I noticed on the largest sprocket of my SRAM Red cassette, after every 8th tooth, the tooth is missing. I looked at one on line and noticed the same thing. What is the purpose of not including these three teeth on the sprocket?
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Can you add a photo -- either of your actual sprocket or a stock photo from SRAM's site?– RoboKarenFeb 5, 2017 at 18:39
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1I can't find a SRAM Red 1098 cassette on google, but things like this are normally there to improve shifting.– BatmanFeb 5, 2017 at 18:54
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RoboKaren....I added a picture. I hope it got uploaded correctly. There is also a pic of one at ebay.com/itm/Sram-Red-Og1090-11-26-10-Speed-Cassette-4333-21-/…– Paul KFeb 5, 2017 at 19:03
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Batman - that makes sense, especially when going to a larger sprocket. It does not look too common, however.– Paul KFeb 5, 2017 at 19:04
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1I edited the picture from ebay in, @PaulK. Feel free to revert or to use a different photo if you want.– RoboKarenFeb 5, 2017 at 23:47
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1 Answer
In general, when you see oddly shaped teeth or variations on a cassette/chainring, its there to facilitate shifting (such as Shimano Hyperglide, and ramps/pins you see on chainrings/cassettes; see this link for some examples).
In this case, SRAM calls it their "Open Glide" technology. To quote them: "OpenGlide tooth ramping allows for faster chain transition between cog postions. We employ OG on the radical OG1090 cassette for sure and higher shift speeds."
And here is a figure SRAM provides:
The marketing blurb from Art's Cyclery says: "SRAM's open glide technology refers to the shift gates created by removing teeth at key spots on the cogs to facilitate fast, effortless shifting going up or down or under power."
Whether it actually shifts better or not is a matter of debate, but a quick search says that generally not. I'd guess SRAM also found that to be the case, because they don't do this on cassettes in their current product line.
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1I have this "feature" on a SRAM force cassette as well. Never found it to work better/worse. I wonder if there are any chain wear effects?– Rider_XFeb 5, 2017 at 21:34
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1I'd guess that it might wear a bit less, but not enough to be significant in any way -- it would depend on the period of the links being caught on a tooth, and that would also depend on the GCD of your chainring size and teeth on the cogs.– BatmanFeb 5, 2017 at 22:01