Rear Deraileur problem, two clicks or one.
#1
Member
Thread Starter
Join Date: Nov 2005
Posts: 35
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Rear Deraileur problem, two clicks or one.
I have this 6500 mile, ten year old Mongoose hybrid with twist grip shift whose RD is no longer shifting correctly. After 4000 miles or so it would only shift smoothly one way, larger cog to a smaller. I went thru the adjustment routine in ParkTools and got it to shift smoothly the other way, smaller cog to larger. But never smoothly in both directions. Right now it takes two 'clicks' on the index to shift to a smaller cog, but the normal one click to a larger. Cable and twist grip work fine. It does not look bent. A replacement RD would be about $25; but I would like to fix it, (Shimano C105 7 speed freewheel Megarange, low normal).
#2
Banned.
Join Date: Sep 2007
Location: Carlsbad, CA
Posts: 6,434
Bikes: '09 Felt F55, '84 Masi Cran Criterium, (2)'86 Schwinn Pelotons, '86 Look Equippe Hinault, '09 Globe Live 3 (dogtaxi), '94 Greg Lemond, '99 GT Pulse Kinesis
Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 389 Post(s)
Liked 270 Times
in
153 Posts
How is the chain? Pretty clean and adjusted properly?
Also the shift cable? It might not have any kinks in it, but is there any slack down near the derailleur or up in the grip-shift unit?
Try lubing & cleaning the chain, and maybe put a drop of Tri-flow or other light oil on all eight of your derailleur pivot points. In fact, shift it to the largest cog, lube those pivot points, then to the smallest cog and lube them all again. Then wipe off the excess and see how she does.
Also the shift cable? It might not have any kinks in it, but is there any slack down near the derailleur or up in the grip-shift unit?
Try lubing & cleaning the chain, and maybe put a drop of Tri-flow or other light oil on all eight of your derailleur pivot points. In fact, shift it to the largest cog, lube those pivot points, then to the smallest cog and lube them all again. Then wipe off the excess and see how she does.
#3
Senior Member
Join Date: Sep 2010
Location: Roswell, GA
Posts: 8,319
Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta
Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 1438 Post(s)
Liked 1,092 Times
in
723 Posts
At 10 years old it is possible that friction is building up somewhere, either in the derailleur or the cables. I would suggest that in addition the lubing the derailleur, as suggested above, you lube or preferably replace the cable and housing. Pay special attention to the short loop of housing going into the derailleur, it often picks up road gunk and water. If you decide to change them out, die-drawn stainless wires and lined cable give good performance and last well. Make sure that they housing runs are the correct length and that the housing ends are cut or filed flat and the correct ferrules are installed.
#4
Senior Member
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,690
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5772 Post(s)
Liked 2,567 Times
in
1,422 Posts
The most likely cause is a sticky cable, especially considering the age. The first place cables bind is usually in the rear loop because of faster wear on the inside of the sharp curve.
There's an easy test, which will confirm rear loop friction, hang the bike so you can pedal and shift by pulling the bare wire away from the downtube. If it shifts smoothly, the rear loop is OK, but if you find the RD doesn't move freely, or hangs up when you slowly ease off the tension. You can sometimes get an even better feel by removing the wheel and feeling/watching for smootheness or binding as you work the RD through the range.
Given the age, if the cables are sticly, odds favor replacement over trying to save them with a clean and lube, though you could give that a shot.
There's an easy test, which will confirm rear loop friction, hang the bike so you can pedal and shift by pulling the bare wire away from the downtube. If it shifts smoothly, the rear loop is OK, but if you find the RD doesn't move freely, or hangs up when you slowly ease off the tension. You can sometimes get an even better feel by removing the wheel and feeling/watching for smootheness or binding as you work the RD through the range.
Given the age, if the cables are sticly, odds favor replacement over trying to save them with a clean and lube, though you could give that a shot.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#5
自転車整備士
Join Date: Apr 2012
Location: Denver, Colorado USA
Posts: 885
Bikes: '86 Moots Mountaineer, '94 Salsa Ala Carte, '94 S-Works FSR, 1983 Trek 600 & 620
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Likes: 0
Liked 3 Times
in
3 Posts
If you end up replacing the cable, you might want to check the innards of the Grip Shift mechanism. All it consists of is a steel spring. Get some silicone grease (the SRAM equivalent is called "Jonnisnot") and lube the spring, then install the cable and re-assemble. Also, if your shifter has an adjusting barrel, unscrew it and lube the threads, then screw it back on.
#6
Senior Member
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 30,225
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1572 Post(s)
Liked 643 Times
in
364 Posts
Shift into a gear combination that makes the derailleur arm point downward. Then prop your bike up against something and look at the derailleur from the back. If it looks like the derailleur arm is pointing toward the tire - that's it.
Whenever i encounter a rear shifting issue that doesn't respond to normal tuneing, the first thing that I do is to check the derailleur hanger alignment. Most of the time, that's the source of the problem.
Whenever i encounter a rear shifting issue that doesn't respond to normal tuneing, the first thing that I do is to check the derailleur hanger alignment. Most of the time, that's the source of the problem.
#7
Senior Member
Join Date: Mar 2003
Location: Beaufort, South Carolina, USA and surrounding islands.
Posts: 8,521
Bikes: Cannondale R500, Motobecane Messenger
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Derailluer pivots can wear out and cause the problems your describing.
#8
Member
Thread Starter
Join Date: Nov 2005
Posts: 35
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Thanks for your replies. I've tried most of the solutions suggested, except changing the cable housing, which I will do. As Diesel Dan says, it may simply be worn out.
I have this 6500 mile, ten year old Mongoose hybrid with twist grip shift whose RD is no longer shifting correctly. After 4000 miles or so it would only shift smoothly one way, larger cog to a smaller. I went thru the adjustment routine in ParkTools and got it to shift smoothly the other way, smaller cog to larger. But never smoothly in both directions. Right now it takes two 'clicks' on the index to shift to a smaller cog, but the normal one click to a larger. Cable and twist grip work fine. It does not look bent. A replacement RD would be about $25; but I would like to fix it, (Shimano C105 7 speed freewheel Megarange, low normal).
#9
Member
Thread Starter
Join Date: Nov 2005
Posts: 35
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Well not so fast! I checked again, and as Retro Grouch cautioned, the DR arm IS pointing toward the tire, ie hanger alignment problem. Anyone ever try placing a shim so the DR would correct to vertical? Maybe a clipped off piece of ziptie or something. Or is it time for a new DR?
Shift into a gear combination that makes the derailleur arm point downward. Then prop your bike up against something and look at the derailleur from the back. If it looks like the derailleur arm is pointing toward the tire - that's it.
Whenever i encounter a rear shifting issue that doesn't respond to normal tuneing, the first thing that I do is to check the derailleur hanger alignment. Most of the time, that's the source of the problem.
Whenever i encounter a rear shifting issue that doesn't respond to normal tuneing, the first thing that I do is to check the derailleur hanger alignment. Most of the time, that's the source of the problem.
#10
Senior Member
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 30,225
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1572 Post(s)
Liked 643 Times
in
364 Posts
Just clamp a big adjustable wrench over the derailleur where it attaches to the frame and gently bend it straight. With a 7-speed I can get it close enough to index by eyeball. On a 9-speed I have to use a gauge (bike shops have them, it's about a $15.00 or $20.00 job.)
Don't be tempted to unbolt the derailleur and try to straighten the hanger. You might ovalize the derailleur mounting hole.
Don't be tempted to unbolt the derailleur and try to straighten the hanger. You might ovalize the derailleur mounting hole.
#11
Senior Member
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,690
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5772 Post(s)
Liked 2,567 Times
in
1,422 Posts
You can't shim hangers. You gently bend them straight.
Steel hangers are very tolerant of bending (cold setting for folks who speak tech) but aluminum hangers much less so. So it's best to straighten the hanger in a single shot, rather than working it back and forth drying to dial it in. In a pinch you can stick an allen wrench into the upper pivot bolt and use that as a bending bar. If you have a replaceable hanger, and the bend is sever, consider shelling out for a replacement.
Steel hangers are very tolerant of bending (cold setting for folks who speak tech) but aluminum hangers much less so. So it's best to straighten the hanger in a single shot, rather than working it back and forth drying to dial it in. In a pinch you can stick an allen wrench into the upper pivot bolt and use that as a bending bar. If you have a replaceable hanger, and the bend is sever, consider shelling out for a replacement.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#12
Senior Member
Join Date: Mar 2003
Location: Beaufort, South Carolina, USA and surrounding islands.
Posts: 8,521
Bikes: Cannondale R500, Motobecane Messenger
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
One trick is to thread a front wheel into the hanger to bend it back. You can sort of eyeball the alignment. I did that with a 20" wheel on a recumbent, as the alignment gauge wouldn't work on the smaller wheel.