6800 Cranks with eg 6700 shifters?

[ab012]

Noticed the 6800 comes with 52/36 as an option (as well as having the same crank for different combinations) which looks interesting. Got me thinking though - does a 6800 crank work well with an otherwise older groupset eg 6700 shifters, or would a full 6800 set be required? Anyone have tried it (or are even currently using it)?

Comments welcome!

Edit ps just noticed perhaps a related thread viewtopic.php?f=34&t=68712" onclick="window.open(this.href);return false; although that deals with 9000 rather then 6800 - would this be similar?

[Duck!]

Shimano will tell us that it won't work, but I can't see any reason why it won't. Cranks are the least sensitive to potential incompatibility between 8,9,10 & 11-sp. bits.

The only time you tend to strike problems is if you try to pair a newer (7900/6700/9000/6800) crank with an older system, because those cranks have slightly wider chainring spacing, and older shifter/FD combinations don't take too kindly to bridging that extra gap.

[jasonc]

so my derailler says i need an X600 series crank (i.e. 5600, 6600). can i use a 6750?

[Duck!]

It won't like it. You can make it work, but it will be rough. I worked on a similar generational mix - FC-6750 in a 7800 group (which 6600/5600 are descended from), and it wasn't happy. You're best to switch to a 6700 F. derailleur as well, which will work with the older shifter (its lever arm is tweaked to give it the longer swing without altering the length of the shift lever stroke).

[jasonc]

so i still need to find a 6650 for <$200....
ta

problem is it's my flat bar....derailleur/shifter compatibility issues with the 6700 series derailleurs

[Duck!]

Hmm, flat-bar.... That complicates things slightly more, 'cos some sets are intended to have a specific FD, to suit the different leverage of the shorter shift levers. What bits have you currently got? I'll have to have a dig around to see what combinations could be effectively (and cheaply! ) bodged together.

[jasonc]

http://www.giant-bicycles.com/en-au/bik ... ifications" onclick="window.open(this.href);return false;

Shifters Shimano SL-R770 flat bar 20 sp.
Front Derailleur Shimano R770
Rear Derailleur Shimano 105 10 sp. - pretty sure it's a 5700

[jasonc]

http://www.giant-bicycles.com/en-au/bik ... ifications

Shifters Shimano SL-R770 flat bar 20 sp.
Front Derailleur Shimano R770
Rear Derailleur Shimano 105 10 sp. - pretty sure it's a 5700

confirmed the RD is a 5700

[Duck!]

Sorry I took a while getting back on this. Rear derailleur model isn't relevant, 10-sp. is 10-sp, regardless of series or shifter type (MTB excepted).

The R770 shifters & front derailleur are designed as a set to work with pre-7900/6700 cranks. I reckon if you match a "regular" non-flatbar-specific FD to the R770 shifters you'll get the longer stroke required to shift across the wider chainring gap of the 6750 crank.

The R770/440 sets had a longer shift lever stroke than the brifters to compensate for the shorter lever, so the FD has a longer cable anchor lever than the "normal" type to convert the longer cable-pull into the same derailleur movement. Fitting a standard FD will use the longer cable pull to cover the wider gap.

[jasonc]

Fitting a standard FD will use the longer cable pull to cover the wider gap.

Thanks for your efforts!

So by the sound of it, if I have to buy a crank anyway, buying the 6650 is an OK deal and will work out around the same price as buying a 6750 and a new FD

[Duck!]

Yeah, if you can get the 6650 crank, do so, 'cos then you won't have to change anything else.