Thompson Posts: Straight vs Setback?

"Comments?"

Read the directions? I think you'll find it says you can reverse the clamp
(put the part that says forward facing rear) to allow the nose to drop more.

"(Pete Cresswell)" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I had a Thompson straight post.

Worked Ok, but I wanted to be able to move the saddle back another

half-inch or

Quoted message said:

so...so I bought another Thompson post that was "7-degree setback".

My first reaction was to wonder why they would express the setback in

degrees -

Quoted message said:

when the point of the whole thing is to move the saddle back in linear

inches or

Quoted message said:

millimeters.

Then I tried moving my saddle from the straigh to the setback post.

Now, at the same degree setting (the print a little gauge on one side of

the

Quoted message said:

post) that let the saddle be flat on the straight post, it's way nose-up

on the

Quoted message said:

setback post. About seven degrees more, I'd guess -)....

The zinger is that on the straight post, I had to adjust to the limit to

get the

Quoted message said:

saddle level ("24" on the Thompson scale) and now, with the setback it

seems

Quoted message said:

like it can't be ajusted flat anymore.

Seems like if you were bending the post back to achieve setback, you'd
compensate on the clip so that the angle of the saddle would be the same

for a

Quoted message said:

given numeric setting.

Comments?

--
PeteCresswell

(Pete Cresswell) said:

Seems like if you were bending the post back to achieve setback, you'd
compensate on the clip so that the angle of the saddle would be the same for a
given numeric setting.

Comments?

I've got both versions of Thomsons.

Think of it as RELATIVE! <G> Both posts are good, I only use the
marks to get the saddle in the same position after removing it for
rail greasing.

Barry

RE/

Quoted message said:

Read the directions? I think you'll find it says you can reverse the clamp
(put the part that says forward facing rear) to allow the nose to drop more.

Reversing the clamp makes it worse.

Expected per the instructions:
"...clamp usually works best with the word "FRONT" facing the front...If the
nose...will not tilt up enough...turn the clamp around for extra adjustment."

But the instructions also say:
"...designed to accomodate seat tube angles of 62 degrees or more....to allow a
maximum 5 degrees of up tilt and 29 degrees down tilt."

No way that sucker's going beyond about 23 on the gauge...and, with the 7 degree
bend, that would be more like a max of 16 degrees...

So, it sounds like I'm doing something dumb....but what?
--
PeteCresswell

(Pete Cresswell) said:

RE/

Quoted message said:

Read the directions? I think you'll find it says you can reverse the clamp
(put the part that says forward facing rear) to allow the nose to drop more.

Quoted message said:

Reversing the clamp makes it worse.

Quoted message said:

Expected per the instructions:
"...clamp usually works best with the word "FRONT" facing the front...If the
nose...will not tilt up enough...turn the clamp around for extra adjustment."

Quoted message said:

But the instructions also say:
"...designed to accomodate seat tube angles of 62 degrees or more....to allow a
maximum 5 degrees of up tilt and 29 degrees down tilt."

Quoted message said:

No way that sucker's going beyond about 23 on the gauge...and, with the 7 degree
bend, that would be more like a max of 16 degrees...

Quoted message said:

So, it sounds like I'm doing something dumb....but what?

You have a Brooks, right? Different saddles have different angles
between saddle rails and saddle top. Many "modern" plastic
leather-covered saddles have a level top when the rails are
tilted slightly up (and by modern I mean everything back to
at least a Concor or a Turbo). Some Brookses may have rails
parallel to saddle, in which case the saddle top will tilt up
more for a given angle of seatpost clamp.

You might be better served by trying parts together before
replacing things. Thomson may be the best setback seatpost
in the world, but it isn't the only one, and if it doesn't
fit it isn't the best for you.

"(Pete Cresswell)" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

I had a Thompson straight post.

Worked Ok, but I wanted to be able to move the saddle back another half-inch or
so...so I bought another Thompson post that was "7-degree setback".

My first reaction was to wonder why they would express the setback in degrees -
when the point of the whole thing is to move the saddle back in linear inches or
millimeters.

Then I tried moving my saddle from the straigh to the setback post.

Now, at the same degree setting (the print a little gauge on one side of the
post) that let the saddle be flat on the straight post, it's way nose-up on the
setback post. About seven degrees more, I'd guess -)....

The zinger is that on the straight post, I had to adjust to the limit to get the
saddle level ("24" on the Thompson scale) and now, with the setback it seems
like it can't be ajusted flat anymore.

Seems like if you were bending the post back to achieve setback, you'd
compensate on the clip so that the angle of the saddle would be the same for a
given numeric setting.

Comments?

How old is the Thomson setback you bought? Not when you bought it,
when was it made? They changed the clamp about a year ago or so.
They call the two clamps the '0 degree' (old) and the '12 degree'
(new). To tell what you have:

"TO TELL THE DIFFERENCE IN 0° AND 12° TOP CLAMPS: Look at the clamp
from the side. 0° clamps have the seat rail groove parallel with the
top of the clamp. The 12° top clamps have the seat rail grooves
sloping at a distinct 12° angle in relation to the top of the clamp.
Also, see sketches on intruction sheet. Instruction sheet is available
on web site. (www.lhthomson.com)"

If you have the older 0 degree, you can contact them to get the 12
degree clamp.

- rick

RE/

Quoted message said:

You might be better served by trying parts together before
replacing things.

Two things are weird in this situation:

- Another Thompson setback works a-ok on my Ellsworth (same model Brooks saddle)
I guess that goes back to what you said about the inharant slant in the Brooks
saddle surface/rails...on the Ellsworth, it's pretty close and the problem frame
has got to be a couple degrees more relaxed.

- The straight Thompson works on the problem frame. Foolishly, I guess, I
expected a setback post to just do that: set the saddle back...and not impose
some limit on angle that isn't there in the straight version. At this point,
it looks like Thompson just used the same moulds (dies?) for the setback as for
the straight post.
--
PeteCresswell