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What is the specification for the current generation 10 and 11 speed Shimano Hyper Glide cassette spline? Ideally an engineering drawing. Further, how is it machined? Rotary broach? I've found models produced by other people on various 3D modelling sites but not a clear spec and few that match the 10/11 speed hubs

Background: I am considering an option to machine a custom cassette carrier and while it's possible to measure one directly, doing so with sufficient accuracy to produce a functional prototype is uncertain.

See attached for what I mean when I say "spline".

Picture of Shimano Hyper Glide cassette carrier and cogs showing the HG spline

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Here's a (reverse) engineering drawing: https://www.peterverdone.com/hyperglide/

Note the splines need to be a slightly loose fit, as freehubs usually have burrs on the splines from steel sprockets digging into the aluminium. If you were to measure a new freehub's splines and make a cassette carrier which just barely fit, that carrier would not fit on most used freehubs without filing the burrs completely away (something mass-produced cassettes generally do not require).

Luckily, the drawing above is for a sprocket and not a freehub; hopefully the clearance is adequate as drawn.

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  • That's perfect, much appreciated. The design definitely looks close to what I'm seeing, superficially. Good point about the burrs too - especially as this will be used on a used wheel.I wonder how they make those internal splines? I imagine with a rotary broach although in my case for low volume I need it EDM'd.
    – Jof Arnold
    Nov 21, 2022 at 19:47
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Regarding the cassette carrier (properly known as the freehub body), it can be considered as two concentric circles, with the inner diameter revealed by the machining depth. The splines are 9 evenly spaced areas and the valleys are the same width as the high points. This gives us a Ultraglide spline pattern. One of the splines is narrow for HyperGlide so that the sprockets can only be installed in a single orientation. This is simply achieved by making one of the valleys wider. The length of the spline is a known number but there is generous tolerance built into every aspect of the design so manua measurements from two or three freehubs you are happy with would give you good enough accuracy to be as good as anything else on the market.

You should note that 11 speed is special because it is 1.85mm longer than 8 speed and 9 speed. 10 speed is a special case because Shimano had a different 10-speed spline for the higher road groups (105 - Dura Ace) which featured an aluminium body with much taller splines to reduce the chance of the sprockets digging into the freehub body. I have only ever seen this design on high end Shimano wheels of the 10sp era. The cassettes were compatible with both types.

I will get a couple of hubs out later and take some photos and make some measurements and perhaps this will assist you.

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  • Yup - I've got a cassette with spacers, and the spacers don't have a narrow slot at all, so they can go on any-which-way. The cogs do have a narrow key-slot.
    – Criggie
    Nov 21, 2022 at 10:36

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