straight post vs offset post
 

If i could use a straight post and keep saddle in the middle should i switch? My saddle isnt slammed all the way foward but getting close. My friend gave me a tompson masterpiece and wouldnt mind using it, it looks like I would be able to adjust the saddle tilt much easier

If that is what you need, that is what you should use. What puzzles me is how folks used to use (universally) posts with significant setbacks like 25 mm. Zero setback posts really didn't appear until the advent of tri and TT bikes. So how come so many people now need to be so far forward when they didn't in the past. Seat tube angles haven't changed that much on the normal road bike, and that is just about the only frame attribute which could affect the post setback that would be needed.

I ride a frame on the large side for my size with 73 degree STA and still have the saddle pushed almost all the way back on a 25 mm setback post. Apparently lots of other folks ride differently.

^Good question. I ride my saddle all the way back on a 25mm offset post. I balance best there. I know a further forward saddle opens the hip angle, making it easier to breathe if one has a lot of drop, but I'd rather focus on my climbing and long distance comfort, so I ride further back.

I had a offset seatpost on my older frame, and I switched over to a straight seat post (much lighter), and never looked back. I actually enjoyed the straight seatpost, it still was very adjustable.

Now to really stir things up!

I am well aware that KOPS is a bunch of crap as the final word on where your saddle should be placed. OTOH I don't think anyone has devised a better STARTING POINT for saddle position that the placement that yields KOPS. It really works as a position for folks to try out first before they move on as comfort and performance optimization dictate. I mean, after all, you have to start somewhere. It just so happens that I am completely satisfied with my riding experience with the saddle at KOPS, and that is the setting that yields my large saddle setback. My point is only to broach the question to OP: how did you arrive at this forward position you are trying to "center" by using a zero setback saddle? Was there a gradual optimization by continually moving the saddle more and more forward from some KOPS-like starting point? Or did you get there some other way?

The setback post will absorb more road vibration which may help provide some additional riding comfort if you have an alloy bike and post.

i ride close to KOPS with a straight seatpost. A contributing factor is the saddle rails (Selle SMP) ... other saddles have fit fine on offset seatposts.

Ultimately I came to my saddle position by what felt the most comfortable while producing the most power, rather than what looked the most traditional.

Ask yourself this Robert. If the OP really understands his fit, do you really think he would ask the question that he did? Probably 60% of all those that ride road bikes could be in a better position.

That said, extrapolating from the pros, they ride a very broad range of setback...from 40mm to 115mm or so. Many factors at play. I move mine around a bit as it turns out....currently around mid pt of 25mm setback post with 73 deg sta. To me, riding behind this closes the hip angle too much for comfortable drop riding.
Not everybody needs to ride in the 'backseat' however and if the OP is light, fit and young and his pedal forces are high enough, then he might be OK with a straight post.

There's another factor here, which is the saddle, and where its sweet spot is relative to your sit bones. I have found my current saddles (Specialized Romins) like to be further forward than others.

True...and not even saddle specific...many will prefer a narrow saddle more forward to support the sit bones and a wider saddle farther back. Rail clamping range varies on saddles as well. So yes, the saddle can be a game changer for setback as you say.

I say middle because it looks like the saddle would be more in the middle by using the straight post instead of pulled mostly foward. My thought was the seat would be better supported and also have more adjusted room also.. I am under the impression the saddle would be in the same spot thou?? Im tying alot of saddles right now,there are that some that get closer to be pulled all the way forward then some with longer rails.I find KOPS work well for me

Modern compact frames also have to compensate for shorter seat tubes by putting the saddle further forward on the rails and/or without setback. as you raise the seat post you need to move the saddle forward to keep the saddle in the same spot. geometry people ;) my 90s trek has the saddle in the middle of a straight post. my 2005ish bike has the saddle slammed forward on a straight post.

Billy i'd switch to the Thomson because they are great posts and the adjustments are so easy. measure from the tip of your saddle to the bolt on your stem and you will get the same position.

Fully agreed. I was only wondering what process OP had used to get there.

That is completely wrong. It doesn't matter whether the seat post is inside a longer seat tube or exposed above a shorter seat tube. The line is the same. The effect you are talking about only relates to seat tube angle, not the length of the seat tube. With the same seat tube angle and reach from the BB to the saddle, it doesn't matter how long the seat tube is or how much post is exposed, only the total of the two. It has no effect on saddle position. Think about it!

There is no reason why it wouldn't be.

Keep in mind, though, that the difference between a standard post and a zero setback post is commonly 25 mm or 1 inch. You may end up on the other side of the middle, i.e. behind the middle instead of in front of it. Not much gained if that is the case. Also reports of a "support" issue with a forward or backward saddle are very rare. And if there is an aesthetic issue, it is pretty much all in your head. More adjustment capability would be valuable if you need it, but if the saddle is in the right place now, what good would that do? Remember that zero setback posts were not (readily) available back in the day and folks did just fine either in front of or behind the center line of the rails. No one gave it any thought.

I agree that the Thompson is a great post and easy to adjust, but if a change doesn't get you anything real, what's the point? If you need it, you need it.

You are right. :)

I was lining up the thomson with the existing seatpost and saddle to get the general idea....but i guess u might be right with why fix it if it aint broke....would like an easier adjusting post thou

doh.. i guess my old and new bike have different angles then.

Every 1 degree more of STA is worth about 1 cm less of saddle setback at average saddle heights. Even over a fairly broad range of saddle heights, the plus 1 degree to minus 1 cm relationship holds up pretty well. When there were no zero setback posts, you had to have a 75 degree seat tube angle to get forward enough for time trialing and triathlon type riding. Now you just ride a normal STA and use the zero setback post. I guess some folks would need both, though.

Two thoughts. One, a seatpost is best when the setback is such that the clamp is somewhere in the middle, not slammed. The ti railed seats I like for comfort tend to break sooner if I clamp the start of the bend and I like having a little more room to go on any adjustment. Slammed and no further possible always felt wrong to me, whether it be stems or seat rails. To me it is like "I can make this bike work. Just watch!"

And two, ease of adjust-ability, esp the ability to dial in the seat tilt accurately and be able to change the tilt and get it back exactly is, in my book, the mark of a good post. (To dial in at the start in the road with just a wrench and no measuring equipment is a huge help and being able to change the tilt say 1/3 of a bolt turn for a saddle sore, then a week later go back that 1/3 turn and have the tilt back exactly is just as or even bigger level of importance. The Thompson heasd is really nice in that respect. I have two mounted on 160 mm setback custom posts (and rails centered - life is good).

Ben

Where do they break?

Yes, the Thompson post is wonderfully easy to adjust and it is close to a best choice when a new Al post is needed. Having said that I never, ever adjust a saddle position or angle once I get it right. The idea of fooling with my saddle angle is completely foreign to me. IMO there is only one right saddle angle for a particular saddle and a particular rider. It may take some work to get it right, but I think changing the angle back and forth after that just falls into the category of head games. Many a process has been irretrievably upset by too much "knob turning". I put bicycle saddle adjustment into that same basket.

Furthermore, the only saddle rails I have ever broken were Al, and even trying to use them was just plain stupid. I don't think it matters where on the rails your saddle is clamped with common rail materials and designs. The rail tolerances for torque ought to be well beyond the differences produced by clamp position.

Pretty much part of your thigh bone length and Bike fit with whatever seat tube angle you got.
Thomson zero set back posts sell well .

At the bend of the rail and edge of the clamp if you use have the clamp set so the corner is into the bend, esp if the corner is a hard angle. Ti is more sensitive than steel in those conditions. You can improve the seat clamp by filing a nice radius into that corner. But it took killing the most expensive seat I had ever owned to learn that. (I'd been slamming steel railed seats for decades.) Bike fit for me was dependent in part on how well that slammed seat worked in the big picture. Another factor that was always at odds with that was the fact that I do best with my rear wheel as far forward as possible to best distribute my weight between the wheels; hence steep seat angles were good. The discovery of large setback posts - a revelation.)

Ben

Living the life of a bike racer means you HAVE to ride. That means riding with saddle sore. At close to 10,000 miles/year, year after year, they will happen. Tipping the seat to get it off the sore is just something you have to do. Either that or write off a large portion of your season, either because you took time off or because of the pain and discomfort. But I agree with the importance of the saddle position. As soon as my week or two of "purgatory" was past, I went right back to the position I had before. And that is why I consider two bolt posts so important. As long as I kept track of how much I changed the tilt by amount of bolt turned, I could go back exactly to where I was before. For that I loved the old Campy (and Zeus) posts that required the special bent wrench. The SunTour posts later and now the Thompsons are lighter and much easier to access with ordinary wrenches but far more important, share that ability to replicate the position exactly and without measuring tools, even on the road.

I went 8 years between my last Campy style post and my first SunTour. During that time I had a single bolt post with "micro-adjust" grooves. After hours of fiddling, I got the position dialed in between clicks. Rode that position for 8 years knowing if I ever touched that bolt I could never get it back again.

Ben