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Headset Spacers
I changed the stem on my bike and I guess it’s a tad shorter, as the distance between the top of the steerer tube and spacer (using one above the stem) is 1 maybe 2mm. When I snug the top cap bolt I believe the bottom of the cap is contacting the top of the steerer and it’s not preloading the headset (hopefully my explanation makes sense, I followed the Park Tool video). When I apply the front brake and push forward it feels like there is play.
So I got some 2 and 3mm spacers and replaced one 5mm with a combo of these and the steerer tube is now a good 4mm below the spacer on top of the stem (maybe 5mm?). Now when I snug the top cap bolt it feels like it’s engaging more (also took several more turns), and I can still rotate the bars easily. Now when I check for play it seems to be gone. Sorry for the long explanation! So, is it okay if that distance between top of spacer down to the top of the steerer tube is like 4-5mm? I rarely touch this area of the bike so I’m not as confident. Everything is now torque to spec and it feels good. |
Yes that's fine - the 1-2 mm people cite is the minimum to ensure that the top cap isn't contacting the steerer top. 4-5mm will achieve the same thing with no downside
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As long as the top bolt of the stem's steerer clamp is below the top of the steerer, you are fine. My preference is to have the steerer long enough to project slightly above the top of the stem and add a spacer above the stem to give me a 3-4 mm gap below the top of that spacer. That accomplishes the gap needed to adjust the headset and assures the steerer is fully supported by the stem. This is particularly useful with a carbon steerer.
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The danger is greater when the top of the steerer is below the stem's top by so much that the steerer is also below the top pinch bolt. With a metal steerer less a concern then with a carbon steerer. It was the introduction of carbon steerers that the "steerer above the stem and add a spacer to allow the preload cap to not bottom out" began to be the way. Andy
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Originally Posted by HillRider
(Post 22353062)
As long as the top bolt of the stem's steerer clamp is below the top of the steerer, you are fine. My preference is to have the steerer long enough to project slightly above the top of the stem and add a spacer above the stem to give me a 3-4 mm gap below the top of that spacer. That accomplishes the gap needed to adjust the headset and assures the steerer is fully supported by the stem. This is particularly useful with a carbon steerer.
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I think a few folks are misreading the OP. He has a spacer above the stem.
OP: as long as there is enough steer tube sticking into the spacer to keep it in place, you are fine. |
Originally Posted by Kapusta
(Post 22354158)
I think a few folks are misreading the OP. He has a spacer above the stem..
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Ironic, the extra stuff (weight) you have to add so you can use a fork with carbon steerer.
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Originally Posted by oldschoolbike
(Post 22355247)
Ironic, the extra stuff (weight) you have to add so you can use a fork with carbon steerer.
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As the OP I wanted to come back and close the loop on this. Short answer - I'm not a very good bike mechanic (but I try!).
When I changed stems...somewhere along the way I accidentally loosened the compression plug that sits inside the carbon steering tube. I didn't know this at the time. I didn't know what it looked like before (lesson learned - use phone for quick photo), so when the compression nut was sitting 5mm or so above the steering tube I didn't know that was wrong. So I need extra spacers to clear this additional height. Fortunately I called the bike shop, explained what I was seeing, and they set me straight (sometimes you just have to see it in person, or photos). |
Ah, this makes sense. Glad you got it fixed. As long as you can 1) preload the bearings with the cap, and 2) have the stemp clamp on tube (and not "clamp on air") you are good. The 1-2mm of clamping on air might be ok but is still suboptimal. Glad you got it fixed.
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Originally Posted by Noonievut
(Post 22353052)
I changed the stem on my bike and I guess it’s a tad shorter, as the distance between the top of the steerer tube and spacer (using one above the stem) is 1 maybe 2mm. When I snug the top cap bolt I believe the bottom of the cap is contacting the top of the steerer and it’s not preloading the headset (hopefully my explanation makes sense, I followed the Park Tool video). When I apply the front brake and push forward it feels like there is play.
So I got some 2 and 3mm spacers and replaced one 5mm with a combo of these and the steerer tube is now a good 4mm below the spacer on top of the stem (maybe 5mm?). Now when I snug the top cap bolt it feels like it’s engaging more (also took several more turns), and I can still rotate the bars easily. Now when I check for play it seems to be gone. Sorry for the long explanation! So, is it okay if that distance between top of spacer down to the top of the steerer tube is like 4-5mm? I rarely touch this area of the bike so I’m not as confident. Everything is now torque to spec and it feels good. edit: bike is a 2021 Bombtrack Hook. Top cap is very narrow/thin. |
Originally Posted by Camilo
(Post 22388649)
Make sure the expansion plug supports the stem clamps from inside the steer tube. If it doesn't reach down that far, consider buying a different expansion plug that is longer.
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