chain questions

[Ric Peregrino]

Hi,

I have some questions about bike chains. Please excuse my ignorance.

As I see it, chains have a fixed set of defining dimensions:

roller outside diameter roller spacing roller thickness inside link height width and length outside
link height width and length

Did I leave any measures out? If so, what? How do contemporary bike chains differ wrt to
these measures?

Lets say I want to change the rear cluster from a 5-speed this make and model to a 7-speed that make
and model. Do the chain dimensions requirements change? Which ones?

As I see it, I'm guessing the roller diameter thickness and spacing don't change, but the link
dimensions change. Is there a spec on max inside clearance slop? Or what?

Thanks for any help, Ric

 

[Sheldon Brown]

Ric Peregrino wrote:
> Hi,
>
> I have some questions about bike chains. Please excuse my ignorance.
>
> As I see it, chains have a fixed set of defining dimensions:
>
> roller outside diameter

.306"

> roller spacing

1/2" This dimension is called the "pitch" of the chain.

> roller thickness

to clear sprocket width. Standard multispeed sprockets are 3/32" (about 2 mm.) Single-speed bikes
often use a wider size, 1/8" (about 3 mm.)

> inside link height width and length outside link height width and length
>
> Did I leave any measures out? If so, what? How do contemporary bike chains differ wrt to these
> measures?
>
> Lets say I want to change the rear cluster from a 5-speed this make and model to a 7-speed that
> make and model. Do the chain dimensions requirements change? Which ones?

The main dimension that interacts with this is the overall width, which generally coincides with the
length of the pins. As you increase the number of sprockets they get closer together, so you need
narrower chains to avoid interference between adjacent sprockets. The interior dimension of the
chain doesn't much vary, though. The narrow chains will work with systems designed for wider chains,
though they may not shift as well.

> As I see it, I'm guessing the roller diameter thickness and spacing don't change, but the link
> dimensions change. Is there a spec on max inside clearance slop? Or what?

No, there isn't. The rollers are the parts that matter for driving. Different side plate designs may
facilitate derailer shifting, these are determined by the manufacturer based on proprietary designs.

If you're serious about this you should look for a very fat, very wonderful book called "Machinery's
Handbook" (Industrial Press, Inc.) It has a lot of information about industrial chain drives, though
nothing related to derailer shifting, because that is used nowhere else than bicycles.

Sheldon "<http://www.amazon.com/exec/obidos/tg/detail/-/0831126256/qid=1045630997/sr=8-2/ref=sr_8_2-
/102-3530900-6722560?v=glance&s=books&n=507846>" Brown
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