Looking at some seatposts for a bike I'm building up. I see some 2 bolt seatposts that look decent, but the design appears to me to not offer as much setback as a typical 1-bolt, in order to have the bolts both accessible. (This is an issue for me, as I use a Brooks, which don't scoot back as much as most other saddles.) Am I correct?

Here's an example of the type of seatpost I'm talking about https://www.ebay.com/itm/XLC-Bike-Bic...item416ae7fbf5

The seatpost you are looking for is called "no seat back" Weird you dont know because you have like 2000 posts.

Thomson seatpost, easton makes one too.

I haven't ever bought a 2 bolt model before and wasn't totally sure. Wish I did know everything! Thanks.

so wait, do you want more setback, or less than normal seat posts ?

The combination of mtn biking of frames with relatively shallow seat tube angles, and the desire to be lighter than whatever came before has led to the majority of modern posts, such as Thomson to have the center of the saddle cradle directly over the post (no setback). Most modern 2-bolt posts are this way, which also has the advantage of being easy to make.

I'm not a fan, especially because I'm mainly a road cyclist, and find reasonable setback necessary to correct saddle position. To my knowledge most modern set back posts tend to be single bolt designs these days (except Thomson, which gets it's setback by bending the post back 3" down) tend to be of single bolt design, again because it's lighter and easier to make. I prefer the old 2 bolt rocker designs like on the original Campy post from the sixties, but in all fairness, once the saddle is adjusted, you never bother with again, so I can live with the (IMO) crappy 1 bolt systems, if that's what it takes to have the correct setback.

I wanted a normal amount of setback. Didn't want to order a 2 bolt model and find I couldn't get the saddle back far enough. I went and ordered an inexpensive 1-bolt Kalloy post from Amazon. Looks like it has about 2cm of setback, so it should do just fine for this bike.

those kalloy posts are just fine. I've used them on a number of non-exotic bikes, even quite long ones for short frames, and they've held my ~220 lbs without any issues at all.

if I had a fancy high end road bike, I'd be looking for something nicer, or a high end mountain bike... but for yoru basic transportation kind of bike, older mid-grade road or mountain or hybrid or whatever, they are just fine.

setback in seatposts is a rearward offset from the centerline of the seat tube..
Center of seat post..

more generally frame -rider fit, its from the plumb line through the BB axis,
that takes in seat tube angle and saddleheight..

+1 single bolt posts may not be quite as nice to adjust, but they're perfectly adequate. In fact, I actually prefer a good 1-bolt design (fine or no serrations).

I wouldn't say they're necessarily low-end, either; I have a 1-bolt carbon post that's pretty sweet.

Thomson designed their seatposts with no set back to be able to machine them in one piece with the lower saddle clamp integral with the post. They did this to achieve greater strength and durability, not because they were attempting to fit a specific frame geometry. The story I heard was that the owner of Thomson had a saddle clamp separate from the post while he was riding and wanted to build a better, stronger seatpost that couldn't do that.

Anyway, there are two bolt seatposts with reasonable set back and a one piece post/clamp. Easton's EA50 and EA70 seatposts offer 10-12 mm of setback and are that design. Thomson makes a 16 mm setback seatpost achieved by "bending" the post to offset the clamp. The only disadvantage to the Thomson design is that you must have a minimum of about 110 mm (4.3") of seatpost exposed to keep the bend above the seatube.

https://www.performancebike.com/bikes...400216__400216
Ritchey makes two bolt setback posts in 25 or 45MM

Ummm. one-bolt posts are the easiest to adjust. This is why shops like and push them. It takes 60 seconds less to set them up than the superior 2-bolt (offset bolt) design.

The downside of the one-bolt post is that they will always slip, eventually. Always. And usually at the worst possible time.

There are two issues in this thread, the need for offset and one vs. two bolts. You can get an offset two-bolt post from many vendors.

If you can live with alu, then the Suntour Superbe Pro or XC Pro posts are the most reliable offset 2-bolt posts ever. Lots of these on Ebay still.

OP linked to a 2 bolt zero set back seat post, there are others that both bolts
are behind the post itself.

like that, Tulio Campagnolo's 2 bolt seatposts are 50 year old designs.

or this one, recent design: 27.2 with 26mm of setback
https://www.universalcycles.com/shopp...0&category=167

A 30.2mm setback
https://www.universalcycles.com/shopp...&category=4309

Many More .. if frame takes other than 27.2 seat post , choices are reduced..

Where Kalloy is better, pragmatically, a full range of diameters are made,
and for B&M shops they dont cost much, unsold, to stock. if you want something else Ask,
both of the above are distributed by QBP, most shops have an account with them.

Half wrong, plain wrong, and right.

One bolt posts are easy to adjust, but many have serrations and the seat angle cannot be "micro-adjusted" to an in between angle. Easy micro-adjustability is one of the best features of the two bolt system.

While some one bolt posts slip, saying they all do eventually is a gross exaggeration. Most of these don't ever slip, but it's a matter of quality. One factor may be rider weight and how centered that is over the cradle. Heavy riders with unbalanced saddles are more likely to see slippage, but even that's rare with better posts.

You are right describing the two issues, offset, and clamp design, and if the OP wants an offset 2 bolt clamp, he can find posts, but the selection is more limited, and none may exist in his post diameter.

If he has to choose, I'd rank proper position over the clamp design, and buy a post accordingly.

Even though this is a 2-bolt post, it's more similar to 1-bolt posts than typical 2-bolt micro-adjust posts in functionality.

Campagnolo (super record) made a nice microadjustable 1 bolt seat post , in the 80's.
ive got 2, from my AlAn bikes owned on that era, 25.0.

I have 2 of these posts on bikes. And more idle in bins. This is a mid-80's replacement for Campy's outstanding 2-bolt offset design from the 70's. The earlier posts were a pain to set up, but once you did, they were bulletproof.

The later one-bolt design had two major flaws. First it used an easily-stripped 13mm hex head bolt to tighten. You going to carry one of these wrenches around in your seat bag?

Second, this post always loosened up - eventually. I have personal experience here, in that I was stranded 30 miles into a wet ride with a seat facing downwards at a 30 degree angle after the clamp assembly slipped. You could forstall the inevitable by liberally coating the bolt with green Loctite, and torquing on the bolt until your eyes bugged out, but these posts will still eventually loosen up.

As did Zeus and doubtless others as well. But even those designs require more guesswork and repeated adjustment than a 2-bolt system: to change the angle slightly, loosen one bolt slightly, tighten the other bolt slightly. Done. With the single bolt system it's hard to get that fine control -- you often overshoot the desired target and need to re-adjust.