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R8000/R7000 chainring compatibility

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R8000/R7000 chainring compatibility

Old 01-03-20, 09:36 PM
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sanmi
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R8000/R7000 chainring compatibility

I “upgraded” my crankset from R8000 to R7000 because I wanted 160mm cranks. I had understood the rings to be compatible so I figured I would move the R8000 rings to the new crank. They fit but look a bit funny because the thickness is a little off where the rings interface with the crank (pics). Any opinions on whether this is purely aesthetic or will affect function? I do have the new R7000 rings I could use.

also, the original cranks had a thin (~1mm) flat disc around the spindle butting on against the drive side. Is this a spacer to adjust chain line or a difference in between R8000 and R7000?





Thanks in advance!
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Old 01-03-20, 10:41 PM
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The rings should work, although they do look funny in the pic; not sure why. I don't think you gain anything by mismatching the rings so I would just use the rings that came with the cranks.

That spacer looks like a bearing shield for the bottom bracket so I would use it with the new cranks. What BB do you have?

Last edited by DOS; 01-03-20 at 10:47 PM.
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Old 01-04-20, 05:17 AM
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sanmi
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It’s an Enduro EVO PressFit 30 with Wheels MFG EVO adaptors
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Old 01-04-20, 06:58 AM
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shelbyfv
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That looks goofy. Put the 7000s back on.
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Old 01-04-20, 08:13 AM
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Well, if the BB cups already have it's own dust cap with a seal, then I don't know what that spacer/washer is for. Do you know if it came with either of the cranks or with the BB?
I don't know what adapter you are using, but the 386EVO Wheels MFG adapter to 24mm spindle comes with "optional" spindle shims. You probably don't need them if your total BB width is 91mm, unless you want to adjust the chainline. Shimano road BB cups are approximately 11.5mm on each side to the dust cap, so a total of 68+11.5+11.5 = 91mm total width. You should measure your third party BB to see how wide they are, and the chainline.
https://wheelsmfg.com/tech/PDF/386EVO-SHIM.pdf





However, your FC-R7000 seems to supposedly use some kind of o-ring with the stock Shimano BBs. I have never used Shimano cranks, so I don't know what the purpose of the O-ring is and where exactly it touches. You can look at the exploded diagram to see the ring and the part number.
Y1F316000
https://si.shimano.com/pdfs/ev/EV-FC-R7000-4331.pdf


If this O-ring is sandwiched between the crank surface and the BB cup dust cap, and you're not using this O-ring, then potentially your chainline is too inward, or the splines on the left arm may bottom out. You could use those spacers that you have to push the chainline back out, or to prevent bottoming out on the spindle. You should first measure your chainline to see what it is, and check for any bottoming out. (well, very first thing to do is to check if the BB is 91mm wide) Some other photos seem to show the o-ring in a recess on the crank arm, so that it doesn't change the chainline whether or not you use it, but it probably helps to seal against water ingress onto the BB through the spindle.

Last edited by tomtomtom123; 01-04-20 at 08:26 AM.
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Old 01-04-20, 08:17 AM
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If the chainring bolts fit through the old chainring and new crank arm spider, then I don't understand what other kinds of problems you are experiencing.

You may want to check the distance between the inner and outer chainrings. The center-to-center teeth distance should be somewhere between 7.5mm to 8mm.

And the chainline should be between 43.5mm to 44mm for a road bike with 130mm dropouts with a standard 8,9,10,11 cassette.

But if you want narrower Q-factor, you could remove those shims and possibly move in both arms by a total of maybe 2mm, but you'll have to check if the splines are not bottoming out, and if the new inward chainline is causing any shifting problems or chain rub.
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Old 01-04-20, 08:41 AM
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Originally Posted by tomtomtom123 View Post
Well, if the BB cups already have it's own dust cap with a seal, then I don't know what that spacer/washer is for. Do you know if it came with either of the cranks or with the BB?
I don't know what adapter you are using, but the 386EVO Wheels MFG adapter to 24mm spindle comes with "optional" spindle shims. You probably don't need them if your total BB width is 91mm, unless you want to adjust the chainline. Shimano road BB cups are approximately 11.5mm on each side to the dust cap, so a total of 68+11.5+11.5 = 91mm total width. You should measure your third party BB to see how wide they are, and the chainline.
https://wheelsmfg.com/tech/PDF/386EVO-SHIM.pdf





However, your FC-R7000 seems to supposedly use some kind of o-ring with the stock Shimano BBs. I have never used Shimano cranks, so I don't know what the purpose of the O-ring is and where exactly it touches. You can look at the exploded diagram to see the ring and the part number.
Y1F316000
https://si.shimano.com/pdfs/ev/EV-FC-R7000-4331.pdf


If this O-ring is sandwiched between the crank surface and the BB cup dust cap, and you're not using this O-ring, then potentially your chainline is too inward, or the splines on the left arm may bottom out. You could use those spacers that you have to push the chainline back out, or to prevent bottoming out on the spindle. You should first measure your chainline to see what it is, and check for any bottoming out. (well, very first thing to do is to check if the BB is 91mm wide) Some other photos seem to show the o-ring in a recess on the crank arm, so that it doesn't change the chainline whether or not you use it, but it probably helps to seal against water ingress onto the BB through the spindle.
That o ring may be specific to the bb (Ultegra bbr60, which is a threaded BB ) that is described in the manual you linked to. I don’t think its necessary for the pf30 bb. I suspect the spacer in OPs pic is from the adaptor. The installation of the r7000 cranks should require the same combination of spacers as the r8000 because the spindles are identical on the two models.
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Old 01-04-20, 01:38 PM
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Originally Posted by DOS View Post
That o ring may be specific to the bb (Ultegra bbr60, which is a threaded BB ) that is described in the manual you linked to. I don’t think its necessary for the pf30 bb. I suspect the spacer in OPs pic is from the adaptor. The installation of the r7000 cranks should require the same combination of spacers as the r8000 because the spindles are identical on the two models.
From the OP's photo, the o-ring appears to be already on his crank arms. They don't interfere with the final Q-factor or the chainline, they fit into a recess into the crank arm to create a water seal, and when the rubber compresses, it fits entirely inside the recess, or at least that's how it looks like in this photo that I found on another forum:
https://singletrackworld.com/forum/t...widget-thingo/
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Old 01-04-20, 09:35 PM
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That spacer you are talking about looks like a dust seal for some bearings, are you sure its not that?

www.buckyrides.com

https://www.etsy.com/shop/Buckyrides
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Old 01-04-20, 11:00 PM
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Originally Posted by jbucky1 View Post
That spacer you are talking about looks like a dust seal for some bearings, are you sure its not that?

www.buckyrides.com

https://www.etsy.com/shop/Buckyrides
Its either a spacer from the adaptor or a BB dust seal.
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Old 01-05-20, 07:43 PM
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sanmi
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I went to put the R7000 rings back on and rounded off a bolt (brilliant, right?). With the help of my LBS I’m all put back together again. The washer was indeed a spacer from the adapter.

Thanks for the helpful replies.
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