Seat Post failure
08-16-13, 07:37 AM
#1
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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.
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.
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"Why is there a hill after every meal, but not a meal after every hill?"
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08-16-13, 08:10 AM
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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
08-16-13, 08:39 AM
#3
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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.
08-16-13, 03:37 PM
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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.
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.
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Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
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Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
08-16-13, 04:25 PM
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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.
08-16-13, 04:38 PM
#7
Banned
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.
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.
08-16-13, 09:36 PM
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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.
08-17-13, 07:55 AM
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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.
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Plan Epsilon Around Lake Michigan in the era of Covid
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Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
08-17-13, 08:05 AM
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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.
08-19-13, 08:38 AM
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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.
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"Why is there a hill after every meal, but not a meal after every hill?"
--Overheard on Grabaawr
"Why is there a hill after every meal, but not a meal after every hill?"
--Overheard on Grabaawr
08-19-13, 09:19 AM
#13
Banned
''//,, 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.
https://www.canecreek.com/products/seatposts
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.
https://www.canecreek.com/products/seatposts
Last edited by fietsbob; 08-19-13 at 09:29 AM.
08-19-13, 09:26 AM
#14
Banned
Probably should be a hardened aircraft grade bolt but they're not easily available at the local Ace.
FAA certified bolts will be really pricy.
08-19-13, 02:39 PM
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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?"
--Overheard on Grabaawr
"Why is there a hill after every meal, but not a meal after every hill?"
--Overheard on Grabaawr
08-19-13, 05:17 PM
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Buy a thomson post and be done with it . Just my $.02.
08-20-13, 03:59 AM
#17
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I've had it happen. It's quite a surprise when you're cruising along and - SNAP - the seat goes out from under you.
08-20-13, 06:23 AM
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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...
08-20-13, 09:33 AM
#20
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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!).
08-20-13, 09:46 AM
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Pish! What's 13 miles? If Cindy Whitehead can ride 50 miles race and win, what are you complaining about?
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