hey all, just got a Canpagnolo aero seatpost. It's about 1cm short (below the limit line). If I ride and race with the post above the limit line is that a terrible awful idea or should I not care?

IMO, often the "line" is not so much of a concern for me WRT the post. looking at many of them the material is often very thick.

but a too short amount of post can damage a seattube if is doesn't span the entire toptube/seattube junction WRT depth. possibly even then.

i'll spare you the embarrassment of explaining how you ended up with a too short seatpost by not asking. BTW, i have a NOS Nehru jacket that's too small for me that i can let you have at cost.

in case you've forgotten or never knew...

Agreed. It depends somewhat on the frame... and how heavy the rider is.

The line is there for a reason. It's up to you if you respect it or not...

There's always fudge room in any line. Figure that it's located in a place that covers the worst case scenario of rider weight, fit, clamp design, etc. So if you're not anywhere close to a worst case situation, you're probably OK fudging a bit.

The operative word here is "probably", and that depends on how much Campagnolo erred to the conservative side. Off the cuff, you're probably safe if you still have at least 2" of post in the frame, and the bottom is below the bottom of the top tube, and you're not heavy or ride bad roads.

Let me see. You bought a high dollar seat post for a bicycle frame that is WAY to small for you and you want to be justified when it breaks and tears your hemorrhoids open because you are violating engineering data. What would your mama or grandmama say?
Cheers,
David in Alaska

There are several things we fellow forumites do not know. We do not know how you ride, what you weigh or how light a seat tube your bike has. You are not likely to damage the post unless you are going to subject it to extremes. But if you are heavy and hit a hard frost heave at speed and you are riding a very light frame, you could dent the seat tube at the end of the post. If you are riding a very light modern steel frame, you might want to consider a longer post just for peace of mind. I have a Campy (Courus) areo post. Nice posts, but they are not long. There are lots of longer nice posts.

Ben

Not necessarily. That post is not very long if it is like mine. Lots of folk like more post showing than that post has. And being Campy, I really don't think the added bending moment if 1 cm is going to do it in. The issue is whether that post could damage the seat tube, doing no harm at all to the rider but possibly devaluing the frame. His hemorroids are not at risk (unless he is like the guy in yesterday's thread who breaks everything).

Ben

Thanks for the constructive comments those of you who weighed in, and who know the product. To the other guys, what's with the attitude?

Ill use this at the track mostly and not so much on the roads. I'm 170lb and it's going on an old Pinarello Columbus steel frame. Should be fine.

Every spec has a tolerance. In this case the tolerance depends on your weight and how you're riding. If you were mountain biking on the thing I definitely wouldn't go above the line. But at your weight, and given how you say you're going to ride the bike, I think you'll be fine. My commuter has a rather short post that I run in a similar position and I've never had an issue. But it's also a heavy, straight gauge, hi-ten frame.

The point is that it's not an exact science and folks who live and die by the rules simply don't know when it's ok to bend them.

That rider and bike information might have been more useful if given right up front. A rider of moderate weight riding on the track using a relatively robust steel frame allows some latitude that for a heavy rider on a rough road using a flea-weight aluminum frame might be ill advised.

The "attitude" is because you specifically asked about violating an industry safety standard and they pointed out, perhaps a bit graphically, possible bad outcomes.

Thanks Hillrider. I was talking more about the judgements attached to the responses, over the graphic elements. Dicks. But what else to expect from roadies. Thanks again.

These seat posts date back to when proper sizing meant just a fistful showing which isn't the trend today especially with compact frames.

The most common C-Record aeropost is 220mm long and a short 180mm model was available. The shortest common modern length is 250mm.

It's the frame you may destroy .. bottom of post to at least the bottom of the lower side of the top tube joining the seat tube is the 'bottom line'.

BITD, I got a Same diameter plain top seatpost, and my Father, Retired Machinist, Home machine shop owner,
turned down the top of The other post to fit inside, to double that thickness, and welded it to the bottom of the Campag Post,
then machined the aluminum welding bead down smooth..

"Now I can never become a grandmama."