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#11
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Unwanted upshifting from 4th to fifth cog
On 5/1/10 4:12 PM, Mike Jacoubowsky wrote:
"bcdrums" wrote in message ... On 5/1/10 3:06 PM, Mike Elliott wrote: bcdrums wrote: I have a typical 9 speed triple road setup, all Shimano except for a SRAM chain. I have bar-end shifters, not brifters. Lately, after I shift from cog 3 to 4, moments later the chain will drop to 5. I adjusted the cable length on the derailler to make the cable longer, but that did not help. I checked the chain for elongation, but it is only about 1/32" long. I looked at the cogs for a clue, but they don't appear to be very worn, or perhaps I am not seeing it. About a month ago I changed the cables and housings for the brakes and shifters, but the problem is more recent. Any suggestions as to what might be causing this? The first thing I check when shifting gets dodgy is the cable tension. I shift to the smallest rear cog and check the shifter cable (the cable, not the housing) to see if there's any slack. If so, I loosen the cable clamp on the rear der and tug the looseness out of the cable.* This might not work for you, of course, because you might have something else going on, but it's generally my go-to procedure. ========== * There are barrel tensioner-like thingies on where the der cables exit the shifters but those have never done anything useful, near as I can tell -- I'm not even certain what they are there for. Mike, I did check the cable tension at your suggestion. It seems okay- it shifts up and down correctly across all cogs while on the stand (of course it does!). In case you are not just putting my leg on about the barrel adjuster, I will send you to Sheldon for his explanation of its purpose. http://www.sheldonbrown.com/derailer-adjustment.html As it turns out, Sheldon also has an article on spontaneous upshifting- which is my problem. I read it, and he said that the most frequent cause is a sticky cable at the bottom bracket, exacerbated by a strong heavy rider (which I am not). I will check this out too. BC Sheldon fan Cytomax dripping down a shift cable has been the cause of many shifting issues. Funny that you can get better shifting by using a bottle that seals better. :-) --Mike Jacoubowsky Chain Reaction Bicycles www.ChainReaction.com Redwood City & Los Altos, CA USA Leak proof bottle? sounds like a business opportunity. I have just now cleaned & re-lubed the cable guides under the bottom bracket. The guides are cut into the shell with a little bridge brazed over the channel so the cable cannot wander off. BC misguided |
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#12
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Unwanted upshifting from 4th to fifth cog
bcdrums wrote:
I have a typical 9 speed triple road setup, all Shimano except for a SRAM chain. I have bar-end shifters, not brifters. Lately, after I shift from cog 3 to 4, moments later the chain will drop to 5. I adjusted the cable length on the derailler to make the cable longer, but that did not help. I checked the chain for elongation, but it is only about 1/32" long. I looked at the cogs for a clue, but they don't appear to be very worn, or perhaps I am not seeing it. About a month ago I changed the cables and housings for the brakes and shifters, but the problem is more recent. Any suggestions as to what might be causing this? Check for kinks or frays in the gear wire, inspect for damaged casing, replace as needed. If you see any plastic ferrules, replace with metal ones. Ensure casing runs are smooth and unimpeded through the full motion of the handlebar. Look for cable adjusters which are cracked or adjusted beyond thread engagement. Check the bolts in your derailleur rollers- are they tight? Is the cassette lockring snug? Any play in the hub or cassette bearing? Inspect for bent changer mount, ensure changer mounting bolt is tight in frame, inspect for bent cage or bash marks on outer side of body. Oil the gear wire where it passes the nylon gear plate on the bottom of your frame. Yours is among the most durable and dependable shifters ever made, highly unlikely to be a shifter problem. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#13
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Unwanted upshifting from 4th to fifth cog
On 5/1/10 5:29 PM, AMuzi wrote:
bcdrums wrote: I have a typical 9 speed triple road setup, all Shimano except for a SRAM chain. I have bar-end shifters, not brifters. Lately, after I shift from cog 3 to 4, moments later the chain will drop to 5. I adjusted the cable length on the derailler to make the cable longer, but that did not help. I checked the chain for elongation, but it is only about 1/32" long. I looked at the cogs for a clue, but they don't appear to be very worn, or perhaps I am not seeing it. About a month ago I changed the cables and housings for the brakes and shifters, but the problem is more recent. Any suggestions as to what might be causing this? Check for kinks or frays in the gear wire, inspect for damaged casing, replace as needed. If you see any plastic ferrules, replace with metal ones. Ensure casing runs are smooth and unimpeded through the full motion of the handlebar. Look for cable adjusters which are cracked or adjusted beyond thread engagement. Check the bolts in your derailleur rollers- are they tight? Is the cassette lockring snug? Any play in the hub or cassette bearing? Inspect for bent changer mount, ensure changer mounting bolt is tight in frame, inspect for bent cage or bash marks on outer side of body. Oil the gear wire where it passes the nylon gear plate on the bottom of your frame. Yours is among the most durable and dependable shifters ever made, highly unlikely to be a shifter problem. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 Thanks for the thorough check list. I oiled the cable where it passes beneath the bottom bracket, although I don't have a nylon plate- the guides are cut into the shell. If that does not solve the problem, I will take out the cable and casing for inspection. They are recent, maybe 5 weeks since installation, but who knows, could be kinked somewhere. I did check the derailler mount bolt, and it is tight. The pulleys line up correctly under the sprockets, so I don't suspect that it is bent. Will be checking all that you suggested. Thanks again! BC |
#14
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Unwanted upshifting from 4th to fifth cog
On May 1, 11:36*am, bcdrums wrote:
I have a typical 9 speed triple road setup, all Shimano except for a SRAM chain. I have bar-end shifters, not brifters. Lately, after I shift from cog 3 to 4, moments later the chain will drop to 5. I adjusted the cable length on the derailler to make the cable longer, but that did not help. I checked the chain for elongation, but it is only about 1/32" long. I looked at the cogs for a clue, but they don't appear to be very worn, or perhaps I am not seeing it. About a month ago I changed the cables and housings for the brakes and shifters, but the problem is more recent. Any suggestions as to what might be causing this? BC shifty I had this once but in the opposite direction -- whenever downshifting from 4th to 3rd it would skip right over and end up in 2nd with the chain noisily unaligned. Turned out to be a bit of the 3rd sprocket that had been hit by something and bent inward slightly. -pm |
#15
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Unwanted upshifting from 4th to fifth cog
On Sat, 01 May 2010 12:06:02 -0700, Mike Elliott
wrote: bcdrums wrote: I have a typical 9 speed triple road setup, all Shimano except for a SRAM chain. I have bar-end shifters, not brifters. Lately, after I shift from cog 3 to 4, moments later the chain will drop to 5. I adjusted the cable length on the derailler to make the cable longer, but that did not help. I checked the chain for elongation, but it is only about 1/32" long. I looked at the cogs for a clue, but they don't appear to be very worn, or perhaps I am not seeing it. About a month ago I changed the cables and housings for the brakes and shifters, but the problem is more recent. Any suggestions as to what might be causing this? The first thing I check when shifting gets dodgy is the cable tension. I shift to the smallest rear cog and check the shifter cable (the cable, not the housing) to see if there's any slack. If so, I loosen the cable clamp on the rear der and tug the looseness out of the cable.* This might not work for you, of course, because you might have something else going on, but it's generally my go-to procedure. Also check the cable for permanent bends or kinks. I've bent them (by snagging on objects) and it makes the cable 'springy'. This is followed by unreliable shifting and self-shifting. The only cure I know of is cable replacement. I've never managed to strighten out permanent bends in cable so it's 100% OK. |
#16
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Unwanted upshifting from 4th to fifth cog
I had an unusual problem with bar-ends recently. The fixing bolt had
worked loose, so the shifters could rotate in the handlebar. I knew it was causing poor shifting, and I would occassionally straighten them, but it was only when I bothered to tighten them up firm and greatly improved the shifting that I realized how much of a problem it was. |
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