General Cycling Discussion - Question about seat post sizes

I just picked up a KHS Aero Track/Aerotrack frame. Based on what I see on the bike now (and Sheldon Brown's seat post database), the frame is made for a 26.8mm seat post. It looks like 27.2 is a more common seat post size these days. What kind of trouble will I get myself in if I use a 27.2 seat post on this frame? Is that sort of a bad idea, not a bad idea at all, or a horrible idea?

I've been reading BikeForums in Google searches for a while now and it's time I learned some of this stuff first hand. Trying to give my expert biker friend a rest.

Thanks in advance.

A horrible idea.

0.4mm doesn't seem like much of a difference, but it is.

A horrible idea.

0.4mm doesn't seem like much of a difference, but it is.

Good to know. No, it doesn't seem like much difference. Is this size still readily available from bike shops?
Anything special I should know about getting a new seat post? Sounds stupid but I really have no idea. I'm looking to build this track frame out to a sweet fixed street bike.

www.sheldonbrown.com (http://www.sheldonbrown.com)

Do a search on seatposts. While you are there, do a search on fixed gear and track bikes, and see what he said about converting track bikes for street use (just so you are aware of the issues).

I think you will find that seatposts come in diameter increments of 0.2mm. Some sizes, I think, aren't that easy to locate. Yours might be in that category. eBay is one place to start. You will need to look at length, too. Google searching might also help with "26.8mm seat post" as the key phrase. Note also I-beam; although I have no experience with them, I-beam seatpost clamps need I-beam-specific saddle rails. And, seatpost clamps vary in their usefulness. Again, www.sheldonbrown.com (http://www.sheldonbrown.com) discusses the issues.

Finally, the SS/FG forum is a goldmine and cesspool of information all at once. It might be useful posting something over there. roadfix is one whose opinions I would value.

What kind of trouble will I get myself in if I use a 27.2 seat post on this frame?.

You wont get into any trouble.....because it wont fit.

You'd be surprised how people want to try to make it fit, with a club hammer!

If you absolutely can't find the proper size, then you can use the next smaller size and a shim. Not the best solution, but it works.

Just get a piece of sandpaper ad sand it down but putting a piece of sandpaper in your hand and rolling the seatpost in your cupped hand with the sandpaper 5-10 turns it will fit and you can paint it.

I just picked up an extra long 26.8 mm mountain bike post on eBay for 6 clams. A little investigation shows this size is not super-hard to find although I'm sure there are more options in another size.

For the record, I wouldn't dream of using a hammer-- my first fixed gear bike had the seatpost hammered in! Totally hacked together.