Chump stumper – rear derailleur

This topic has 34 replies, 11 voices, and was last updated 8 years, 2 months ago by huskerdont.

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May 9, 2017 at 1:06 pm #919374

huskerdont
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Apologies that this is kinda long and involved; feel free to ignore if not your thing.

History:

1) Stupidly stated that 9-speed bike never needed adjusting.
2) Replaced OE rear derailleur with Sora. Worked okay ~1 year.
3) Installed replacement chain and cassette (SRAM 971, 11/28).
4) Broke chain on first ride. Lots of noise and a wreck; perhaps bent derailleur?
5) Bike shop replaced chain with random, unwrapped chain pulled out of the bin, assuring me it was a SRAM 951.
6) Installed replacement chain. Bike skipped in larger 3 or 4 cogs, no matter how adjusted. Sometimes it wanted to shift on its own, and sometimes it just jumped while staying on cog.
7) Discovered that random, out-of-bin chain had a sticky link. Thanks, LBS!
Purchased new SRAM 971 chain in actual original packaging … at a different shop.
9) No longer jumps, but still tries to shift or skip in larger cogs. Sora derailleur appears to have a lot of play in it–much more than Ultegra on other bike, but not sure what’s normal for Sora.
10) Installed 10-speed Tiagra derailleur that was a spare to another bike. Shifts beautifully, except…
11) I can get it to shift up to the largest cog (28), or the smallest cog (11), but not both. Limits from limiting screws are fine–the derailleur can move to all positions, it just doesn’t want to stay on the largest cog unless I adjust it so much that it won’t go to the smallest.

Opted for the smallest cog since this is a triple and I can go to the small ring if needed. Barring other ideas, next step is to eventually take to shop to see if mount on frame is bent (no derailleur hanger). Mount could have been bent in wreck, and it maybe does look possibly a little wonky.

Or I could just ride it since it’s now shifting like an (8-speed) dream.
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May 9, 2017 at 1:12 pm #1070529

EasyRider
Participant

Could it be a shifter/rear derailleur compatibility issue?

May 9, 2017 at 1:37 pm #1070510

huskerdont
Participant

@EasyRider 159758 wrote:

Could it be a shifter/rear derailleur compatibility issue?

It could be, though I would expect that if I were trying to use a 9-speed derailleur for a 10-speed setup instead of vice versa, plus it shifts so well in every other regard. This was a consideration before I threw this on there, and I read conflicting advice on forums about whether it would work due to spacing, but it does seem to shift well so I think the spacing issue isn’t one. It’s just hard to find non-Sora 9-speed derailleurs nowadays so I thought I’d try this. I’m certainly amenable to picking up a 9-speed if I can find something better than Sora.

May 9, 2017 at 1:44 pm #1070511

drevil
Participant

5) I’ve never seen a SRAM chain not say what model they are on each outer plate (like this). Maybe they exist, but I’ve ne’er seen it.

I’m a mtb guy, so take this with a grain of salt, but I thought that 10-speed Dynasys used a different pull.

https://www.bikerumor.com/2011/10/19/question-can-i-use-9-speed-derailleurs-with-10-speed-shifters/
“JOE @ SHIMANO: Not really. Anything with Mega9 on it was designed to work together as a 9-speed system, and anything with DynaSys on it is 10-speed only. The cable pull ratio is different. The 10-speed stuff pulls a lot more cable, and the lever arm on the rear derailleur is much longer. We designed it this way so when you do your shifts from the smallest cog all the way up, the lever feel is the same all the way through the range. Also, the 9-speed was more of a universal system, too, but the DynaSys is an exclusive mountain bike system.”

http://www.sheldonbrown.com/speeds.html
“Shimano “Dyna-Sys” shifters and derailers use a longer cable pull than other Shimano models, and must be used together.”

May 9, 2017 at 1:45 pm #1070512

Crickey7
Participant

You matched cage length?

In a totally unrelated bit of information, I have a brand new 10 speed Tiagra medium cage derailleur I’d let go for practically nothing.

May 9, 2017 at 1:51 pm #1070514

EasyRider
Participant

What shifter are you using?

May 9, 2017 at 1:51 pm #1070515

huskerdont
Participant

@Crickey7 159763 wrote:

You matched cage length?

In a totally unrelated bit of information, I have a brand new 10 speed Tiagra medium cage derailleur I’d let go for practically nothing.

I believe the cage length is supposed to be fine for this cassette–28 on large cog.

If/when I replace, I’d like to do it with a 9 speed.

May 9, 2017 at 1:53 pm #1070516

huskerdont
Participant

@EasyRider 159765 wrote:

What shifter are you using?

The 9-speed, I think it’s Tiagra.

May 9, 2017 at 2:28 pm #1070531

Harry Meatmotor
Participant

This smells like a slightly tweaked RDer hanger.

Or, dirty/not-well-lubed cables and housing.

May 9, 2017 at 2:33 pm #1070532

huskerdont
Participant

@Harry Meatmotor 159770 wrote:

This smells like a slightly tweaked RDer hanger.

Or, dirty/not-well-lubed cables and housing.

Thanks. Cable is new, so it’s possible it’s the hanger area/mount. Will take it in to have it looked at.

Thanks to everyone for their ideas.

ETA: (Poorly focused) pic of mounting area/RD:

[ATTACH=CONFIG]14731[/ATTACH]

May 9, 2017 at 3:06 pm #1070533

Drewdane
Participant

@huskerdont 159757 wrote:

Opted for the smallest cog since this is a triple and I can go to the small ring if needed. Barring other ideas, next step is to eventually take to different shop to see if mount on frame is bent (no derailleur hanger). Mount could have been bent in wreck, and it maybe does look possibly a little wonky.

Or I could just ride it since it’s now shifting like an (8-speed) dream.

I don’t have any advice for you except the bolded bit.

May 9, 2017 at 3:28 pm #1070534

huskerdont
Participant

@Drewdane 159773 wrote:

I don’t have any advice for you except the bolded bit.

Yeah, this shop has been good to me over the years, doing things like replacing a shattered chain ring while I was at work, so this is why I didn’t name names, and I’ll eventually give them another chance. But I was disappointed. Maybe it was just this one mechanic. And I should have probably insisted on getting the same level of chain (and a new one), so it’s partly on me.

May 9, 2017 at 6:38 pm #1070553

EasyRider
Participant

@huskerdont 159757 wrote:

Limits from limiting screws are fine–the derailleur can move to all positions, it just doesn’t want to stay on the largest cog unless I adjust it so much that it won’t go to the smallest.

How are you accomplishing this?

May 9, 2017 at 7:11 pm #1070554

huskerdont
Participant

@EasyRider 159793 wrote:

How are you accomplishing this?

With the adjuster.

May 9, 2017 at 7:48 pm #1070555

EasyRider
Participant

Your derailleur hanger doesn’t really look bent to me, but as you say, not a great picture. Maybe, it’s off a bit since your wreck. Certainly a bent hanger is a suspect, because ever since then, with new chains and new rear derailleurs and new cassettes, you’ve had trouble getting the chain onto the largest cogs and keeping it there.

No offense intended, but if it’s not a bent derailleur hanger, I’d look at installation error, since you’ve replaced most everything else, and the problem you had with the Sora RD is now repeating itself with the Tiagra. Even improper pinch bolt orientation can influence shifting. If you’ve already followed the Big Blue Book to a ‘t’, then disregard.

Re: the sticky link chain from the bin … did the LBS install it for you, or did they sell it to you and you installed it yourself? I wouldn’t be in a hurry to return to a shop that installed a new chain without checking it’s operation through the range of gears — especially if they knew the last chain had snapped in use and caused the bike to wreck!

May 9, 2017 at 8:00 pm #1070556

Vicegrip
Participant

A hanger can be bent enough to cause issues and not be visibly bent. A hanger checker in good hands is the way to tell. Sounds like 1. A mismatch between the index shifter and RD pull ratios. 2 slop in the system. 3. Something else not described but discover-able in person.

Bring it over. Much to my kids embarrassment I tend to yell “stump the chump” and general answers at the radio when I recover from laughing at/with Click and Clack the Tappet brothers.
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