Headset spacer diameters?

Discuss light weight issues concerning road bikes & parts.
Post Reply
Posts: 55
Joined: Wed Mar 07, 2018 5:01 am
Location: Canada

by CraigKnobovitch

Are headset spacers all the same exterior diameter? I'm going to have an FSA OS-99 stem on my next bike and I want the spacers (carbon please) to be flush with the stem. don't want any weird ridges/lips. Any suggestions?

by Weenie

Posts: 5725
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

No, they are not. Many of the superlight carbon spacers will be especially thin.

User avatar
Posts: 8608
Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

They’re not all the same outer diameter but very close, trouble is often not the exact same diameter as the stem collar. But I know what you’re talking about. It’s hard to get spacers of an outside diameter to match your stem precisely. In many cases these days, the outside spacer diameter is larger than the stem collar diameter, creating the ridge you’re trying to avoid. The lightness of the spacers has nothing to do with their finished outside diameters, they are just sometimes thin walled with inner ribs that center the spacer around the steertube, but maintain the standard outside diameter. Some stems these days with unique profiles (newer Pro Vibe for example) have spacers available that match the stem profile, but then they rarely match the headset cover where they meet up. When I find spacers that match the stem diameter perfectly I keep them matched. I’ve had the greatest success in this regard matching spacers with the Deda Zero 100 stems. But superlight stems often have a collar diameter smaller than most spacers. Good luck.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

Post Reply