it clanks when i’m in gear 1-4 and if i shorten the chain it rubs on derailleur
cassette is within specs of defaileur
by Seaworth_ford
it clanks when i’m in gear 1-4 and if i shorten the chain it rubs on derailleur
cassette is within specs of defaileur
by Seaworth_ford
17 Comments
it it mounted correctly? kinda looks like it’s not sitting on the lip of the hangar properly but hard to tell from the photo.
You’re probably exceeding the derailleur’s capacity. Looks like you’re running a very large sprocket. What’s the chainring size?
If you run a single 32T chainring and an 11-50T cassette:
**Front Capacity:** 32 – 32 = 0
**Rear Capacity:** 50 – 11 = 39
**Total Capacity Required:** 0 + 39 = 39
*Result:* You need a rear derailleur with a total capacity of **at least 39 teeth** (and a maximum cog size of 50T). [[1](https://www.youtube.com/shorts/GtfcD2Qxyhc), [2](https://www.reddit.com/r/bikewrench/comments/ym90dp/do_i_need_a_long_cage_derailleur/), [3](https://rinascltabike.com/bike/drivetrain/derailleur/)]
Do the maths and find that derailleur’s total capacity on their web site. You might need to reduce the size of your chainring.
That derailleur looks like a mid size capacity and you need large.
Looks like a shorter cage derailleur and you need a long cage
I think you’ll have to wait for someone with the same derailleur for this one – as you said the cassette is within spec (50t) as stated on AliExpress – and it looks (based on my Deore and SRAM) to be in the correct position when on the largest gear, but it’s definitely too “folded up” when in the low gears.
I wonder if the derailleur needs a b-link
The T9 RD supports up to an 11-50T cassette. Which means it has a capacity of 39T. A properly sized chain, largest cog and chainring length +4 links at sag (hardtails are always at sag conveniently) should yield an appropriate chain length.
If the chain is measured this way then what I would do is verify there’s a 3mm gap between the jockey and cog when shifted to the largest cog. With slack chain vs short chain situations, usually the chain has been sized incorrectly and the B screw isn’t set correctly either.
If you are unable to get the jockey to get closer to the cassette in the largest cog by turning the B screw anti-clockwise, the chain is too short and that’s the issue that needs to be fixed first.
If uncertain about the chain length, just take a minute to measure it again and verify that isn’t the problem.
Edit: I don’t have a T9 personally, but I’ve set up a couple of them and they work pretty well. It’s sort of unfortunate that the SRAM B screw guides don’t really work for them, but what can you do?
Just because the cassette size is within the derailleur specs does not mean it will work. That is necessary but not sufficient. The total capacity must also be in spec. Capacity is the difference (range) of the cassette, plus the range of the front chainrings. In your case, it appears that the cassette’s max sprocket is in spec, but the total capacity exceeds this derailleur’s maximum because the size difference of the front chainrings is too great.
To handle a greater capacity, the derailleur needs a longer cage.
You have a choice, to make . You need to either get a;
1. Larger chainring, if it will fit.
2. New cassette with a smaller tooth low gear, think 42T.
3. Or a new long cage rear derailleur.
Your choice, but nothing else is going to fix this problem.
I would get a new derailleur.
Can you please remove the wheel and post a pic from the other side showing the backside of the hanger?
So… From what has been said so far the cassette is in spec for the derailleur and the derailleur is the long cage version.
If we assume this is true and it’s not the derialler and it’s not the cassette… 1. What is the chainring setup here? 2. Is this a replacement with like parts or new setup?
What is happening at the front? Is this a 1x setup? My feeling is with that much chain slack looks like you have a double or triple on the front. Total mech capacity includes and front chain rings. Sorry if I’m jumping to conclusions!
Wrong derailleur size for the cassette capacity.
You can find adapter-cages for some derailleurs, eg. RADr cage from oneup for 10sp.
Is the b-limit screw threaded way in? If so, back it out until the pulley is closer to the largest cog in the biggest front & rear gear, then you can typically remove a link so it fits in small/small.
My guess, with very limited info, is the chain is too long but the b-limit screw is turned way in to try & take up slack in small/small. I could be wrong as I don’t know this derailleur really well and I can’t see all the adjustment screws up close.
Check the B-gap. The derailleur and the cassette are compatible, so it must be it
Your pictures don’t show the attachment at the hanger. I’d make sure that it’s actually connected properly before doing any other troubleshooting.