Offset cogs to adjust chainline..
#1
Thread Starter
Senior Member

Joined: Jan 2007
Posts: 1,242
Likes: 332
From: bradenton FL
Bikes: 1991 Diamondback Master TG 1990 Trek 850 Antelope
Offset cogs to adjust chainline..
I rember hearing a while ago about cogs that are offset,but dont know who makes them.Since Im going down to a 16t cog i figured I would get a cog that gives a 45mm chainline for my RD crank/Messenger ring mated to a Formula rear hub.
Can someone help me with brands that make them,or where to buy them?
Thanks
Can someone help me with brands that make them,or where to buy them?
Thanks
#2
Senior Member
Joined: Nov 2008
Posts: 155
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From: Seattle
Bikes: '06 DK Cincinnati, '09 Mercier Kilo TT
I'd favor adjusting chainline with a new bottom bracket/chainring position. Are you running the chainring on the outside of the spider? If so, moving it to the inside will give you approximately a 42mm (instead of 45mm) chainline with a 103mm bottom bracket.
#3
A little North of Hell
Joined: Mar 2006
Posts: 4,892
Likes: 4
certain hubs and cogs will give you a wider chainline, like Goldtec hubs and EAI cogs.
https://www.sheldonbrown.com/chainline.html
the collar one these Plazmatic cogs might be too wide.
https://www.webcyclery.com/product.ph...cat=415&page=1
https://www.sheldonbrown.com/chainline.html
the collar one these Plazmatic cogs might be too wide.
https://www.webcyclery.com/product.ph...cat=415&page=1
#4
thread derailleur
Joined: May 2008
Posts: 1,095
Likes: 1
From: beyond Thunderdome
Bikes: 82 Bianchi ECO Pista, Pake, Kilo TT, some *** bmx i found underneath an old house
EAI cogs should give you something like a 43.5 mm chainline. You can indeed get a 42mm chainline with the Sugino RD's by moving the chainring inside the spider, but you also have to get a 107mm bb to compensate for moving it in that far. I'd rather just buy a new cog and live with the inconsequential chainline difference.
#5
Thread Starter
Senior Member

Joined: Jan 2007
Posts: 1,242
Likes: 332
From: bradenton FL
Bikes: 1991 Diamondback Master TG 1990 Trek 850 Antelope
EAI cogs should give you something like a 43.5 mm chainline. You can indeed get a 42mm chainline with the Sugino RD's by moving the chainring inside the spider, but you also have to get a 107mm bb to compensate for moving it in that far. I'd rather just buy a new cog and live with the inconsequential chainline difference.
I dont wanna move my ring to the inside though,the whole reason for me getting the RD/Messenger and BB combo was so I didnt have to do that.I didnt pay attention to the specs on chainline though. Not a big deal with the chainline off 3mm though
#6
Senior Member
Joined: Jan 2005
Posts: 1,301
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depending on the thread depth on your hub, it is also possible to put a spacer behind the cog. i run a 1mm spacer behind an EAI cog in order to use a road double with the chainring in the outside position.
in my case the cog threads are essentially level with the face of the cog, even with the spacer, and the lockring threads actually protrude beyond the face of the ring...thread engagement is essentially unchanged with the spacer. i've put maybe 3k on the wheel set up this way. no issues. ymmv.
in my case the cog threads are essentially level with the face of the cog, even with the spacer, and the lockring threads actually protrude beyond the face of the ring...thread engagement is essentially unchanged with the spacer. i've put maybe 3k on the wheel set up this way. no issues. ymmv.




