Shimano XT rear derailleur on C'dale 07

[charbergs]

Hello all,
My wife and I bought the Cannondale Road Tandem 2007 model in March. We changed out the horrible seats and bought a longer telescoping stoker stem from Control Tech, but otherwise we've loved the 1082 miles we've put on it!

I just had it serviced in preparation of Tour de Palm Springs, and the LBS tech said that even after changing out the cables and housing, he couldn't get the Shimano XT rear derailleur working perfectly. I have only occasionally noticed this, more recently than before. It is often sluggish to react, and sometimes it spontaneously shifts one gear without my intension of shifting.

I expected the rear derailleur to last longer than 1000 miles- am I wrong to have expected this? And if I decide to replace it, should I upgrade?

Thanks for the advice!
Charlie

[stapfam]

Hello all,

I expected the rear derailleur to last longer than 1000 miles- am I wrong to have expected this? And if I decide to replace it, should I upgrade?

Thanks for the advice!
Charlie

And so would I. I use the Tandem off road in conditions that are not benificial for long life on anything but I get about 2,000 miles on an XT rear derailler before it remotely starts to cause a problem.

Now saying that- Last Time I replaced the XT rd- I got a good deal on an XTR. It does not work any better (Or I don't think so) but after about 1800 miles- there is no play and no need to think about replacing it

[TandemGeek]

I expected the rear derailleur to last longer than 1000 miles- am I wrong to have expected this? And if I decide to replace it, should I upgrade?

Did he check to make sure the rear derailleur hanger isn't bent? If I was a betting man, that would be my diagnosis based on the description of the shifting behavior.

Park Tools makes an alignment tool that any descent shop should have on their peg board and it takes less than five minutes to check. If it's just a little off (an accidental bump or the bike falling over on the right side can cause it), they can use the tool to square it away which is all it probably needs. If it was way off, the C'dale rear derailleur hangers are replaceable. If you have a good eye you can usually do a visual check of the alignment: the hanger should be perpendicular to the ground with the rear wheel installed (and when it's not installed as well... as a difference there could indicate a bent/twisted/warped rear drop-out or stays)

Here's the deal, better rear derailleurs like the LX, XT, XTRs really don't wear out for tens of thousands of miles, even when they're poorly maintained. The idler and jockey wheels will wear out, but they are replaceable parts and they really have to be in horrible shape before they create any problems as they merely keep the chain centered as it runs through the cage up to the rear cassette cogs. You can also damage a rear derailleur in a number of different ways, the most common being the aforementioned bike drop or knock-over where the drive side hits the ground.

Anyway, assuming the hanger is bent a new and more expensive derailleur won't fix the problem. That said, the earlier models of XTR rear derailleurs (dark grey) were a little bit better for tandems than the XT because they came with a spring tension position switch that had a normal and high-tension position: the latter was ideal for tandems with their very long derailleur cable runs and made shifting feel a bit more crip than what you'd find on a stock XT model. I can't speak to the '07 XT vs XTR as I haven't had to fix one and haven't bothered to look at the spec sheets.

[cyclesteve]

Check the shifter and shifter cable.

[SDS]

I would add to the advice above, make sure every place the cable could rub is properly lubricated, particularly the cable guides under the bottom brackets.

[antiquepedaler]

I'd have to agree with all these guys. The problem isn't the XT derailleur....they're pretty much bullet proof and last for years.

As far as the derailleur hanger is concerned....Just look at it with the bike vertical to see if it leans in..they can't hardly get bent out. I've corrected dozens of bent ones by putting them in a vice and very gently persuading the bend back to straight with an adjustable wrench. Check it by placing it on a flat surface.

[TandemGeek]

Just a quick follow up...

I'm assuming you paid the shop for this 'tune-up' service. If so, and before fixing it yourself, I'd give the owner a call and ask him how much of the money you paid he'll be willing to return if it turns out that they failed to provide the service you paid for in the event that you resolve the issue based on feedback you received from people who didn't even have the benefit of putting their hands or eyes on your tandem.

Nothing peeves me off more than stories of folks who buy or take tandems into shops where "mechanics" send the bikes out the door that don't work the way they should. A properly adjusted tandem shouldn't mis-shift, drop chains, overshift, or have lousy brake performance (excluding any need for normal break-in of pads/rims/rotors), creak, groan, or otherwise give their owners trouble and they darn well shouldn't come back with new nicks, dents or problems that they didn't have when they went in.

[Retro Grouch]

Did he check to make sure the rear derailleur hanger isn't bent? If I was a betting man, that would be my diagnosis based on the description of the shifting behavior.

That would be my bet too. The more cogs you have on your rear cassette the more fussy your derailleur will be about hanger alignment.

[stokessd]

Replace your cables. I had front derailleur issues on my '07 road and replacing with beefier stainless shifter cables cleaned up the issue greatly. I'd guess slight misadjustment, cable stretch, combined with a little wear pushed you over the edge into crap shifting. Replacing the cable I'd bet will help you.

Sheldon

[zonatandem]

XTR Derailleur currently has 17,500+ miles on it; no issues (so far!).

[streetlightpoet]

+1 on hanger, but assuming the cable's already been replaced.

[charbergs]

Thanks to all for the replies. They make me happy that I decided to not replace the RD.

I will say that, to the shop's credit, they replaced the cable, housing, and hanger, all with still lack of perfect performance. We took the bike out for a 56 mile hilly ride in Marin with much improved performance prior to bringing the bike in, but it isn't perfect. Still occasional slippage, etc.

I'm content with it for now- perhaps a more tandem saavy mechanic would help. Any recommendations for such in the Bay Area?

Thanks, everyone!
Charlie