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  1. #1
    Senior Member genel's Avatar
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    Seat Post failure

    Shortly after I started home (13m) the saddle mount on the seat post failed. It is a single boltstyle and the bolt failed. It fell in the grass along the bike path and was lost forever. I searched for about 15min. Unfortunately it took the top half the clamp with it. So the spare bolt I carry was useless.

    Riding the full 13m while standing was quite a workout.

    LBS had a spare clamp that fit so all is well. I thought I was covered by carrying a spare bolt, but Murphy never sleeps.
    "Why is there a hill after every meal, but not a meal after every hill?"
    --Overheard on Grabaawr

  2. #2
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    Seat Post failure

    I am trying to visualize how it is possible to loose the bolt, nut and collar...how loose was the bolt? Figured the loose clamp would've had your seat post slipping like crazy. Need more details....I mean I've lost a kickstand on a motorcycle, but this seems bizzare

  3. #3
    Rocketship Underpants Dwayne's Avatar
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    Quote Originally Posted by Bjforrestal View Post
    I am trying to visualize how it is possible to loose the bolt, nut and collar...how loose was the bolt? Figured the loose clamp would've had your seat post slipping like crazy. Need more details....I mean I've lost a kickstand on a motorcycle, but this seems bizzare
    Bolt wasn't loose, it broke, at least that's the way I understand it. Wouldn't be as tragic on a two-bolt seatpost, but on a one-bolt, yup, there goes the whole kit and kaboodle.
    '94 RSBikes Stampede (commuter), '05 Prophet, '09 Scattante XRL Team
    Retired/Sold: '10 C-Dale Slice 4, '97 C-Dale Super-V, '05 C-Dale R5000 (hit by car)

  4. #4
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    Seat Post failure

    Crazy. Better than a wheel I suppose.

  5. #5
    Mad bike riding scientist cyccommute's Avatar
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    Quote Originally Posted by genel View Post
    Shortly after I started home (13m) the saddle mount on the seat post failed. It is a single boltstyle and the bolt failed. It fell in the grass along the bike path and was lost forever. I searched for about 15min. Unfortunately it took the top half the clamp with it. So the spare bolt I carry was useless.

    Riding the full 13m while standing was quite a workout.

    LBS had a spare clamp that fit so all is well. I thought I was covered by carrying a spare bolt, but Murphy never sleeps.
    Pish! What's 13 miles? If Cindy Whitehead can ride 50 miles race and win, what are you complaining about?
    Stuart Black
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  6. #6
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    A seatpost clamp bolt broke? That's gotta be one of the rarest failures of all possible failures, right up there with brake lever mounting bolt failure and top cap bolt failure. I wouldn't ride that bike until you get it exorcized; stem might break.
    Chaad--'95 DeKerf Team SL, '02 Lemond Buenos Aires, '05 Novara Buzz, '73 Schwinn Collegiate, '06 Mountain Cycle Rumble, '09 Dahon Mariner D7, '12 Mercier Nano, '12 Breezer Venturi

  7. #7
    coprolite fietsbob's Avatar
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    so what better an excuse to buy a new seatpost can you get.

    Lapade and a bunch of other cheap posts are often specified just to keep the price point down ..

    how about a Cane Creek Thudbuster .. I have a LT on my BiFri, thinking of a ST for my Koga WTR, it has a sus post now

    thats fine , but zero setback the other has setback .. seat tube is a bit steep.

  8. #8
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    Seat Post failure

    Ok even if the bolt busted how does the clamp fall off? All of my bikes I have to remove the seat post and remove it from the top. Still confused, and baffled. It's going to keep me up tonight.

  9. #9
    Mad bike riding scientist cyccommute's Avatar
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    Quote Originally Posted by Bjforrestal View Post
    Ok even if the bolt busted how does the clamp fall off? All of my bikes I have to remove the seat post and remove it from the top. Still confused, and baffled. It's going to keep me up tonight.
    The bolt keeps the whole clamp assembly in place, especially for a single bolt clamp. Remove the bolt and everything falls to pieces. I'm not sure what kind of clamp you are using, however. All of the single bolt clamps I've used are tightened from under the saddle and the bolt goes into a threaded "nut" on top of the clamp. The "nut" sits in a recess that keeps it from turning. I've had a couple of PITA dual bolt systems that used a bolt under the saddle for leveling but those are pretty rare.
    Stuart Black
    Solo Without Pie. The search for pie in the Midwest.
    Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
    Days of Wineless Roads. Bed and Breakfasting along the KATY
    Twisting Down the Alley. Misadventures in tornado alley.
    An Good Ol' Fashion Appalachian Butt Whoopin'.

  10. #10
    Senior Member
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    Quote Originally Posted by cyccommute View Post
    Quote Originally Posted by Bjforrestal View Post
    Ok even if the bolt busted how does the clamp fall off? All of my bikes I have to remove the seat post and remove it from the top. Still confused, and baffled. It's going to keep me up tonight.
    The bolt keeps the whole clamp assembly in place, especially for a single bolt clamp. Remove the bolt and everything falls to pieces. I'm not sure what kind of clamp you are using, however. All of the single bolt clamps I've used are tightened from under the saddle and the bolt goes into a threaded "nut" on top of the clamp. The "nut" sits in a recess that keeps it from turning. I've had a couple of PITA dual bolt systems that used a bolt under the saddle for leveling but those are pretty rare.
    I was thinking of the seat post collar, this makes much more sense thank god I thought I was loosing my mind!

  11. #11
    Senior Member rebel1916's Avatar
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    Great opportunity to go carbon. Lighter, stronger, more comfortable.

  12. #12
    Senior Member genel's Avatar
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    To answer a few of the questions. The seat post is a suspension post that came with the Cannondale. The bolt goes up through the mount on the post through the clamp. It is(was) quite tight as any loosening allows the saddle to shift positions. The bolt fails at the bottom of the upper clamp. This is the third time I've had one fail. First time I was only a mile or so from a hardware store, Second time I had a spare with me. This time, as I said, the upper clamp and the broken bolt section, fell in the grass along the bike path, and disappeared, so my spare bolt was useless. My best guess is about 8000 miles between failures, so not something I worry all that much about. Probably should be a hardened aircraft grade bolt but they're not easily available at the local Ace.
    "Why is there a hill after every meal, but not a meal after every hill?"
    --Overheard on Grabaawr

  13. #13
    coprolite fietsbob's Avatar
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    ''//,, I have a Cane Creek Thudbuster seat post, now.. an excellent suspension seat post.

    It's not a telescopic seatpost.. and so will not have the saddle wiggling radially around the posts axis.

    CC offers several rider weight appropriate Elastomers .. to fine tune them.

    http://www.canecreek.com/products/seatposts
    Last edited by fietsbob; 08-19-13 at 09:29 AM.

  14. #14
    coprolite fietsbob's Avatar
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    Probably should be a hardened aircraft grade bolt but they're not easily available at the local Ace.
    or the auto parts store , [try] bolts marked 8.8, are stronger than the generic mild steel in hardware store bolts.

    FAA certified bolts will be really pricy.

  15. #15
    Senior Member genel's Avatar
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    Quote Originally Posted by fietsbob View Post
    or the auto parts store , [try] bolts marked 8.8, are stronger than the generic mild steel in hardware store bolts.

    FAA certified bolts will be really pricy.
    Oddly enough I never thought of the Auto Parts Store, I'm on it!
    "Why is there a hill after every meal, but not a meal after every hill?"
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  16. #16
    ride for a change modernjess's Avatar
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    Buy a thomson post and be done with it . Just my $.02.

  17. #17
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    Quote Originally Posted by chaadster View Post
    A seatpost clamp bolt broke? That's gotta be one of the rarest failures of all possible failures, right up there with brake lever mounting bolt failure and top cap bolt failure.
    I've had it happen. It's quite a surprise when you're cruising along and - SNAP - the seat goes out from under you.

  18. #18
    Senior Member Germany_chris's Avatar
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    Quote Originally Posted by modernjess View Post
    Buy a thomson post and be done with it . Just my $.02.
    Hes should definitely spend $100 on a new seat post over $1.50 to fix his current one.
    I'm an angry angst ridden anarcho-punk socialist you should just generally disregard my posts--Germany_chris

  19. #19
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    Quote Originally Posted by billyymc View Post
    I've had it happen. It's quite a surprise when you're cruising along and - SNAP - the seat goes out from under you.
    Wow, really? Okay, it's not that I don't believe it, but I just want to make sure that something else isn't going on.

    I mean, I've been a strong, aggressive, 200lb rider since the mid-80s, back in the days when MTB specific stuff was kinda rare, and we'd even run road gear on the trail to get lighter stuff, or even drill out clamps and stuff to shave grams. Bombing trails from the Apennines to the Rockies to Moab, not only have I never broken a seat clamp bolt, I don't recall seeing anyone break one. I've also ridden the road all that time too, and never seen that, either. Pedal spindles snap, seat rails break, handlebars crack, frames break, fork dropouts fail...I've seen just about everything break except seat clamp bolts and stems.

    So forgive me for being very surprised to hear the OP has had two seat clamp bolt failures. I just wonder if it could be due to a stripped nut, overtorqued bolt, or wrong bolt threading or spec. I just cannot imagine how a seatclamp bolt head could shear off...
    Chaad--'95 DeKerf Team SL, '02 Lemond Buenos Aires, '05 Novara Buzz, '73 Schwinn Collegiate, '06 Mountain Cycle Rumble, '09 Dahon Mariner D7, '12 Mercier Nano, '12 Breezer Venturi

  20. #20
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    Quote Originally Posted by chaadster View Post
    Wow, really? Okay, it's not that I don't believe it, but I just want to make sure that something else isn't going on.
    Yes really. I can't really tell you why it broke - don't think it was overtorqued or damaged in any way. It was on a 2007 Specialized Tricross Comp (2007). I bought it used with almost no miles at all on it, and I had been riding it for a year or so when it occurred. I inspected the bolt - didnt seem to be any real problems with it. Fortunately I was only a mile from a LBS and had it fixed up within just a few minutes.

    Replaced it with a larger diameter bolt (that still fit the clamp/post). It's a single bolt clamp. The owner at the LBS - in the business for at leaset 30 years - didn't express any surprise at the broken bolt. Have about 8k miles on the bike since then, no issues with the new seat bolt (yet!).

  21. #21
    Senior Member PatrickGSR94's Avatar
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    Quote Originally Posted by cyccommute View Post
    Pish! What's 13 miles? If Cindy Whitehead can ride 50 miles race and win, what are you complaining about?
    Rob Greenfield just completed his Off The Grid bike ride across America journey, and I heard on a recent episode of the Outspoken Cyclist podcast that he rode across an entire state standing up, with no saddle. 300+ miles.

    http://www.greenfieldadventures.org/...ss-america/cp4
    2011 Felt Z85 105 | Ultegra | KMC | Selle Italia | Vuelta | Topeak
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