Road Cycling - Seatpost - Straight or Setback?

Putting the finishing touches on the new MJ and rode it all weekend with a straight post - it felt good but I'm wondering what relative differences I might experience with a setback post? Will I feel it in the longer overall reach or in the setback position of the knees? Or even at all?

Without going into the KOPS explanation, what are the advantages and disadvantages?

55/Rad

I think it is just a function of your physical measurments. Thigh and/or torso length.

Putting the finishing touches on the new MJ and rode it all weekend with a straight post - it felt good -but I'm wondering what relative difference I might experience with a setback post? Will I feel it more in the longer overall reach? Or more in setback position of the knees? Or even at all?

Without going into the KOPS explanation, what are the advantages and disadvantages?

55/Rad

it may not be as comfortable when your in the drops, but might feel a little better on your knees over a longer ride.

I think most frames are designed to be used with a seatpost with setback. Its pretty unusual to see a staight post on a road bike. Both Shimano and Campy posts have setback.

I used a setback seat post for a long time and then after I had a bike fitting about a month or so ago, the guy recommended a straight post since my seat was all the way forward and my knees still weren't over the pedals. It made a huge difference for me switching to a straight post. I feel like I am getting more power and taking the hills much easier.

I think it all depends on your size and the bike you ride. If you fit your bike ok, then I don't think it matters which post you have. The important thing is to have the right position on the bike so you aren't wasting energy or causing health problems with your knees or back or whatever.

Okay, now, EVERYONE go read Keith Bontragers synopsis on the whole KOPS thing. It makes complete sense, even if you're not a bike fit geek. Bottom line - KOPS has no basis in physiology. It's a broad ranging 'coincidence of averages'.

As far as I'm concerned, seat angles are generally too steep, and they're steep largely because chainstays are too short - Which hints at the core issue which is that a lot of riders have the wrong CG in relationship to wheelbase - which relates directly to handling.

For the past 20 years of my exposure to the road scene, it's all been about "Push your seat back" - seats all the way back on the post which is more often than not layback. Look at the pro peloton even today. You see the same phenomenon. Seats pushed all the way back. What does this tell you? It tells you.....

....seat angles are generally too steep.

You put a straight seatpost into the mix, and you exacerbate the problem. My advise would be if you're lumped with a 73 degree seat angle, which is almost everyone but the fortunate custom bike purchasers - you NEED a layback post. I've had good luck with the Ritchey WCS and Campy posts, so they're worth a look.

If this stretches you out and you feel as though you're reaching for the bars, don't be afraid to try a shorter stem.

Okay, now, EVERYONE go read Keith Bontragers synopsis on the whole KOPS thing. It makes complete sense, even if you're not a bike fit geek. Bottom line - KOPS has no basis in physiology. It's a broad ranging 'coincidence of averages'.



"Still, it is easy to see how the KOPS method can get by. It usually puts the rider in the range of correct fit, although in my experience, the more anatomical proportions vary from the norm, the more off the mark the KOPS method is." - Keith Bontrager

So KOPS puts the rider in the correct range and from his long article, one can infer that KOPS will get you "in the ballpark". EVERYONE will need to fine tune and fiddle to get comfortable.

I don't even understand Bontrager's method and not being able to communicate it in a succinct manner only leads to more confusion.

KOPS may not be perfect but even by KB's own admission it will get you in the correct range and it's easy to remember for people to use.

My position doesn't follow KOPS but it's close. As for setback, it depends on your seat position. Going for more setback makes you lower the saddle for the same leg extension- that moves the full extension point more forward-as if you are climbing all the time. It limits my rpms and power on the flats (for me).

For UCI regulations, the tip of your saddle cannot pass forward of the vertical centerline of the bottom bracket. Obviously most people will not encounter that issue even with a straight post but setback totally depends on your body and bike.

I know I can ride a Thompson straight road post or a setback but an extreme setback post doesn't work for me. Compensation with a short stem is unacceptable as the front end handling/balance becomes awkward as well as being unable to get the proper position on the bike. The setback on a Dura Ace or ITM Millenium is fine for me, any more than that and I have to slam the seat forward as much as possible.

The point is that even if KB is debunking KOPS, he seems to validate it in the same breath while not being able to come up with a concise alternative.

Hate to play Devils Advocate here, but if KB successfully debunks a myth - which I think he does successfully and succinctly in this case - it's irrelevant what 'coincidence of averages' appears.

If you notice a pattern in something, but that pattern is simple coincidence - has no basis in science/physiology - what is stopping you from believeing the facts? Would you prefer to keep believing in a myth? Are you more comfortable with facts or circumstance?

Also, if you point something out as being incorrect, please tell me where the rule is that states you must therefore also come up with a plausable solution or alternative?
You can't point me to one, coz there isn't one. It's simple fear of accepting that something, may in fact, be wrong. You cannot accept the fact that what you believe or were told is wrong, therefore you shoot the messenger. Not challenging the validity of their facts but rather challenging them for an alternative solution, as if somehow you couldn't possibly go on with the knowledge that something you believe in could be wrong. How could it be wrong! How could 15,000 Lemmings be wrong!!

Okay, okay - enough juvenile theatrics from me. I'm starting to sound like a tosser. I think you get my point.

Also, in KB's article on KOPS and fit, he does in fact hint at his fitment system. Obviously he's keeping tight lipped about it, as is his right. His articles are one of the first I read that even mentions CG as a critical factor of fit and handling, which is part of the reason that I respect his opinion.

I think next generation fit systems will be able to incorporate physiological requirements, but also CG as it relates to handling, riding style, and terrain requirments. That's something that we don't really know much about.

I give up; what's "CG", and can ya gimme an 'ideal' distance that the tip of the seat should be behind the bottom bracket, in cm.

I've been riding for at least 15 years, and I still stuff around with my position.

CG is Center of Gravity.
There is no ideal distance, it depends on the person. My only comment was that you cannot compete in a UCI race if the saddle is forward of the centerline of the bb-not really an issue for normal road bikes.

Also, if you point something out as being incorrect, please tell me where the rule is that states you must therefore also come up with a plausable solution or alternative?
You can't point me to one, coz there isn't one. It's simple fear of accepting that something, may in fact, be wrong. You cannot accept the fact that what you believe or were told is wrong, therefore you shoot the messenger.

You are assuming that he is correct besides, HE is the one proposing a "plausable solution" not me. As I said, he is unable to concisely convey what he is advocating while "debunking" KOPS. He has alot of unproven hypothesis, just like alot of other fit systems. He is trying to debunk to validate his system which is?

I'm questioning KB's system and so I'm shooting the messenger? gimmie a break.

I am saying that by KB's own admission KOPS works. For example, for someone trying to get right on a bike by himself KOPS is a good starting point lacking any other formula out there.

ANY formula is not perfect! I gaurantee that you will make adjustments after ANY fitting.

you know what? i am an individual. i am not a statistic or a coincidence of averages or anything like that. i had my seatpost and saddle set professionally, and always fought lower back pain. after a winter season on a spin bike and screwing around with different setups, i brought my saddle more to the fore.

now, my geometry is a 73.5 degrees on a 58cm TT and 58cm down tube (as measured center to center)>>> so this year i raise the saddle and pushed it forward and i don't have the lower back pain i once had and feel more power when you have to get after it.

Keith Bontrager is largely correct, but he is a huge advocate of 'comfort' bikes, and i don't come close to the geometries of the bikes he designs and advocates.

RacerX is right on in his posts.

Kinda hard for somebody to tell you how you'll feel with one or the other since your on the bike. Some lbs will let you try one and bring it back as long as its in the same condition. You might ask.

I used an old school book that had the Eddy B fit set up where you use a plumb bob to set saddle fore/aft. I guess I fit rite in with that system b/c I am always comfortable on my bike. And it even says in the book that this is a starting point adjust as necessary. I test rode a Derosa w/ a set back post and I felt like a monkey swinging from a tree. Not my thing I guess but perhaps it is yours. Having said that I have changed stem length several times and even change it for early and late season riding.

I use the old-school method of plumb-line as well, and with a pretty standard road light-touring frame (ie generous chainstays), I still need an in-line seatpost to position my saddle far enough forward, just have odd proportions between my upper and lower legs.
In the old days, when seatposts came in one style only, then builders used to alter the seat-tube angle to fit the rider. Now that you can achieve +- 2cm of adjustment by replacing the seatpost, so the angle becomes fairly irrelevant to the fit.

CG is Center of Gravity.
There is no ideal distance, it depends on the person. My only comment was that you cannot compete in a UCI race if the saddle is forward of the centerline of the bb-not really an issue for normal road bikes.

i have a "normal" road bike, and the tip of my seat is ahead of the center-line of the BB. it happens to be the most comfortable position for me...or does that rule mean the whole seat? because that would be weird...

How does that happen? It is almost impossible to have the tip of the saddle pass the vertical centerline of the bottom bracket even with a straight post and seat pushed all the way forward.

In any case, it is not UCI legal but that obviously is not a concern for you so it doesn't matter as I have repeatdly said.

Maybe he has a setback turned completely around making a "sitforward".

55/Rad

upon closer inspection, it would appear that the seat on my road bike does NOT go ahead of the centerline of the BB. but the seat on my pursuit bike (selle italia flite with a generic seatpost) does, and i still have quite a bit of room on the rails to slide if even farther forward.

the road bike seat crosses the BB at it's rear-most point, with 1.5 cm of rails still to go out back. and it's also on an american classic post, which has the narrow top cap, so techincally, if i wanted to, i could make the nose of the saddle cross the centerline no problem.

it seems like a pretty arbitrary rule for the UCI to have though...

i just sold a track frame that had a curved seat tube, but it was almost straight up and down, and i'm pretty sure that the nose of the seat was always ahead of the BB.

that had to have been the grossest-riding bike for me ever...49cm seat tube, 58cm top tube.

I wrote a whole long winded response but then kinda realised it was pointless anyway.

Bottom line for me, personally, is that I'm of the belief KB sucessfully writes off KOPS as having no scientific merit. I don't care that he doesn't offer up a neatly packaged CDROM system that I can buy from my LBS for $99.95. Part of the way of the world is that ideas get challenged, science often proves things wrong - It's why fireworks isn't magic and medicine isn't the tool of the devil.

55 Rad, If you're just starting out, sure, use all the traditional methods, but keep in mind they're largely based "on tradition, some statistics, and the inventor's coaching instincts and experience." Basically I'd recomend a layback post without question. It's a good start on the long winded process of getting fitted to the bike correctly. You might consider looking into eventually getting fitted by various methods, and if you're really keen, start doing some research yourself. Think of it as a dynamic, rather than a rote process.

upon closer inspection, it would appear that the seat on my road bike does NOT go ahead of the centerline of the BB.

What did I say? Most road bikes don't have this issue.


but the seat on my pursuit bike (selle italia flite with a generic seatpost) does, and i still have quite a bit of room on the rails to slide if even farther forward.

maybe because it's a pursuit bike and not a road bike.



it seems like a pretty arbitrary rule for the UCI to have though...

No it is not. Seriously, in a UCI race they will not let you ride if the nose of the saddle is ahead of the bb. This is especially true in TT's and track. If you ride that way in a road race, you would probably just crash out yourself. They dont look in a road race.
It is considered cheating and was placed to stop bikes like Obree's and keep bikes looking "standard" for record attempts.