I'm currently building up my Jamis frame. The seat tube is too large for any of the seatposts I have here, so I'll need to buy a new one. I currently ride with the saddle pushed right back on the seatpost (and probably need a bit more) and measurements suggest I haven't gained much if anything in the way of seat tube angle with the new frame (won't manage it outside of a custom frame methinks).

So, seeing I need a new seatpost anyway, buying one with more set back is smart if not essential. The current post on the Trek has a 15mm set back. I guess I'm looking for 25mm (1") or a bit more.

Any suggestions on where to get one? Other than the lbs, it'll be an online order. Chainreaction is my favourite online shop but surely there are some good American online companies (Sheldon Brown will only ship here if I order more than $100 ).

The other question is sizing. The micrometer tells me the hole is 27.4mm. BUT, I've only seen posts listed at 27.2mm. Is the size given the size the post is milled to or the size it's intended to fit into? If the former, you'd need room for the thing to slide. I realise that 0.2mm is a poofteenth of a cat's hair, and so aren't worried about buying a 27.2mm post, but if I'm buying new, I'd might as well get the right size - this is really only relevant if buying online or ordering, if the lbs has the right thing in stock, we can just shove it in the hole to see.

Richard

FSA SL-220 has above average setback. I don't know exactly how much. I got mine at Glory Cycles online. I can't help on sizing.

There are seatposts with varying amounts of setback. If you check the websites for Performance, Nashbar, Colorado Cyclist and Excel Sports, you should get a lot of pictures. Easton has one with a huge amount of setback, for example. The seat clamp is completely behind the post. Seatposts also come in a variety of diameters. You can call or email and find out if a 27.4 mm seatpost is made. My guess is that if the opening is 27.4, you'll want a seatpost that is slightly smaller than that. I'd do some talking/calling/emailing to find out more.

-soma5

Thanks for that. Frustratingly, I can get what I want but only in carbon fibre. I don't want carbon fibre. The most setback I can get in ally is 25mm. Maybe that's all I need, but I won't know until I buy and try.

Richard

Been looking for a picture of it- but it is an MTB seat post that has the lay back fitting for the saddle instead of the inline Type- but it has a bend in the post to put the Saddle even further back. Believe it is made by Thompson and if it is, it will be expensive. It may not be suitable for a road bike but will not be made in CF. Look at the MTB sites as they are common on the Full suspension bikes.

I've looked at the Thompsons. I sort of fear the bend will be too low - this is a traditionally styled frame and has been sized accordingly ie, a rather high seat post with not a lot sticking out of the bike. However, you are right in observing that mtb is more likely to give me what I'm after.

Richard

Funnily enough- I have the reverse problem on most bikes in trying to get the saddle as far forward as possible. Another reason for Compact frames. The OCR3 is the only bike I have where the seat looks right on the post- But Luckily-I can still get the saddle in a comfortable position.

And Boreas has an inline post and the saddle still looks too far forward on the post.

Several of the Easton EA or EC series seatposts have 25mm setback. You won't find much more than this on a post without a bend in it as the leverage gets too big for the post to withstand. If that won't do it you may have to add 10mm to the stem.

That might explain why FSA has carbon stems that go back further but not ally ones. Thanks for that.

There's a nice FSA I can get from ChainReaction for a decent price (postage from the US tends to be a bit scary, though not always) that'll give me the 25mm set back. I might just go with that.

Thanks for your help. You've clarified how far I can go and I've got a few more online shops on my list now.

Richard

+1. As much as I hated to remove my thompson elite, I needed more setback on my Mondonico. It has proven to be a worthy replacement.

Check out Wallingford Bike (Wallbike.com) in New Orleans. They sell a CLB alloy single-bolt seat post that has about 30 mm setback. There are several thicknesses, but I'm not sure if 27.4 is one of them.

I found that undersized seat posts can lead to frame stress at the seat pillar. I don;t think its safe to use a 27.2 if it seems to mike at 27.4. Thre is another thing to try, take the frame to a good pro or frame shop and ask them to check the proper size.

I tried the Thomson that Stapfam is suggesting, and while it is a fine piece, it does not have 25 or 30 mm of setback, it's more like 15 to 19 mm. They didn't bend the shaft to get extreme setback on an inherently setback designn, they bent it to get setback on inherently NOT setback design. That is not a high-setback part.

Theres also a Selcof part, I think it's called Bidimensional or something, and while complex, it can get into the 30-35 mm range. But it is more expensive in the US than a Thjomson! For NZ, who knows?

Road Fan

I just bought and installed this one from Nashbar. Setback is 28mm, which I figured I'd need with my new Brooks B17

Yes, it's a "mountain" seatpost, but as far as I know the only difference is that mountain posts tend to be longer. If the extra length bothers you, cut a few inches off the bottom of the tube.

I've no qualms about fitting mtb parts (she'll be running a DeoreLX rear derailleur ).

That looks like the post, but how does it give the 28mm set back? In the photo, it looks very little.

Richard

Checked out the web site at ovalconcepts.com and it is indeed sped'd for 28mm. Possible the bolt arrangement allows that more easily than a single bolt seatpost.

To be honest, I'm taking them at their word, as I'm not sure exactly how setback is measured. All I know is I was worried about the limited ability of the Brooks rails to allow the seat to be moved back, and I am currently in about the middle of the possible range of adjustment. I now have about 3/8" to 1/2" of adjustment available in both directions if I need it. This is on a Surly Cross-Check.

Do any of the seatposts (shouldn't that be "saddle" posts?) that you own now have enough setback? If one does, maybe you could just use a shim to fit the larger seat (saddle) tube:
https://www.pricepoint.com/detail/128...tpost-Shim.htm

Another option is the classic American Classic seatpost. It has one clamp bolt and one angle adjust bolt, and the top clamp is very narrow. So the saddle can be slid back farther than the edge of the lower clamp. The risk is that in the extreme rearward position the saddle rail is supported over a width less than for say, a Campy Two-bolt or a Thomson. For both of those the upper clamp is as wide as teh lower clamp, so the saddle rail can only be supported over the entire clamp width. If your a lard-butt like me, I'd worry about over stressing saddle rails. But it should be ok for racing snakes or smaller folks.

Road Fan