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xendistar
06-Feb-2011, 10:06 AM
What the correct way to measure a chain to ensure it is the correct length??

I know I can measure it against the old one but I want to check it is the correct length as I have a bit of chain suck and I am about to put a new chain on the bike.

gorehound
06-Feb-2011, 10:19 AM
Count the links Tim.

Tango
06-Feb-2011, 10:21 AM
Count the links Tim.



... as a chocolate fire guard ;)

SteveMTB
06-Feb-2011, 11:13 AM
never used it myself as I always measure from the old chain which the LBS setup for me but certainly worth a look

http://www.epicidiot.com/sports/chain_length_calculator.htm

MTBLeague
06-Feb-2011, 01:45 PM
Count the links Tim.



2nd that, then you can see how much the old one has streached.

SteveMTB
06-Feb-2011, 02:00 PM
Count the links Tim.



... as a chocolate fire guard ;)



... or tits on fish :)

xendistar
06-Feb-2011, 03:21 PM
I know I can count the links on the old chain but I have always had chain suck on this bike so I want to check that the chain is the right length for the bike. I will try Steve's web site suggestion and see how that compares to what the old chain length is.

steve_sordy
06-Feb-2011, 05:59 PM
I have seen a few methods for determining chain length:

One that I remember in use for a long time is to run the chain over the big to big, avoiding the derailleur and then add six chain links. Must say, that although I used it, I never felt happy with it. Bike shops seem to use it because that is what I get when I checked a new bike.

One I discovered quite recently and the one I prefer is the following:
Leave the chain running through the derailleur, go big to big and shorten the chain until the derailleur is pointing forwards at 45 degrees.

I was warned to ensure the rear shock is fully compressed when you do this, but I'm assuming that this is general advice because on some bikes it will make no difference.

When I was suffering grieviously from chainsuck, after trying everything else, I took a further two links out (ie. one inch of chain). I resolved not to ride big to big and I have had no problems.

PS: The chainsuck problem was eventually fixed when I removed the nearly new Wipperman Connex chain and replaced it with a new Shimano HG73. No more chainsuck. :) :) :)

Kevolution
06-Feb-2011, 11:27 PM
I go small to small and set the chain length where it sits against the chain coming around the top jockey wheel.
It's generally 1 link shorter than the Shimano method, but it runs quiet and works for everything other than bikes with massive chain growth thru the suspension.
I factor this in on those suspension systems and live with the slightly more noisy and slower gear selection.

steve_sordy
07-Feb-2011, 08:21 AM
I go small to small..... It's generally 1 link shorter than the Shimano method, but it runs quiet......



Thanks Kevolution for the "small to small" method. I'd heard of it but wasn't sure exactly how to do it. But what is "the Shimano method"

steve_sordy
07-Feb-2011, 02:55 PM
I found out what the Shimano method is:

Shimano Method
Run the chain over the largest ring and over the smallest sprocket on the cassette and through the derailleur as normal. Adjust the chain length so that the derailleur hangs vertically.

Sir_Queuesalot
07-Feb-2011, 03:53 PM
I go small to small and set the chain length where it sits against the chain coming around the top jockey wheel.
It's generally 1 link shorter than the Shimano method, but it runs quiet and works for everything other than bikes with massive chain growth thru the suspension.
I factor this in on those suspension systems and live with the slightly more noisy and slower gear selection.



Ditto

fredmundo
07-Feb-2011, 05:44 PM
Hmmmmm, I don't quite get the short to short method....
But i suppose just now that I don't really need to know it seeing as I ride a hard tail anyway.

xendistar
08-Feb-2011, 06:05 PM
Got to be honest I don't understand the short to short method either. The bike is a hard tail

Hobo
08-Feb-2011, 06:36 PM
Always used big-big add 2 links on a triple crankset.

TBH I'm not sure what it is now I'm running a double - I think I took out 2 links. I went too short initially and the guide pulley was hitting the cassette despite adjusting B tension.

Kevolution
08-Feb-2011, 10:00 PM
On a HT I fnd it cuts down on chain slap on the stays.
So it can be more beneficial on them.
Basically, if you run the chain on the granny ring and smallest sprocket and take out as much of the slack as possible without pulling the cage forward, you're setting the chain length to suit the length of the cage on the mech rather than just setting a single standard for all types of mech.
It's just a bit of fine tuning, but it's quicker and easier to measure.

xendistar
08-Feb-2011, 10:15 PM
So what you mean is let the rear gear spring up to its parked position, thread the chain around small cassette gear to small chain wheel gear and then find the shortest chain length without pulling then jockey wheel etc. down (sorry I am thinking about this through wine faded brain)

fredmundo
09-Feb-2011, 07:15 AM
That is how I read it xendi. A note of confirmation would be ace as it totally sounds like less hassle than big to big and pull the chain so the mech is at the right angle.

steve_sordy
09-Feb-2011, 08:53 AM
That is how I read it xendi. A note of confirmation would be ace as it totally sounds like less hassle than big to big and pull the chain so the mech is at the right angle.



For the avoidance of doubt: :D

Not a right angle! Pointing forward at 45 degrees!

fredmundo
09-Feb-2011, 01:14 PM
the 45 degree angle (from vertical) is certainly correct for the big to big method Steve.

The short to short method is the one we're querying. Kevolutions description makes it sound entirely like the mech should be in the position it will fall back to with no gear cable or chain attached.

steve_sordy
09-Feb-2011, 01:42 PM
the 45 degree angle (from vertical) is certainly correct for the big to big method Steve.

The short to short method is the one we're querying. Kevolutions description makes it sound entirely like the mech should be in the position it will fall back to with no gear cable or chain attached.



You are correct about my error, sorry for the confusion! :o

My LBS guy said to adjust chain length so that the chain just fails to rub on anything at the back.

steve_sordy
10-Feb-2011, 12:26 PM
When I was replacing my chain (removed while I applied BikeTape), I compared the "small to small" and the "big to big" methods.

The "big to big" required two extra links (ie 1").

So, given that my current set up is "big to big" with two links removed (in an unsuccessful attempt to prevent chainsuck), I have ended up with "small to small". :)