Quantcast

B screw not contacting hanger correctly

Sandwich

Pig my fish!
Staff member
May 23, 2002
19,897
4,046
borcester rhymes
So I am putting together the spooky and have come across a small but confuing issue. The b-screw on my used tiagra derailleur does not "properly" contact the hook on the derailleur hanger. The screw effectively hangs halfway off, and I'm not solidly convinced that it won't wear the hook out over time and move forward, reducing b tension. Image attached.




You can see where the screw has been gnawing at the hanger even before ever being ridden. I fixed this issue on my MTB by putting a nut on the end of the screw and it makes firmer contact.

That being said, 2/3 of my shimano derailleurs have this issue. The BMC is a direct mount, XT on a direct mount BMC hanger (no weird intermediate link). This is a regular old derailleur on a regular hanger. Is it possible that I just have two wack-ass derailleur hangers? Am I missing something? Neither screw is maxed out. I can probably jerry rig this like the BMC but I feel like something must be wrong.
 
Last edited:

jstuhlman

bagpipe wanker
Dec 3, 2009
15,180
10,504
Cackalacka du Nord
all the lower end sram ones (x9, then gx) used to do this on me. i too stuck a nut on the end. at some point i think i determined that the metal on the cage was soft and let the screw develop play. no issue since switching to xo1.
 

canadmos

Cake Tease
May 29, 2011
17,217
15,427
Canaderp
Hmm strange. I thought most newer derailleurs, like made in the last 15 years, mostly had a tab thing on the main hanger bolt, which stops this from happening.

Did some googling and maybe you could flip the screw around, so the head is up against the hanger tab? Obviously can't adjust it once it's all assembled..
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
12,885
9,768
On SRAM @canadmos is referring to this part pointed to with the red arrow. That tab wedges against the hanger, the bolt then wedges against the little stick out toe to the left. Haven't had anything Shimano for a little while to know what they have.

277582.jpg
 

jonKranked

Detective Dookie
Nov 10, 2005
80,427
19,773
media blackout
zooming in it looks a little scraped up. does it appear to be out of alignment? I've seen happen a couple times on derailleurs that got mangled... iirc you said you had to replace a bent pulley cage no? it's possible that wasn't the only thing derped up
 

Sandwich

Pig my fish!
Staff member
May 23, 2002
19,897
4,046
borcester rhymes
zooming in it looks a little scraped up. does it appear to be out of alignment? I've seen happen a couple times on derailleurs that got mangled... iirc you said you had to replace a bent pulley cage no? it's possible that wasn't the only thing derped up
Anything is possible, and I am open to "manually realigning" the bolt if that might fix it. I tried an older LX derailleur with the same mounting setup on for size and it's exactly the same...so I don't think the issue is with the derailleur, but I'm open to being wrong. I didn't take any photos but imagine the same picture with a black derailleur knuckle instead.

I will probably order some metric nylon lock bolts similar to what i have on the BMC. Good enough is OK if it works for as long as I own the bike or drivetrain, and that setup allows me to continue to adjust the B screw. I believe that replacement hangers are still available through commonwealth, but it's difficult for me to tell whether that will resolve this issue or whether this is already a replacement hanger. It is super clean and has no marks on the "tooth" other than the ones I put on it.
 

jonKranked

Detective Dookie
Nov 10, 2005
80,427
19,773
media blackout
Anything is possible, and I am open to "manually realigning" the bolt if that might fix it. I tried an older LX derailleur with the same mounting setup on for size and it's exactly the same...so I don't think the issue is with the derailleur, but I'm open to being wrong. I didn't take any photos but imagine the same picture with a black derailleur knuckle instead.

I will probably order some metric nylon lock bolts similar to what i have on the BMC. Good enough is OK if it works for as long as I own the bike or drivetrain, and that setup allows me to continue to adjust the B screw. I believe that replacement hangers are still available through commonwealth, but it's difficult for me to tell whether that will resolve this issue or whether this is already a replacement hanger. It is super clean and has no marks on the "tooth" other than the ones I put on it.
roger that. i figure lets rule that out if nothing else.

maybe @SuspectDevice knows something about this.

also, commonwealth as in commonwealth cycles the bike company?
 

SuspectDevice

Turbo Monkey
Aug 23, 2002
4,072
256
Roanoke, VA
That’s the shitty stock hanger that Sapa outsourced to Taiwan. Buy one from Ricky, it has a longer tab and also rotates the deraileur further clockwise for faster wheel removal.