[Morryjg]

I need to get some new chain rings for my old roady. I have a feeling it's whatever standard Shimano is (130mm from what I've seen) but I don't know how to determine exactly. What is the that measuring?

 

[MtnbikeMike]

BCD is the bolt circle diameter. It's the diameter of a imaginary circle that goes through the center of each chainring bolt.

 

[Morryjg]

hmmmmmmm........so maybe just use a piece of string or something to get the diameter and then measure that.

Thanks!

 

[Wumpus]

If they are road cranks(105, ultegra), it is the standard 130. Shimano does not make a compact road crank(110mm).

 

[Morryjg]

If they are road cranks(105, ultegra), it is the standard 130. Shimano does not make a compact road crank(110mm).

And this stuff is so old that compact was not even in existence. It's an old Shimano 600 groupo that had Bio-Pace chainrings. It's my first bike that I bought with my very own $$$. I just want to get it running again for fun, but hate the bio-pace stuff.

 

[Silver]

hmmmmmmm........so maybe just use a piece of string or something to get the diameter and then measure that.

Thanks!

Or just measure across from bolt to another, no?

 

[Westy]

Or just measure across from bolt to another, no?

That does not work well with a 5 bolt crank.

 

[Serial Midget]

Ah... BIOPACE, one of Shimano's many answers to questions that were never asked. If you ever follow someone with biopacerings you'd swear their rings where warped. ink:

And this stuff is so old that compact was not even in existence. It's an old Shimano 600 groupo that had Bio-Pace chainrings. It's my first bike that I bought with my very own $$$. I just want to get it running again for fun, but hate the bio-pace stuff.

 

[Wumpus]

Or just measure across from bolt to another, no?

Measuring BCD: This 110 mm BCD ring measures 64.7 mm center-to-center.

Multiplying this dimension by 1.7 will give you the actual BCD for a 5 bolt chainring.

Use 1.4 for 4 bolt chainrings


http://www.sheldonbrown.com/gloss_bo-z.html

 

[JRB]

If you have access to a QBP catalog, they have a little template you can use to tell.

 

[johnbryanpeters]

Or just measure across from bolt to another, no?

Measure center of BB to center of chainring bolt, multiply by two.

 

[zahgurim]

How easy is it to find a 5x130mm set of chainrings? I haven't been able to find any locally...
Does anybody know of an online source?

 

[Morryjg]

How easy is it to find a 5x130mm set of chainrings? I haven't been able to find any locally...
Does anybody know of an online source?

I was looking here for my replacements. Scroll down to the Salsa chainrings....
http://www.excelsports.com/new.asp?page=7&major=1&minor=12

 

[Wumpus]

These are shimano, but they have fsa, also.

http://www.universalcycles.com/shopping/index.php?category=645

 

[Pau11y]

I like FSAs. They have shift ramps and pins. I don't see them on the Salsas, but I could be blind.

 

[recidivist]

Salsa makes both cheap rings w/o the shifting geegaws (cheap, lots of tooth counts), and the 'Pro' rings (more expensive, limited tooth counts) with the shifting rings. Remember you only need the ramps and stuff on the big ring...