How to determine the correct chain length

[marc two tone]

chain length

my technique as originally advised from LBS.
put chain on granny at front..then,bottom cog at rear.
then simply make sure lower trail of chain cannot touch top jockey and other chainlinks wrapped around it as cage will be at its maximum rear position,remove links accordingly til lower trail of chain misses top jockey.
at that ,chain cannot be too long.
works for me but as ever there are other conditions depending on
amount of gears etc.as mentioned somewhere above.

 

[dyna-ti]

I close my eyes and guess

 

[Neil]

I pretty much go off the chain that was already on.

 

[mattbrown]

big, big and mech at 45 deg is a what i use

 

[haydnw]

Crikey, plenty of options here then! Thanks everyone, I'll have a play around and see what happens.

 

[bduc61]

I am using

big ring front
smallest ring back
axis of the two derailleur jockeys wheels should be on a vertical line

 

[Xesh]

I am using

big ring front
smallest ring back
axis of the two derailleur jockeys wheels should be on a vertical line

That's what I use if it's a short cage (road stylee) rear mech.

If using the long cage, or Megarange gears, then I use the granny ring and smallest sprocket and then shorten the chain until it just clears the mech cage (like mechagouki and marc two tone).

 

[orange71]

Crikey, plenty of options here then! Thanks everyone, I'll have a play around and see what happens.

no no no, now you've got to test each one empirically and see which is the most accurate

 

[Tad]

Crikey, plenty of options here then! Thanks everyone, I'll have a play around and see what happens.

no no no, now you've got to test each one empirically and see which is the most accurate

Then feed back some thorough statistical analysis using the methodology described in this thread here:

http://www.retrobike.co.uk/forum/viewtopic.php?t=80706