Shimano have many series of components corresponding to different grades and categories of bikes (e.g. their high-end series for MTB is XTR while Dura-Ace is for Road), but they also have what they call non-series components which do not bear a series name.

For example, looking at their 2021-2022 line-up chart for SLX, I can see that they list the FH-M7110 (series) and FH-MT510 (non-series) freehubs.

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They look similar, but the SLX is significantly more expensive and looks to have a better construction.

Now, are non-series components only meant to be cheaper versions of series components? Why not just include in the line-up chart a compatible component (if available) from lower grade series such as Deore, which is just below SLX? I find it hard to determine the relative quality of non-series components. With series components it is easy, just look at the name.

1 Answer 1


Some are mainly meant for OEM use (i.e. for selling to bike manufacturers). This is especially true at the cheap end of the market. You can still buy bikes (or at least BSOs) with Shimano 3x6 gearing, and the prominent text "Shimano equipped" on the frame. The bulk profit on these parts should be high (though not per item) as the tooling was paid off long ago, volumes are high, and materials cheap.

Others are legacy parts, kept for compatibility. These would have started as series parts but the series has moved on. This would include drivetrain parts for fewer speeds than that series currently has, like 9-speed 105, or rim brake parts sold under a series that's now disc-only.

Sometimes these are technically new parts compatible with an old version of a series but perhaps using new subcomponents. This would lead to a part number that has never been in a series.

There are a few parts that don't fit tidily in a series but for which there's a market - or they fit with a few series (like brake pads).

In short, it's because there's a market to make money off these parts outside the series structure.

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    OEM will bang a series (e.g. SLX or XT) derailleur and crank on a bike, then put in a much cheaper bottom bracket, hubs, headsets etc because no one looks at these and presumes the whole bike is SLX or XT. This works better if the hubs are non-series and just have "Shimano" printed on them.
    – mattnz
    Commented Mar 4, 2023 at 19:57

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