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What specifically is incompatible between Shimano MTB hubs and their road cassettes

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What specifically is incompatible between Shimano MTB hubs and their road cassettes

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Old 12-11-17, 03:01 PM
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SethAZ
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What specifically is incompatible between Shimano MTB hubs and their road cassettes

In another thread I mention that I didn't use some Shimano MTB hubs to solve a particular design issue I had with a wheelset I'm building specifically because Shimano says their 11-speed MTB hubs aren't compatible with their 11-speed road cassettes.

Meanwhile White Industries CLD hubs claim 11-speed cassette compatibility without regard to MTB or road, and I've seen photos of wheelsets people did for both disciplines with no mention of having had to do anything special.

So what, specifically, makes a Shimano 11-speed MTB hub incompatible with an 11-speed road cassette? Is it just something like the shape or depth of their freehub splines that, while technically different, in practice doesn't really make a difference?



ps: this reminds me of the differences between the .223 Remington rifle cartridge and the 5.56x45mm NATO cartridge, which technically are different in ways that in certain corner cases might cause issues, but in practice, in most guns, are completely interchangeable without issue
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Old 12-11-17, 05:02 PM
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The Shimano MTB 11 speed freehub is 1.85mm narrower than the Shimano Road 11 speed freehub. Spacers are available to fit MTB 11 speed cassettes on the road hubs.

The MTB version has the largest sprockets not engaging the freehub; they are attached to a carrier that has the biggest sprocket over hanging the non-spline are of the hub next the spokes. Because the largest road sprockets are considerable smaller than the MTB largest sprockets, it was deemed that there was not space to do the without hitting the spokes.
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Old 12-11-17, 05:05 PM
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Wait til the 14 sp. cassette hits the fan, er market.
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Old 12-11-17, 05:11 PM
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Originally Posted by nfmisso View Post
The Shimano MTB 11 speed freehub is 1.85mm narrower than the Shimano Road 11 speed freehub. Spacers are available to fit MTB 11 speed cassettes on the road hubs.

The MTB version has the largest sprockets not engaging the freehub; they are attached to a carrier that has the biggest sprocket over hanging the non-spline are of the hub next the spokes. Because the largest road sprockets are considerable smaller than the MTB largest sprockets, it was deemed that there was not space to do the without hitting the spokes.
Ah, ok. So a road cassette wouldn't fit on a Shimano MTB hub because it would stick out 1.85mm further? Do hubs like the White Industries just accomodate them both by having a longer free hub that works as-is with a road cassette, but requires a 1.85mm wide spacer to go on first before a MTB cassette?

edit: oops, yes you answered the second question in your response.
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Old 12-11-17, 05:51 PM
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Originally Posted by SethAZ View Post
Do hubs like the White Industries just accomodate them both by having a longer free hub that works as-is with a road cassette, but requires a 1.85mm wide spacer to go on first before a MTB cassette?
This is exactly what American Classic does with their 29" MTB RACE wheels.

I run them with a road cassette and no spacer.
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Old 12-11-17, 06:00 PM
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Originally Posted by SethAZ View Post
Ah, ok. So a road cassette wouldn't fit on a Shimano MTB hub because it would stick out 1.85mm further?
If I have this right, Shimano 11-speed MTB cassettes will fit on a 10-speed road freehub body but an 11-speed road cassette will not. The 11-speed road cassette requires a specific 11-speed freehub body which is wider than a 10-speed body.
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Old 12-11-17, 06:15 PM
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Originally Posted by HillRider View Post
If I have this right, Shimano 11-speed MTB cassettes will fit on a 10-speed road freehub body but an 11-speed road cassette will not. The 11-speed road cassette requires a specific 11-speed freehub body which is wider than a 10-speed body.
The new Ultegra 8000 11-34 cassette will also fit on a 8/9/10 speed freehub. The other 8000 series cassettes will not.
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Old 12-11-17, 11:00 PM
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Originally Posted by davidad View Post
Wait til the 14 sp. cassette hits the fan, er market.

With it's mating single side plated chain. I saw that patent blurb too. Andy
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Old 12-12-17, 03:47 AM
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Old 12-12-17, 08:13 AM
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Originally Posted by Andrew R Stewart View Post
With it's mating single side plated chain. I saw that patent blurb too. Andy
Those patents are from 1999 so Shimano has had plenty of time to do something with them. Shimano never commercialized the ideas and, after they expire in 2019, it's very likely neither will anyone else.

A Google search turned up this web site which had me wondering for a few minutes until I saw the date:

https://factoryjackson.com/2016/04/0...urai-unveiled/
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