Results 1 to 19 of 19
  1. #1
    mtbr member
    Reputation:
    Join Date
    Sep 2007
    Posts
    876

    Carbon Seatpost?

    What type of carbon seat post are you guys using? I'm using an Easton EC 90 but I'd like to get one without any flat on it. The flat can cause the set tube inset to become unbonded by the seat post clamp bolt, and also illiminate any dirt and water getting down the seat tube.

    Mojo

  2. #2
    mtbr member
    Reputation:
    Join Date
    Dec 2008
    Posts
    211
    What do you mean by the flat causing the seat tube to become unbonded? Are you referring to the flat section at the back of the EC90 seatpost? In what way would that cause any damage to the frame? It seems highly unlikely to me that the EC90 would be causing any problems there, also considering how many Mojo/SL there are out there with the EC90 post.

    Do you have a Mojo or Mojo SL? The regular Mojo uses aluminum seat tube inserts, whereas the SL utilizes a full carbon construction.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Sep 2007
    Posts
    876
    Quote Originally Posted by Crossmaxx
    What do you mean by the flat causing the seat tube to become unbonded? Are you referring to the flat section at the back of the EC90 seatpost? In what way would that cause any damage to the frame? It seems highly unlikely to me that the EC90 would be causing any problems there, also considering how many Mojo/SL there are out there with the EC90 post.

    Do you have a Mojo or Mojo SL? The regular Mojo uses aluminum seat tube inserts, whereas the SL utilizes a full carbon construction.
    On the Sl's the carbon insert has a tendency to break away around the slot where it goes into the seat post frame tube because of the flat on the ec90, at least mind did on my 2008. It's not a big deal because it isn't a crack. I just figured since I've got a new triangle I'd rather prevent it from happening again.

    Mojo

  4. #4
    mtbr member
    Reputation: GuruAtma's Avatar
    Join Date
    May 2004
    Posts
    3,468
    The EC 90 is the post Ibis chooses to put on their complete bikes. I'd hope it doesn't hurt the frame. Easton says the flat part is to protect the post from being over tightened.
    功夫大师喜欢骑着他的自行车在山上。

  5. #5
    mtbr member
    Reputation:
    Join Date
    Dec 2009
    Posts
    17
    About to build my Mojo this week, I have got a Ritchey WCS Carbon One-Bolt to go on it.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Dec 2008
    Posts
    211
    Quote Originally Posted by Mojo Man
    On the Sl's the carbon insert has a tendency to break away around the slot where it goes into the seat post frame tube because of the flat on the ec90, at least mind did on my 2008. It's not a big deal because it isn't a crack. I just figured since I've got a new triangle I'd rather prevent it from happening again.

    Mojo
    Don't you think that was just a quality issue of your frame rather than a construction flaw? Have you heard of other Mojo owners who've suffered from the same problem?

  7. #7
    Curmudgeon
    Reputation: shif's Avatar
    Join Date
    May 2008
    Posts
    86
    FSA K-Force SB25.

    Continuous one-piece carbon fiber construction
    2-bolt adjustable head
    25mm set-back design, lengthens the cockpit.

    I use carbon assembly paste and have never gotten this thing stuck in my Mojo frame.



    Cheers,
    S

  8. #8
    mtbr member
    Reputation:
    Join Date
    Sep 2007
    Posts
    876
    Think about it, the slot in the post insert is designed to allow the insert to compress/tighten around the seat post. If you mount the insert slot below the seat post frame tube and bond it with glue, the slot will want to break away from the frame tube because of this compression/clamping movement. This breakaway is then exagerated if there is a flat on the seat post tube.

    Actually the bottom of the insert SLOT should be above the frame tube so the entire insert slot can be free to compress/tighten around the seat post. But that wouldn't look astatically pleasing to the eye.

    Do you follow?

    mojo
    Last edited by Mojo Man; 05-03-2010 at 07:14 AM.

  9. #9
    mtbr member
    Reputation:
    Join Date
    Aug 2009
    Posts
    407
    New Ultimate

    140 grams.

    fairwheel bikes has them.

  10. #10
    mtbr member
    Reputation:
    Join Date
    Sep 2007
    Posts
    876
    Wow, for that price I'll just put some bondo on the flat area that gets clamped for my EC90.

    I can't believe they sell posts in the $570.00 range. Must be for roadies

    Mojo

  11. #11
    mtbr member
    Reputation:
    Join Date
    Dec 2008
    Posts
    211
    What I still don't get is that if this was a common problem, we should be hearing a lot of people complain about it as the EC90 must be the most used seat post on the Mojo SL.

    Sorry for going on about this, but as I'm about to order an EC90 myself, I want to straighten out the facts.

  12. #12
    mtbr member
    Reputation:
    Join Date
    Dec 2008
    Posts
    1,306
    I ditched my EC90 due to the flat spot letting water & dirt into the frame/bottom bracket area.Tried a o-ring & some clear tape, but it still didn't completely fix the problem.Went with a New Ultimate 31.6 x 300 = 130 grams.Fairwheel bikes has them for $230.00.

  13. #13
    mtbr member
    Reputation: getbusyliving's Avatar
    Join Date
    Mar 2007
    Posts
    417
    Get a dropper-type seatpost and never look back. If the extra grams give you anxiety, trust me that the weight gain will be way more than offset by the speed and smiles you gain on the downhill. (OK, that was a little off subject but I'm a big believer.)

  14. #14
    mtbr member
    Reputation:
    Join Date
    Sep 2007
    Posts
    876
    Quote Originally Posted by Crossmaxx
    What I still don't get is that if this was a common problem, we should be hearing a lot of people complain about it as the EC90 must be the most used seat post on the Mojo SL.

    Sorry for going on about this, but as I'm about to order an EC90 myself, I want to straighten out the facts.
    It's hard to see the bond separation unless you remove the post and squeeze the tube insert

    Mojo

  15. #15
    Church of the Wheel
    Reputation: mtb143's Avatar
    Join Date
    Aug 2007
    Posts
    743
    Quote Originally Posted by getbusyliving
    Get a dropper-type seatpost and never look back. If the extra grams give you anxiety, trust me that the weight gain will be way more than offset by the speed and smiles you gain on the downhill. (OK, that was a little off subject but I'm a big believer.)
    +1

    I also ditched my EC90 for a dropper post. I had solved the water leak problem with some silicone aquarium sealant, but thought I'd try a dropper post just to check it out. I thought maybe for racing I'd throw the EC90 back on. But once my eyes were opened to the dropper world, there was no way I could ever go back to a rigid post. You'll have to pry it out of my cold, lifeless hands, along with the rest of the bike.
    "I thought you'd never love me without my Mojo." -Austin Powers

  16. #16
    mtbr member
    Reputation:
    Join Date
    Sep 2009
    Posts
    420
    Quote Originally Posted by Crossmaxx
    What I still don't get is that if this was a common problem, we should be hearing a lot of people complain about it as the EC90 must be the most used seat post on the Mojo SL.

    Sorry for going on about this, but as I'm about to order an EC90 myself, I want to straighten out the facts.
    Is that a frame crack or cosmetic ??

    if you are talking about a regular Mojo, and not the SL, there was a run of frames (my '07 fell into it) where the bonding agent was bad and the aluminum insert (the insert on the SL is carbon) comes unbonded and can be repaired with JB Weld. The new regular Mojo frames shouldn't have this problem, your EC90 post should be fine. If you still don't want to use it, send it to me, and I will test it with my JB Welded frame.

  17. #17
    mtbr member
    Reputation:
    Join Date
    Dec 2008
    Posts
    211
    Thanks for the post, I hadn't seen the other thread before. It occurred to me that if one were to widen the slit cutout in the seat tube insert as to match it to the width of the flat section of the EC90, the problem should be solved. I wonder what Hans thinks of this solution...

  18. #18
    mtbr member
    Reputation: doismellbacon's Avatar
    Join Date
    Sep 2007
    Posts
    2,090
    Quote Originally Posted by Crossmaxx
    What I still don't get is that if this was a common problem, we should be hearing a lot of people complain about it as the EC90 must be the most used seat post on the Mojo SL.

    Sorry for going on about this, but as I'm about to order an EC90 myself, I want to straighten out the facts.
    Search the forum, there were several people who reported the same problem occurring with that post.... Ibis addressed it in their characteristically gracious and straight forward fashion.... as I recall it didn't pose any structural problem (although some guys got their panties bunched up nonetheless).

  19. #19
    mtbr member
    Reputation:
    Join Date
    Sep 2007
    Posts
    876
    Quote Originally Posted by Crossmaxx
    Thanks for the post, I hadn't seen the other thread before. It occurred to me that if one were to widen the slit cutout in the seat tube insert as to match it to the width of the flat section of the EC90, the problem should be solved. I wonder what Hans thinks of this solution...
    Yes, but if your are using a non flat sided seat post you are removing contact area that can aid in gripping the seat post.

    Why not just get a post w/o the flats?

    It's a joke how much carbon posts are selling for, at least the EC90 is a better deal, too bad for the flat area.

    Mojo

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •