# Ultegra 6800 or 6700 with CX70 for 'Cross?



## Dopamine (Jun 2, 2009)

I'm going to start putting together a new rig for CX this fall after not racing in 7 years and still owning an ancient alu Redline Conquest Pro with Ultegra 6500 on it (LOL). 

Anyway, I know what I'm going to do for frame/fork/wheels and I'm just curious what group folks think is better in the mud: Ultegra 6800 or the 6700 group with CX specific CX70 cranks and CX70 front derailleur? 

I have not ridden 6800 at all yet although I am going to swap 6800 onto my road bike next week and try it out extensively before the fall. But that's road use, I am wondering if the 10 speed 6700 setup with the CX70 crank and front der might be better in the mud than the 11 speed group. The CX frame I'm getting does have top tube cable routing so I could run a top pull CX70 front der and keep it out of the muck. The frame has a roller mount as well though so I could run the 6800 bottom pull front der as well. Definitely going 36/46 double whether I go with CX70 or 6800 crank.

So anyway, just looking for recommendations from those that have raced on 6700 and/or 6800 in the frozen Hell of cyclocross.


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## pretender (Sep 18, 2007)

CX70 crank will give you more options for chainrings. I'd make the road and CX setups the same so you can swap cassettes, wheels, etc.


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## SlowJoeCrow (Sep 3, 2009)

If your frame has top tube cable routing, definitely go for the CX70 top pull derailleur and ditch the pulley to keep things simple and mud resistant.


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## Dopamine (Jun 2, 2009)

SlowJoeCrow said:


> If your frame has top tube cable routing, definitely go for the CX70 top pull derailleur and ditch the pulley to keep things simple and mud resistant.


Yep this is what I'm thinking as well - why deal with the pulley if I don't have to. Even if the 6800 front der shifts slightly better than a 6700 under normal conditions, I doubt it will with a mud caked pulley. 6700 with CX70 gear it is.


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## MShaw (Jun 7, 2003)

Dopamine said:


> Yep this is what I'm thinking as well - why deal with the pulley if I don't have to. Even if the 6800 front der shifts slightly better than a 6700 under normal conditions, I doubt it will with a mud caked pulley. 6700 with CX70 gear it is.


I have the 6800/CX70 combo that the OP is asking about. Its not *quite* as slick shifting as the 6800 front derailleur as on my road bike, but it works well.

HIGHLY recommended.

Skip the pulley and get the top pull.

M


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## jroden (Jun 15, 2004)

It sounds stupid, but if you can live with a standard crank, I'd be happiest with an older octalink model because the bottom bracket doesn't suck, or something in a square taper matched with a Phil Wood sealed BB. The external BB's are not great, but the BB30 design seems worse.


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## pretender (Sep 18, 2007)

jroden said:


> It sounds stupid, but if you can live with a standard crank, I'd be happiest with an older octalink model


The CX50 and CX70 cranks are essentially that, but come with 36/46 chainrings.


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## jroden (Jun 15, 2004)

the octalink uses a nice cartridge bearing that lives inside the bb shell which is a real plus in the muddy world. While i like the shimano external bb's, the do seem to die after a season in the slop. I have an octalink that i'm sure is seized solid into my winter bike from all the roadsalt and it continues to spin great after maybe 7 years


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## pretender (Sep 18, 2007)

Oops my bad.


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## skr29er (Aug 7, 2013)

MShaw said:


> I have the 6800/CX70 combo that the OP is asking about. Its not *quite* as slick shifting as the 6800 front derailleur as on my road bike, but it works well.
> 
> HIGHLY recommended.
> 
> ...


so to confirm, you are using 6800 11S shifters with the CX70 FD? This is what I want to do but had been told they were not compatible? Shifts well? Issues with chain rub? What crankset?


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## jct78 (Dec 12, 2011)

skr29er said:


> so to confirm, you are using 6800 11S shifters with the CX70 FD? This is what I want to do but had been told they were not compatible? Shifts well? Issues with chain rub? What crankset?



i've been using 6800 with a CX70 crankset. the cranks are 10spd which causes some minor rub issues but nothing major. there's a 6800 46/36 crankset that's also available. They weren't around last summer when i spec'd my bike but that should solve any shortcomings of the cx70 and 6800 combo. that said, i won't be upgrading my cranks anytime soon.


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