Rear derailleur not shifting right/slipping
01-22-19, 12:43 PM
#1
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Rear derailleur not shifting right/slipping
Hi guys, in the commute forum I was talking about this but I haven't been able to unravel it.
I get major slippage in 6, as well. My bike is a Trek FX3, which is mostly new (~500 miles ridden to date), and the derailleur is a Shimano Alivio T4000. I've never crashed or bashed or otherwise harmed the bike in any way. I will say that the issue started last week after I had the rear wheel off to fix a flat. Visual inspection reveals no super obvious issues (to me, an amateur youtube/google-brain mechanic at best) - the derailleur and its hanger don't appear bent or anything.
Any ideas what I could check? I imagine this is probably a rookie error but I'd like to stop the gear slippage cuz it's pissing my knee off. Appreciate it!
However...I've got an issue with my rear derailleur. The low and high gears seem okay (9 cogs) but the 3-6 range is all out of whack, 4 especially. A lot of times, 4 just doesn't want to catch. Downshifts from 5 usually do nothing until I click it again, then I'm in 3. Going back up one from there drops me into 6, then I can click down into 5. That's actual chain position - the indicator seems right but doesn't match the chainring. Also, I'm having slipping in some lower gears as well.
Any ideas what I could check? I imagine this is probably a rookie error but I'd like to stop the gear slippage cuz it's pissing my knee off. Appreciate it!
01-22-19, 01:28 PM
#2
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Your derailleur housing has probably settled in, or you'll hear people call it "cable stretch," but it's usually more of the former. I'd check that first by turning the adjusting barrel where the housing meets the rear derailleur a half turn counterclockwise as if you were unscrewing it. Do a half turn, see if that improves it. If it's a little better, but not fixed, do follow it with a quarter turn, etc. Extremely common for bikes ridden their first x hundred miles.
Usually, the signs are skipping or rubbing when trying to shift into a larger cog. Your description isn't right on the mark, but I'd still try that first.
Usually, the signs are skipping or rubbing when trying to shift into a larger cog. Your description isn't right on the mark, but I'd still try that first.
01-22-19, 08:52 PM
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Sudden problem, look for a sudden cause. Did you lay the bike on its right side, even gently? Maybe remove and remount the rear wheel making sure to get it right.
Also, learn how to routinely adjust the derailleur as wear accumulates.
Also, learn how to routinely adjust the derailleur as wear accumulates.
01-23-19, 07:30 AM
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Started after a wheel reinstallation, eh? Make certain that your rear wheel is fully seated in the dropouts..Check the ends of all your shift housing runs to ensure that they have not gotten dislodged from their sockets. Then follow this procedure from the beginning to properly set up your shifting: https://www.parktool.com/blog/repair...eur-adjustment Don't skip any steps or go to the next one until you are satisfied with the current step.
01-23-19, 05:56 PM
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I wonder if the RH QR spring is on backwards. if so it will slightly cock the wheel in the frame and can give almost but not quite shifting sensations. Andy
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AndrewRStewart
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01-23-19, 08:59 PM
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The derailleur hanger is probably out of alignment, usually presents itself as problems in the middle range of the cassette. Unless you have a derailleur alignment gauge tool it can be hard to tell if it is out of alignment with the naked eye unless it is really bent. You did not say if you put the bike in a stand to take out the wheel, but I have seen people bend hangers by putting the bike on the ground on the derailleur after the rear wheel is removed.
I reread the OP and did not see the fact it is a new bike, could very well be the lack of cable tension on the RD as someone stated above.
I reread the OP and did not see the fact it is a new bike, could very well be the lack of cable tension on the RD as someone stated above.
Last edited by Carverbiker; 01-23-19 at 09:03 PM.
01-24-19, 03:14 PM
#7
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Thread Starter
Your derailleur housing has probably settled in, or you'll hear people call it "cable stretch," but it's usually more of the former. I'd check that first by turning the adjusting barrel where the housing meets the rear derailleur a half turn counterclockwise as if you were unscrewing it. Do a half turn, see if that improves it. If it's a little better, but not fixed, do follow it with a quarter turn, etc. Extremely common for bikes ridden their first x hundred miles.
Usually, the signs are skipping or rubbing when trying to shift into a larger cog. Your description isn't right on the mark, but I'd still try that first.
Usually, the signs are skipping or rubbing when trying to shift into a larger cog. Your description isn't right on the mark, but I'd still try that first.
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Don in Austin
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