Chain jumps only on the 11 tooth. Ideas?

Triathlon Forum
1

I can probably race without it, but the chain jumps in the 11 tooth cog under heavy load. Shifts smoothly up and down in both small and big rings.

Do any of you have any ideas as to what could cause it?

2

high limit screw set ok?

nothing holding the chain off the sprocket like a spacer or the cassette nut?

3

What other poster said.

Would check for stiff link. Sometimes if link isn’t “that stiff” it will be ok on other cogs, but skip on 11.

Also, make sure the cassette lock ring is for an 11 cog. I’ve mistakenly used one that worked for a 12, but was too large diameter for an 11.

4

Had the same problem recently. It turned out to be a bent tooth on the second cog that was catching the chain when it was on the 11.

5

The other possibility is a bent derailleur hanger.

6

Split link fitted incorrectly, ie upside down?

7

I found found a pic on how how to orient the connex link.

When I clicked on the link it was a picture of the incorrect orientation.

http://www.boox.net/topics/bicycles/brompton/2speed/chain/

There was also a pic of the proper orientation.

I will flip it around when I get back to my bike and hope that is the culprit.

If not I will check for a stiff link.

Thanks all for responding.

Likely a good reminder that reading is fundamental.

8

12t lock ring with 11t sprocket is worth checking for too
.

9

Summary of things to check:
Stiff linksGunk between sprocketsTooth wear on sprocket alignment of chain
limit screwderaileur alignmenthangerb-tensionlock ring too large

.

10

I can probably race without it, but the chain jumps in the 11 tooth cog under heavy load. Shifts smoothly up and down in both small and big rings.

Do any of you have any ideas as to what could cause it?
Are you running mech or electronic?

11

I can probably race without it, but the chain jumps in the 11 tooth cog under heavy load. Shifts smoothly up and down in both small and big rings.

Do any of you have any ideas as to what could cause it?

Dura-Ace 7800 rear derailleur?

-SD

12

Winner. I had the connex link reversed. Flipped it and no more jumps.

13

Yes, if it’s a Connex link then it’s installed upside down. I had this exact problem a couple of weeks ago; flipped the link and it was perfect.

14

Just going to chime in that I also recently had this problem with a Connex link. IMO I suspect everyone who uses a Connex link has this problem at some point and thereafter is conscious of the correct installation.

15

Yeah a good hour of my life I won’t get back…

They could stamp an arrow on to the link and save us folks who throw out instructions after the initial install some trouble.