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XT rd tension

Old 03-01-21, 10:21 AM
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XT rd tension

Hey all - is there any way to increase the cage’s spring tension? The chain is sized correctly but it sits on the cable in the lower cogs because the rd can’t keep it taut. I'm pretty sure it's the b-tension spring and not the cage itself.

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Old 03-01-21, 11:18 AM
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I don't have one right here, but this video may help.
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Old 03-01-21, 11:30 AM
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It is not unheard of for either spring to break, if perhaps you noticed a sudden loss of chain tension(?).
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Old 03-01-21, 11:32 AM
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I doubt it from the pic, but have you exceeded the RD capacity? Probably fine, especially if thatís a double, but worth confirming as a first step. How did you size the chain?
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Old 03-01-21, 11:43 AM
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And here's the corresponding RJ video for the pivot bolt/spring:
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Old 03-01-21, 12:06 PM
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Other question not related to chain length- is the RD cable adjuster missing or broken?
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Old 03-01-21, 12:41 PM
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Originally Posted by curbtender View Post
I don't have one right here, but this video may help. https://youtu.be/1sZS49JmXK0
I saw that too and don't think that's it.

Originally Posted by dddd View Post
It is not unheard of for either spring to break, if perhaps you noticed a sudden loss of chain tension(?).
Nope. New rd to me anyway so nothing to go off of with this one.

Originally Posted by Sir_Name View Post
I doubt it from the pic, but have you exceeded the RD capacity? Probably fine, especially if thatís a double, but worth confirming as a first step. How did you size the chain?
Nope, all good on capacity. I sized like Shimano suggests: big/big + 2 links. Chain length looks spot on.

Originally Posted by panzerwagon View Post
And here's the corresponding RJ video for the pivot bolt/spring: https://www.youtube.com/watch?v=bgiNuJNynMc
That's awesome for seeing how the parts are put together. I'm not too hopeful that's the fix for this rd though, I think the spring is just worn. I think this might be a good solution though:
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Old 03-01-21, 12:41 PM
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Originally Posted by rccardr View Post
Other question not related to chain length- is the RD cable adjuster missing or broken?
Missing but en route. Doesn't affecting shifting though
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Old 03-01-21, 12:59 PM
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You could try flipping the B screw around so that it screws in from the "inside" and the screw head rests on the B screw stop on the der. hanger. It would give you a little extra kick back on the der. Maybe not enough to make up for all that chain slack though.
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Old 03-01-21, 01:06 PM
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That derailleur looks like it has a short cage, which was uncommon for that model. If it were replaced, maybe the spring tension wasn't set properly.

FWIW, here is my M737 in small/small; your chain looks long but its hard to see; a pic of big ring/big cog should be clearer.

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Old 03-01-21, 01:18 PM
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Originally Posted by DorkDisk View Post
That derailleur looks like it has a short cage, which was uncommon for that model. If it were replaced, maybe the spring tension wasn't set properly.

FWIW, here is my M737 in small/small; your chain looks long but its hard to see; a pic of big ring/big cog should be clearer.

Yeah that's definitely what the chain is supposed to look like.

It took me a minute but I figured out why my RD looks different, it's because it has an XTR GS cage installed on it. It's not a short cage though. It has "Max 32T, Total 33T" printed on it.
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Old 03-01-21, 01:20 PM
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Originally Posted by DorkDisk View Post
That derailleur looks like it has a short cage, which was uncommon for that model. If it were replaced, maybe the spring tension wasn't set properly.
RD-M739 came in both GS (32/33) and SGS (32/38) versions. The RD-M735 even came in a short cage version (28T max cog I think), but not sure if M739 was available in that version.

https://www.disraeligears.co.uk/Site/...96_scan_2.html

I believe this is the "middle cage" version.

(Edit: not sure why the link is not working, but here's the main link: https://www.disraeligears.co.uk/Site/..._M739_SGS.html. Look under 'Documents')

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Old 03-01-21, 01:21 PM
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Originally Posted by shoota View Post
Yeah that's definitely what it's supposed to look like.

It took me a minute but I figured out why my RD looks different, it's because it has an XTR GS cage installed on it. It's not a short cage though. It has "Max 32T, Total 33T" printed on it.
That'd be the medium cage
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Old 03-01-21, 01:35 PM
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Originally Posted by shoota View Post
That's awesome for seeing how the parts are put together. I'm not too hopeful that's the fix for this rd though, I think the spring is just worn. I think this might be a good solution though: https://www.youtube.com/watch?v=A7Coy083--0
Before you start drilling, you might consider at least trying disassemble/clean/re-grease/re-assemble, and make sure the spring is in the tighter setting of the two. That might prove sufficient (plus appropriate b-tension adjustment).
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Old 03-01-21, 02:01 PM
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Originally Posted by panzerwagon View Post
Before you start drilling, you might consider at least trying disassemble/clean/re-grease/re-assemble, and make sure the spring is in the tighter setting of the two. That might prove sufficient (plus appropriate b-tension adjustment).
Oh for sure! Now that I have an idea how the parts fit together I'll give that a go first.
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Old 03-02-21, 01:31 AM
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It could be that a previous owner somehow over-tensioned the spring while trying to get it re-installed.

Sometimes people get confused as to how reassembly is done, and the cage gets twisted too far with the stop pin removed.

Perhaps also the spring is from different derailer than this setup, so the spring anchor holes aren't clocked right for this spring(?).
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Old 03-03-21, 04:14 PM
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I have ran into an issue like this, and it was that the screw that is the stop for the Jockey Wheel plates was removed and was replaced but the cage plates had rotated causing very little tension on the cage plates and a drooping chain like that.
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Old 03-04-21, 09:40 PM
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Originally Posted by dddd View Post
It could be that a previous owner somehow over-tensioned the spring while trying to get it re-installed.

Sometimes people get confused as to how reassembly is done, and the cage gets twisted too far with the stop pin removed.

Perhaps also the spring is from different derailer than this setup, so the spring anchor holes aren't clocked right for this spring(?).
like this?
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Old 03-05-21, 08:48 PM
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Oh yeah, that spring looks mangle-ated, definitely wound too tight at some point, gad.

Doesn't mean that it can't still be used, just has to be tensioned to suit it's new "configuration".
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