In the M9100 series parlance, the HB-MT900-BS Front Hub is an inline machined hub design for straight pull spokes. Offered here only as a 28 hole version (for 3x lacing only) with the 110mm axle width for a 15mm thru-axle system, this is the so-called Boost variant. Shimano just doesn't add a longer axle, as that is how many competitors do it, but widen the hubs shell so the bearing width is increased ensuring the wider assembly is actually stiffer- as intended. Otherwise why bother? The anodized aluminum shell is built to perfection, and carries the 110mm long oversized aluminum axle that features cone wrench flats for disassembly and adjustment.

Unlike most hub and wheel manufacturers Shimano eschews sealed cartridge bearings, which the engineers feel struggle to manage the angled forces a wheel is regularly forced to endure, creating counter forces that add friction and can limit bearing life. High quality stainless steel ball bearings ride in what Shimano calls a grinded cup and CBN cones. The seals used are a dual Labyrinth and Contact system that is known for incredible effectiveness. Servicing such hub bearings is actually quite simple, but unless you really ride the MT900-BS front hub long and hard in terrible conditions, it is actually quite possible you will never service the hub. The bearings, grease, cup and cone, and seals are simply that great. As you can adjust the hub, you control your destiny.

This isn't hyperbole, as our full service shop has barely cracked open a top-level Shimano road or mountain hub for required service over the last decade, and we have sold a great many Shimano hubs and wheels. Our techs are also major fans of the simple spline mount Center Lock rotor system, which makes for fast and easy rotor changes, with ideal accuracy and consistency. Shimano does include an anodized aluminum Center Lock lockring with the hub. The 15mm thru-axle is generally supplied by the frameset or fork manufacturer, not Shimano. If you need reliability, top-level hub performance and plan to build your front wheel up with forgiving and widely available j-bend spokes, keep it simple and pure with the XTR-level HB-MT900-BS Front Hub.