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Aero seatpost on slight compact frame?(9 posts)

Aero seatpost on slight compact frame?Abol98
Apr 4, 2002 8:27 AM
In selecting the components for my current build, I've run in to a log jam in picking out a seat post.

The frame is a Bianchi XL EV2 from last year. With the full aluminum frame, I'd like to add a trick carbon seat pin, but I wonder if any of you think there's a real advantage to the aero posts offered by USE ($170) and Weyless ($80).

I was thinking that by the time the air flow reaches the seatpost, it's already 'dirty' from the steerer tube, bars, stem, etc. How much aero advantage do the blade-like posts have, and is it worth the 100 grams or so of weight added over a traditional post?

I climb and descend a lot, and don't do many races. When I'm out of the saddle on an incline, I know that I definately can detect the difference of 100 grams when it's located around the seat cluster.

Any thoughts? If I don't go aero, I'll probably pick up an Easton CT2, which is my most cost-effective choice at 65$.
aero steapost = no advantagestr8dum1
Apr 4, 2002 8:34 AM
theres a site on the web (dont remember link but with a little effort you can find it)that shows data proving theres no aero advantage to one of those posts.
What's stupid about aero seatposts is...tempeteKerouak
Apr 4, 2002 9:11 AM
That because of their sizes, it is sometimes very difficult (impossible?) to find a saddle bag that will have a long enough strap to attach the narrower, but much bigger mast.

I own one! The *Mike Burrows* that comes with my Giant, and I am quite annoyed with it for that reason. It is otherwise fine and easy to adjust, but then I also believe a seatpost should be as simple as possible; you don't play that much with 'em once you have it dialed into position... Sure, I find it looks good on the compact frame. But I will not consider it an advantage at all.
what if you...JS Haiku Shop
Apr 4, 2002 12:04 PM
went to the home depot and picked up a $3 package of velcro straps, trimmed one down to size, and used it to supplement the length of the saddlebag strap? would that work?
But of course! I'd stitch them together... Me=stupid! (nm)tempeteKerouak
Apr 5, 2002 10:32 AM
Aero InfoTonyR
Apr 4, 2002 9:11 AM
The site for the aero info is www.slowtwitch.com. It's a primarily for triathletes, though there is useful info on there as it pertains to regular cyclists.

What the windtunnel showed was that a compact frame with a aero tube, and NO RIDER, was better than a conventional frame and tube with no rider. Strangely enough, when you put a rider on both bikes the later config. seemed to be slightly better. Their results showed that the most aero config. would be a bike (I don't think that there was any difference between compact and conventional frames), with an integrated seat tube mast, which had an aero-post fitted. The higher the seattube the better (little post showing).

In any case, other than for looks it doesn't sound like you really need to go in this direction.

TR
re: Aero seatpost on slight compact frame?JimP
Apr 4, 2002 12:11 PM
I used an Easton CT-2 for the last 2 years. The post is OK but the seatclamp does need to be REALLY tight to keep the seat from slipping and changing the angle. Another issue is whether your frame has an internal wedge clamp or an external type. If it is the wedge type, the Easton and other carbon tubes will be dented by the wedge and if tightened too much, can cause the post to collapse. The round USE carbon post comes as a 25mm or 27.2mm and then is fitted by using the appropriate USE aluminum shim which eliminates this problem. USE recommends using the 25mm post and a shim for a 27.2 frame instead of the 27.2mm size for this reason.
re: Aero seatpost on slight compact frame?Abol98
Apr 4, 2002 1:45 PM
JimP .... Thanks for the heads up. Here's a pic of the frame. That looks like an external clamp, no? If I go with the Easton do you think I should go with the 25 and a shim? I'd love the USE, but I think I can get the easton for 60$ less, unless I troll around on Ebay...
re: Aero seatpost on slight compact frame?JimP
Apr 4, 2002 2:37 PM
I looked up the pic of the Bianchi and it sure looks like an external type clamp with the binder bolt behind the seattube. I do not know what diameter seatpost the Bianchi requires but the Easton CT-2 seatpost should be fine without a shim. My problem was that my Aegis uses a 26.8mm seatpost with an internal wedge clamp that really put dents in the first CT-2 I had. I now have the USE carbon post with the shim so I am not worried about crushing the post.