# Difference between Ultegra A-Type and B-Type chainrings? (9 spd triple)



## bas (Jul 30, 2004)

Ultegra chain rings part # cr5670 (B-39), cr5671 (B-52) for B Type

Anyone know the difference between A Type and B Type?

I have A-Type on my bike in the stock 52/42/30 set up.

My 9 speed derailleur took a tank last year, so I bought a 10 speed derailleur as "it should work" from what the dude at performance bike told me. 

Well, it does work, but it there isn't as much clearance some where, as it is different the 9 speed, and it looks like a smaller middle ring would work perfect (39T).


I bought this from performance bike, 130mm bolt pattern. http://www.performancebike.com/shop/profile.cfm?SKU=2948&subcategory_ID=10041

I assumed it wouldn't work, since I don't have the inner 74mm bolt pattern to bolt the inner 30 up to. I didn't tear my chain rings apart, as I assumed it would not work.

Why would Shimano list different parts for triple 9 speed and double 9 speed? Right?

I've read some threads,

http://forums.roadbikereview.com/showthread.php?t=56853&highlight=ultegra+chainrings
http://forums.roadbikereview.com/showthread.php?t=80036&highlight=ultegra+chainrings
http://forums.roadbikereview.com/showthread.php?t=88107&highlight=ultegra+chainrings


Sheldon Brown has some info on A/B Type Rings for Dura Ace..

http://www.sheldonbrown.com/dura-ace.html

but it appears Dura Ace is different.

It looks like my crank does connect to the 30T inner, and therefore doesn't need the 74mm inner connector..

So I guess I can just go with Ultegra replacement rings for a 9 spd crank with the 130mm bolt pattern?


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## Al1943 (Jun 23, 2003)

Any 9-speed 130 BCD chainring (except D-A triple) will work BUT triple chainrings are made as a matching set. For maximum performance you'll need to use Shimano 9-speed triple chainrings, but Shimano doesn't sell them individually. A 39t ring made for a double will fit and work but it's not ramped and pinned to work in a triple so shifting from the 30 to the middle ring will probably not be as good as if you had a triple middle ring. TA Specialties and FSA make chainrings to fit triple cranks and can be bought individually. They may or may not shift as well as Shimano rings. I put TA Alize rings on my wife's Ultegra triple and had to do some fine tuning to get them to shift well. The tips of the teeth are thicker than Shimano's. I used a file to bevel the backside of the middle ring teeth.

Al


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## bas (Jul 30, 2004)

Al1943 said:


> Any 9-speed 130 BCD chainring (except D-A triple) will work BUT triple chainrings are made as a matching set. For maximum performance you'll need to use Shimano 9-speed triple chainrings, but Shimano doesn't sell them individually. A 39t ring made for a double will fit and work but it's not ramped and pinned to work in a triple so shifting from the 30 to the middle ring will probably not be as good as if you had a triple middle ring. TA Specialties, FSA, and IRD make chainrings to fit triple cranks and can be bought individually. They may or may not shift as well as Shimano rings. I put TA Alize rings on my wife's Ultegra triple and had to do some fine tuning to get them to shift well. The tips of the teeth are thicker than Shimano's. I used a file to bevel the backside of the middle ring teeth.
> 
> Al


So the B type 39T special order ring 9 spd, triple, should work. Assuming I can mix and match A/B type.

I wonder if I can beat the crap out of a double chain ring with a ballpeen hammer to get the ramp up. :mad2:


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## C-40 (Feb 4, 2004)

*confusion...*

You're confused about several things. The A and B types refer to the location of the ramps and pin to insure proper shifting with a matching A or B middle ring. 

You bought a double crank inner ring that does not have the ramps and pins to shift from the little ring on a triple to the middle ring. What you need is a properly ramped triple crank middle ring.

I don't understand your comments about the 74mm bolt pattern. If you have a 30T little ring, that's what it mounts to - a 74mm bolt pattern on the crank. Of course the DA triple uses an an oddball bolt pattern for the little ring, so you can't use DA parts.

If you want the crank to work properly you need a 39T triple middle ring. The rings can be bought separately, contrary to what has been posted. If you want perfect shifting, then a type B big ring would also be required, but I suspect it's not that critical.


http://aebike.com/page.cfm?PageID=30&action=details&sku=CR6656

http://aebike.com/page.cfm?PageID=30&action=details&sku=CR5672


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## bas (Jul 30, 2004)

Hi

Yes, the package that I had bought for the double ring, and it had an x that it was for the double. The mechanic at performancebike said it should work, and to bring if back if there were any problems (they were busy). There was another marking on the package for 130mm/74mm to use the same packaging for a triple. But when I initially examined my bike, I said, damn, its got to be missing the inner 74mm bolt pattern, how will it bolt up to the 30t. I really looked my crank over last night, and saw the 30t bolts directly to the crank (maybe I was awake last night?).

So, now this is becoming all clearer anyways after I read this (on a previous page), and your explanation:

http://www.beyondbikes.com/bb/items.asp?cc=CMR-CHR-SHI

"For best shifting performance, A type rings should be used only with A type rings, and B type rings only with B type rings. FC-7701 9 Speed, 130mm Arms, Nickel Plated Chainrings. 2014 Aluminum More Info"

So I should get b type 53/39 or 52/39 or A type 53/42 replacements which will work.

I will 'switch' to the 52/39 B type as replacements (which is what I'm looking for). That is better than what the guy who does special ordering at the performance bike told, that the A/B type has to do with the bolt patterns (but he wasn't sure). (I can't blame him, thousands of parts, etc, no description in the catalog saying what A/B type means)..

Now I'm understanding now that A/B type has more do with the shifting and ramps after your explanation.

The only strange thing is that my original ultegra 52/42/30 is A Type, which I guess they don't make anymore.

I think the 39T will help the 10spd derailluer I put on. That 42T is just a little too big for it.

I feel a lot more confident about ordering 52/30 B rings. I just hope the 30T A ring works well with all this crap.







C-40 said:


> You're confused about several things. The A and B types refer to the location of the ramps and pin to insure proper shifting with a matching A or B middle ring.
> 
> You bought a double crank inner ring that does not have the ramps and pins to shift from the little ring on a triple to the middle ring. What you need is a properly ramped triple crank middle ring.
> 
> ...


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## Al1943 (Jun 23, 2003)

C-40 said:


> If you want the crank to work properly you need a 39T triple middle ring. The rings can be bought separately, contrary to what has been posted. If you want perfect shifting, then a type B big ring would also be required, but I suspect it's not that critical.
> 
> http://aebike.com/page.cfm?PageID=30&action=details&sku=CR5670
> 
> http://aebike.com/page.cfm?PageID=30&action=details&sku=CR5672


That 39 B ring is for a double. Note that it says it is an "inner" chainring.


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## C-40 (Feb 4, 2004)

*correction...*



Al1943 said:


> That 39 B ring is for a double. Note that it says it is an "inner" chainring.


How about this? I know it's 10 speed. I just remebered that Shimano never made a 39T middle ring for a 9 pseed triple. There's also FSA rings readily available in 53/39 for a triple. I've got four sets.

http://aebike.com/page.cfm?PageID=30&action=details&sku=CR6656


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## wim (Feb 28, 2005)

Don't waste too much thought on this A and B stuff. Here are two verbatim usenet responses to a question similar to yours:

Sheldon Brown, Harris Cyclery, West Newton, MA:
"If you have poor shifting skills, matching the chainrings by the letters will give slightly better shifting, but if you're a reasonably skilled cyclist, it really doesn't matter."

Peter Chisolm, Vecchio's Bicicletteria , Boulder, CO:
"Put any 130mm BCD 39 t ring on there-any maker, Shimano, TA, Sugino, anything. It'll work just fine."


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## C-40 (Feb 4, 2004)

*hopefully...*



wim said:


> Peter Chisolm, Vecchio's Bicicletteria , Boulder, CO:
> "Put any 130mm BCD 39 t ring on there-any maker, Shimano, TA, Sugino, anything. It'll work just fine."


I imagine he meant any 39T triple middle ring. A 39T double ring with no ramps wouldn't be great idea. The 30/39 shift is always the slowest anyway. With no raps, I'd think it would shift pretty slow.


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## bas (Jul 30, 2004)

C-40 said:


> How about this? I know it's 10 speed. I just remebered that Shimano never made a 39T middle ring for a 9 pseed triple. There's also FSA rings readily available in 53/39 for a triple. I've got four sets.
> 
> http://aebike.com/page.cfm?PageID=30&action=details&sku=CR6656


What about this:

http://aebike.com/page.cfm?PageID=30&action=details&sku=CR4358


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## bas (Jul 30, 2004)

C-40 said:


> I imagine he meant any 39T triple middle ring. A 39T double ring with no ramps wouldn't be great idea. The 30/39 shift is always the slowest anyway. With no raps, I'd think it would shift pretty slow.



I can't seem to find online a 52T A type...

I have only found a B Type 52T.. argh..


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## C-40 (Feb 4, 2004)

*solution..*



bas said:


> I can't seem to find online a 52T A type...
> 
> I have only found a B Type 52T.. argh..


I thought you wanted a 39T middle ring? Shimano never made a 39T 9 speed middle ring or a big ring to go with it.

I'd just get a 53 and 39 in the 10 speed models. The 30T ring should work OK.

http://aebike.com/page.cfm?PageID=30&action=details&sku=CR6654

http://aebike.com/page.cfm?PageID=30&action=details&sku=CR6656

Another alternative is to get FSA rings. I've had great luck with FSA triples.

http://aebike.com/page.cfm?PageID=30&action=details&sku=CR3965

http://aebike.com/page.cfm?PageID=30&action=details&sku=CR2028


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## Jeff G (Jul 22, 2005)

*I have a similar problem*

I switched the original chainrings that came on my bike (8 speed triple w/105 frt & rear der.) to Salsa outer and middle. Tooth count was the same as original, but the rings aren't ramped and pinned like the originals ( horrible shifting no matter how mch I try and adjust the frt der). The ones I replaced were steel with no brand name on them. If I read the posts correctly, shimano "B" type are for double cranks and the "A" type are for triple cranks, right? I have found a couple of places online that have 105 chainrings and before I spend anymore money I want to make sure I order the right ones. Any suggestions would be most appreciated. By the way my LBS didn't recommend FSA rings and recomended Salsa, thats why I ordered the Salsa's.


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## Al1943 (Jun 23, 2003)

bas said:


> Ultegra chain rings part # cr5670 (B-39), cr5671 (B-52) for B Type
> 
> Anyone know the difference between A Type and B Type?


There use to be an explanation for the A and B difference at the old Branford bike site. The difference is the ramp and pin synchronization. I think the way it works, and I could be wrong, when Shimano double cranks were offered with with either a 42 or a 39 inner ring the 42's were all type "A" and 39's were type "B" and the big rings were either A or B. And for ideal shifting performance A's should be matched with A's and B's with B's. In reality it's not required. My 39t double ring is a B. I don't know if all 39's are B.

Al


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## bas (Jul 30, 2004)

Al1943 said:


> There use to be an explanation for the A and B difference at the old Branford bike site. The difference is the ramp and pin synchronization. I think the way it works, and I could be wrong, when Shimano double cranks were offered with with either a 42 or a 39 inner ring the 42's were all type "A" and 39's were type "B" and the big rings were either A or B. And for ideal shifting performance A's should be matched with A's and B's with B's. In reality it's not required. My 39t double ring is a B. I don't know if all 39's are B.
> 
> Al


The shimano 9 spd 6503 FD is only good for a 22 tooth difference (30-52).

I can't find a A type ring in 52. Only B type. 

I see the A type ring 53.

Nashbar has the full set for $80 http://www.nashbar.com/profile.cfm?sku=2955

So I guess I'll have this problem again when I goto replace the rings.

Now I just need to find a 9 spd FD to replace this 10 spd I have.
.


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## LO lefty (Nov 1, 2008)

So the impression I'm left with after reading all this is: for optimum results, mate type A with type A, and B with B. Is that it? I need to replace my 105 double [39-53], and the further I dig, Oy!, the more confusing it gets.


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