Ultegra 10 Spd CS6600 11-23T)

For some reason my cassette got loose after my ride. I decided to take it apart and clean it. Now I am not sure about the spacers placement. I have three black ones with grooves and one silver, more like a washer. What is the position for the silver one?

I feel like an idiot!

I think the silver one goes closest to the hub. That's how it is on one of my wheelsets to keep the chain a little further from the spokes, but it could be different depending on the wheelset I'd imagine.

Yes the "silver" one is actually a very thin spacer that goes on he hub first before the 3 large cog carrier. After the carrier is the next cog without spacer in between and then spacer cog spacer cog etc.

This is unless the thin silver spacer is foil like. If it is foil like then it goes on to the lockring.

I took the "silver" spacer off my old wheel set ( the silver ring closest to the spokes before the 3 large cog carrier) to put it on my new wheel set (Easton EA90 exp). It wouldn't fit on the new free hub so I didn't use it. I rode the bike 30 miles and all seems fine and tight.

Why would the spacer fit on one free hub and not another?

Everything else fit as it should have.

OK....short answer - "because"

The silver spacer was designed to allow the use of Shimano 10spd deep splined cassettes on 8/9 freehub bodies. For 7800 Shimano designed a deeper spline for 10spd only usage to allow the freehub bodies made out of AL from galling. Its really simple actually, but it is hard to explain for lots of people for some reason. 3rd party hubs sometimes have different spacing and different spacer requirements.

I just learned this the hard way when I installed a casette on my friends new Mavics, seems the required spacer was different than the older Mavics he had and the cogs ended up loose on the spline after a couple hundred miles.

Perfect, Thank you!

And for next time, check out Shimano Techdocs.

Specifically, this pdf: https://techdocs.shimano.com/media/te...9830608752.pdf

Thanks for the links. I found this there for the 6700 and explains why I didn't need the spacer: