So my wife has a Trek Roscoe with shimano gearing. The last few rides when she back peddles while stopped her chain will derail the front sprocket. I come from a motorcycle background so this is a bit different where do I start derailleur bent? Thanks for any help.
Wife's chain derailing?
Dtfuzzy
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So my wife has a Trek Roscoe with shimano gearing. The last few rides when she back peddles while stopped her chain will derail the front sprocket. I come from a motorcycle background so this is a bit different where do I start derailleur bent? Thanks for any help.
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Does it fall of the chainring backpedaling in any/all of the cogs (largest to smallest), or just some specific ones? I've certainly had the chain drop off the largest cog of my cassette backpedaling, but never the chainring.
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I've seen this when the freewheel or freehub is gummed up and needs serviced or replaced. It causes slack at the top of the chain during coasting and backpedaling and allows the chain to fall off when backpedaling due to movement added to the slack. The issue is compounded when the derailleur springs are weak.
Now that you say that.... it usually happens after a climb while stopped getting ready to start she back peddles and it derails so it would be in the highest gear or two? But it's off the crank not the cassette?
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Well, I would look at what @Wabatuckian mentioned, make sure that something isn't amiss in the freehub body. The other possible symptom of a sticky freehub body could also be increased chain slap if it's dragging. Only other things I can come up with over them interwebs would be chain wear, really odd chain line or a bent chain ring. The latter would "probably" stay on while under tension pedaling forwards, but maybe not backpedaling. Is it ALL Shimano? (i.e. the chain, cassette, chainring/crank). Has anyone done any maintenance to the bike recently? Any crashes?
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Are you able to post a video?
I will see if I can repaclate it tomorrow?
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If you have a stand, put the bike on it and get the rear wheel spinning forward. Check the top of the chain for sag. I've seen them go all the way down to the chainstay.
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Don't over think this
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Hey now, take it easy. That's what we do here.
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Is this occurring most often in the largest rear gear? This is gearing is traditionally considered a "no-no" due to extreme cross-over on the chain-line. If this is the case, good news! There's nothing wrong with her bike. Its completely normal. The crossover condition will improve as the drive train wears in. If its a critical nuisance, take it to your LBS. There are minor adjustments to the hi-lo rear der limit settings, b-tension setting, and the shop can double check the rear der hanger's alignment. If the bike is a 2x (2 chain rings up front), then the additional chain ring (typically the larger one) may be aggravating the condition even further.
I just refreshed my SRAM drive train. I had this EXACT situation for the first ~50-60 miles (5k ft of climbing) and then the chain stretched and settled in. The condition improved with every ride until it no longer occurred. On this particular bike I am running a 1x12, 34t x 11-52t, all Eagle XO, except the cranks are Eagle GX (carbon cranks don't last long for me, so no XO).
Well after reading some comments and getting the bike on a stand this is what I found. In low gear I could get it to derail off the bottom of the crankset with some back peddling. I adjusted the low gear limits for the derailleur and cleaned things up I can't get it to derail now.
So we'll test it on a ride next at least I can tell her what to look out for? Thanks guys for the input.
So we'll test it on a ride next at least I can tell her what to look out for? Thanks guys for the input.
that's interesting that it is derailling off the crankset. i usually see this happening where it comes off the rear cassette (into the spokes), or sometimes it tries to upshift several sprockets.
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That's exactly where my chain was derailling (or reverse chainsucking?).
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Still overthinking this...
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