Could have been curtains tonight - seat post failure

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Could have been curtains tonight - seat post failure

40 posts & 25 voices | Started 6 months ago by mcmoonter | Latest reply from mcmoonter

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mcmoonter - Member

Out road riding tonight, just riding along, maybe 15-20 mph, rolling into Milnathort, and my seat post snapped dumping me on the road. Thankfully there were no cars around, my riding buddy just missed me. I've got the mother of all road rashes on my arse, but happy to have survived with just that.

Years ago I had marked the seat post with a centre punch, that's where the crack started from. No warning, no creaks, just catastophic failure.

It was an easton EA70 post. If anyone has marked such a post with a centre punch, I'd think about replacing it.

Posted 6 months ago #
cynic-al - Member

mcmoonter - Member
Years ago I had marked the seat post with a centre punch, that's where the crack started from. No warning, no creaks, just catastophic failure.

Either....Easton is crap...you were unlucky...and/or hole-punching stress bearing components where they are most likely to fail is not the best idea!

Good to know you are still fighting...see you Sunday?

Posted 6 months ago #
allthepies - Member

Amazing that all those years ago you marked the point it would fail. Mystic Meg or what.

Posted 6 months ago #
cynic-al - Member

TBF the pic doesn't indicate an older stress fracture.

So it's EVEN MORE MYSTIC.

Posted 6 months ago #
druidh - Member

So - two saddles and a seatpost so far this year??

One could jump to conclusions...........

Posted 6 months ago #
mcmoonter - Member

TBF the pic doesn't indicate an older stress fracture.

Aye, you can see the punch mark just above the 'E'. New clean break. I'd imagine it would be the same way a glass cutter works.

So - two saddles and a seatpost so far this year??

One could jump to conclusions...........

2011's not been a good year for the MC butt to bike interface

Posted 6 months ago #
njee20 - Member

Nope, you're wrong, metal parts don't just fail catastrophically, only carbon

Glad you were alright though! Looks nasty!

Posted 6 months ago #
simon67 - Member

Exactly the same thing happened to my mate. Worst accident he's had. Went into shock & hate to think what might have happened if there had been a car behind (was on road). I had to ride his bike home without a seat for 4 or 5 miles!

Got to check your hardware before every ride!

Posted 6 months ago #
bjj.andy.w - Member

Same thing happened to me with a ea70 aswell. Well, apart from the centre punch.

Posted 6 months ago #
boxelder - Member

Why use a centrepunch?
And why on the front, where it would be under tension?

Glad you're OK and all...

Posted 6 months ago #
takisawa2 - Member

Anyone ever snapped a Thomson like this ?
Just curious.

Posted 6 months ago #
imnotverygood - Member

Looks nasty. Glad you are ok? Out of interest were there any warning signs?

Posted 6 months ago #
fenred - Member

Personally I wouldn't mark a seat post with anything sharper than permanent ink.

Glad you're OK but perhaps a lesson learned.

Posted 6 months ago #
amt27 - Member

fast fracture

Posted 6 months ago #
mcmoonter - Member

Out of interest were there any warning signs?

None.

Falling in the dark on tarmac at speed is scary. Thankfully it doesn't take long to hit the ground. The shock kicked in immediatly, then the realisation that had a car been there I'd have been toast.

We had an ice cream cone while we waited for a lift home. No Cindy Whitehead riding for me. I could barely stand.

Posted 6 months ago #
Waderider - Member

Years ago I had marked the seat post with a centre punch

Speaking as an engineer, the fault is mainly yours. Glad you'll 'bounce' back though.

Posted 6 months ago #
falkirk-mark - Member

centre punching changes the grain of the metal. if you want to mark a seatpost use a scribe

Posted 6 months ago #
bjj.andy.w - Member

takisawa2 - Member
Anyone ever snapped a Thomson like this ?
Just curious.

I bloody hope not 'cause that's what I got after the Easton.

Posted 6 months ago #
mcmoonter - Member

There was a thread on here a few years back and a couple of folk had centre punched their posts. That's where I got the idea from. I'll use a magic marker on my replacement.

EDIT
http://singletrackworld.com/forum/topic/resetting-seat-post-height-how-do-you-mark-yours-bendeestiq

Posted 6 months ago #
spacemonkey - Member

We used to use Tippex back in the day. Still does the trick now.

Posted 6 months ago #
cynic-al - Member

Pete - sounds rough, glad you are OK acceptable to be less of am man than Cindy

simon67 - Member
Got to check your hardware before every ride!

I do that most days

takisawa2 - Member
Anyone ever snapped a Thomson like this ?
Just curious.

Never. They NEVER break. I'll mark mine just to check.

Oh and a scribe would have had no effect? Pur...lease!

Posted 6 months ago #
falkirk-mark - Member

Oh and a scribe would have had no effect? Pur...lease!

It has permanently marked mine (ex Glasgow shipyard steelworker)

Posted 6 months ago #
jools182 - Member

allthepies - Member

Amazing that all those years ago you marked the point it would fail. Mystic Meg or what.

Posted 6 months ago #
Waderider - Member

It doesn't change the grain of the metal. The grain is set by forging or casting and cooling conditions. Applying a punch introduces a weak point that a crack can originate from, a stress riser. If there is a thread on centre punching posts it was mainly populated by norks.

People on this forum fall into the trap that STW is the source of all wisdom. In reality STW is populated by pedants, the self opinionated, and the mentally ill. Such as the regular posters. Best just go out on your bike and avoid the madness. And get an education elsewhere.

Posted 6 months ago #
flap_jack - Member

I had a post fail 8 weeks ago - whilst on the turbotrainer ! Dumped me onto the patio from great height. Smacked up wrist and knee still not fixed...

Posted 6 months ago #
falkirk-mark - Member

It doesn't change the grain of the metal. The grain is set by forging or casting and cooling conditions. Applying a punch introduces a weak point that a crack can originate from, a stress riser. If there is a thread on centre punching posts it was mainly populated by norks

When the metal is cold worked by forging, stamping or rolling its shape is permanently changed (DEFORMED) this is only possible because of defects (DISLOCATIONS) in the grain structure which move through the crystal structure. These dislocations or slips in the grain structure allow the overall change in shape of the metal. Each grain can have a very large number of dislocations (only visible under a powerful microscope).
Night Night

Posted 6 months ago #
cynic-al - Member

You miss my point

Night night :hug:

Posted 6 months ago #
M6TTF - Member

Hole punch clearly wasn't enough - you should have got a pipe cutter and marked it all the way round for perfect realignment

Posted 6 months ago #
jedi - Member

pmsl @ m6ttf

Posted 6 months ago #
mcmoonter - Member

I had a post fail 8 weeks ago - whilst on the turbotrainer ! Dumped me onto the patio from great height. Smacked up wrist and knee still not fixed...

I feel your pain. I can't imagine what a bar failure would feel like.

Posted 6 months ago #
flap_jack - Member

nor can I. I have nightmares about stems punching their way into my chest cavity.

When the post failed I didn't have my hands on the bars - leaning back and taking a breather - so I dropped like a sack of cement...

Posted 6 months ago #
billyboulders - Member

I don't get why you needed to punch a mark on the post OP - surely the easton "E" is a visible enough mark seeing as your punch is right on it? "E" just in the seatclamp = right height or am I missing something?

Glad your OK tho!

Posted 6 months ago #
imnotverygood - Member

Is steel4real still posting? If so there might be something he'd like to say....

Posted 6 months ago #
ps44 - Member

It's happened to me once off road, but it was more of a gentle bend and snap that sudden fail. Didn't fancy riding home with the broken spike that was left protruding but couldn't be removed due to deformation so had to call out a severely hungover wife to collect me...who drove over with a bucket between her legs in case of any 'accidents'

Posted 6 months ago #
boxelder - Member

I can't imagine what a bar failure would feel like.

I had some Orange bars go years ago. On a late evening ride around Ennerdale. They failed quite slowly - few seconds and obviously one side was fine. I fell off, but semi-controlled. Going dark and alone a fair way from home, I stuck a stick in the broken end as a spigot and rode back 'lightly'.
Sudden fail wouldn't be nice.

Posted 6 months ago #

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