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Bent hanger -- Bent frame? ... shifting problems
[58 cm Rivendell Ramboulliet -- steel frame, Dura Ace bar ends]
Days ago I had a clipless newbie style slow-speed side crash which bent the derailleur hanger and the Ultegra rd-6500gs triple der. My LBS straightened the hanger and replaced the bent der with a Dura Ace rd-7700GS. The new der shifted fine on the stand -- but on the road I experienced problems, particularly when downshifting from 15 to 14 teeth cogs (Ultegra 12-27, 9 sp cassette). The prob seems to be erratic, not yielding to any amount of adjustment. Rivendell suggested the frame may have been bent in the crash -- triangle pushed to the left. It looked like the hanger was bent something on the order of 2-3 degrees -- wild visual guess. Generally, how frequently is a bent hanger accompanied by a bent frame? Tough question, I know. My immediate concern is whether I need to find a shop that is equipped for frame checking and alignment. I've read Sheldon and others regarding bent hangers and I've not seen bent frames being mentioned as an associated issue, though the possibility is obvious. Dave |
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#2
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Bent hanger -- Bent frame? ... shifting problems
DaveH wrote:
Rivendell suggested the frame may have been bent in the crash -- triangle pushed to the left. It looked like the hanger was bent something on the order of 2-3 degrees -- wild visual guess. Try the "string test" to check frame alignment: http://sheldonbrown.com/frame-spacing.html (scroll down near the bottom) Also make sure the shift wire is anchored at the correct place on the derailleur. Art Harris |
#3
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Bent hanger -- Bent frame? ... shifting problems
On Thu, 04 Oct 2007 17:51:02 GMT, still me
wrote: On Thu, 04 Oct 2007 16:22:48 -0700, M-gineering wrote: Bent frame isn't very likely with just toppling over. If you can ride the frame no handed without the frame veering left or right it's fine. I'd investigate free movement of the shiftercable first. Is the cable properly located underneath the bracket? Last bit of outer cable not to short, kinked, badly cut. missing ferrule etc? And another good one: cable properly clamped in the groove on the derailleur body? Not to mention, bent frames are more likely to affect the movement at the limits, not in the middle of the cog. It's possible, but I would think the bend would have to be severe for that to happen. How good a job did they do on the hanger straightening? Any chance they left it "non flat" ? Marten and Still, I did the string test for rear triangle displacement at: http://www.faqs.org/faqs/bicycles-fa...ection-50.html The test indicates the seat tube deviates to the right by 1/16". This suggests the rear tri is displaced 1/32" to the left. This doesn't sound like much; but indeed, I just did some extensive no-hands riding and there is a mild but distinct tendency to veer to the right. I thought something didn't feel right about the ride feel before a bent frame even occurred to me but it was a bit vague and assumed it was my imagination. Still, you would not think this would be enough to effect shifting, especially in the middle cogs as noted. I talked to Rivendell and they agree with this. Regarding hanger straightening: The LBS appeared to take his time with what is obviously a special tool. I must assume at this point that it's ok. Regarding cable issues Marten: Everything's ok, as far as I can tell. Not sure what to do. I'm tempted to put an Ultegra derailleur back on it. I live in the sticks and this LBS is not equipped to straighten frames. The FAQ page suggests manual straightening. Not crazy about that idea. I'll figure it all out. Dave |
#4
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Bent hanger -- Bent frame? ... shifting problems
On Thu, 04 Oct 2007 11:23:49 -0700, Art Harris
wrote: DaveH wrote: Rivendell suggested the frame may have been bent in the crash -- triangle pushed to the left. It looked like the hanger was bent something on the order of 2-3 degrees -- wild visual guess. Try the "string test" to check frame alignment: http://sheldonbrown.com/frame-spacing.html (scroll down near the bottom) Also make sure the shift wire is anchored at the correct place on the derailleur. Art Harris Art, Please see my latest post in the original thread. Thanks -- Dave |
#5
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Bent hanger -- Bent frame? ... shifting problems
DaveH wrote:
[58 cm Rivendell Ramboulliet -- steel frame, Dura Ace bar ends] Days ago I had a clipless newbie style slow-speed side crash which bent the derailleur hanger and the Ultegra rd-6500gs triple der. My LBS straightened the hanger and replaced the bent der with a Dura Ace rd-7700GS. The new der shifted fine on the stand -- but on the road I experienced problems, particularly when downshifting from 15 to 14 teeth cogs (Ultegra 12-27, 9 sp cassette). The prob seems to be erratic, not yielding to any amount of adjustment. Rivendell suggested the frame may have been bent in the crash -- triangle pushed to the left. It looked like the hanger was bent something on the order of 2-3 degrees -- wild visual guess. Generally, how frequently is a bent hanger accompanied by a bent frame? Tough question, I know. My immediate concern is whether I need to find a shop that is equipped for frame checking and alignment. I've read Sheldon and others regarding bent hangers and I've not seen bent frames being mentioned as an associated issue, though the possibility is obvious. Much more likely to be a simple error/oversight; derailleur alignment/adjustment/cable problem. You should be able to return to the shop which 'upgraded' your gear system and watch the Campagnolo "R" tool alignment then a full frame alignment gauge. If the rear end were off to one side enough to give shifting problems, you'd likely have noticed a difference when riding no hands. p.s. if there are plastic ferrules on your casing, have them replaced with real ones. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971 |
#6
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Bent hanger -- Bent frame? ... shifting problems
DaveH wrote:
[58 cm Rivendell Ramboulliet -- steel frame, Dura Ace bar ends] Days ago I had a clipless newbie style slow-speed side crash which bent the derailleur hanger and the Ultegra rd-6500gs triple der. My LBS straightened the hanger and replaced the bent der with a Dura Ace rd-7700GS. The new der shifted fine on the stand -- but on the road I experienced problems, particularly when downshifting from 15 to 14 teeth cogs (Ultegra 12-27, 9 sp cassette). The prob seems to be erratic, not yielding to any amount of adjustment. Rivendell suggested the frame may have been bent in the crash -- triangle pushed to the left. It looked like the hanger was bent something on the order of 2-3 degrees -- wild visual guess. Generally, how frequently is a bent hanger accompanied by a bent frame? Tough question, I know. My immediate concern is whether I need to find a shop that is equipped for frame checking and alignment. I've read Sheldon and others regarding bent hangers and I've not seen bent frames being mentioned as an associated issue, though the possibility is obvious. Dave Bent frame isn't very likely with just toppling over. If you can ride the frame no handed without the frame veering left or right it's fine. I'd investigate free movement of the shiftercable first. Is the cable properly located underneath the bracket? Last bit of outer cable not to short, kinked, badly cut. missing ferrule etc? And another good one: cable properly clamped in the groove on the derailleur body? -- /Marten info(apestaartje)m-gineering(punt)nl |
#7
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Bent hanger -- Bent frame? ... shifting problems
On Thu, 04 Oct 2007 15:57:48 -0500, A Muzi
wrote: DaveH wrote: [58 cm Rivendell Ramboulliet -- steel frame, Dura Ace bar ends] Days ago I had a clipless newbie style slow-speed side crash which bent the derailleur hanger and the Ultegra rd-6500gs triple der. My LBS straightened the hanger and replaced the bent der with a Dura Ace rd-7700GS. The new der shifted fine on the stand -- but on the road I experienced problems, particularly when downshifting from 15 to 14 teeth cogs (Ultegra 12-27, 9 sp cassette). The prob seems to be erratic, not yielding to any amount of adjustment. Rivendell suggested the frame may have been bent in the crash -- triangle pushed to the left. It looked like the hanger was bent something on the order of 2-3 degrees -- wild visual guess. Generally, how frequently is a bent hanger accompanied by a bent frame? Tough question, I know. My immediate concern is whether I need to find a shop that is equipped for frame checking and alignment. I've read Sheldon and others regarding bent hangers and I've not seen bent frames being mentioned as an associated issue, though the possibility is obvious. Much more likely to be a simple error/oversight; derailleur alignment/adjustment/cable problem. You should be able to return to the shop which 'upgraded' your gear system and watch the Campagnolo "R" tool alignment then a full frame alignment gauge. If the rear end were off to one side enough to give shifting problems, you'd likely have noticed a difference when riding no hands. p.s. if there are plastic ferrules on your casing, have them replaced with real ones. I wonder if the Dura Ace 7700gs triple rear derailleur is incompatible with my Sugino XD-2 48/36/36 crank since the problem is worst on the largest chainring, though I know that can be typical. |
#8
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Bent hanger -- Bent frame? ... shifting problems
DaveH wrote:
On Thu, 04 Oct 2007 15:57:48 -0500, A Muzi wrote: DaveH wrote: [58 cm Rivendell Ramboulliet -- steel frame, Dura Ace bar ends] Days ago I had a clipless newbie style slow-speed side crash which bent the derailleur hanger and the Ultegra rd-6500gs triple der. My LBS straightened the hanger and replaced the bent der with a Dura Ace rd-7700GS. The new der shifted fine on the stand -- but on the road I experienced problems, particularly when downshifting from 15 to 14 teeth cogs (Ultegra 12-27, 9 sp cassette). The prob seems to be erratic, not yielding to any amount of adjustment. Rivendell suggested the frame may have been bent in the crash -- triangle pushed to the left. It looked like the hanger was bent something on the order of 2-3 degrees -- wild visual guess. Generally, how frequently is a bent hanger accompanied by a bent frame? Tough question, I know. My immediate concern is whether I need to find a shop that is equipped for frame checking and alignment. I've read Sheldon and others regarding bent hangers and I've not seen bent frames being mentioned as an associated issue, though the possibility is obvious. Much more likely to be a simple error/oversight; derailleur alignment/adjustment/cable problem. You should be able to return to the shop which 'upgraded' your gear system and watch the Campagnolo "R" tool alignment then a full frame alignment gauge. If the rear end were off to one side enough to give shifting problems, you'd likely have noticed a difference when riding no hands. p.s. if there are plastic ferrules on your casing, have them replaced with real ones. I wonder if the Dura Ace 7700gs triple rear derailleur is incompatible with my Sugino XD-2 48/36/36 crank since the problem is worst on the largest chainring, though I know that can be typical. Doesn't sound likely. Does the DA rear have a weaker spring than the original? Sluggish shifting to smaller sprockets is usually because the spring is too light for the friction in the path. |
#9
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Bent hanger -- Bent frame? ... shifting problems
DaveH wrote:
[58 cm Rivendell Ramboulliet -- steel frame, Dura Ace bar ends] Days ago I had a clipless newbie style slow-speed side crash which bent the derailleur hanger and the Ultegra rd-6500gs triple der. My LBS straightened the hanger and replaced the bent der with a Dura Ace rd-7700GS. The new der shifted fine on the stand -- but on the road I experienced problems, particularly when downshifting from 15 to 14 teeth cogs (Ultegra 12-27, 9 sp cassette). The prob seems to be erratic, not yielding to any amount of adjustment. Rivendell suggested the frame may have been bent in the crash -- triangle pushed to the left. It looked like the hanger was bent something on the order of 2-3 degrees -- wild visual guess. Generally, how frequently is a bent hanger accompanied by a bent frame? Tough question, I know. My immediate concern is whether I need to find a shop that is equipped for frame checking and alignment. I've read Sheldon and others regarding bent hangers and I've not seen bent frames being mentioned as an associated issue, though the possibility is obvious. A Muzi wrote: Much more likely to be a simple error/oversight; derailleur alignment/adjustment/cable problem. You should be able to return to the shop which 'upgraded' your gear system and watch the Campagnolo "R" tool alignment then a full frame alignment gauge. If the rear end were off to one side enough to give shifting problems, you'd likely have noticed a difference when riding no hands. p.s. if there are plastic ferrules on your casing, have them replaced with real ones. DaveH wrote: I wonder if the Dura Ace 7700gs triple rear derailleur is incompatible with my Sugino XD-2 48/36/36 crank since the problem is worst on the largest chainring, though I know that can be typical. Crank's not the problem. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971 |
#10
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Bent hanger -- Bent frame? ... shifting problems
DaveH wrote: I wonder if the Dura Ace 7700gs triple rear derailleur is incompatible with my Sugino XD-2 48/36/36 crank since the problem is worst on the largest chainring, though I know that can be typical. Crank's not the problem. I replaced the DA 7700gs rear derailleur with a new Ultegra 6500gs. It now shifts perfectly. Smoother, more incisive -- it is a mystery. Now I must solve the bent frame problem. No hands it veers right, requiring a slight left body lean to maintain a straight line. I had an experienced friend confirm this. Mild, not terminal, but psychologically intolerable. I'm guessing I can find a frame man near Wash DC, 2 hours away. It is tempting to try the FAQ's manual straightening method. I think the rear-end needs to be pulled to the right ~1/16". Dave |
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