# Seat Post cracked



## Rogus (Nov 10, 2010)

Just had my '15 Defy Advanced Pro 0 seat post crack going over a railroad track, one I have ridden over the same way numerous times. I weigh about 200 lbs give or take. So, not what I consider a super heavyweight. Bike has 35,000 miles on it. 

I've never heard of something like this happening to anybody and I have a lot of cycling friends. 

Wondering if any other Defy owners have run into this happening or even on other brands. 

Giant's decision to use a proprietary seat post is making it more difficult to easily replace it.

If I don't get any responses in the Giant Forum, I guess I will try a different category and risk CX's wrath if it's not an appropriate choice.


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## Peter P. (Dec 30, 2006)

You weigh 200lbs.

Yes; that qualifies as a "super heavyweight". Combine that with a carbon fiber post and the shock of riding over anything, including train tracks, and expect your seatpost to fail.

I have a 160lb. cycling friend who could feel his carbon fiber Ritchey seatpost flex. He was so unnerved by it, he swapped it out for an aluminum post.

Unless Giant makes a Defy seatpost in aluminum or an adapter to convert the seat tube to a conventional post, there's little you can do.


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## Opus51569 (Jul 21, 2009)

A 2015 with 35,000 miles on it? What's that line from Indiana Jones: "It's not the age, it's the mileage..." Your bike may only be 4 years old, but you got a lot of use out of it.


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## Rogus (Nov 10, 2010)

Opus51569 said:


> A 2015 with 35,000 miles on it? What's that line from Indiana Jones: "It's not the age, it's the mileage..." Your bike may only be 4 years old, but you got a lot of use out of it.


Not exactly complaining about it's failure as it's been ridden a lot in 4 years. I just never heard or seen of a seat post cracking like that. Hoping to hear how often it happens. 

Appreciate your response.


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## rideit (Feb 8, 2005)

Two words:
Fatigue cycles


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## Peter P. (Dec 30, 2006)

Rogus said:


> Hoping to hear how often it happens.


I weigh 135lbs. and had something similar happen with an aluminum post. I can't recall if it cracked, but the post head loosened on the shaft and spun around loosely. After that, I only purchase one-piece seatposts.


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## MaxKatt (May 30, 2015)

I don't know how even Clydes break all the stuff I see here...handle bars, seat posts, spokes. 

220lb and while I try to avoid potholes and major obstructions, everyone occasionally hits stuff. Never even had a pinch flat.

...actually, one pinch flat years ago on my dual suspension MTB hammering down a trail full of baseball and grapefruit size stones. I was still surprised it didn't soak up the hit. Front tire.


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## FasterStronger (Jun 6, 2014)

I had a Defy for 5 yrs (weighed about 200lbs when I first bought it) and then a Propel SL and a TCR - haven’t had that happen to any of them. I would chalk it up to use and fatigue buy a new post and move on -thankfully you didn’t get hurt.


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## Tallboy1959 (Jun 19, 2017)

What he said.


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## Rogus (Nov 10, 2010)

Appreciate the responses. I am aware of material fatigue. Wasn't asking why it happened, but hoping to find out if it had happened to anybody else. I know manufacturers forums don't get much traffic, but so far no reports of it happening except to me. Maybe a bigger sampling can be obtained in components. Just trying to satisfy my curiosity about seat post failure


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## Swerny (Mar 4, 2008)

i think you will be heard pressed to find anyone with 35,000 miles on their 4 year old bike to compare to


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## Rogus (Nov 10, 2010)

Swerny said:


> i think you will be heard pressed to find anyone with 35,000 miles on their 4 year old bike to compare to


Does it make a difference what time frame 35K miles is put on the seat post? It's the same amount of riding, just done in shorter time frame than most seem to do.


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## Djbilbstar (Mar 22, 2021)

Dear All

I broke my back 8 weeks ago, my 2 month old giant carbon seat post failed.

I’m around 20kg + under weight restrictions bike had only done 1100km.




















Rogus said:


> Just had my '15 Defy Advanced Pro 0 seat post crack going over a railroad track, one I have ridden over the same way numerous times. I weigh about 200 lbs give or take. So, not what I consider a super heavyweight. Bike has 35,000 miles on it.
> 
> I've never heard of something like this happening to anybody and I have a lot of cycling friends.
> 
> ...


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## mamaphil (Feb 1, 2021)

Djbilbstar said:


> Dear All
> 
> I broke my back 8 weeks ago, my 2 month old giant carbon seat post failed.
> 
> ...


Get well soon!

Are you talking to Giant about this failure? I hope they somehow "make it right" with you. What kind of seatpost is this and what kind of bike did it come on? Whats your weight and mileage?


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## Djbilbstar (Mar 22, 2021)

mamaphil said:


> Get well soon!
> 
> Are you talking to Giant about this failure? I hope they somehow "make it right" with you. What kind of seatpost is this and what kind of bike did it come on? Whats your weight and mileage?


Thank you.
Have been some communication between the company sold me bike and Giant between them and not direct to me, returned the bike to company that sold it to me and there own report (not giant) suggested inadequate adhesive bond on seat going into carbon seat post. When returned bike was expecting Giant to also receive request bike but for some reason they have not even checked it

Ive got bike back and doing my only independent check on it and await response. Had only done 1100km two months old and weight around 105kg, well with in limits.

they offered me an upgraded bike worth £600 more than original bike, while carbon had worse group set, but was told if accept offer then case closed and can not claim.

so thinking my next steps, do not need surgery but life time of back issues and in constant pain so one would hope the £600 upgrade does not represent what my injury is worth.

hopefully I can ride bike again or pick up my son and not be in fear of doing so, can not sit for more than 30 minutes to an hour.

such a shocking design of seat post only been used to one lump of metal and no parts that are glued into other parts.

aware of shimano bounding issues and might of been down to where these things are been bounded and the humid weather not allowing the adhesive to bound correctly.


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