Downhill 110×20 vs 110×20 Boost

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Downhill Spacing: 110×20 vs 110×20 Boost

Trailmech Enduro Front 110x20, 110x20 Boost
Trailmech Enduro Front 110×20, 110×20 Boost

This topic is one, where confusion still exists about front hubs for Gravity. And that is because the way we refer to identification of hubs type and application. There are two components: a) width and b) axle diameter.

Historically there was only 110×20, or just 20 mm front. Classic Downhill for 26” wheels. Then the Boost arrived and it came with the same width of 110 mm. The flange spacing is different, though, as the Boost is for larger, 650b and 29” wheels.

Trailmech Enduro Front End Caps
Enduro Front End Caps. Left to right: 110×20 non-Boost, 110×20 Boost, 110(100)x15, 110×15 Torque Caps

You do not get to see flange spacing stated in hub’s description. However, the Boost designation is always there for Boost compatible hubs. Flange spacing impacts the stiffness and strength of the wheel. The width did not change – 110 mm, so it should be possible to use “older” 110×20 hub with newer 110×20 Boost fork, right? No, and for the same reason why it is not possible to convert from non-Boost to Boost. The rotor mount position is not the same. It is 5 mm farther from the center of the hub. Thus, 110×20 Boost hub shell is different: wider with altered rotor mount placement. End caps are incompatible as well.

Check the end caps photo above: leftmost – 110×20 Downhill, next to the right from it – 110×20 Boost.

The rightmost there is yet another interesting standard – Torque Caps.