# 36 tooth chainring for New Dura-Ace 7900 or Ultegra 6700 Compact Cranksets



## natedg200202

Hello everyone, 

I am learning about Shimano groups and have a question. I notice on Shimano's website they don't appear to offer a 36/50 compact chainring setup for either the Dura-Ace 7900 or Ultegra 6700 cranksets. 

Does anyone know if Shimano offers the 36 tooth small chainring by itself? Is there an aftermarket 36t small chainring that someone makes that would work well?

I guess it's not a big deal, but my gear charts show a 36 would work better for me most of the time and I would like to have the flexibility to use the 36 and put back on the 34 when I go to the mountains. 

Thanks for the input.


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## BikeFixer

Shimano doesn't offer it in a 36. You would need to go aftermarket for that


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## natedg200202

Thanks BikeFixer. So, has anyone tried an aftermarket 36 tooth chainring on their 7900 or 6700 cranks? 

It seems simple enough to find one and slap it on, but I'm not sure if the ramps on the large chainring are specific to mating with the smaller 34t chainring. If so, shifting could be a little slow with an aftermarket 36.


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## Guest

I'd bet much of what you might lose due to the lack of ramps you'd gain from reducing the tooth difference from 16 to 14.


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## BikeFixer

The ramps will make some difference and that's the whole point of the new system is to have super awesome front shifting. It will still be better than old style though so it will probably be more than acceptable


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## DavidSmith

Yep, we tried a Specialités TA 36 tooth chainring on the 2010 Ultegra group. Categorically does not function properly, forget it. The new 6700 chain design is such that the teeth spacing on the chainring is clearly incompatible and the chain "jumps" vertically and uncontrollably at each crank revolution. Popped the Shimano 34T back on and end of problem. A 36T would still be nice to have though, I'm still waiting!


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## natedg200202

DavidSmith, 

Thanks - this is the response I was looking for; someone who has tried an aftermarket 36 and it sounds like it is a no-go. Bummer. When you say teeth spacing, do you mean the width or something about the lengthwise profile? That's really interesting if the new chainrings need a specific Shimano chain to operate properly. Seems like they are very disparate to make sure you have to buy their replacement chains, which is big bucks for them. 

It doesn't seem like a big deal, but on my gear charts, a 36/50 works perfect. It's all just educational for me at this point. I currently ride 10s Campy and am only dreaming of a DI2 group in the future. 

Thanks for the responses. 

Nate


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## DavidSmith

Nate,
I don't have the exact tech explanation as I just clearly confirmed in situ that there was severe incompatibility problems and then moved on...It would appear to be a length-wise problem as the chain could not sit properly between the chainring teeth. Anyway, my LBS had no other alternatives in mind so we're stuck with the 34/50 combination for the moment.
Rgds,
D.


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## Floridaboy

I have the same problem with a 36t Stronglight ring. The chain does not sit on the teeth. However, I substituted a FSA 34t for a 36 on my Pinarello which has a MOST chainset and it works fine. Pity Shimano doesn't have 36t as that setup is ideal for my riding on the flatlands here.


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## Floridaboy

BikeFixer said:


> The ramps will make some difference and that's the whole point of the new system is to have super awesome front shifting. It will still be better than old style though so it will probably be more than acceptable


 Regarding the ramps or pins, I have the 6600 chainset on my '09 Scott. When the chain is at the extreme angle of small chainring and small sprocket, the chain catches in one place on a pin on the big ring. It's very annoying and I can't see how to cure it. Any suggestions?


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## SystemShock

Have _never_ understood why Shimano offers ONLY 50t and 34t chainrings for their compacts. Compact's becoming pretty popular, so... wtf?

SRAM, FSA, Sugino, and others are way ahead of them on that. :frown2:
.


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## Dr_John

> Have never understood why Shimano offers ONLY 50t and 34t chainrings for their compacts. Compact's becoming pretty popular, so... wtf?


Yeah, I wish they'd pick it up a bit. Look how long it took them to even get around to Dura Ace compact crankset. I don't buy the 'top-of-line, performance-only' argument, since they made a 7800-series triple.


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