Shimano CS-6600 on WH-R500 wheel - spacer/no spacer?
 

I got a used 12-27 Ultegra cassette to go on my budget/commuter bike. It came with all of the in-between spacers, but not the low 1.0mm spacer pictured in here: http://techdocs.shimano.com/media/te...9830608752.pdf

Do I need it with the particular wheel I am using? The wheel PDF doesn't mention it. The 8 speed HG50 I took off didn't have a spacer.

Yes, you need the spacer for any 10-speed Shimano cassette installed on any 8/9/10-speed Shimano freehub body. The only exception would be if you had a 7800 Dura Ace hub or the 10-speed only Dura Ace or Ultegra wheels. You have none of these.

BTW, The WH-R500 wheels are a real bargain for good utility wheels. I have a pair on my rain/beater bike and they came true and properly tensioned right out of the box.

My vote is yes, based on a 10-spd cassette on my Bontrager hubs. If Shimano cassette, then 1 mm spacer is required. If SRAM cassette, then no spacer is required.

this is a question you can answer for your self. Regardless of the hub or cassette brands the same basic rule applies.

Like with threadless headsts, where the stack must be higher than the steerer, the cassette's last sprocket must overhang the body so the lock ring can compress the cassette without bottoming on the freehub body. So if you don't have overhang, add a spacer behind the cassette to establish it.

I'm a little confused by your question (or maybe I don't know what I'm talking about). You say you have a CS-6600 12-27 cassette. I think the CS-6600 only comes in 13-25, 14-25, 15-25 and 16-27 sizes and don't need a spacer. Any other size, including your 12-27 would need the spacer.

See the OP's first post. The attached Shimano document shows a 12-27T option for the CS 6600.

All of the CS-660 cassettes you reference, plus the 12x27 and several others you missed, require a 1 mm spacer behind them on any Shimano 8/9/10-speed freehub body.

Incorrect. Only the 11 & 12 tooth cassettes do. The 13+ tooth ones do not. See

http://techdocs.shimano.com/media/te...9830608752.pdf

Likely that means the 13+ tooth ones will not fit on 10-speed-only wheels.

Interesting to know. Also, interesting that it took 10 months to determine that. :)