Shimano 11 speed MTB cassette on an 11 speed road hub, which spacer should I use? I have a Shimano 11 speed mountain bike cassette and a Shimano 11 speed road hub. Without a spacer there is considerable wobble of the cassette, and I read that a spacer is required. My wheels came with two spacers, that I measured with calipers at **1mm thick** and **1.85mm thick**. Which thickness of spacer should I use?

For 11s MTB cassette on road 11s HG hub, use 1.85mm spacer.

Bike-Components.de lists the following:

> 1 mm: Thickness: 1 mm Application:
>
> * using a 10-speed (Road) cassette with aluminium spider (e.g. CS-7800, CS-7900) on an 8-/9-/10-speed freehub
> * using a 10-speed (Road) cassette on an 11-speed (Road) freehub (1 mm + 1.85 mm) Manufacturer Part Number: Y-1Z807000
>

>
> 1.85 mm: Thickness: 1.85 mm Application:
>
> * using a 8-/9-speed cassette (Road) and an 8-/9-/10-/11-speed cassette (MTB) on an 11-speed (Road) freehub
> * using a 10-speed (Road) cassette on an 11-speed (Road) freehub (1.85 mm + 1 mm) Manufacturer Part Number: Y-4T724000
>