This may be a real basic question, but what are the rules for swapping chainrings from crankset to crankset?

Are all 130 BCD chainrings compatible? All Shimano? Are there differences between double and triple?

Basically, I have a Shimano 600EX crankset, with biopace rings. I would like to replace one or both of those rings. It has a 42t small ring, and I want a 39t ring. I would prefer to get rid of the biopace at the same, but that is not really required.

It would seem like I could use any 130BCD chainrings. Is that right? Even later 9 speed rings?

And what about triple rings? I would some day like to get a ultegra 6503 9 speed triple crankset for my wife's bike, but again I would prefer a 39t middle ring, and most of those come with 42t. Can I use any ring, or are they triple specific?

Jared

Your 600 crank should take almost any 130mm BCD ring without any problems. You can run into trouble sometimes with super cheap and nasty rings where the BCD isn't quite right, or the tabs for the mounting holes are too long, too short, not rounded enough, etc. For anything reasonably well made, you won't have any trouble.

On a triple crank, it's advantageous to have the middle ring designed for a triple, because it will have shifting pins and ramps to help the chain get up from the inner ring. An inner ring from a double will still fit, it just won't necessarily shift as well.

AFAIK, all 130 5 bolts are interchangeable, as far as it fitting on the crank. Shift ramps, etc, are. another story
The only oddball I know of is in 110bcd land, where Campy has one "offset" bolt position.

+1 with what you've been told. I send my BP stuff to a certain BF member up North, and swap in 130BCD stuff all the time.

The 7700 DA triple requires a middle ring that also mounts the granny ring. Unique to that crankset, and why I have one for sale. Most sellers of just the middle ring charge as much as a crankset.

However, with only one "shoulder," they make great SS cranksets.

I know it's been said that all 130 bcd chainrings should be pretty much interchangeable, but does it matter if they were designed for 5,6,7,8 speeds or 9,10,11?
For example, I have a 7sp 1050 crankset. Will these work? Should I avoid them just because they're dirt cheap?
https://www.amazon.ca/Fancyes-Chainr...9LRN352D/?th=1

Yes, those chain rings should work just fine with a 7-speed freewheel or cassette. Personally, I'd run a 9-speed KMC or SRAM chain.

Can't speak about the quality of those rings. How they will wear or shift may not be optimal, but that will depend on your use and expectation.

9/10 speed rings may have the teeth offset on the rings so they are slightly closer together to account for the narrower 9/10 speed chains. This could possibly mean that when in the inner chainring and the outer sprocket in the rear, the chain may 'clip' the teeth on the outer chainring. This depends on the frame design & components, but can be remedied by adding thin (0.5mm or so) washers between the rings and the crank's mounting point. M10 washers should work.

Great, good to know. Thanks!