Where to clamp bike to work on it?

Paul Cassel wrote:
wrote:

I also have an Al frame and thought a carbon seatpost the way to go. I
got a USA Alien and found no difference in the ride AT ALL. I think the
idea of carbon being softer is when you have carbon seat and chain stays
which may absorb some vibration, but the straight tube transmitted all
the vibration just like the old Al seatpost did.

no, it's a real physical effect. if you don't notice, that's fine for
you, you don't have to use one, but don't deny existence for everybody else.




I clamp to the seatpost anyway and so far have had no problems. If I had
to do it again, I"d not spend the money on the plastic post.

"jim beam" wrote in message t...
| Paul Cassel wrote:
| wrote:
|
| I also have an Al frame and thought a carbon seatpost the way to go. I
| got a USA Alien and found no difference in the ride AT ALL. I think the
| idea of carbon being softer is when you have carbon seat and chain stays
| which may absorb some vibration, but the straight tube transmitted all
| the vibration just like the old Al seatpost did.
|
| no, it's a real physical effect. if you don't notice, that's fine for
| you, you don't have to use one, but don't deny existence for everybody else.

But is there enough material to make a difference? Taken to an extreme, if you had a seatpost in which 11 inches was aluminum and only one inch carbon, would you expect to feel any difference at all? If not, how long does it need to be before you actually do notice a difference? Would a standard road bike with maybe 6 inches of exposed post be enough for seatpost material to be relevant?

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

In article
,
" wrote:

I've got a Lemond Alpe D'Huez that I¹m growing increasingly fond of.
One thing I¹ve noticed is at higher tire pressure, road vibration is a
bit much on my rear. 90ish feels a bit slow. 100-110 feels good.
120 feels real good on perfectly smooth, brand new pavement but when I
hit cracks in the pavement it¹s not the most comfortable thing in the
world. One of the things that I think could help with this a tad is a
carbon post. My concern then is where to clamp the bike to work on
it? I¹m afraid putting enough pressure to properly secure the bike on
a carbon post would crack it. The aluminum front triangle of the
frame is also insanely thin * flicking it with your finger nail feels
like you could dent it. I¹d be afraid to clamp to this as well.
Ideas?

I¹m sure some of you will tell me to ride @ 90psi, it¹s plenty and
absorbs the road better. Thing is, most of the roads I ride on are
really, really smooth and the higher pressures just feel faster (not
to mention they seem to reflect a slightly faster overall average at
the end of my ride, for the same course with the same perceived energy
output). I can actually see the shape of the tire deform a bit @ 90,
at 110 it seems to pretty much hold its shape. There¹s a chance I¹ll
find I¹m no faster (nor do I feel any faster) @ 120 than at 105-110,
but I won¹t know until I can try it without lifting off the saddle for
every crack in the road (few and far between as they may be).

I inflate to ~120 psi, then do not inflate again until
the tires are 75-85 psi; then back up to 120 psi. I have
high resistance to any sort of bicycle maintenance, including
tire inflation. I enjoy riding.

--
Michael Press

On Fri, 08 Aug 2008 00:39:59 -0700, Michael Press
wrote:

I inflate to ~120 psi, then do not inflate again until
the tires are 75-85 psi; then back up to 120 psi. I have
high resistance to any sort of bicycle maintenance, including
tire inflation. I enjoy riding.

I guess I don't enjoy riding enough and waste 2 (two) minutes a week
on inflating tires... I guess I should reevaluate my priorities.

Paul Cassel wrote:
wrote:

I also have an Al frame and thought a carbon seatpost the way to go. I
got a USA Alien and found no difference in the ride AT ALL. I think the
idea of carbon being softer is when you have carbon seat and chain stays
which may absorb some vibration, but the straight tube transmitted all
the vibration just like the old Al seatpost did.

I clamp to the seatpost anyway and so far have had no problems. If I had
to do it again, I"d not spend the money on the plastic post.

I think seat posts are one of the least favorable places to use CF.

Peter Cole wrote:

I think seat posts are one of the least favorable places to use CF.
Off-topic but too interesting not to sha I know a guy who builds up
racing bikes professionally. He used an iron saw to cut a rather big
marking in his CF seatpost, so he could easily set it back to that point if
he needed to adjust it. I would have nightmares riding on a bike with a
damaged carbon fiber seatpost, but he didn't pay much attention to it. He
laughed when I expressed my fears.

Derk

Peter Cole wrote:
Paul Cassel wrote:
wrote:

I also have an Al frame and thought a carbon seatpost the way to go. I
got a USA Alien and found no difference in the ride AT ALL. I think
the idea of carbon being softer is when you have carbon seat and chain
stays which may absorb some vibration, but the straight tube
transmitted all the vibration just like the old Al seatpost did.

I clamp to the seatpost anyway and so far have had no problems. If I
had to do it again, I"d not spend the money on the plastic post.

I think seat posts are one of the least favorable places to use CF.

that's because you're a luddite and don't know what you're doing.
rejecting a material with much superior fatigue properties for
application where fatigue resistance is a priority? that's just plain
stupid.

Derk wrote:
Peter Cole wrote:

I think seat posts are one of the least favorable places to use CF.
Off-topic but too interesting not to sha I know a guy who builds up
racing bikes professionally. He used an iron saw to cut a rather big
marking in his CF seatpost, so he could easily set it back to that point if
he needed to adjust it. I would have nightmares riding on a bike with a
damaged carbon fiber seatpost, but he didn't pay much attention to it. He
laughed when I expressed my fears.

Derk

well, i wouldn't do it, but otoh, carbon doesn't have the same notch
sensitivity or fatigue sensitivity as an aluminum post, so he's not
taking the same kind of risk as you might imagine.

Mike Jacoubowsky wrote:
"jim beam" wrote in message t...
| Paul Cassel wrote:
| wrote:
|
| I also have an Al frame and thought a carbon seatpost the way to go. I
| got a USA Alien and found no difference in the ride AT ALL. I think the
| idea of carbon being softer is when you have carbon seat and chain stays
| which may absorb some vibration, but the straight tube transmitted all
| the vibration just like the old Al seatpost did.
|
| no, it's a real physical effect. if you don't notice, that's fine for
| you, you don't have to use one, but don't deny existence for everybody else.

But is there enough material to make a difference? Taken to an extreme, if you had a seatpost in which 11 inches was aluminum and only one inch carbon, would you expect to feel any difference at all? If not, how long does it need to be before you actually do notice a difference? Would a standard road bike with maybe 6 inches of exposed post be enough for seatpost material to be relevant?


i thought of making that distinction, but decided to ague the facts.
you're absolutely right, i doubt someone with 3cm of post showing can
feel a thing, but with a correctly sized modern frame, i.e. with maybe
20cm of post showing, it's a no-brainer.

On Aug 8, 1:39*am, Michael Press wrote:
In article
,



" wrote:
I've got a Lemond Alpe D'Huez that I¹m growing increasingly fond of.
One thing I¹ve noticed is at higher tire pressure, road vibration is a
bit much on my rear. *90ish feels a bit slow. *100-110 feels good.
120 feels real good on perfectly smooth, brand new pavement but when I
hit cracks in the pavement it¹s not the most comfortable thing in the
world. *One of the things that I think could help with this a tad is a
carbon post. *My concern then is where to clamp the bike to work on
it? *I¹m afraid putting enough pressure to properly secure the bike on
a carbon post would crack it. *The aluminum front triangle of the
frame is also insanely thin * flicking it with your finger nail feels
like you could dent it. *I¹d be afraid to clamp to this as well.
Ideas?

I¹m sure some of you will tell me to ride @ 90psi, it¹s plenty and
absorbs the road better. *Thing is, most of the roads I ride on are
really, really smooth and the higher pressures just feel faster (not
to mention they seem to reflect a slightly faster overall average at
the end of my ride, for the same course with the same perceived energy
output). *I can actually see the shape of the tire deform a bit @ 90,
at 110 it seems to pretty much hold its shape. *There¹s a chance I¹ll
find I¹m no faster (nor do I feel any faster) @ 120 than at 105-110,
but I won¹t know until I can try it without lifting off the saddle for
every crack in the road (few and far between as they may be).

I inflate to ~120 psi, then do not inflate again until
the tires are 75-85 psi; then back up to 120 psi. I have
high resistance to any sort of bicycle maintenance, including
tire inflation. I enjoy riding.

--
Michael Press

I seem to get more flats below 90 psi. I weigh about 195ish.