newish: Soma Crane threadless up stem for 26 and 31.8

[eddief]

http://www.somafab.com/archives/product/crane-crmo-stem

Safe for carbon steerers ya think?

[R3awak3n]

I would not put it in a carbon steerer. I think the reason they don't recommend it is the same reason they don't recommend more than 30-40mm of spacers in carbon steerers.

[dddd]

I'm thinking that there is a difference between using a tall stack of spacers and using a stem that is extended the same amount either in height or in extension.
On a couple of occasions, I have noticed noises that seemed to originate from the upper headset when a tall stack of spacers was used.
A clamped-on stem (or clamping spacer) is less likely to cause the upper headset cone to rock in response to bending loads on the steerer, versus a free stack of spacers compressed from above by the clamped stem imo.

I haven't heard of any warnings not to use a very long horizontal stem extension with a carbon steerer, even though a lengthened horizontal extension, if anything, would feed more bending force into the steerer in normal use than one that is extended vertically like this one.

But I have a concern with any stem design that might concentrate force at the very end of a carbon steerer, though I have no evidence that this stem would tend to do that more than any other stem, but for those stems that leave some steerer length extending above the top of the stem.

So as long as the recommended steerer insertion/engagement length of this stem is conservatively respected, I believe that it would be perfectly fine on a carbon steerer.