Bicycle Mechanics - Derailleur Hanger --- Maintenance?
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I have an S-Works Roubaix that is 2 years old with about 9,000 miles on it. I have never touched the derailleur hanger.
Should I replace the hanger as a preventative maintenance matter?
It is recommended to remove it once in a while from the frame to check the interface between hanger and frame?
What torque is usually used on the single screw that holds the hanger to the frame/drop out?
It has never occurred to me to do preventative maintenance on a hanger absent some indication of a problem. I can't see a reason to replace one absent some indication of damage or after an accident where you susp[ect it took a good hit. Periodically eye ball for indications of damage (particularly if you've had a crash); make sure bolt is tight when you do any maintenance on the derailleur. As far as torque, attached will tell you how much to torque the deraileur mounting bolt (attches derailleur to hanger) but says nothing about how much to torque the hanger itself http://www.parktool.com/repair/howtos/torque.pdf. It probably depends on the hanger -- my Cannondale use two very small bolts for attaching the hanger to the frame that I found the hard waycan easily get stripped if tightened too much.
01-29-09, 07:04 PM
There should be no wear on a derailleur hanger so no maintenance required unless it gets bent or the derailleur mounting hole gets stripped. For a removeable/replaceable hanger I would think that the only periodic maintenance woulld be making sure the hanger mounting screws are snug as well as the derailleur mounting bolt.
01-30-09, 12:22 AM
Not a bad idea to check the hanger alignment. Park has a tool for doing it or I'm sure your LBS can do it. On the other hand if it is shifting OK the alignment is probably OK as they go hand-in-hand.
^ I can attest that a hanger off by less than a millimeter will make it impossible to correctly use a full range of 9 gears. Probably worse on 10.
01-30-09, 01:23 AM
Something any top-end shop should consider purchasing:
01-30-09, 01:35 AM
The poor man's method of measuring derailluer hanger alignment is to find a wheel whose axle has the right size thread and mount that to the derailleur, then do some measurements (the first wheel I tried worked).
With the bike's own rear wheel in place, remove the rear derailleur. Thread the other wheel onto the derailleur hanger where the derailleur would normally mount. You can then measure the lateral distance between the two rims at various points (not the easiest thing to do, but try as best as you can) and if these measurements are all equal then the hanger is correctly aligned. Obviously, both rims need to be laterally true for this to work.
Unfortunately, it's not a very accurate method, but I believe it is the most accurate method you can do at home without a fancy tool.
02-12-09, 09:07 PM
I wouldn't replace it preventativly unless you are having a problem with it. It should also be noted that even though there are bolts holding it to the frame when the wheel is off, the hanger is held in place mostly by the pressure of the wheel being mounted. So there is very little wear on a hanger unless it takes a hit.
02-13-09, 12:05 AM
I never messed with my der hangers ... until I finally KNEW that I had bent one ... and broke down and bought the Park Tool tool.
Once I fixed the bent one, I checked the alignment on the others. Too true: a slightly mis-aligned der hanger was responsible for degraded shifting ... that I didn't even realize WAS degraded ... until I got them perfectly aligned.
If you'll use the tool on multiple bikes or for work, buy it. If not, get your trusted LBS to align the sucker for you....
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