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GHC

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Posts: 65
Reply with quote  #1 
Have a bike needing new front crank and derailleur.  Will be a Ultegra compact crank, down to deciding which Ultegra series.  (If this matters, the bike currently has ultegra 6800 series in the rear)

(Additional color if it matters.  The shift levers on the bike will with both.   Have ridden other bike with Ultegra 6800 front derailleur and crank and think they are nice.  Having not ridden the 8000 series, the main difference I see on the new front derailleur is the cable tag on the 8000 series is tucked away and doesn't require an inline barrel cable tension adjuster.  I have figured out the barrel adjuster on the 6800 series, so am mostly interested in figuring out if the front shifting on the 8000 combo is any different/better in comparison to the 6800. I don't care about minimal weight diffs between the two.)

Which bring me to the question.

Q:  Has anybody ridden both the 6800 and 8000 series front mechanical derailleur's with "matching" series cranks up front who can compare front shifting?.   Or any other feedback.

Thanks team.  
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Barrettscv

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Reply with quote  #2 
I have the Ultegra R8000 compact crankset & front derailleur on my Canyon Endurace CF SL. The bike originally came with a 5800 series compact crankset and derailleur, so the R8000 was an upgrade. I also have the 6800 Ultegra compact crankset on two road bikes with caliper brakes and 130mm rear road hubs.

Each of these work well, but I would strongly encourage the use of the R8000 Ultegra on any gravel bike and on any bike with disc brakes. The 6800 Ultegra compact cranksets when installed on a 142 wide rear hub will cause the chain to contact the large chainring when the derailleurs select the small chainring and small cog.

It has less to do with shifting performance, per se. I think that it has to do with ensuring that the chain adequately clears the big ring when the chain is on the small ring and towards the outside of the cassette. Regardless, I'd go with the R8000 on a disc brake gravel bike.

With the R8000’s, Shimano redesigned chainring tooth profiling, increases clearance between chain and leading teeth to providing improved compatibility with frames featuring the disc brakes and wider dropout spacing.

Well, I learned that the chainline issue, when combining a 142mm thru-axle disk brake frame with the Ultegra 6800 crankset, is no joke. When I first attempted to use a 6800 Ultegra compact on my Canyon Endurace, I was unable to use the two smaller cogs while on the inner chainring.

The chain was rubbing against the derailleur cage when using the 11t cog of the cassette and the 34t chainring of the compact Ultegra 6800 crankset. The next cog, a 12t, could have been used but the chain had almost zero clearance from the cage. If the front derailleur was adjusted to eliminate any chain and derailleur cage interference while using the 11t cog, the chain would then contact the pins and the leading teeth on the 50t chainring and jump between the two chainrings.

I eventually sourced a R8000 crankset and matching front derailleur for the Canyon Endurace. This combination allows the use of all 22 chainring and cassette cog combinations without any interference of any kind.
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dangle

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Posts: 209
Reply with quote  #3 
The 8000 series front derailleur is soooo much better than anything previous. Easy to adjust and more tire clearance. The long arms of the previous generations (like 6800) were pretty notorious for rubbing larger tires too. There's no reason to go with a 6800 front derailleur.

The matching cranks to front derailleurs and hubs and all that stuff is way overblown. Just get the crank in your price range that you like.
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GHC

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Reply with quote  #4 
Thank you both for the info and valuable feedback!!

8000 it will be.

Thanks again.
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clarksonxc

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Posts: 110
Reply with quote  #5 
Quote:
Originally Posted by Barrettscv
I have the Ultegra R8000 compact crankset & front derailleur on my Canyon Endurace CF SL. The bike originally came with a 5800 series compact crankset and derailleur, so the R8000 was an upgrade. I also have the 6800 Ultegra compact crankset on two road bikes with caliper brakes and 130mm rear road hubs.

Each of these work well, but I would strongly encourage the use of the R8000 Ultegra on any gravel bike and on any bike with disc brakes. The 6800 Ultegra compact cranksets when installed on a 142 wide rear hub will cause the chain to contact the large chainring when the derailleurs select the small chainring and small cog.

It has less to do with shifting performance, per se. I think that it has to do with ensuring that the chain adequately clears the big ring when the chain is on the small ring and towards the outside of the cassette. Regardless, I'd go with the R8000 on a disc brake gravel bike.

With the R8000’s, Shimano redesigned chainring tooth profiling, increases clearance between chain and leading teeth to providing improved compatibility with frames featuring the disc brakes and wider dropout spacing.

Well, I learned that the chainline issue, when combining a 142mm thru-axle disk brake frame with the Ultegra 6800 crankset, is no joke. When I first attempted to use a 6800 Ultegra compact on my Canyon Endurace, I was unable to use the two smaller cogs while on the inner chainring.

The chain was rubbing against the derailleur cage when using the 11t cog of the cassette and the 34t chainring of the compact Ultegra 6800 crankset. The next cog, a 12t, could have been used but the chain had almost zero clearance from the cage. If the front derailleur was adjusted to eliminate any chain and derailleur cage interference while using the 11t cog, the chain would then contact the pins and the leading teeth on the 50t chainring and jump between the two chainrings.

I eventually sourced a R8000 crankset and matching front derailleur for the Canyon Endurace. This combination allows the use of all 22 chainring and cassette cog combinations without any interference of any kind.


I have a 2017 Salsa Warbird, full 6800 groupset and 142mm rear spacing.  I tried to mimic your situation, but in the 34x11 the chain did not contact the 50T ring.
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Barrettscv

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Reply with quote  #6 
Yes, the 430mm chainstays on the Warbird should allow the chain to clear the big chainring when on the 34x11 combination. My Canyon has shorter chainstays, which contributes to the problem.

Given that the R8000 front derailleur and crankset have several advantages, as detailed in the prior posts, spending a few dollars more for the 8000 has merit.
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