thumb that says rear derailleur should be 45degrees when on certain rings..?? I’m sure that’s the one I used last time but cant find anything about it.

Thanks again

Especially good for the eighties music…

Put in small / small and make sure the top jockey wheel doesn’t touch three chain below ( but only just).

@jonba…not sure if you meant to write what you did…but your method would leave an unnecessarily long chain…

Big-Big, through derailleur, when derailleur is at 45 degrees you’ve got the chain at the right length.

Works for me on both FS & HT as long as for FS I remember to let the air out of the shock and fully compress.

There are other ways that are slightly different but probably also work.

i always built my bikes with big/big +2. Just built a FS with the big XT 11spd cassette and my old formula no longer works. : £40 chain cut too short

allan23 is correct.