Charliestolen

Hi. I was wondering if someone could help me with a doubt. I use a 105 r7000 cause I really find useful to have 160mm cranks in my TT bike. I want to go bigger on my chainring (currently 53/39) but When I was going to buy dura ace 9000 a representative of Shimano told me it wasn’t compatible. Is this the case? I don’t want to buy the wrong ones and have never changed chainrings. If it doesn’t work, can someone recommend a brand and model to buy? I just want to keep my 160mm 105 crankset 🙏🏼
Thanks in advance!

cxwrench

The D/A chainring will most likely bolt on to the 105 crank but the contours and color won't be the same. I've never tried this so I can't say for sure. The max 7000 series c-ring for a 7000 crank is indeed 53.

Charliestolen

thanks for the fast response! So it would work, just would be an esthetic difference between the pieces? I don’t mind that honestly. I care primarily if the performance of the components will be ideal. ThNks!

FBinNY 

I must have missed something. When the person at Shimano said what wouldn't work, didn't he suggest what would?

In any case, in these days of very tight index shifting, compatibility entails various concerns.

First, as always is the bole circle diameter, along with the diameter of the seating area on cranks that use it. More subtle considerations include,
counterbore based on direction of the bounting bolts
tooth offset to chainring face,
tooth profile
position of anti-jam pin
Position of shift gates
cosmetics, etc.

Sometimes incompatibility is absolute, as in BCD, but often "official" incompatibility is about more subtle stuff that might affect performance is some way, either slightly or more significantly. Some of these factors can be worked around or lived with, so further inquiry is called for.

cxwrench

I said "it will most likely work" and followed that up with "so I can't say for sure". I'm in no way saying "yes, it will work". You'll have to try and see.

FBinNY 

I'm with CXwrench here. But will add that "working" depends of the mechanics skills, and the rider's acceptance of not quite perfect.

So rather than say it "will" work, I'd say it could probably be made to work reasonably well.

Charliestolen

thanks for your reply. No, I tried to ask what would work and he just said “I can only say you can only go 53/39 in Shimano but they are removable”. I guess that meant, “you can try something else but nothing Shimano will work”. I understand what you are saying and I guess the only way to find out is to try. It is an expensive gamble though. I am also considering just getting the 54/40 chainring from aero coach. They confirmed their chainrings work with r7000. Again, all those factors you mention could be incompatible so yeah… not an easy one to decide.

Charliestolen

understood. Thanks for making that clear 👍🏼

Iride01 

I have a Shimano 105 5800 crank/spider with Ultegra R8000 52/36 rings on it. The profiles, shape and finish of the Ultegra doesn't quite match the 105, but mechanically it does bolt up correctly. I even have a Ultegra R8000 left crank arm on it. Other than the mechanic at the bike shop, no one else has noticed or if they have they haven't let on.

AFAIK, design wise, all the four arm Shimano stuff from the same speed group will bolt up to each other for rings and crank arms. It just might not look aesthetically pleasing if you are a perfectionist.

Though are you wanting to go bigger than the 53/39? If so, double check that the bike shop guy wasn't concerned about the increased height you might need to be able to get on the front DR if you have what they still call a braze-on front DR. If you have a clamp on, it should be no issue to get it higher unless you have weird shapes on your seat tube. I've never ventured bigger than a 53 ring. So I can't say for certain about the braze on. But pro's routinely put bigger rings on their bikes and they likely have braze-on FDR's too.

Also, I might could imagine that the DuraAce with larger than 53/39 rings also has a larger BCD or PCD. But I haven't looked. Nor do I really think it does. Just that it might.

Barry2 

I've no idea if it fits... But THESE seem it indicate it could.

Barry