Triple chainring question
 

I'm in the middle of changing out chain rings from a triple crankset and I was curious about the middle one.

I've found dedicated big and small rings but nothing for the middle. So my question is, will a standard one that you may use for a double work in its place? I understand my bcd and that's not an issue.

Modern middle chainrings designed for a triple crank will have shaped teeth and shifting enhancements to aid the shift from the granny ring to them. These are lacking on chainrings intended for use as the small ring on a double. So, you could use the smaller chainring from a double set as the middle of a triple but shifting from and to the granny will be a bit compromised.

Also chainrings are usually made and sold in sets so the shifting aids "line up" properly. A chainring from a different configuration probably won't shift as well anywhere as matched sets.

Depends on your definition of "works" -- I'm content to throw any two or three plain chainrings together and shift between them using a friction DT lever, but brifters may not work so gracefully without a matched set of rings with ramps and pins.

I haven't been able to find a complete set for a triple. It may be that way because it's for an older 9 speed. I have been fortunate to find a ultegra 6500 triple big ring and finding the small ring 6500 is easy. I've found some 6500 rings that are either 39 or 41 but don't specify if they are for triple.

For something you expect Indexed shifting to work , the middle chainring will have the shifting easing features of pins and ramps
on the inside face..

where the inner most of a Double will Not ,it will be smooth , since it wont have a chain climbing up from another
smaller chainring to the left of It.

<shopping the Brick and Mortar stores ,that may also sell online & ship, you can call them on the Phone and Ask >

That's what I was going to say. What is your objective?

The bike that I ride most frequently these days is a Rans Rocket. I've got 60/50/39 chain rings that shift just fine with a friction shifter. I don't think that any of the chain rings have any shifting aids on them but I'd have to go down and check to be sure.

I'm glad y'all mentioned that. I've come across some rings that are smooth and wondered if they'd work. So are you saying the smooth rings definitely will not work?

It's not so much that they won't work as that the shifting won't be smooth and quick if you are using an indexed shifter. You should still be able to get the chain onto that ring. It just might take a little patience and tolerance for noise.

What's your BCD?

Not at all, I'm saying that everything on a bicycle works together so often one part, the shifter in this case, can dictate which other parts it will work with.

My personal philosophy is, if I already own parts, I'll bolt up almost any combination and see it I can make it work to my satisfaction. If I'm buying parts, however, I'll always hold out for stuff that I know matches.

That makes sense, thanks. One more thing, what does it mean when it says a-type in regards to the chainring?

I think it has to do with double vs. triple shifting aids.

I have used that type of chainring for decades, But my Front Derailleurs have never been Indexed, they're friction levers.

& I am realistic on shifting speeds , so by reading the terrain ahead, anticipate the gear I need before I need it, whenever I can.

the parts Engineers have decided the ramp and pin locations get the shifting even a partial second faster
if you pair them as they designed them ... so the features of a 50t outer would be different for a 30-39-50
than it would be for a 34-50 double or even 39-53 vs 42-53..

In short it refers to the two large ring's size. A rings, IIRC is a (53)52-42 pairing and B type is for a 53-39 pairing on a double. A rings should be used with other A rings and B rings with other B rings for the best possible shifting. They can and have been mixed by others and will work, but less smoothly than with a proper pairing.

I have one STI shifted bike without ramps and/or pins on the chain rings and it shifts just fine...YMMV. You may also try looking for a 5500 42T chain ring.

Brad

Thanks guys! Y'all have been a ton of help!

Same here - I've never had any problem shifting a non-pinned middle ring with brifters . . . but you will have to try it on your bike to be sure, as obviously some folks here have had problems.

Personally, I just find that friction shifting works better than index shifting on triples. So that's what I use on all my bikes with triples (I have 3 of them, two are friction front and back (6 speed rear), and one is friction front, Index 9-speed in back, using Shimano Dura Ace 9-speed downtube shifters. That's actually my cleanest shifting bike of all.