What is the difference between "Hyperglide" cassette and HG10/HG11/HG12 cassette? I thought the later are also of "hyperglide" kind.

Is the freehub body for the former cassettes shorter by 1.85mm than the body for the later cassettes?

For instance, Tune uses this terminology here.

  • You may find this answer of interest: bicycles.stackexchange.com/a/88160/54500 (HG10/11/12 usually refers to the compatible chains).
    – Rеnаud
    Commented Aug 23, 2023 at 13:57
  • @Renaud Sorry, I'm not sure I follow: Tune only says Hyperglide or HG, are you saying this is their way of saying yours HG regular and long? What do they need that 0.6mm spacer for?
    – Ecir Hana
    Commented Aug 23, 2023 at 14:19
  • Indeed, the product pages of 12-speed road groupsets mention a new "12-speed" hub (but they announce that the cassettes are 11-speed hub compatible), so crossing with Tune info, it would mean that there are now 3 lengths for road hubs "historic", "11-speed" and "12-speed". But on the MTB side, only the "historic" is used, even for 12-speed cassettes (with 11T smallest sprockets) - and to make it even more confusing, it looks like the new 12-speed GRX will switch to Microspline, so the common assumption that gravel = rugged road may not hold anymore.
    – Rеnаud
    Commented Aug 23, 2023 at 14:47
  • @Renaud You meant, "historic" = "Hyperglide", "11-speed" = "HG10/HG11/HG12", "12-speed" = they don't seem to make that one, yet, correct? So that is to say, that one can take a 12-speed MTB cassette and fit in on "11-speed" hub, correct? And to fit 11-speed MTB cassette on "11-speed" hub one need 1.85mm spacer, correct? But then, what is the 0.6mm spacer for? I thought it is either "regular" or "long". Perhaps you meant that there is a weird 12-speed cassette which needs both 1.85mm and 0.6mm spacers to fit on 11-speed road hub?
    – Ecir Hana
    Commented Aug 23, 2023 at 14:54
  • As I understand it: HG10=historic, HG11=HG10+1.85mm, and from what the video of Tune says, it looks like HG12=HG11+0.6mm. But on the product pages of the 12-speed cassette, they write that the cassettes are compatible with both 11 and 12 speed hubs (which probably means that a such 12-speed used on a 12-speed hub would require the 0.6mm). To mount a 12-speed MTB (that uses a HG spline, that is the exception) cassette on an 11-speed road hub, you need the 1.85mm spacer. Most 12-speed MTB cassettes are using Microspline or XD splines, and cannot therefore be mounted on HG splines.
    – Rеnаud
    Commented Aug 23, 2023 at 15:07

1 Answer 1


You seem to be asking about the freehub body dimensional standards as opposed to the features of the cassettes that go on each one per se, so I'll limit it to that.

One of the confusing things is a lot of the terms in circulation are arbitrary. "HG12" in particular is the worst kind of made-up term. We have Microspline and L2 as distinct names for the newer Shimano freehub body types; adding a 3rd term is needless.

HG or Hyperglide is sometimes referred to as HG 8/9/10, Shimano 8/9/10, etc. The Shimano term for it is HG spline M. It's 35mm long from cassette mounting shoulder to the end of the freehub body. All Shimano-made freehub bodies of this type are steel or titanium. Many other companies have made it in aluminum, which the form factor was not originally designed to accomodate, and problems with grooves worn into the splines as a result are common. This freehub body also takes 11-speed and 12-speed HG spline cassettes where the small cog is 11t or bigger and the large cog is 34t or bigger. Thus the terms 8/9/10 etc are also bad because they seem to indicate limits that aren't necessarily true. (The same has always been also true for 7, since the 8/9/10 vernacular would seem to preclude it, but 7-speed HG cassettes go on with the addition of a 4.5mm spacer).

HG10 is a made-up term that should not be used. It sometimes is used to indicate the above type, the notion being to truncate the "8/9/" away. Road-myopic sources do this particularly. It's a bad term because it leaves ambiguous whether it might be referring to the obsolete deep-splined aluminum Shimano 10-speed-specific freehub body design found on Dura Ace 7800 parts and a few other wheels/hubs. While seldom intentionally used this way now, they are the only actual 10-speed-specific Shimano freehub body type ever made, creating the possibility for confusion. In the technical literature of the time, Shimano themselves identified it only by the number "10" in the "Speeds" and "Aluminum" in the "Freehub Body" Material" fields of their compatibility charts, whereas other road hubs were "8/9/10" and "Steel".

HG11 refers to Shimano 11-speed road freehub bodies, which Shimano calls HG spline L. It is the version of the Hyperglide spline pattern that is 36.85mm long. It takes 11- and 12-speed Hyperglide spline pattern cassettes with large cogs of 32t or less. With a 1.85mm spacer it takes 11- and 12-speed Hyperglide cassettes with a large cog of 34t or more, or any 8/9/10-speed Hyperglide cassette.

HG12 is likely a reference to the aluminum 12-speed-specific road freehub body, called HG spline L2. This is Shimano's second attempt at revamping the HG spline pattern into a design that works sustainably in aluminum. In this design the freehub body only accepts 12-speed road cassettes. In the other direction, the same cassettes go on the other freehub bodies as above (HG Spline M or L depending on whether the largest cog is 34t or greater, plus a 1.85 spacer as needed). (In other words, the new wheels only take the new groups, but the new groups do go on most of the old wheels). L2 shares the same 36.85mm length as road 11 above. "HG12" could be confused with Microspline, which is a non-Hyperglide spline pattern that exists to accommodate 10t small cogs.

An important piece of subtext is that durable HG freehubs can be made of titanium for almost the same weight as aluminum, but much more expense. Al HG freehubs function but are problematic, and the attractiveness of the weight/cost proposition has led many companies to make them anyway, though not Shimano itself. That is the dynamic driving a lot of what's happened.

  • 1
    Excellent, thanks a lot! One last thing, do you know how that 0.6mm spacer of Tune came into existence? I don't know of any cassette that would need 1.85mm + 0.6mm on HG11.
    – Ecir Hana
    Commented Aug 23, 2023 at 19:30
  • 2
    Awesome answer, saving it as technical reference material!
    – MaplePanda
    Commented Aug 24, 2023 at 5:33

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