what your ideal STA?

[Climb01742]

looking at stock geo charts of lots of builders, it seems that many -- if not most -- seem to favor a 73.5ish STA in the "heart" of their size range. say 54, 55, 56 sizes.

compare this to cervelo's idea of a constant 73* angle throughout their sizes. their idea being that, for more riders, they can get a good fit with a 73* angle.

for me, the 73* makes a good fit possible, where a 73.5* with the usual accompanying longish TT, make a good fit almost impossible. (my ideal being a 72.5*.)

so...what's your ideal STA? because i think cervelo is on to something...that for more riders, a 73* would works.

[Ray]

I always thought it was 72 or 72.5, but Tom Kellogg put a 73 on the custom he designed for me. I have way fewer than no complaints with that bike, so I guess 73 it is. Although I have several 72.5 and 72 bikes that fit well enough to ride very well also (rode my Rivendell for the first time in quite a while yesterday - jeez what a sweet ride!). In another year and a half or two, I'll have E-Ritchie's take on it. All of which is short for, "I don't know - I'm leaving it to the experts".

-Ray

[Kevin]

Because of my severe knee problems, my STA is 71.5. Anything steeper than that results in me being unable to walk for a week.

Kevin

[Smiley]

Climb , a 73 STA could work for many today with the availablity of the many off-set seat posts and non off-set posts , this goes along with the newer saddles that have much longer rails . So unless your a FREAK I guess that anybody can make a 73 seat angle work as long as you can tune the KOP with saddle rails and seat post off-set or not .

[BarryG]

for me, the 73* makes a good fit possible, where a 73.5* with the usual accompanying longish TT, make a good fit almost impossible. (my ideal being a 72.5*.)
All other things being equal, doesn't a greater STA translate to a shorter TT, effectively pushing the saddle forward relative to the BB (less setback)?

Barry

[Kevin]

Climb , a 73 STA could work for many today with the availablity of the many off-set seat posts and non off-set posts , this goes along with the newer saddles that have much longer rails . So unless your a FREAK I guess that anybody can make a 73 seat angle work as long as you can tune the KOP with saddle rails and seat post off-set or not .


I guess my wife is right, I am a freak. :banana:

Kevin

[Dr. Doofus]

All other things being equal, doesn't a greater STA translate to a shorter TT, effectively pushing the saddle forward relative to the BB (less setback)?

Barry

That's why you use a post with more setback. Doof likes 73 STA 57TT+130 stem in a 58cm c-t-c (or 57 if he had the money for a Pego). Get a 58 with a 74STA, the TT better be 56 (with a 130 stem) or 57 (with a 120), and use a post with 5-10mm more setback. The saddle stays where it is relative to the BB -- its the stem and the setback of the post that you use to adjust for any difference in frame setback (or STA if you have to speak in such terms).

Please don't take this as a thread hijack attempt, but...seems to this doof that custom is more about craftsmanship and subtle distinctions in ride quality that a cultivated-palette rider can appreciate, rather than the absolute need for some special fit...and when it is about fit, its about front end height for somebody who is riding the wrong type of bike (should be riding a sport-touring or audax frame, but wants the racer "look").

Anyway, the masters worked out frame setback (please don't say STA) a long time ago. A stock frame with the right vertical proportions will allow anyone to get the pedaling position right with the right amount of seatpost setback (c'mon...the range from a Thompson to an Easton is 5cm...that's enought o fit any range of folks)...so its all about the front end and whether its too low or at theright height for one's flexibility and core strength (crap doof is going in the direction he was trying to aviod).

Crikey. 73 gets most folks in the ballpark. Then its up to the seatpost (which is sort of goofy, but that's what we've all been doing with frames in our respective sizes for years...doof is out of his depth...repeat after me...72-74 is the right range, anything outside of that is goofy) Cervelo may do everthing that way for production cost reasons.

I and I wouldn't worry about it. If doof knocked off a small bank, he'd just send the measurements to RS or DK or DP and let them worry about it. Then he would just ride the bike.

[Climb01742]

for me, the down side of a steeper STA is...most stock TTs are so long that to then get my right reach i would have to use a very short stem. with saddle setback and short stem, i could get my three points right, but the handling would be funky.

whereas a 73* (and the "cockpit" length TTs that, say, cervelo choses for each of their different sizes) seems to allow for more people to get their three point right without freaky short stems. i'm not pushing cervelos as bikes, i'm just saying that they seems to have come up with an interesting sizing/geometry idea.

[Climb01742]

I and I wouldn't worry about it. If doof knocked off a small bank, he'd just send the measurements to RS or DK or DP and let them worry about it. Then he would just ride the bike.

doc, i totally agree. with a custom, let the builder do it. but the question is about stock frames and geo's. it just seems like many stock frames preclude a lot of riders from finding a *good* fit, rather than just an acceptable fit. and just that cervelo seems to have solved it in an intersting way.

[Dave]

I have one bike with a 72.5 degree STA and another with a 74.5. Both fit the same within 2mm, since the TT length is 1.5cm less on the frame with the steep STA. The steeper STA requires a seatpost with a larger setback (FSA K-force) but both have the saddle well centered on the seatpost.

The key to analyzing the fit is comparing the frame's reach. Reach is the TT length minus the setback. Setback is the c-c frame size times the cosine of the STA (if it's not listed in the geometry chart). If two frames have the same reach, they will require the same stem length to fit the same.

To figure out the difference in the seatpost setback, take the saddle rail height times the difference in the cosines of the STAs: (cosA-cosB) x saddle rail height.

[BarryG]

for me, the down side of a steeper STA is...most stock TTs are so long that to then get my right reach i would have to use a very short stem.
Climb, I was trying to say that the steeper the STA, the shorter the top tube. You seem to have it backwards?

Barry

[coylifut]

I have two bikes that fit identical. My Merckx has a 72.5 sta with a 57 top tube and my Spectrum has a 73.5 sta with a 56.5 top tube. Same size stem on both and same effective reach. I use a zero set back post on the Merckx. I've looked at countless geo charts for bikes in the 56-57 range and the vast majority seem to have a 73 sta. I can fit most stock frames. As Doofus points out, I went custom for what the builder brings to the equation as far as ride and craftmanship. However, I really have benefited from Tom's fit advice. I've been told that he does fittings, even on non Spectrum bikes, for a customary fee. If I lived in his neck of the woods, I'd strongly consider it.

[coylifut]

Climb, I was trying to say that the steeper the STA, the shorter the top tube. You seem to have it backwards?

Barry

I don't know if I'm following this. If two bikes have equal top tubes, the one with the steeper sta will have a longer effective reach.

[Climb01742]

barry, i have it straight, but i may have stated it in a confusing way. ideally, yes, to get the right reach, a steeper STA would go with a shorter TT...but for me, most stock frames in the 54-55 sizes have the steeper STA and a TT that is too long...resulting in a very short stem if i wanted to hit my right reach.

dave, you're dead on about reach. my point is just that i bet more riders could nail their reach more easily if more stock frames had 73* STA. only referring to stock geo's.

[bostondrunk]

Climb, I was trying to say that the steeper the STA, the shorter the top tube. You seem to have it backwards?

Barry

Barry,

Here is what you are missing....

Lets say you have a frame with a 54tt and a 73 STA.
And lets say you switch to a frame with a 54tt and a 74 STA.

Technically, the tt's are the same physical length, but the get the same position over the bottom bracket, you will have to push your saddle back on the frame with the 74 STA, effectively giving you a longer tt or reach to your handlebars.
Capiche?!
<burp>
Of course, then you may also have to consider HT angles, etc...? Jerko can probably explain more about this....

[BarryG]

Thanks - got it. We were looking at it from different directions.

I've got a chronic battle with my left knee and from experience, I need the saddle forward. STA less than 73.5 and I'm running up against the back of the saddle rails. Current ride is a 57cm st with a 74 STA and 56cm tt.

Barry

[bostondrunk]

Thanks - got it. We were looking at it from different directions.

I've got a chronic battle with my left knee and from experience, I need the saddle forward. STA less than 73.5 and I'm running up against the back of the saddle rails. Current ride is a 57cm st with a 74 STA and 56cm tt.

Barry

If you are not already using one, try a zero setback post like the thompson. Or try finding a saddle with rails that go back further, etc.
:beer:

[Climb01742]

maybe the easiest way to explain what i'm babbling about is...go here...scroll down...and read the part about their geometry ideas on stock frames. just seems to make sense to me.

http://www.cervelo.com/bikes/2005/R25-Team.html#Geometry

[BarryG]

If you are not already using one, try a zero setback post like the thompson.
Love the Thompson . . . :p

[Roy E. Munson]

what your ideal STA

The one on the bike I buy right off the shelf. The rest gets straightened out with stem length, seatpost setback, bar height, and saddle positioning.

[David Kirk]

For me its 72 with 180's and 72.5 with 190's.

Dave

[bostondrunk]

The one on the bike I buy right off the shelf. The rest gets straightened out with stem length, seatpost setback, bar height, and saddle positioning.

hahaha, off the shelf......rookie!!





:banana:

[lnomalley]

what is your leg length? how do you sit on a bike?

you can't isolate one aspect of the bike from the person riding it.....in a vacuum the angles don't matter. the bike doesnt do anything until a person sits on it. its the relationship of the angles to the person on the bike that matters....

[zap]

BarryG-what problems are you having with your knee?

[Dr. Doofus]

Climb-O-Matic-Fanatic --

I feel exactly where you'er going. Cervelo hit the cockpit problem on the head and came up with a reasonable bell-curve solution. If you have the flexibility and core strength to ride their bikes as designed (i.e. not with a 100 stem flipped upside down over 30mm of spacer) you'll fit on their bikes fine with a stem proportional to the frame size. With many bikes, the cockpit is the same even though the vertical dimensions are different -- for example, doof can "fit" on a 57-59 Pego the 57 would be right for handling and weight distribution (yeah...what the jerk said)....

the 73 solution works for most people...the front end height is the potential deal breaker

[BarryG]

BarryG-what problems are you having with your knee?
Sorry for being OT but to answer Zap: chronic acheyness, anterior and anteromedial - i.e. right at patella and maybe slightly medial or medial/superior to the patella. Forces me to curtail mileage and take 1-2 days off between rides. Local Serotta fitter also does custom orthotics and I've been working with him - he adjusted the orthotics and just shimmed the cleat and will try that. There's some "extra" motion when watching the knee through the pedal stroke. Anywho, seems to be chondromalacia. Next step might be him lending me Time pedals to try instead of my Speedplay X and see if that helps.

Barry

[zap]

BarryG-I'm going to throw a monkey wrench to your problem. Having gone through patellar problems this time last year, I've done quite a bit of research. I am not a health expert and my focus was on relieving patellar tendon stress due to OSD.

I'm curious as to why your saddle is so far forward with the knee problem you described.

A forward position as it relates to Kops puts a lot of stress on the knee. It doesn't appear to be commonly prescribed, but to relieve anterior stress, the saddle gets moved back so that your position related to Kops is 1-2cm back. Saddle also gets moved up if it was too low.

Cyclingnews.com has some excellent articles in the health and fitness section on knee problems and fit recommendations by Steve Hogg (sp.). Cleat back position is also discussed and helped eliminate some of my lateral knee movement in my good knee.

Trying out shims, orthotics and float pedals such as Time is text book fitting and I hope it works for you. But it's possible that a change in saddle position might do the trick.

Something to think about and discuss with your fitter if you havn't done so already

Best of luck.

[BarryG]

Zap, appreciate the input. I'm aware of the common wisdom on saddle position adjustment for anterior knee pain - it just doesn't work for me. The position I've arrived at from experience coincidentally works out to be KOPS with an angle at extension somewhere in the 25-30 degree range. Whenever I move the saddle back or up a bit, the knee just gets worse. Still experimenting . . .

Barry

[Needs Help]

For me its 72 with 180's and 72.5 with 190's.

Dave
Is that because longer cranks close down the angle between your thigh and your chest at the top of the peddle stroke? So, as the cranks get longer you steepen the STA to open up your chest-thigh angle more? Do you worry about getting more weight forward onto your hands?

On the other hand, if you employ a post with more setback as the STA gets steaper, wouldn't that collapse the chest-thigh angle even more than before?

[David Kirk]

yo needs -

Nope........as the cranks get longer they move the foot forward when the cranks are horizontal. So the seat needs to be moved forward to keep the knee-pedal relationship the same.

Dave

[weiwentg]

haven't posted here before, but this is a topic that's dear to my heart. my ideal STA, according to Seven Cycles, is 75.5 degrees for a post with low or no setback. I have a 55.7 TT. I have a 41 (!!) ST. on my small Giant TCR, with its 74 STA, I have a thomson post and the saddle all the way forward. this issue dissuaded me from getting Cervelo. sure, they keep the STA at 73 so they can vary the reach according to the size, instead of making the variance not constant like everyone else does. I wonder, though, if maybe shorter riders tend to require steeper seat angles because they maybe tend to have shorter legs, and that if true, everyone else has realized this except them.

[Brian Smith]

so...what's your ideal STA? because i think cervelo is on to something...that for more riders, a 73* would works.


73 degrees as a stock angle for the mode of frame sizes is not a new nor uncommon choice. I think that most posters, if not readers, of this forum might have more compelling reasons than "what works for most people in general" to choose their seat tube angles. Custom frames are available for a reason!

Anyway, 73 degrees for the mode of frame sizes is a good choice for a manufacturer, if not for an individual. Body dimensions vary enough and peoples' preferences other than KOPS vary enough that it is safe to say that what a manufacturer's choice for a stock sized frame should not dictate in any way what we want to ride or to purchase.

-Brian Smith

[Climb01742]

brian, you are absolutely right. no argument there. but that wasn't really my point. and i'm sorry if i did not make my point clearly enough to be clear what i'm talking about.

there have been many debates here about why do all you guys need custom frames? can't you just get a stock geo to work for you?

well, personally i can't. for exactly the reason you state.

so my point was...could more people make stock geo's work if the stock geo's of more manufacturers were different? i have a stock merckx team sc. STA of 73* and TT of 55cm. i can make that geo work really well for me. when i test rode a cervelo, i could make their stock geo work, also with a 73* STA. contrast that to the vast majority of stock bikes in my basic range -- 54,55,56 -- which have 73.5* STA and i can't make them work without an insanely short stem.

so it was just an abstract discussion of what might be good stock geo's for most folks. not trying to argue anyone into using any particular STA. i'm gonna go ride. :rolleyes:

[TimB]

(Sorry to chime in so late...)

When Smiley fit me two (almost three) years ago, we ended up with a 75.5 degree STA. Anything slacker, and I was still way too far back and couldn't even get close to KOPS.

I think 'ideally' I could have gone with 74.5, as time has gone by I think I've learned that I naturally prefer to be somewhat back from KOPS, but I've managed to get comfortable by pusing my saddle back on the American Classic post.

BTW, the dimensions are 55c-c ST and 54 CC TT with 1.5cm HT extension.

[Dr. Doofus]

The Doofus line:

1) KOPS is a coincidental relationship. Leg entension is the important element, and pelvic stability (see Bontrager and Hogg and some others)

2) Moving the rider backward to achieve KOPS won't screw up the weight distribution. Moving the rider excessively forward (like when someone designs a 59cm bike with a 74 STA and a zero setback post) will either screw up the weight distribution or create a bike with an unusually long front-center.

3) For the majority of frame sizes, 73 STA creates the right amount of frame setback for an adult male to do two things with a properly sized frame:
a) slide in a seatpost that will allow him to put the depressed part of the
saddle in line with the seat tube (the E-RITCHIE sweet spot), give or
take a cm.

b) put a proportional-length stem on the bike and achieve a comfortable
upper-body position without excessive spacers or flipping the stem

4) If said male cannot achieve a) and b), then he doesn't need a "racing" bike. He needs a sport touring or audax bike.

5) 72-74. Read your CONI manual. Ride your bike.

Doofus (board iconoclast who thinks that 99% of bike riders don't need custom bikes)

[coylifut]

brian, you are absolutely right. no argument there. but that wasn't really my point. and i'm sorry if i did not make my point clearly enough to be clear what i'm talking about.

there have been many debates here about why do all you guys need custom frames? can't you just get a stock geo to work for you?

well, personally i can't. for exactly the reason you state.

so my point was...could more people make stock geo's work if the stock geo's of more manufacturers were different? i have a stock merckx team sc. STA of 73* and TT of 55cm. i can make that geo work really well for me. when i test rode a cervelo, i could make their stock geo work, also with a 73* STA. contrast that to the vast majority of stock bikes in my basic range -- 54,55,56 -- which have 73.5* STA and i can't make them work without an insanely short stem.

so it was just an abstract discussion of what might be good stock geo's for most folks. not trying to argue anyone into using any particular STA. i'm gonna go ride. :rolleyes:

can you list a sampling of theese bikes that are size 56 with a 73.5. It seems the vast majority of charts I've seen are 73. The reason why I'm asking is I like a 73.5.

[Climb01742]

coy--a few are 56s with 73.5* are: colnago c50, derosa dual, pinarello dogma ( 73.2*), and i believe orbea's and specialized. a bunch actually. you're in luck!

[chrisroph]

I've got really long femurs and like a 72 although frames that are 72.5 work fine (merckx, look 281) and I can even ride a 73 with enough sp setback (csi with c record post).

[iPaul]

I too have the same problem as Climb01742 with finding that perfect stock sized frame. I'm currently on a 54 c-c frame with 73.5 SA with a 55 TT, 11 cm stem. This works pretty well for me, however, I'd prefer to get further back but the seat is all the way back and even if I could this will make the 55 TT a bit long unless I use a 10 cm stem. To get enough setback, most frames in my size have 56 TT, so the reach still is long for me even at the 73 degree SA. Then there is the short Headtubes :crap: . I checked out the Cervelo's and yes they seem to make sense in the reach department, but the headtubes are just too low for my liking. I guess the idea set up for out type is the Look 481 which has a 55.8 TT and a 72.5 SA.