Re: [ST] Chain Information

[Blake Sobiloff <sobiloff@xxxxxxxxx>]

On Apr 2, 2006, at 11:55 AM, Matthew Heyer wrote:
> So I may be looking into a new chain.  That said, I'm a bit  
> ignorant as to what all of the numbering/codes mean.  In my little  
> bit of searching, it appears that the first number (525, 530, 630,  
> etc) is about a tensile strength - and the higher the number, the  
> greater the tensile strength.

Almost. From the EK Chain FAQ at <http://www.ekchain.com/faqs.htm>:

"The numbers indicate a chain’s dimensions, tolerances, minimum  
tensile strength and other specifications, using a system instituted  
by the Japanese Industrial Standards Committee. The JIS standard is  
very similar to chain standards developed by ISO, ANSI, DIN and others.
The first digit (4, 5 or 6) denotes a chain’s pitch – the center-to- 
center distance between chain pins. Originally these numbers  
specified pitch in eighths of an inch (i.e. a 400-series chain had a  
pitch of 4/8, or 1/2 inch), but now metric dimensions are used. A 400- 
series chain has a pitch of 12.7mm. A 500-series chain has a pitch of  
15.875mm. A 600-series chain has a pitch of 19.05mm.

The second and third digits indicate the chain’s width, measured  
between the inboard surfaces of the inner sideplates. An EK chain  
ending in ‘20’ measures 6.35mm between the plates. If the number ends  
in ‘25’ or ‘28’, the dimension is 7.94mm. If the number ends in ‘30’  
or ‘32’, the width is 9.53mm.

Because wider chains are typically stronger as well, the second and  
third digits also indicate a chain’s strength, relative to other  
chains with the same pitch. Higher numbers correspond to greater  
strength, i.e. a 525 chain is stronger than a 520. This additional  
strength is achieved through increased roller diameter, pin diameter,  
pin length and plate thickness.

You should always replace your old chain with one having the same JIS  
number. Never replace a sealed chain with a non-sealed chain."


> The letter designation after this first number then appears the be  
> the type of chain (o-ring, x-ring, and other variations).  However,  
> this is still confusing as RK and DID use some strange coding here.

Yep, those aren't part of any standard, so each manufacturer uses  
their own unique coding.

> Lastly, I know that the ST uses a 108-link chain - am I correct  
> that you just buy one longer than that and take it down to what you  
> need?

Yep, typically, unless you're lucky enough to find someone stocking  
pre-cut chains.
--
Blake Sobiloff <sobiloff@xxxxxxxxx>
<http://sobiloff.typepad.com/>
San Jose, CA  (USA)


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