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Shimano Ultegra 16T Cog question

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Shimano Ultegra 16T Cog question

Old 07-29-21, 11:23 AM
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Pacelineg
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Shimano Ultegra 16T Cog question

I'm wanting to change out one my 16T cogs on an Ultegra Cassette. My original 16T cog is stamped "16A". The replacements I've found are all stamped "16B".

Can someone tell me what the difference is between one stamped 16A versus 16B?

Thanks
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Old 07-29-21, 11:33 AM
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Likely designed to work with adjacent cogs of a different size. Shift ramps and all that....
You "probably" wouldn't notice a diff.
I've mixed cogs on various 9 speed cassettes and didn't notice anything on my less expensive gear train.
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Old 07-29-21, 11:41 AM
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What Bill said. Clean off your "16A" really well and hold it up next to the picture in your post, and you'll probably see differences how the teeth are formed. If you want to get really geeky, you could buy some 16Bs and grind down the wide spline so that the cog can be installed in any of the 8 possible orientations to see which ones shift the best.
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Old 07-29-21, 12:06 PM
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Agree with both Bill & Scott above that it may not make a difference but I have had problems a couple times in the past with mixing a cog from another cassette with different gearing and it was always a little hesitant going into that gear. Played around with grinding the wide spline and moving the cog around, checking all adjustments, new chain, slightly worn chain, etc., but some of the non-series cogs didn't work as good as the proper matching cog. Just sayin'. I say try it and it may work fine but at worst it's mostly just an annoyance. Also you can go to the Shimano site and get a part number for the original cog and do a search with that or check with your LBS who will almost certainly have to order it. Try checking the photos of other 16t cogs from Ultegra and 105 or Dura Ace even and see if you can match the shifting cutouts of your original. I believe the cogs themselves are the same thickness for 10 & 11 speed so that increases your options.
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Old 07-29-21, 01:46 PM
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Thanks for the input guys, much appreciated.

I found this compatibility list.

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Old 07-29-21, 01:58 PM
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I don’t see an issue using B for A considering both are 1t to adjacent cogs. I have found issues subbing a 1t designed cog in a 2t cassette. In those cases there was one ramp instead of two. Tried multiple clocking of cog, but didn’t help enough.

John
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Old 07-29-21, 02:12 PM
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My original, which I can't find anywhere, looks like this.
I went ahead and ordered a 16B. I'll report my findings after I test it.


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Old 07-29-21, 02:22 PM
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Some really quick work in MSPaint to put them side by side:

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Old 07-29-21, 02:30 PM
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Thanks Scott, that helps.

Digging through some Shimano documentation it looks like 16A is used on 11-23T, 11-25T and 12-25T cassettes. The 16B is only used on the 11-32T cassette. That other chart I posted had me scratching my head because I have an 11-25T cassette.


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Old 07-29-21, 03:07 PM
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In my experience from a prior attempt to build a custom cassette by combining cogs from two cassettes, even if the suffix of the individual cogs match, there could still be shifting issues.

Bike Forums - View Single Post - Custom 12-28 cassette

If you view your cassette from the rear and slightly to the side, as you rotate the cassette, the light hits it at a certain way when all the shift ramps are lined up, at least between the cogs with only a one tooth jump.
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Old 07-29-21, 03:57 PM
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Originally Posted by SoSmellyAir View Post
In my experience from a prior attempt to build a custom cassette by combining cogs from two cassettes, even if the suffix of the individual cogs match, there could still be shifting issues.

Bike Forums - View Single Post - Custom 12-28 cassette

If you view your cassette from the rear and slightly to the side, as you rotate the cassette, the light hits it at a certain way when all the shift ramps are lined up, at least between the cogs with only a one tooth jump.
Thanks for your link, that's an interesting read. So much for getting a good nights sleep now until I receive and test out the replacement cog I ordered.
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Old 07-29-21, 05:08 PM
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Here's the "A" version if the "B" doesn't work out. 1pc Shimano Ultegra CS-R8000/6800 16T Cog for (11/12-25T 14-28T) 689228409439 | eBay The photo of the cog looks wrong but the part # matches up (Y1Y916000) so maybe wrong photo.
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Old 07-30-21, 07:41 AM
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Originally Posted by Crankycrank View Post
Here's the "A" version if the "B" doesn't work out. 1pc Shimano Ultegra CS-R8000/6800 16T Cog for (11/12-25T 14-28T) 689228409439 | eBay The photo of the cog looks wrong but the part # matches up (Y1Y916000) so maybe wrong photo.
I saw that one but skipped over it because I was only paying attention to the photos. Thanks for the link, I'll keep it as backup should the cog I ordered not work.
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Old 07-30-21, 07:51 AM
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Originally Posted by Pacelineg View Post
Thanks Scott, that helps.

Digging through some Shimano documentation it looks like 16A is used on 11-23T, 11-25T and 12-25T cassettes. The 16B is only used on the 11-32T cassette. That other chart I posted had me scratching my head because I have an 11-25T cassette.

There you go... looks like the 16A is designed to shift with a 15 and 17 on either side, and the 16B is designed to have a 14 and 18 on either side. It's too bad Sheldon Brown's page tends to stop at 10-speed stuff, because there are some neat color-coded charts showing Hyperglide cog compatibility. Like here: https://www.sheldonbrown.com/k10.shtml#shimano9
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Old 08-06-21, 01:30 PM
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I received and installed the 16B cog. I just wanted to report back that it shifts perfectly fine on my 11/25.

Thanks for all your input, it's much appreciated!

Last edited by Pacelineg; 08-06-21 at 01:33 PM.
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Old 08-06-21, 01:35 PM
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Originally Posted by Pacelineg View Post
I received and installed the 16B cog. I just wanted to report back that it shifts perfectly fine on my 11/25.
Congratulations! What was wrong with the original 16T cog?
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Old 08-06-21, 01:59 PM
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Originally Posted by SoSmellyAir View Post
Congratulations! What was wrong with the original 16T cog?
It would skip.
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