Head tube+stack height vs steerer length

[mmoore]

Im trying to design a head tube that is as long as possible to re-use a carbon fork (enve GRD)

The question is how close does the top of the fork steerer need to be to the top of the stem? Stem in question is a Ritchey WCS C260 if that matters.



The stack of the headset would mean at a 140mm head-tube i have ~1.5mm below the top of the stem. Top headset assembly is a Cane Creek Slamset (zs44/28.6) and there will be a compression type expander in the fork steerer as is most appropriate for carbon.

[mmoore]

I jumped the gun on posting this question. The answer is as below.


The Techdocs for Ritchey stems, it says no more than 3mm below the stem top but also no less than 2mm... and there is another warning that after the first test ride you NEED to cut carbon steerers down to that spec. Page 5 of the ritchey document linked below.

Similarily the ENVE techdocs give the same 2mm below the stem requirement.

I should have looked it up before i posted.

https://eu.ritcheylogic.com/eu_en/ma...category/id/2/


Box

[Andrew R Stewart]

There are some carbon steerers that are recommended to have the steerer extend ABOVE the stem by a few MMs, use a spacer to allow top cap to draw down and preload headset. Some feel this is the most conservative approach, as to reduce the chance of a cracked steerer at it's top end from an over tightened stem or miss use of a compression plug.

BTW some also will say that designing around a fork's steerer length is placing the horse behind the cart. I take it that the steerer can't be cut down? Is it's compression plug bonded in place? Andy.

[mmoore]

There are some carbon steerers that are recommended to have the steerer extend ABOVE the stem by a few MMs, use a spacer to allow top cap to draw down and preload headset. Some feel this is the most conservative approach, as to reduce the chance of a cracked steerer at it's top end from an over tightened stem or miss use of a compression plug.

BTW some also will say that designing around a fork's steerer length is placing the horse behind the cart. I take it that the steerer can't be cut down? Is it's compression plug bonded in place? Andy.

the fork steerer is already cut as low as i would ever want it from the last bike it was on. that bike used a really short head tube and internal bearings so i have no reference. if it were truly too short to get the fit i want, it wouldnt be a consideration.

here are the base calcs.
194mm steerer length
-14mm cane creek EC44/33
-2mm Cane creek slamset
-40mm stem
+2mm tightening space

spot on 140mm head tube in that case...which is nice because i already have one of those. any other length would be back to my machinist with a new length of 7005.


i will use the standard Enve compression plug so i dont cause any issues.