Dura Ace 7900 rear shifter is slow to shift

chris1001

Hi,

I've been having problems with the shifters on one of my road bikes ever since I 'upgraded' from 7800 shifters & mechs to 7900. I guess that the revised hidden cable routing doesnt help matters. The rear gears are slow to engage (generally on the downshift) - as through the rear mech hasnt moved to the next full indexed stop, the shift lever is also slow to return back to its rest position after moving to select the next gear, kind of feels like the cable is dragging in the liner. I've tried using new 7900 gear wire and new SP41 outer, but this only helps for the first 300 or so miles, after that it gets lazy again. I've very tempted to just lube the damn cables, but everthing I've read advises not to lube the Dura Ace cables as they are coated and the liners are pre-lubed.

Any hints or suggestions, or advice on a suitable lube that might sort this would be much appreciated!

Cheers

Chris

rozzer32

Will probably be cable stretch with the new cables, the cable tension will just need a tweak with the barrel adjuster.

keyser_soze

rozzer32 wrote:

Will probably be cable stretch with the new cables, the cable tension will just need a tweak with the barrel adjuster.

+1 - cable stretch almost definitely. Turn the barrel adjuster anti clockwise 1/8 of a turn at a time until it stops being so damn lazy!

chris1001

Cheers guys, will keep tweaking, hopefully thats all that is needed.

Dmak

Personally I'd just drown the mech in GT85 repeatedly, I love the smell of the stuff! May not be the solution but it's a thought.

chris1001

Tempted if it cant be sorted by cable tension adjustment, although it's wash out all the teflon grease!

chris1001

Adjustment hasn’t helped, the rear mech was lined up pretty well and no amount of tweaking has given me a precise and reliable shift (tested extensively today during the BHF Peak district ride!), pretty certain that its cable friction, might try some of those expensive 'Gore' cable kits, and run with a longer rear mech loop. If that fails I'll strip down the right hand shifter and see if that’s got something mucking up the indexing stop.

marin_maniac

Get your self a Shimano cable kit from Ribble. £25 buys you enough SP41 outer in the colour of your choice. The inner cable you get is the same in the DA kits, i.e. With a PTFE coating.

I've got 6700 and 5700, the 6700 is run with Jagwire racer cables and the 5700 is run with the standard Shimano cables that came with the groupset. Out of the two. The 5700 has a slightly lighter shifting action and needs less fettling.

When I can be bothered, the 6700 will get treated to the Shimano kit I've recommended to you.