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Discussion Starter · #1 ·
Came up after last ride, bike has never been down on RD side. It I try to backpedal I can only get maybe 1 revolution before the chain drops to the next lower cog and then binds the RD.

Suggestions on the cause? I have already went thru the trim and the limits screws and checked them, thinking maybe a bent RD hanger???

Drivetrain is 2014 Shimano XT other than the cassette which is a XX10sp 11-36.
 

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Well, drivetrains are designed with forward pedaling in mind. If the gear that it falls off is toward the extremes of chain angle then this is to be expected.

With regard to causes of a mis-alignment (if this is the cause).... the hanger could be bent, cage or derailleur bent, limit screws off, cable tension incorrect or the cable housing itself might be causing some drag.
 

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How many miles do you have on the cassette? After a lot of miles the back edges of the teeth on the cassette can develop burrs/ridges, which then might prevent the chain from dropping onto the cassette smoothly and/or falling to the next cog.
 

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Discussion Starter · #5 ·
Cassette is band new, cable tension is fine as that is the first thing I checked along with the limit screws and trim adjustment.

I went ahead and ordered a park hanger tool, waiting on it to come in. Only other change was a swap out from the stock HG81 (Shimano SLX) cassette to the SRAM XX cassette.

Not that I back pedal a lot, but at times depending on the terrain and technique needed I need to be able to do it and not have the RD bind up.
 

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B screw ... people don't believe it but the B screw too far out will cause this.
New cassette... Old(er) Chain?
Hanger alignment (you're getting the tool so that will soon be eliminated)
 

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When was the last time you lubed your chain?
 

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Discussion Starter · #8 ·
I am anal about bike maintenance, bike gets washed almost after ride and chain is wiped down and lubed every week or so.

Bike only has 300 miles on it, so I wouldn't think it is an older chain issue.
 

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Discussion Starter · #10 ·
Very recent, just happened after I put the XX cassette on the new wheels. I had to re-adjust the RD trim which I expected, and everything rides like it should during normal pedaling. It is only when you back pedal does it drop and bind the RD.

The trails here are really tight in areas, some of them are littered with rocks and boulders so sometimes you need to be able to back pedal as part of your technique.
 

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Since the issue occurred right after you changed the wheel and cassette I think you can probably eliminate anything unrelated to that such as bent hanger, etc. and focus on things that could have happened during that swap. I think thomllama's suggestion regarding a new cassette/old(er?) chain might just be a bullseye. How many miles on the chain?

The two other things that changed are the limits (only would affect big or little cog) and cable tension. Cable tension can be off a turn or two (at the barrel adjuster) from ideal and still shift pretty good.

I would put the bike on a stand and in any gear except the big or little one and pedal backwards very slowly. When you see the chain catch move the cranks even slower and carefully note what is happening with the chain, jockey wheel, and cog. Manually manipulate the derailleur slightly one way or the other and see if anything changes. Repeat until you have an epiphany.
 

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Discussion Starter · #12 ·
Well issue was found today by my awesome mechanic. Bike only has 300 miles on it, chain is cleaned no less than every other week with citrus cleaner with a parks chain cleaner, then dried and lubed immediately after.

Seems the nice factory KMC chain Giant put on a $5k bike took a crap on me, put on a new SRAM 1091R and all is well again.
 

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Discussion Starter · #14 ·
No it seemed fine, but then again maybe it was just stiff enough to not run smoothly. Never really noticed how loud the stock chain was, the new one is whisper quiet.
 

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To be honest, sounds like you're overly cleaning the chain and stripping the lube out. Especially a new chain, I'd never used any degreaser on it till it needs to be "stripped" and soaked in oil.

New chain should only be wiped with a slightly moist rag with rubbing alcohol for the first 1/4 of its life. Using citrus cleaners that early and frequently will strip the factory lube which no after market product can truly replace. Only exception is super muddy or fine sand locations, and either of those a chain (and the rest of the bike as well) won't last long compared to normal riding conditions.

Also using a chain cleaner machine with the citrus I'm guessing it's still on the bike and there's no way you'll be able the completely rinse all the cleaner out. Any lube you add after that is being broken down by the bits of degreaser left behind inside before you spin the pedals once.
 

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I have taken to keeping the factory grease on, and ever since then my chain life has increased, as has my cassette life. I use Chain L, and just put the first application on the new chain, and the slightly thinner lube makes the outer grease wipe off better. There may well be a good bit of lube penetration with that first application too. I really only blast the outer grit off now....I never get into cleaning the chain thoroughly. The new lube gets applied once I wipe the excess crud off, then more crud is removed (with excess lube) after working the chain about a bit
 

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Discussion Starter · #17 ·
Due to the type of trails we have here in Oklahoma, you cant let the chain go as long as you all suggest. Our trails are fine dirt/sand, as an example the brand new chain I had put on last night was thickly coated brown inside and out with sand by the end of my 12mile ride. Was already starting to make more noise, had to clean and lube it last night right after the ride. the factory grease is no bueno for this area of the USA as it collects everything.

If you leave the sand/dirt on them it will kill the chain in a matter of a couple of months. The chains will start making horrid grinding noise and the drivetrain will start making all sorts of noise when pedaling.

The only time I've had issues with chains is with the cheaper KMC chains that the factory uses on the bikes, the higher end SRAM and Shimano chains have given me no issues so far. My Spec Epic FS bike had the same issues with the stock KMC chain, it was replaced with a SRAM 1070 and using the same cleaning cycle went over a 1000 miles and was still good when I got rid of the bike.
 
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