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Bicycle Mechanics - Dura Ace 7800 7900 compatibility

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oldenjhon

08-17-11, 02:18 PM

I'm sorry if this question's been asked before but a search would not yield the answer I needed. I have a full 7800 set up and want to swap my cranks out for the 7900 set, but I've read that there are compatibility issues with the 7800 front derailleur. Does anyone have a definitive answer as to whether this is true or not? Are there any other issues with using a 7900 crankset with a 7800 set up? Anyone with experience combining the two? Thanks in advance

joejack951

08-17-11, 04:59 PM

No experience but from what I've read the only issue would be trying to use a 7800 front derailler with 7900 shifters or vice versa. Shimano changed the cable pull ratio for 7900 shifters/front deraillers. Given that both cranksets use the same tooth counts for the chainrings and the chainring spacing is the same (I haven't read otherwise at least) I can't see how you'd have any problems.

This is where I've read about the front derailler issue: http://www.bikeradar.com/gear/category/components/groupset/road/product/review-shimano-dura-ace-7900-groupset-09-34164/

jmess

08-17-11, 09:31 PM

On my 6603 equiped bike I replaced a FSA compact crank with a 6703 triple crank and besides having better gearing it shifts great with the 6603 FD. I would bet the 7900 double would work fine with 7800 FD.

Davet

08-18-11, 06:59 AM