I have been thinking about a new seat post for my bike and was wondering about the benefits of carbon. I see Specialized talking about "Zertz" inserts and I have no clue what that means. If anyone has the answer or some general thoughts about a carbon seat post it would be much appreciated.

the zerts are inserts put into the carbon that is suppose to help dampen the shock.
I have never really delved into the main theory behind it, but I personally believe it is just a sales gimmick.
I really don't believe there is any benefit to them.

Bontrager makes a nice carbon post with one adjusting bolt on the side, for the fore and aft or tilt, as well as different degreeded set-back

My Roubaix Pro had the Specialized seatpost. I had to replace it. Despite using a torque wrench at the proper setting the post was damaged by an off-set seatpost clamp, making it unsafe to ride. I later came to learn that the carbon in the Specialized post is especially thin. I've got over 300 miles on a new alum Bontrager seatpost with a single allen wrench adjustment. I notice absolutely no difference between the ride of the old carbon and the new alum posts. Lowering you tire pressure by five lbs is likely to make more of a difference than the seatpost.

Disclaimer: This is just my experience. The experience of others may vary, as I suspect you'll find quickly enough.

My Specialized Sequoia Elite has Zertz inserts in the front and rear forks.
Can't tell you if they make a difference or not, but they look nice.
HAMMER MAN is probably right...just a sales gimmick.

I've got a Specialized Roubaix Triple Comp and it has Zertz inserts and the ride is definitely smoother than my Cannondale but Cannondales are known for "presenting" all the road to be experienced plus I couldn't tell you how much is due to the Zertz and how much is just having a carbon frame and forks and post and bars. I too am always leary of many of the claims around these types of add-ons.

So, even if Zertz is just a sales gimmick...what do you guys think about a carbon seat post?

is the zertz insert necessary for safety's sake? There is a specialized frame that is currently being sold at a nice price, but is missing the zertz insert on the seat stays. The sale is just the frame, nothing else (fork, seatpost, etc).
Would I need to put a zertz insert in it before I ride?

I don't see how a missing insert could lead to it collapsing. Thanks!

Don't like Carbon Fibre. It has a habit of being damaged without giving any outward signs that it is damaged. When C.F. is damaged- it breaks without any form of warning whatsoever. It can be damaged in so many ways. Problem in production, Overtightening of the seat clamp, Sudden impact that damages it internally without any sign that you can see, and the worst one out of the lot-It can break for no apparant reason.

It may be light and it may take some of the sting out of a harsh ride but not for me.

So when Boeing starts selling their 787 carbon fibre plane I guess you won't be flying on it

My new Sirrus Comp has the zertz on the seat stays and front fork . . . Specialize offers documentation to show they work, but I think it really is just a marketing gimmick with cool looks.

As for the carbon seat post, a very subjective opinion -- it is nice. On the three longer rides I've had on the bike (30+, 40+ and a 60+) my rear end was not complaining about the time in the saddle. The saddle is stock, nothing special, so I have to think the carbon post helped smooth out the ride, as compared to my old ride (an old mtb.). Of course, my experience is very limited and I cannot speak to the durability of the seat post . . .

This is worth some "butt-gauge" testin...
I was wonderin that myself.
I'm loath to screw with my Roubaix Elite setup considerin the wonderous nature of the ride. But maybe it would be worth using an alloy post/seat and swapping back and forth between the carbon and alloy whilst running the same bumpy road section (and maybe include a 3rd option - Rockshox sus seatpost). Considerin I really need to back off on any hard ridin this week, it might be the opportune time to really screw things up on my bikes...

Zertz looks like a good idea but that isn't sufficient. I have no
experience with them.

My 'cross bike has a low end carbon FSA (SLC?) seatpost. I use
a cheap Al post for when I put the bike up in the workstand and
I have compared them on the road. The carbon is smoother but
I don't think enough to matter. It is a nuissance (sp??) to tighten
so it won't slip and won't be destroyed. I wouldn't do it again.

I ride with an Origin 8 CF seat post on my Surly LHT. Does it cushion the ride? Who knows? I tend to stand when I got over big bumps anyway (RR tracks, uplifted concrete & asphalt road joints, etc.) but on straight pavement, it rides quite smoothly. There are horror stories about them failing without warning (as Stapfam warns) and there are definite arguments over proper installation (greased or not greased).

Occasionally I think about it cracking and ramming the end somewhere not intended to accept such intrusions but mostly I just ride it and like it. At this point I can't even remember why I had my LBS install it on the new bike: for weight? for road bump absorption?

No.


Carbon fibre is a special material for a special use. It is not a strong material and can get damaged by abuse very easily. Hence in the hands of the average person I would not trust C.F. to be strong enough.
When it comes to The highly technical manufacture as used in Transport (Planes, Boats, Cars) There would be certain safety margins built in like being overbuilt and testing before it could be deemed as safe. However, as an example,- What happens to the body work of a Formula 1 car in an accident? And although that is not overbuilt, it is tested and x rayed before use and F1 body work can fail without an accident.
I used to be a glass Fibre laminator and had to repair too many Boats that have had a slight knock last year that has gradually caused a problem that is now severe, so I do talk with some knowledge.

To trust my backside to a seat post that can fail at any time with the loose shards of pointed glass sticking upwards, is not something that I would readily do.

Okay, you made up my mind!

I wouldn't have a clue. $15 Kalloy seat posts work just fine for me. Except on my hardtail MTB where I use a Thudbuster. But that's for a bike I use for fast riding on serious singletrack with rocks and roots and dips and bumps.

Ditto. That Thudbuster is expensive but for comfort- without going to full suspension, that I cannot afford, is probably the next best thing. As to the Normal MTB- Kalloy again.

I'm not sure how one would fall out, but I wouldn't risk it. It's there for suspension, and I have to believe every time the seatstay flexes, the zertz deflects the energy, absorbing the shock.

Steve

Good disclaimer

I've the zertz post that came stock on my Roubaix Comp about 12,000 miles now and another few thousand trainer miles without problem. Can't say it particularly makes a difference (as I've nothing to comapare it to), but zero problems with the seatpost.

Steve

Let me begin by saying that I am not an engineer, nor do I have any engineering coursework in my college background.

That said.....in years past some car makers would glue a small dense block in car trunks to keep panels from vibrating, and I think that is called a 'Harmonic Damper'. Perhaps they think something with a different density can dampen some frequencies.....but I personally suspect it it hype.

I got one of those frames. Was at a Specialized dealer on Saturday and they do not sell replacement Zertz inserts. He did mention the insert was not needed for structural strength. He knew of individuals who removed the insert to save weight.

Best sentence in this thread so far.

Thanks! I had hoped to be able to get inserts for the frame, but it's problably really hard to put it in the frame
Please keep us updated on how it rides when you get your frame up and ready.


As far as carbon, the only carbon I have is in the forks. I don't think I'll ever get a carbon seatpost because of other posts. I don't do any harsh riding, but I just don't want that on my mind. I'm not that big either, 180lbs but don't want to chance it.

I'm a big boy and have had cf seat posts on both my road bikes for more than five years now. I snapped a steel bolt on one of them but the cf has held up just fine.

I really hope no one takes that as advice without checking with Specialized first. Folks used to drill their frames to save weight too, but I don't think I'd do that either.

Steve