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I have a 10 speed D/A 7900 drive train. Would like 11 speeds on the rear with an 11-32 cassette. Can I run, say 11 speed Ultegra 6800 rear derailleur/chain/cassette with my 10 speed D/A 7900 crankset and front derailleur? Much cheaper option. Wheels will take 11 speed cassette. In other words, can I change out only the rear derailleur, chain and cassette to the 11 speed Ultegra 6800 stuff and use all 11 speeds?
 

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Adorable Furry Hombre
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Need a new right-shifter (may as well do a new cable) as well.

Cranks are cranks in this case
 

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Never Give Up!
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You will need to switch is out your right shifter, the pull ratio between a 10 and 11spd gearing is setup differently, it simply won't shift very well...

I've tried it my self, ended up switching over almost everything to an 11spd group set with the exception of my cranks, they remain as a Ultrega 10spd
 

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Thanks. That's what I was afraid of.
I think you'll need new brakes too because the levers don't play well with the old brakes. Not certain about that.

Ultegra 11 speed is really cheap (last I checked). I got a full set from Ribble for $540 last year. It;ll be easier and probably cheaper than trying to jerry-rig with individual parts to just do it right and buy a full set. Your old 7900 should have decent ebay value too if it's in okay shape. So it might net out to next to free.

That being said I wouldn't bother for just one extra gear. 11 speed does shift a bit better than 10 but it not a big deal and won't change your riding experience.
 

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Banned Sock Puppet
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All good answers here. To clarify, Shimano changed the shifting pull ratios for the latest generation going from 5700/6700/7900 to 5800/6800/9000. I'm not absolutely sure when they changed the pull ratios for brakes.

So if going from 10-speed to 11-speed, you must change the chain, cassette, rear derailleur and rear shifter. You can see how your existing rear brake feels with the new shifter and old caliper. My guess is it may feel mushy.

Of course, then you will have unmatched shifters. Regardless, there is no reason to change the crankset even if you do change the front shifter, but you must change the front derailleur in that case.
 

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'brifter' is f'ing stupid
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Cable pull ratios matter but the fact that a 10 speed shifter has 9 clicks and an 11 speed shifter has 10 should tell you they don't play well together. How on earth would you shift to the last cog on an 11 speed cassette w/ a 10 speed shifter even if the cable pull ratio was the same? :idea:
 

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I think you'll need new brakes too because the levers don't play well with the old brakes. Not certain about that.

Ultegra 11 speed is really cheap (last I checked). I got a full set from Ribble for $540 last year. It;ll be easier and probably cheaper than trying to jerry-rig with individual parts to just do it right and buy a full set. Your old 7900 should have decent ebay value too if it's in okay shape. So it might net out to next to free.

That being said I wouldn't bother for just one extra gear. 11 speed does shift a bit better than 10 but it not a big deal and won't change your riding experience.
I ran an Ultegra 6800 groupset with 7900 cranks and brakes and it worked no problem. I did not notice any difference in the braking from my other bike which was full Ultegra 6870 (Di2). The only difference I noticed is that the newer brakes are more reliable when getting mud in them. On the older generation of Shimano I noticed I'd have to clean out the calipers more often because they wouldn't fully spring back once you pulled the lever.
 

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Banned Sock Puppet
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Cable pull ratios matter but the fact that a 10 speed shifter has 9 clicks and an 11 speed shifter has 10 should tell you they don't play well together. How on earth would you shift to the last cog on an 11 speed cassette w/ a 10 speed shifter even if the cable pull ratio was the same? :idea:
Hmmm. Somehow I don't think this is what the OP was thinking. :idea:
 

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So.... if you are riding in mud, there is not much difference.... other than the fact you can't get into the '11'?
What are you talking about? I said everything except the brakes and crank is 11 speed. So yes, I have my full range range of gears.
 

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What are you talking about? I said everything except the brakes and crank is 11 speed. So yes, I have my full range range of gears.
No u didn't, you said 10 speed DA drive train, go look. Don't ride in mud!
Maybe u are confused about what 'drive train' means?
 

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No u didn't, you said 10 speed DA drive train, go look. Don't ride in mud!
Maybe u are confused about what 'drive train' means?
Actually no. Here's the relevant part of my original post.

I ran an Ultegra 6800 groupset with 7900 cranks and brakes and it worked no problem.


Since you seem to be having a hard time with this, let me break down the components for you
Shifters - Ultegra 6800
Front derailleur - Ultegra 6800
Rear derailleur - Ultegra 6800
Cassette - Ultegra 6800 (11-28 since you must be super pedantic)
Crankset - Dura Ace 7900
Brakes - Dura Ace 7900

So yes, I have my full range of gears with perfect shifting thank you. Also, maybe you are confused on what 'u' means. 'U' is a letter of the alphabet, not a word. 'You' is a word that refers to a person.

I mean FFS people on this forum are worse than the elitist cyclists out on this road. I'm trying to help someone with their post and someone comes out of left field and creates a useless argument no one cares about. Really encourages great posts on these forums. I think I'll just get off and leave you guys to answer the "What gearing should I get?!?!" post for the 100th time :rolleyes:

Edit: Just to make sure we are really clear here's the picture of a brake



And here's one of a crankset

 

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I just read "10 speed", u remember seeing that!

edit: I guess 6800 is 11 spd, but who knows. I did see that u have an `11`, good, but I hope u're not matching that with a 53.
But I stand by my recommendation.... Don't ride in mud!
 

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But in the immortal words of 'spinal tap', .... 'this goes to 11!!!"
Agreed,
It goes to 11. It's better, faster and louder. Money is no object
 
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