Stupid lug on chainring

[Yellow Fang]

I have just changed the chainrings on my bike. There's a lug on the outer chainring that is interfering with the chain. Does anyone know what it's for. I have not noticed any of these before. Also, how are you supposed to get rid of it. None of my allen keys seem to fit.

 

[ColinJ]

Isn't it supposed to help shifting up to the big ring?

 

[Deleted member 1258]

I have just changed the chainrings on my bike. There's a lug on the outer chainring that is interfering with the chain. Does anyone know what it's for. I have not noticed any of these before. Also, how are you supposed to get rid of it. None of my allen keys seem to fit.

Its difficult to see from your picture but it looks like it should go on the outside of the big ring lined up with the crank. Its to stop the chain going down between the crank and the chain ring if the chain unships.

 

[User6179]

I have just changed the chainrings on my bike. There's a lug on the outer chainring that is interfering with the chain. Does anyone know what it's for. I have not noticed any of these before. Also, how are you supposed to get rid of it. None of my allen keys seem to fit.

The lug should be on the outside next to crank arm I think

 

[bpsmith]

Here you go.

 

[youngoldbloke]

The lug should be on the outside next to crank arm I think

^^^This

 

[Ajax Bay]

^^^
Just undo the chain ring bolts, turn the outer chain ring round and rotate it until the 'lug' aligns with the crank arm, and rebolt.

"When replacing the chainrings, you need to pay attention to their rotational alignment.
"The outer (largest) ring usually has a small pin sticking out from its surface. The ring should be installed so that the pin is positioned behind the crank-arm, where it can help avoid a total chain jam in the event of the chain over-shifting and falling between the outer ring and crank."
(Source)
More care with the adjective 'stupid', perhaps.

 

[ColinJ]

Ah, yes - if it is one of those pins - I couldn't tell from the original photos.

I was riding alongside someone once when I noticed that he didn't have the pin lined up with the crank. I told him that his chainring needed turning round ....

Rider: "Why, what difference does it make?"

He asked the question at exactly the moment that he tried changing up onto the big ring but overshifted and got the chain stuck between the ring and crank ...

ColinJ: "It stops THAT happening!"

 

[raleighnut]

Yep, chainring fitted backwards and upside down, you couldn't have fitted it more wrongly if you tried.



Seriously though it's an easy mistake to make if you don't know what the little pin does.

 

[Tigerbiten]

I removed mine as it never stays lined up with the crank arm.

I use a Schlumpf HSD, so I spin the chainring 2.5 times faster than the cranks in overdrive mode ........

 

[gaijintendo]

I've seen that before and never really thought about its use. Thanks for the thread.

 

[biggs682]

Its difficult to see from your picture but it looks like it should go on the outside of the big ring lined up with the crank. Its to stop the chain going down between the crank and the chain ring if the chain unships.

thats my thought as well

 

[Ajax Bay]

thats my thought as well

Welcome, belatedly, to the club. Thanks for sharing.

 

[biggs682]

Welcome, belatedly, to the club. Thanks for sharing.

better late than never though

 

[youngoldbloke]

Some years ago I ordered chainrings from a well known supplier in the north of England to replace the Biopace chainrings on my Peugeot 525. After unpacking them I noticed the pin was missing from the outer. I contacted the supplier and after a long and difficult negotiation they admitted that they should have supplied one with the chainring, and were willing to send me one FOC, but only if I paid their carriage charge (currently £4.00 on orders under £50 - it was of that order at the time). Given the size and weight of the pin and the fact that it was their error they eventually somewhat reluctantly agreed to my suggestion they should pop it in an envelope and stick a 2nd class stamp on it. Meanwhile I'd constructed a pin with a short length of plastic tubing and an appropriately sized bolt, and the pristine new pin has remained in the spares box ever since.