Critical Connector Pin Placement: Dura Ace 10spd/7801 Chain

Discuss light weight issues concerning road bikes & parts.
Post Reply
User avatar
Posts: 232
Joined: Tue Mar 20, 2007 5:07 pm
Location: Palo Alto, CA

by baldkingpin

After having installed/ridden/raced scores of every incarnation of Dura Ace chain over nearly 20 years without a single failure, I read the installation instructions closely for the first time. I've been installing the chains, specifically the connecting pins, correctly (from outer side, using reinforced connecting pin in new 7801, etc.), with one big exception, to wit: I haven't ever paid attention to whether I install the pin in the front or back of the link.

So, I was surprised to learn that in their installation directions Shimano states, "we strongly recommend to set the connecting pin in the hole of the outer link on the front side in the direction of travel. The chain's level of strength is [thereby] enhanced..." Here's a link to the Shimano pictorial chain installation directions, with the above recommendation: ... 612411.pdf

Is this something most of you are aware of that I somehow never read, heard, etc.? I looked at my bikes and all happen to be installed this way except for my primary race bike that I ride most. :shock:

I'm not concerned the chain'll snap and I'll die, but I'm curious how much extra strength is gained by using the front link hole? Can any of you engineer/physics types explain this in lay terminology?


User avatar
Posts: 4446
Joined: Wed May 18, 2005 6:24 pm
Location: BELGIUM

by strobbekoen

The forces pulling on the chain will be working on the outside instead of the inside of link.

User avatar
Posts: 784
Joined: Thu Sep 15, 2005 10:19 am
Location: Greece

by Taz

I do not think this is correct.
Both the inside and outside plates are subject to exactly the same force regardless of the orientation of the chain.
IF there is a reason (which I highly doubt) the only one I can think of has to do with the bendind of the chain during shifting.

User avatar
Posts: 1112
Joined: Tue Oct 23, 2007 12:28 pm
Location: Australia

by Stats

I read that too some time ago... I just did what it said... i figure if Shimano have the technology to tell you the new chain is 0.6% more efficient in 7900 - then they'd be able to tell if the front or the back of the chain is better for the connecting pin to be place through...

But in saying that - i would have thought it wouldn't have mattered that much...

and if it ain't broke...

Posts: 1
Joined: Sun May 12, 2013 8:56 am

by pc7

Shimano's gibberish made me so upset that I decided to make a drawing. From all I figured out A (correct) and B (incorrect) correspond to the following images:

Or for those preferring a pdf:

Steve K
Posts: 15
Joined: Fri Mar 02, 2007 6:34 am
Location: PGH/Reading PA

by Steve K

I've always assumed that you push the pin in from the drive side and break off the guide on the non drive side so that the lip of the pin may aid in shifting up to the larger cogs in the cassette, but perhaps moreso to not catch the ramps and pins as easily on the big ring when in the small small combination.

User Name
Posts: 597
Joined: Tue Jun 07, 2005 3:32 pm

by User Name

Ha. I, too, was apparently doing it 'wrong' for many years without an issue. Some time in the '90s, a guy at a shop showed me how to do it, and that was it -- I did what he showed me, and never noticed the instructions. Oops.

If you're pinning a chain at the top (above the chain stay), Shimano says that the "pulling" link should be an "inner" link.

Oh yeah: holy old threads, Batman

Post Reply
  • Similar Topics
    Last post