Bicycle Mechanics - Shimano 6703 crank spacer and ring?

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jmess
01-17-10, 08:36 PM
Does anyone know what the purpose of the ring behind the spacer is? I have a new 6703 crank and may have lost the ring. It wasn't in the bag the spacer and cap came in. So if I install the crank without the ring what impact will it have? I think the ring is a new feature of Shimano cranks. A 7803 crank I have doesn't have a ring under the spacer.

The Shimano part number for the ring is Y-1F3 1600, I assume any Shimano dealer can order one for me. I haven't found one online yet.

http://i2.photobucket.com/albums/y23/jmess52/CrankSpacer.jpg

AEO
01-17-10, 08:56 PM
the axle is designed to work with a multitude of BB widths. the spacer takes up the slack on narrower BBs.

having said that, just try it. My 5600 double said I needed it, but it works perfectly fine without it on a regular 68mm BB.
jmess
01-17-10, 09:27 PM
I have the spacer but not the ring that goes under it. I was wrong, the 7800/7803 cranks use the same ring part number. So the ring isn't unique to the new Shimano cranks. I am wondering if it is more of an additional water seal.

AEO
01-17-10, 09:31 PM
good question... I honestly have no idea.