Spacer on top of stem ?

[gbb]

A must or not with a carbon steerer?
Mine never did. I've always struggled to get my headset bang on, tonight I took one from under and fitted it on top...its spot on now.

I'm guessing it's not a necessity IF the stem has been cut correctly and it leaves enough gap for the top cap to compress the bearings WITHOUT it bottoming out.

Any thoughts or experiences ?

I frequently suffer from a shimmy at speed, that's the reason I was experimenting...,next ride will tell.

 

[Yellow Saddle]

I like to fit a small spacer on top. It prevents the top of the steerer from compressing, something it does quite easily if the stem is just too tight and the gap just too big inside.Carbon steerers can crack like a reed would if you compress it. Not a big issue, but still.

As fir shimmy. It has nothing to do with spacers.

 

[gbb]

I like to fit a small spacer on top. It prevents the top of the steerer from compressing, something it does quite easily if the stem is just too tight and the gap just too big inside.Carbon steerers can crack like a reed would if you compress it. Not a big issue, but still.

As fir shimmy. It has nothing to do with spacers.

Not spacers per se perhaps but if I were unable to satisfactorily tighten a headset without one...or the right ones if you prefer...could you argue the lack of spacer MAY be contributory to a poorly adjusted headset and by extension, the shimmy.

Just theorising.

 

[Yellow Saddle]

Not spacers per se perhaps but if I were unable to satisfactorily tighten a headset without one...or the right ones if you prefer...could you argue the lack of spacer MAY be contributory to a poorly adjusted headset and by extension, the shimmy.

Just theorising.

A loose headset will reduce shimmy, not increase it. This is because shimmy is a wave-like response to the elasticity in the front 1/3 of the frame that feeds itself with energy derived from forward motion. A loose headset will introduce an inelastic element that will dampen the wave, not feed it.

 

[gbb]

Ah well, at least now I have a better adjusted headset,

 

[fossyant]

Same reasons as Yellow Saddle, small spacer on top, always better to be clamping the entire tube, rather than risk putting undue pressure on the top of the steerer because the stem isn't clamping it fully.

 

[Tangoup51]

When it comes to carbon steerers i've seen recommendations that vary 3-5mm gap between the top pinch bolt and the tip of the steerer tube, so a spacer is always required if you wish to follow that path anyway.