cedricbosch

I have an Ultegra 6600 group that's around 3 years old, ridden pretty much every day. After three years it still shifts, but it just doesnt have the same precision as before. Now, I'm no mechanical slouch, and I've replaced the chain/cassette/cables/housing and kept it well-tuned. But I feel it's getting a little sloppy- longer shift times, sometimes it hesitates to shift, etc. No matter how much I fiddle with it, it's nowhere near close to a new group.

So, how long should a group be expected to last? And what exactly causes it to wear down?

bradtx

cedricbosch, Friction causes the wear and is helped with lubricants, but can't be eliminated compleately. A woman I know commutes fair weather daily and racked up about 9K miles on her LX/XT group. If I remember correctly her husband then installed new RD pulleys/bushings, a cassette, two new chain rings, chain and new cables/housing. Her shifters were okay, but her route is fairly flat with few shifts.

Brad

njkayaker

Anywhere from 1 month to many years. There are too many variables to make any general prediction. Usage (ie, mileage), grit, maintenence/lubrication are all important and highly variable.

FBinNY 

There are people still riding Campy Record stuff from the late sixties, so the answer is pretty open ended. But Index imposes other issues that didn't matter so much back in the days of wider cassette spacing and friction shifting.

Index depends on the shifter precisely latching into detents in exact positions, and with wear those will get sloppier. Also the RD wears at the pivots, which develop play changing the dimensions and rigidity of the pantograph. Both will cause a system to shift less crisply over time, though it can be compensated for with rider touch.

The systems life isn't related to time or mileage, but to the frequency of shifting. Someone who rides in the rolling terrain of Connecticut or Pennsylvania shifts much more often per mile than one in Kansas, or even Colorado, which has higher mountains but mostly long steady climbs and descents.

If you adapt, you should be able to keep riding your stuff, or could consider replacing the most worn element, though not everything. Also be aware that other things change shifting properties, including chain wear. As they wear chains become more flexible sideways, and so shift more sluggishly especially on the smaller cassette sprockets.

HillRider

As FBinNY noted, shift frequency is really the big factor. A friend completly wore out a set of 8-speed 105 brifters in just under 9000 miles but he seems to shift every 100 feet. I've got a set of the same 105 8-speed STI's with over 30,000 miles and they still work pretty well.