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Clydesdales/Athenas (200+ lb / 91+ kg) Looking to lose that spare tire? Ideal weight 200+? Frustrated being a large cyclist in a sport geared for the ultra-light? Learn about the bikes and parts that can take the abuse of a heavier cyclist, how to keep your body going while losing the weight, and get support from others who've been successful.

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Old 07-09-11, 05:09 AM   #1
Nicface
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Carbon seat post - weight limit

Hi guys,

I picked up my beautiful new Specialized Dolce Elite today! Hurrah!

Then I read the manual, and saw that any carbon, weight bearing components have a weight limit of 240lb or 109kg. I currently weigh 115kg. Eek. And the seat post and possibly other bits are carbon - but not the frame!!

I'm a little annoyed, as I researched this before buying this bike. The weight limits table lists the limit as 275lb, or 125kg, so I thought I was fine. But this is the first I've seen of weight limits on carbon components.

I had assumed that since the bike comes with a carbon seat post as standard, that would be taken into account in the total bike weight limit? But apparently not.

Anyway, I'm not terribly over the limit - just 6kg. Do I need to wait until I lose 6kg to ride my beauty? (Though I did ride her home from the LBS today...)

Any advice will be much appreciated!!
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Old 07-09-11, 06:02 AM   #2
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I'm not familiar with the specs on your bike, but the first thing I would check is whether the seat post is, in fact, carbon, or just carbon-wrapped alloy.
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Old 07-09-11, 06:07 AM   #3
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Hi Craig,

Thanks for the reply! Seatpost is Specialized Elite, carbon wrapped alloy, two-bolt clamp, 27.2mm - so I might be ok on that front.

The fork, however, is Specialized FACT carbon legs, alloy crown & steerer, Zertz inserts - so maybe that's going to break on me!! Oh dear.
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Old 07-09-11, 06:27 AM   #4
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I believe you are correct that the seatpost is carbon wrapped only, in which case you shouldn't run into any problems.


As for the forks, I don't believe they are considered weight bearing due to the riders weight being distributed across the entire frame, however the riders weight is directly applied to the seatpost, bars, stem.
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Old 07-09-11, 08:41 AM   #5
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You can get all of the opinions you want from the BF peanut gallery, but this is probably a case where a quick phone call to the shop that sold you the bike (or Specialized themselves) makes more sense...
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Old 07-09-11, 02:25 PM   #6
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Looks like the same fork as on my Secteur. I was 286 when I got it, 254 now. Have over 1000 miles on the bike with no issues.
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Old 07-09-11, 02:27 PM   #7
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This is very interesting - I don't think I have heard of any carbon seat post failures in the local area due to weight or otherwise...

See:

http://www.bikeforums.net/showthread...rophic-Failure

http://www.bustedcarbon.com/2010/01/...-seatpost.html
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Old 07-09-11, 03:15 PM   #8
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Not that I have a real aversion to carbon (outside of the cost), but for a seatpost it's just not necessary. For less than the price of most carbon posts you can get an ovalized Alu post that doesn't weigh a whole lot more (in the overall sense.)

40 - 60g difference might be a large percentage difference between a carbon and alloy post, but let's be realistic. 40g is the same as leaving your sunglasses and helmet visor at home. 60g is a little less than the weight of a Clif Bar.
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Old 07-09-11, 05:03 PM   #9
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It's not just weight. Carbon does kill some of the road buzz, which is nice on rough roads and/or a long ride.
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Old 07-09-11, 05:43 PM   #10
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It's not just weight. Carbon does kill some of the road buzz, which is nice on rough roads and/or a long ride.
A comfortable saddle and decent shorts work pretty well. I see very few carbon parts on most randonneuring bikes, and we're sort of known for bad roads and long rides.

If you're talking about a frame, fork, stem or bars, sure... chatter reduction. But a post? Given identical bikes, one with a carbon post and one with an alu post, would you really be able to tell a difference by feel alone over a section of pavement?
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Old 07-09-11, 06:46 PM   #11
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If you're talking about a frame, fork, stem or bars, sure... chatter reduction. But a post?
It's a marketing gimmick, obviously. Not something I'd ever "upgrade" to on my own, but also not something that was going to keep me from buying the bike.
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Old 07-09-11, 08:35 PM   #12
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Hi all,

Thanks for the replies!

Turns out the seat post is carbon coated alloy, so I think we're good there!

The fork is carbon, and Specialized advised that they have a weight limit of 250lbs, so I'm very slightly over by 1.7kg. Boo.

Still, I think I'll be ok, and should be able to lose that weight quite quickly. And I don't imagine that one gram over 250lbs, and the entire fork will collapse! Happy to be corrected though

Thanks again.
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Old 07-09-11, 10:06 PM   #13
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Quote:
Originally Posted by Nicface View Post
Hi all,

Thanks for the replies!

Turns out the seat post is carbon coated alloy, so I think we're good there!

The fork is carbon, and Specialized advised that they have a weight limit of 250lbs, so I'm very slightly over by 1.7kg. Boo.

Still, I think I'll be ok, and should be able to lose that weight quite quickly. And I don't imagine that one gram over 250lbs, and the entire fork will collapse! Happy to be corrected though

Thanks again.
There's the real breakage limit, the marketing breakage limit and the legal department breakage limit.

The engineers design it and fab a few up for testing and determine that the fork can withstand 800 pounds or so. Marketing gets a hold of it and says "We can advertise it with a 500 pound weight limit and stomp the competition!" Then legal gets the ad copy and says "Cut that in half, just to cover our butts."
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Old 07-10-11, 11:38 AM   #14
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There's an amount of force that will break pretty much anything, a fork or a seat post included. With bike parts, they've been tested to find that point, and then they set a limit well below it. Companies that can be sued like to cover their asses. I wouldn't exceed the weight limit by much, but a few kg isn't much.

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It's not just weight. Carbon does kill some of the road buzz, which is nice on rough roads and/or a long ride.
It's true, but how significant is it? I have an aluminum and a carbon fiber tripod, and with a telephoto lens, I get sharper photos from the carbon one, because of the vibration dampening. This is well known in the photographic community. On the other hand, I have a carbon road bike with curved stays in the rear triangle, forming a spring. I feel very little road buzz. I test rode its next model up, with straight stays, and felt more road buzz. Both are carbon. So it's not just the material, it's how it gets put to use.

Anyway, I've always heard that a carbon seat post makes sense if you have a lot of seat post showing, but for most people it's not going to make an appreciable difference.
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Old 07-10-11, 03:08 PM   #15
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Anyway, I've always heard that a carbon seat post makes sense if you have a lot of seat post showing, but for most people it's not going to make an appreciable difference.
In a blind test, I don't think I could tell the difference between my carbon seatpost and my aluminum Thomson Elite post...
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Old 07-11-11, 09:24 AM   #16
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In a blind test, I don't think I could tell the difference between my carbon seatpost and my aluminum Thomson Elite post...
Maybe. You should try.
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Old 07-11-11, 10:50 AM   #17
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Originally Posted by CliftonGK1 View Post
There's the real breakage limit, the marketing breakage limit and the legal department breakage limit.

The engineers design it and fab a few up for testing and determine that the fork can withstand 800 pounds or so. Marketing gets a hold of it and says "We can advertise it with a 500 pound weight limit and stomp the competition!" Then legal gets the ad copy and says "Cut that in half, just to cover our butts."
I tend to believe this. A lot of it has to do with how one rides also. I would expect that if one is "gentle" with their bike, such as raising one's butt off the seat and onto the pedals when going over little unevenness in the pavement; that one wouldn't have many issues. I know that I tend to be careful with my bikes because they cost quite a bit, and I want to "protect" my investment. I know that I am over the weight limit with my wheels, but have never had any "problems" with them. Not even a flat.
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