Carbon seatpost in aluminium frame?
07-02-13, 01:47 AM
#1
Senior Member
Thread Starter
Join Date: Jun 2012
Location: Turkiye
Posts: 352
Likes: 0
Liked 0 Times
in
0 Posts
Carbon seatpost in aluminium frame?
I am thinking about replacing my current 400mm alloy seatpost (who the hell would need it that long?!) to make my bike a bit lighter. Current stick is about 310 grams. I was checking for the options and found some alumunium seatposts around 220g with a reasonable price. If i can save 90 grams that would be good. However i wonder if a carbon seatpost would be a wiser choice considering it might help for a more comfortable ride. Though, i am not sure it is a good idea to clamp this gentle material within an aluminium frame. I think it will be broken or be crushed under the pressure. What would you recommend?
07-02-13, 02:36 AM
#2
Senior Member
Thomson Elite, ~$100 (or Masterpiece, ~$140).
Alloy and lighter than most carbon seat posts. They look awesome, too.
/thread
edit: also, ffs people, carbon is not a 'gentle material'...
Alloy and lighter than most carbon seat posts. They look awesome, too.
/thread
edit: also, ffs people, carbon is not a 'gentle material'...
07-02-13, 03:22 AM
#3
Senior Member
I have the S-works SL Pavé seatpost. Weight is about 200 grams, has a zertz insert and the cool one bolt fastening system.
First: My first S-works, Wohoo!
second: It's light. Okay the thomson elite masterpiece is even lighter, but also, looks
third: I can understand how someone might not like the one bolt system (I didn't) but now that I'm used to it, it makes adjusting so much easier and faster.
fourth: Not sure if the zetrz insert does anything, but it's a cool little gizmo. I suppose it helps with a little bit of vibration
You have to be skilled to break carbon, but overtightening will do it. I use pretty minimal force and toothpaste to keep the seatpost in place.
Would not go back to alloy
First: My first S-works, Wohoo!
second: It's light. Okay the thomson elite masterpiece is even lighter, but also, looks
third: I can understand how someone might not like the one bolt system (I didn't) but now that I'm used to it, it makes adjusting so much easier and faster.
fourth: Not sure if the zetrz insert does anything, but it's a cool little gizmo. I suppose it helps with a little bit of vibration
You have to be skilled to break carbon, but overtightening will do it. I use pretty minimal force and toothpaste to keep the seatpost in place.
Would not go back to alloy
07-02-13, 03:37 AM
#5
Senior Member
Thread Starter
Join Date: Jun 2012
Location: Turkiye
Posts: 352
Likes: 0
Liked 0 Times
in
0 Posts
Lightest alu post i found is this Ritchey. I will invest my money on this:
https://www.evanscycles.com/products/...29872#features
https://www.evanscycles.com/products/...29872#features
07-02-13, 04:11 AM
#6
Banned.
Join Date: Apr 2010
Location: Somewhere
Posts: 1,041
Bikes: something
Likes: 0
Liked 0 Times
in
0 Posts
It may seem like a sham but really your best bet is carbon friction paste, reduces the amount of clamping force needed aswell.
07-02-13, 04:52 AM
#7
Super Moderator
Join Date: Jul 2004
Location: Ffld Cnty Connecticut
Posts: 21,889
Bikes: Old Steelies I made, Old Cannondales
Liked 1,013 Times
in
648 Posts
__________________
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike.
FYI: https://www.bikeforums.net/forum-sugg...ad-please.html
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike.
FYI: https://www.bikeforums.net/forum-sugg...ad-please.html
07-02-13, 05:21 AM
#8
Senior Member
While I have never heard of this and have never seen this done I CANNOT recommend this as a mechanic. I have seen carbon seatposts seize inside of aluminum frames before and toothpaste strikes me as being a perfect glue since it's primary solvent/ carrier is water and it normally contains many other types of minerals and electrolytes that will just act as bonding agents once the carrier fluid dries out.
It may seem like a sham but really your best bet is carbon friction paste, reduces the amount of clamping force needed aswell.
It may seem like a sham but really your best bet is carbon friction paste, reduces the amount of clamping force needed aswell.
So far the toothpaste has worked really well for the past two years. No seizing, adjustment is always easy, no hassle. At some point I'm thinking of turning the frame upside down, washing the old stuff away with a bottle brush and applying new paste. Then again so far the old stuff has kept elastic and easy to handle so maybe not.
Trick is to use the cheap foamy white stuff, NOT the gel. I can really understand how a gel might jam the post, but the white stuff works wondrously well.
07-02-13, 05:31 AM
#9
don't try this at home.
My original carbon seat post was pitted and had white aluminum corrosion dust after a few years. I just cleaned it off an kept using it (until the saddle clamp quit working) It would be good to pull a carbon post on an aluminum bike once a year for inspection.
The consensus on BF is that carbon posts don't make enough difference on soaking up vibrations to notice.
The consensus on BF is that carbon posts don't make enough difference on soaking up vibrations to notice.
07-02-13, 05:35 AM
#11
Senior Member
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,682
Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build
Likes: 0
Liked 58 Times
in
36 Posts
When aluminum/carbon interfaces on bikes were "new", there was some thought about electrolytic reactions causing sacrificial failure of the aluminum especially in the presence of electrolyte rich perspiration. What ever happened to that concern? It doesn't seem to be considered much at present.
07-02-13, 05:38 AM
#12
ka maté ka maté ka ora
Join Date: Oct 2008
Location: wessex
Posts: 4,423
Bikes: breezer venturi - red novo bosberg - red, pedal force cg1 - red, neuvation f-100 - da, devinci phantom - xt, miele piste - miche/campy, bianchi reparto corse sbx, concorde squadra tsx - da, miele team issue sl - ultegra
Likes: 0
Liked 4 Times
in
4 Posts
I've successfully used tubing cutters to remove excess material from an overly long seat post. You can too. Or you could waste your money on a replacement.
07-02-13, 05:40 AM
#13
pan y agua
Join Date: Aug 2005
Location: Jacksonville
Posts: 31,475
Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike
Liked 894 Times
in
458 Posts
Lightest alu post i found is this Ritchey. I will spend my money on this:
https://www.evanscycles.com/products/...29872#features
https://www.evanscycles.com/products/...29872#features
Definitely not an investment. It's an expenditure, and a rather questionable one at that.
Once you cut your current seatpost to length, you might be saving 25 grams.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
07-02-13, 05:45 AM
#14
Senior Member
Join Date: Jan 2009
Location: GA
Posts: 1,155
Bikes: Helix, HonkyTonk, NailTrail
Likes: 0
Liked 2 Times
in
2 Posts
I am thinking about replacing my current 400mm alloy seatpost (who the hell would need it that long?!) to make my bike a bit lighter. Current stick is about 310 grams. I was checking for the options and found some alumunium seatposts around 220g with a reasonable price. If i can save 90 grams that would be good. However i wonder if a carbon seatpost would be a wiser choice considering it might help for a more comfortable ride. Though, i am not sure it is a good idea to clamp this gentle material within an aluminium frame. I think it will be broken or be crushed under the pressure. What would you recommend?
Turn the seatclamp so that the stress relief in the frame (some have it front, some rear, some side), doesn't line up with the same seam where the tightning bolt is. Some small change to create a stress riser.
It's hard to beat the Ritchey WCS parts. One bolt is nice and easy also. Get a torque wrench if you go carbon. The 0 set back ones are super stiff, none stiffer out there, al or carbon.
07-02-13, 06:07 AM
#16
Super Moderator
Join Date: Jul 2004
Location: Ffld Cnty Connecticut
Posts: 21,889
Bikes: Old Steelies I made, Old Cannondales
Liked 1,013 Times
in
648 Posts
As long as it doesn't sieze up like mine 
__________________
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike.
FYI: https://www.bikeforums.net/forum-sugg...ad-please.html
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike.
FYI: https://www.bikeforums.net/forum-sugg...ad-please.html
07-02-13, 01:40 PM
#17
Banned.
Join Date: Apr 2010
Location: Somewhere
Posts: 1,041
Bikes: something
Likes: 0
Liked 0 Times
in
0 Posts
Carbon friction paste didn't work. Or it might have, but that would have meant using a lot more torque than I was ready to apply.
So far the toothpaste has worked really well for the past two years. No seizing, adjustment is always easy, no hassle. At some point I'm thinking of turning the frame upside down, washing the old stuff away with a bottle brush and applying new paste. Then again so far the old stuff has kept elastic and easy to handle so maybe not.
Trick is to use the cheap foamy white stuff, NOT the gel. I can really understand how a gel might jam the post, but the white stuff works wondrously well.
So far the toothpaste has worked really well for the past two years. No seizing, adjustment is always easy, no hassle. At some point I'm thinking of turning the frame upside down, washing the old stuff away with a bottle brush and applying new paste. Then again so far the old stuff has kept elastic and easy to handle so maybe not.
Trick is to use the cheap foamy white stuff, NOT the gel. I can really understand how a gel might jam the post, but the white stuff works wondrously well.
07-02-13, 01:43 PM
#18
Senior Member
In finland it's sold as pepsodent xylitol. Green tube
Last edited by elcruxio; 07-02-13 at 01:50 PM.
