Easton CF seatpost - Relief Area Design ?

Easton EC90 Carbon seatpost
Moots Vamoots Ti Frame (with integrated seatpost clamp).

--First issue:

Easton's seatpost literature says,

"Relief Area DesignTM (RAD), a patented Easton design feature. The
relief area is a flattened section of the seat post quill that
protects the post from being pinched when the seat tube collar is
tightened"

Is there any reason why the flattened section should be facing
rearward (mated to the seatpost clamp), forward (180 degrees /away/
from the seatpost clamp), or other . . . or does the very presence of
the flattened section serve the intended purpose, regardless of
seatpost orientation?

--Second issue:

Same literature -- regarding seatpost installation -- says:

"Do not use a rotating motion. Scratches on the seat post can cause
stress concentrations that could result in seat post failure."

What am I missing here? While I could see a back-and-forth rotating
method scratching the post /more/, isn't a straight shove down likely
to scratch the post as well? Is it a directional issue? Is it crap??

TIA,

Neil

Neil Brooks wrote:
Easton EC90 Carbon seatpost
Moots Vamoots Ti Frame (with integrated seatpost clamp).

--First issue:

Easton's seatpost literature says,

"Relief Area DesignTM (RAD), a patented Easton design feature. The
relief area is a flattened section of the seat post quill that
protects the post from being pinched when the seat tube collar is
tightened"

Is there any reason why the flattened section should be facing
rearward (mated to the seatpost clamp), forward (180 degrees /away/
from the seatpost clamp), or other . . . or does the very presence of
the flattened section serve the intended purpose, regardless of
seatpost orientation?

--Second issue:

Same literature -- regarding seatpost installation -- says:

"Do not use a rotating motion. Scratches on the seat post can cause
stress concentrations that could result in seat post failure."

What am I missing here? While I could see a back-and-forth rotating
method scratching the post /more/, isn't a straight shove down likely
to scratch the post as well? Is it a directional issue? Is it crap??

TIA,

Neil

Dear Neil,

The rear-facing theory of the flattened portion of the seat post
probably assumes that it lets metal post flanges under an
over-tightened metal collar on the rear deform locally into the void,
rather than gouging into the carbon fiber.

The no-rotate policy is probably based on the pipe-cutter school of
seat post installation. A long, deep scratch running up the length of
the seat post is less likely to turn into a crack--the potential crack
would be in faint compression from the collar. In contrast, a deep
pipe-cutter scratch around the post would be the best way to break the
seat post off, if it was exposed, as the weight of the rider would put
one side of the crack into tension.

Neither tip seems likely to make a lot of difference in anything except
an exceptionally delicate or ill-fitting seat post--round seat posts
have been living long and happy lives for over a century and are
routinely twisted from side to side during installation.

Carl Fogel

wrote:



Neil Brooks wrote:
Easton EC90 Carbon seatpost
Moots Vamoots Ti Frame (with integrated seatpost clamp).

--First issue:

Easton's seatpost literature says,

"Relief Area DesignTM (RAD), a patented Easton design feature. The
relief area is a flattened section of the seat post quill that
protects the post from being pinched when the seat tube collar is
tightened"

Is there any reason why the flattened section should be facing
rearward (mated to the seatpost clamp), forward (180 degrees /away/
from the seatpost clamp), or other . . . or does the very presence of
the flattened section serve the intended purpose, regardless of
seatpost orientation?

--Second issue:

Same literature -- regarding seatpost installation -- says:

"Do not use a rotating motion. Scratches on the seat post can cause
stress concentrations that could result in seat post failure."

What am I missing here? While I could see a back-and-forth rotating
method scratching the post /more/, isn't a straight shove down likely
to scratch the post as well? Is it a directional issue? Is it crap??

TIA,

Neil

Dear Neil,

The rear-facing theory of the flattened portion of the seat post
probably assumes that it lets metal post flanges under an
over-tightened metal collar on the rear deform locally into the void,
rather than gouging into the carbon fiber.

The no-rotate policy is probably based on the pipe-cutter school of
seat post installation. A long, deep scratch running up the length of
the seat post is less likely to turn into a crack--the potential crack
would be in faint compression from the collar. In contrast, a deep
pipe-cutter scratch around the post would be the best way to break the
seat post off, if it was exposed, as the weight of the rider would put
one side of the crack into tension.

Neither tip seems likely to make a lot of difference in anything except
an exceptionally delicate or ill-fitting seat post--round seat posts
have been living long and happy lives for over a century and are
routinely twisted from side to side during installation.

Carl Fogel

Logical, and pretty much as I assumed.

Thanks much, Carl.