This post is inspired by a recent thread concerning the safety/advisability of running a saddle all the way back on the rails. It seems that a great many people (including myself) need to do this just to get the saddle far enough back to establish a comfortable/efficient position on the bike. This prompts the question as to why? This leads inextricably to the conclusion that most frames have too steep of a seat angle. Again this prompts the question as to why?

My theory is that:
• There is a misguided belief that steep seat angles make a bike handle more quickly.
• Stemming from this manufactures build bikes with “aggressive angles” to cater the market perception that they are more performance oriented.
• This creates a vicious circle of marketing hype and disinformation that perpetuates the situation.
• Confronted with a market in which it is next to impossible to purchase a stock frame with a reasonable (read relatively slack) seat angle, riders opt for setback seat posts and saddles with long rails so they can get the position they need.

IMHO, a dose of reality would include:
• The realization that seat angle does not directly impact bike handling.
• An acknowledgement that bike handling is more a function of wheelbase and steering geometry than anything else.
• The understanding that steering geometry is mostly about “trail”. Trail is determined primarily by the relationship between head angle and fork rake. Seat angle has nothing to do with it.
• The understanding that wheelbase is only indirectly affected by seat angle. This is through the limits that any given seat angle imposes on chainstay length. With a seat angle of 72 to 73 degrees, it is still possible to build a bike with short enough chainstays to make the handling crisp enough for any conceivable road usage.

How it should be:
• Production frames should have seat angles that allow the average person to establish a KOPS (knee over pedal spindle) seating position with a “0” setback seat post and the “typical” saddle in the middle of the rails. I am not saying that KOPS should always be the goal, just that it is a reasonable common denominator of setup.
• Those that need more/want setback could get there via modestly setback seat posts and sliding the saddle back on the rails without resorting to extreme solutions.
• Those that need/want less setback could get there by sliding their saddle a little forward.

Bottom line, IMHO most production bikes are built with unrealistically steep seat angles relative to the real needs of the average rider. Seat angles should be 72 to 73 degrees on production road bikes, even on frames made for performance/racing applications. Seat angles steeper than 73 degrees do not serve the needs of the average rider and therefore have no place on productions bikes regardless of their intended purpose.

There, I said it and now feel much better. Those who disagree, feel free to flame away.

If STAs were all 72-73 degrees, it would force the use a slightly longer chainstays, to provide tire clearance with the seat tube.

If all STAs were 72-73 degrees, there would just as many people with the opposite complaint that you have.

LOOK used to produce frames with a 72.5 degree STA across the entire size range, but they have discontinued that practice. I had one and needed a no-offset seapost to make it work for me. With a standard 20mm setback post, the saddle would have been shoved nearly all the way forward.

You may have longer than average femurs or just want your knee to be further behind the pedal spindle than most people. I can get my knee about 2cm behind the pedal spindle with a 74.5 degree STA and average 25mm setback post, if the saddle is all the way back. If I really wanted the saddle that far back, I'd buy one of several posts with 30-35mmm of setback.

You can get the saddle too far back and create handling problems, unless the chainstays are made longer to shift the weight toward the front of the bike.

No, the problem is you haven't looked around enough for a frame that fits right. There is nothing radical about today's frame geometry.

So basically, frames should be designed for "You"!

Most frames are designed around what the manufacturer will work for the average rider that purchases their frame.

The STA's you suggest would be horrible for me and I could never ride a production bike. As it is the STA's are not steep enough for me to get KOP positioning. I need a 74.5 degree STA on a 58cm frame to get a proper fit with a 0 degree seat post.

"Most" people have no problem getting fitted to a production bike properly. It's the people on the fringe that have problems. I'm on the fringe, just as it sounds like you are....not in the middle.

I had to go custom to get a properly fitted frame....one that has a steep STA with a 58cm top tube because I have short femurs and a short inseam overall.

For me (6' tall with a 32.5" inseam) the best fitting bike is one with a 74.5 degree STA, 57.5cm TT and a 13cm-13.5cm HT (non integrated head set). That means a steep, long and low bike compared to most people....hence the need for custom.

So I would argue that angles are not steep enough on the production side of things, and I know of several people that I ride with that find similar problems with their fit.

You sound like a Rivendell fellow traveler....they use slacker seat tube angles in their frames. My prob is the opposite...I have to use a zero offset post to get the saddle forward enough to achieve KOPS, with theirs or a more standard frame. Guess my Roubaix is right for me at least in that regard, because once I ditched the set back seatpost, and put in a zero offset post, my saddle is now right in the middle of the rails to achieve KOPS.

You also have to realize that KOPS is a "basic" starting point. I'm a short guy (5'4") with a Look 555 (49cm). 51cm top tube, 100mm stem, 65mm reach bars. My seat height is around the 66.5cm range. I am about 1.75 - 2cm behind the pedal spindle on my setup with a zero setback post I am just forward of the center of the rails on my ERA saddle.

This position works well for me. I feel that my weight is centered on the bike. My legs are fairly long for my short height. I don't know if going forward anymore would make me "faster" but I've got no knee, back, neck, shoulder, etc issues with this current setup.

I would agree with others that have said you sound like you are not the "norm" for bike a fit and that a custom frame may be the way to go. You're outside the bell curve of standard size maybe?

There are things called "setback seatposts" to fix this problem. My frame has a 73 degree seat tube, and I use an Easton EA 70 post that puts me way back, and still lets me clamp the saddle on the center of it's rails. (and allows me to spin up into the 130's when needed)
People who need a more forward seat position can get a 74 degree frame and use a zero offset post. 98% of riders can use either a 73 or 74 degree frame. Just pick a post that allows you to place the saddle midway on the rails. If you are in the 2% that has trouble getting fitted, you may have to go custom.

I agree with most everything you said except:

1.) Bikes shouldn't be designed for you
2.) Bikes should be designed for normally setback seatposts.......zero setbaqck seatposts should be sent back to the hell from which they came & should be outlawed (Along with ERGO bars, wound-up forks, straight bladed forks, integrated headsets & toppolino wheels) (That is sarcastic BTW).

Len

A really big shew!

On the other hand, with a 73 sta and a zero setback post, I need the seat shoved pretty much all the way forward to get my knee in a comfortable position over the petal spindle.

The other problem you're facing here is this statement- Seat angles steeper than 73 degrees do not serve the needs of the average rider and therefore have no place on productions bikes regardless of their intended purpose.

99.9% of production bikes do not serve the "needs" of the average rider, period. But man, do they serve the "wants" of the average rider.

A bike that serves the "needs" of the average rider would probably look a lot like a raleigh 3-speed from the 70s- upright seating position, reasonable range of gears for the average rider, no quick releases and lots of racks. Not sexy. Not sexy at all. And unless you're in the beard and helmet-mirror, spd-sandals with wool socks riding crowd, sexy counts for a lot.

Thank you all for your replies. Clearly, I have hit a nerve. My post was labeled a “rant”, and I guess hitting a nerve was part of the goal. For the record:

• Nowhere in my post do I say that stock frames should be made for me. I am clearly on the fringe of the fit bell curve. My femurs are, as some have supposed, proportionately very long. My two “factory” bikes have 73 degree seat angles and require me to use a combination of setback seat post and saddle slammed all the way back on the rails. My custom frame is a 72 degree seat angle and gives me a set up with the saddle more centered on the rails but still using a setback seat post.

• My central points are: One, “fashion” and “perception” not sound design drives a lot of what we see in production bikes. Two, the seat angles we see on the majority of production bikes are steeper than what is needed for the average rider and that they are this way for fashion/perception reasons. Three, the needs of the average rider, even the average “performance” rider, would be better served by slightly slacker seat angles. This is especially true, if the intention is to spend hours in the saddle.

• My custom frame has measures out as follows:
SA = 72
HA = 73
TT = 570 mm horizontal
ST = 560 c-t
Chain stays = 410 mm
Wheel base = 1000 mm
Fork rake = never measured, steel fork, trusted the builder to do the right thing.
The bike has more than enough clearance to run 25 mm tires, is very stable at high speeds, and can change direction quick enough for any road racing application. This tends to supports my contention that steep seat angles are not necessary to achieve a reasonably short wheelbase and “performance” handling characteristics.

• I am fully aware that there are a bunch of people that who are at the opposite end of the femur length bell curve from me. They, like me, are best fitted with a custom frame.

• I agree with Buck-50 that want the average rider “needs” and “wants” are two different things. However, I remain firm in my contention that the “wants” portion of the equation is heavily influenced by marketing hype and disinformation.

Clarification / other observations

Thank you all for your replies. Clearly, I have hit a nerve. My post was labeled a “rant”, and I guess hitting a nerve was part of the goal. For the record:

• Nowhere in my post do I say that stock frames should be made for me. I am clearly on the fringe of the fit bell curve. My femurs are, as some have supposed, proportionately very long. My two “factory” bikes have 73 degree seat angles and require me to use a combination of setback seat post and saddle slammed all the way back on the rails. My custom frame is a 72 degree seat angle and gives me a set up with the saddle more centered on the rails but still using a setback seat post.

• My central points are: One, “fashion” and “perception” not sound design drives a lot of what we see in production bikes. Two, the seat angles we see on the majority of production bikes are steeper than what is needed for the average rider and that they are this way for fashion/perception reasons. Three, the needs of the average rider, even the average “performance” rider, would be better served by slightly slacker seat angles. This is especially true, if the intention is to spend hours in the saddle.

• My custom frame has measures out as follows:
SA = 72
HA = 73
TT = 570 mm horizontal
ST = 560 c-t
Chain stays = 410 mm
Wheel base = 1000 mm
Fork rake = never measured, steel fork, trusted the builder to do the right thing.
The bike has more than enough clearance to run 25 mm tires, is very stable at high speeds, and can change direction quick enough for any road racing application. This tends to supports my contention that steep seat angles are not necessary to achieve a reasonably short wheelbase and “performance” handling characteristics.

• I am fully aware that there are a bunch of people that who are at the opposite end of the femur length bell curve from me. They, like me, are best fitted with a custom frame.

• I agree with Buck-50 that want the average rider “needs” and “wants” are two different things. However, I remain firm in my contention that the “wants” portion of the equation is heavily influenced by marketing hype and disinformation.


I could ride your custom frame, we have the same dimensions it seems. I also have the 73 ST angle on both my stock frames with the "standard" 25mm setback seat post and the saddle clamped at the very front area of the rails. It fits me. I mean you can clamp the saddle there, what's wrong with it?

I do understand where you're coming from though. Whenever I check out a geometry chart, and I see a higher than 73 ST angle, I think it won't fit me without a larger setback seatpost. Or maybe a saddle with more rail adjustment. But I don't want to change my saddle type.

Dude get a 35mm setback seatpost (FSA, Easton, or many track seatposts) and call it a day.

And.. to the extent that STA affects fore-aft distribution of rider weight, it does affect handling. Mmmmkay?

Dude:

1. I have two FSA SL-220 seat posts.

2. All else being equal, STA has no direct effect on weight distribution, saddle position does. Leave the saddle where ever you want and change the STA, you will not have changed the weight distribution. This, of course, assumes the appropriate adjustments in seat post and/or clamp position on the rails to keep the saddle in the same position relative to the BB.

A really big shew!

Hey, that's me! :D

Wants and needs? What the hell does that have to do with proper fit, eh? The last few bikes I've had--at least as far back as 1987--have all had 73 degree seat tubes. They've all worked just fine.

There is more than enough variety in off the shelf frames to suit the majority of the population. The minority might, indeed, need custom frames, but hey: that's what happens when you're at the extrema of a normal distribution.

Can we also rant about stem angles, 1/2 size stem lengths, cranks lengths, HT lengths as well ....... at least with frames you do have the option of custom!

Anyone remember Greg LeMond, a famous cyclist from the previous century? In his 1987 Complete Book of Bicycling, he also rants about steep seat tubes. This thread made me dig out my copy and read about asking my dealer what the angle of the seat tube is :)

There are things called "setback seatposts" to fix this problem... If you are in the 2% that has trouble getting fitted, you may have to go custom.

You can get zero offset seatposts (which I need), 10mm offset (USE Aliens), 25mm seatposts (which my wife needs...basically anything out there with a "setback") and 35mm offset seatposts (FSA makes one). Chances are, you're not using the right offset. If not, then get a custom frame.

Lemond also had long femurs, hence his bias toward slack STAs. Back in those days, seatposts with longer setbacks were not common either.

Well I gotta agree with the original poster, IMHO the average cyclist will have trouble with the 74 degree angle and have to either move the seat back or get an offset post. Both options make little sense to utilize as a standard approach. What advantage do you get from doing either option instead of making the frame the right geometry to begin with? Is it a weight saving? Is it done because there is no easy way to make a "set-forward" seatpost for people who need it so they start with the assumed shortest leg length? Couldn't you just flip a regular offset "setback" seatpost around?

Seatpost with 20-25mm of setback have been the standard for a very long time. No offset or straight-up posts are most often used with MTBs because there is no tire to seatpost interference problem.

Steeper STAs are often used on road bikes to allow the chainstays to be made shorter.

Blanket statements about STAs are never accurate. You'll always find someone who has a problem. One of these problems is created by the idea that the knee must be located over the pedal spindle. There are several reference points to measure from and not all of them will produce the same fore/aft position. I've known riders with long femurs who had no pedaling problems with their knee slightly forward of KOP. They just moved the saddle all the way back on a 20mm setback post.

I can figure out a way to use any angle in the 72.5-75 degree range, using a post with 0-35mm of setback.

Folks who need a 72 degree STA and a post with a lot of setback to achieve KOP might do as well with a more forward position. It never hurts to try it. Moving the saddle further back can compromise handling, unless the frame is also designed with longer than normal chainstays to put more weight on the front of the bike.

What's the purpose of the bike in question? Isn't my fixed gear track bike immune from this rant?

What's the purpose of the bike in question? Isn't my fixed gear track bike immune from this rant?

No, it's not. Your bike is all wrong for you. You unwittingly succumbed to apparent marketing pressure and bought a frame that is only suitable for two now retired pro cyclists. Please return your frame immediately and order a custom frame with a 71.45 degree seat tube.

Thank you, and have a nice day.

Not exactly disagreeing, but your post seems to suggest that zero-setback posts are somehow 'right', and setbacks somehow only a fix for a problem that exists on nearly every bike sold (since they come as stock on virtually every bike.) You also seem to suggest that 'most' bikes have 74ish angles, and that 72-73 are 'rare.' I don't know if that's your intent, but that's how it reads to me.

I don't see it that way. As I reckon the market, only small road bikes have steep seat angles. The far majority of bikes I look at do have the 72-73 degree angles you think they should. TT bikes are steep too, but in any case, both those and smaller bikes are for fully valid ergonomic reasons. TT bikes are steeper to keep thigh-torso angles appropriate with the flatter position, and smaller bikes need steeper angles to keep top tube lengths appropriate while keeping toe overlap reasonable. That's an often overstated problem, but for sale to the 'stock' end of the market, it's a reasonable choice. It's also true that smaller folk aren't proportioned the same way as taller, with legs 'shrinking' faster than torsos. On balance, that makes steeper angles fit the bell curve better for most of those folks.

Meanwhile, road bikes with 72-73 degree angles are generally intended to be used with setback seatposts. Sometimes that's because of the desire for short stays, and the handling (via balance) and drivetrain stiffness that can allow, but it's also an historical artifact. Setback seatposts are the way they were 'always' made, and so what is 'right' for road bikes. Sure, they could design more to the 71-72 angles and equip everything with zero offset posts and achieve the same thing, but the vast majority of road riders would think they looked ugly and 'wrong.'

Probably worth a note that historically, zero offset posts come mainly from the mtb world, where they were used to fix the problem of the too-slack angles that the cruiser-frame conversions that started the movement caused. Thus, it could be argued that zero-offset posts are never 'correct,' but only patches for poor bike-rider-use combos. OTOH, I prefer two-bolt posts, and they often seem to be easier to work with in zero offset models. So, whatever.

...Sure, they could design more to the 71-72 angles and equip everything with zero offset posts and achieve the same thing, but the vast majority of road riders would think they looked ugly and 'wrong.'
gets it atmo.
should be a sticky!
e-RICHIE©™®

since this is a rant..... First, I think KOPS is mostly historical BS. A starting point for someone on their first road bicycle and nothing more. It might work for some people but this is purely coincidental. Besides those of you who are on exact KOPS or 1cm behind KOPS or anywhere else in relation to KOPS - I think KOPS is very difficult to measure *accurately* (at best to nearest 5-10mm?) even with plum line because the foot has to be dead-level to measure it correctly. And those of you who pedal even a little bit heels down under load will automatically move the knees back, placing you behind KOPS *dynamically*, those with toes down pedalling style will have the reverse effect. So I think KOPS and STA are not related all that much.

The STA too-steep issue is more in small and medium size frames (48-56cm range). If you look at >=58cm and even larger sizes they are mostly ~72-73 STA already. If you are Mr Average and need 50-55cm frame then I do think the off-the-shelf STA is ~0.5-1.0 degrees too steep, if you want to look at majority of riders. Hence set-back post!

Having said this I now ride a 73 STA frame (53-54cm size) with a Thomson Elite 2-bolt zero-offset post and my saddle is ~5-10mm off the dead-centre on rails. I did not measure my KOPS and I dont care either. Moving much further back causes me lower back pain. I personally think that if you ride a zero-setback post with your saddle someone near the middle of the rails than this frame STA is made for you. Enjoy.

I think that folks with tight backs and tight hamstrings (like me!) are more likely to need a steeper STA (~73.5-74.5) and those with more flexible backs/hams are more likely to fit well on slacker STA (71-73).