Road Bike, Cycling Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
211 Posts
Discussion Starter · #1 ·
In the bag with the in line cable adjusters also came a thin metal disk with a hole in it the exact same size as the bottom bracket. When you put the disk over the bb hole, the edge of the disk appears to be about .25 inch bigger diameter than the bottom bracket.

Someone said you put the disk on the drive side and lock it in place with with the drive side cup.

It is supposed to stick up a bit right above the carbon bottom bracket so if the chain derails to the inside it ends up flopping down on the disk instead of marring the carbon.

Anyone use/know about these?
 

·
Registered
Joined
·
1,859 Posts
Bingo

eflayer2 said:
Someone said you put the disk on the drive side and lock it in place with with the drive side cup.

It is supposed to stick up a bit right above the carbon bottom bracket so if the chain derails to the inside it ends up flopping down on the disk instead of marring the carbon.
This is exactly what it is for. Carbon fiber is softer than many metals, so it is more easily scratched and gauged. A dropped chain can easily grind up the carbon fiber on the BB shell (which obviously is a highly stressed part of the frame), and the disk can prevent the chain from hitting the shell to begin with.
 
1 - 3 of 3 Posts
Top