Okay at this point I'm just embarrassed to ask, but I want to graduate.

When you say "fit coordinate" and be able to list them, I get confused. Are we talking about body measurements by themselves or with components, i.e., stem, bars, cranks? Sorry.

-J

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Jehovah and family unity above all.

Well, since you asked about fixing, how about fixing the year-old bug in the profile setting for bike coordinates?

It's posted on the Development Forun from last January and does not allow numbers to be placed into the software you've designed. The error message reads "Are you sure all values are in mm and not cm?"

After you respond affirmatively, it returns the message "All values must be in mm."

I'd just like to get to grade school and record my data. I finally measured yesterday, using a drywall T-square and 2 levels I had in storage.

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DFL > DNF > DNS

I've got the same question as VelocityDriven. I am guessing that it would be a series of measurements such as seat height, cockpit length (seat to pads vs. seat to bar tips vs. both?), drop from saddle to aerobar pads etc. It would be great if you could list them all out with any suggested conventions for measurement. For example with the bar drop, I would guess you measure from top of saddle nose to elbow pads? Ongoing thanks for your help. Bill

further with respect to fit coordinates, are those of us who do not have a bike (whether ill fitting or not) and do not have a properly certified fitter (or one who has the proper tools/instruments) or, worse yet, has both, but from past experience and reputation, does not exhibit close to the passion/caring that you do about fitting generally (or customers), doomed to not graduate, and spend our days in shop class, or Home Ec?

2 bikes I'm looking at would be the speed concept and transition - likely in XL size. Given the S/R of 44.5 and 56.5 (Trek) and 42.1 and 54.2 (Trans), would I expect these to "fit" the same with a 2 cm stem adjustment and a 2cm spacer height adjustment. Would that be correct? Would that imply that, at those sizes, the transition is shorter and lower? Perhaps the XXL transition is a better comparison frame at 554 450.

regardless what the geometry of a bike is, there is a specific way you fit aboard that bike. there are certain places you contact that bike. for example, the saddle height is a "fit coordinate." if you have two bikes, and one has a seat post that's 54cm in length, and another's seat post is 56cm in length, one of these bikes is just going to have more seat post sticking out in order to get it to correspond with your saddle height, right? now, if i measure from the center of the bb straight up to the top of my saddle, midway between that saddle's nose and its tail, that measure is about 78.5cm (on my tri bike). that's a fit coordinate.

my saddle sits (on my tri bike) with its nose about even with the bb. that's a fit coordinate. it describes how i fit aboard my bike. again, that fit coordinate exists irrespective of the bike's geometry. if one bike has a seat angle of 77�, and another has a seat angle of 80�, i'm going to have to move the saddle back slightly on the 80� frame; or forward a bit on the 77� frame; because what's important is that my saddle needs to be where i need it to be, both in its height, and in its fore/aft placement. that's non-negotiable for me.

it's just like a suit. if my inseam is 34", and i'm getting a new suit, and the pants come with a 35" inseam, i'm sorry, i'm not going to wear it like that just because that's how it comes from the factory. the suit pants are going to have to be taken up to match my inseam. likewise, if a bike comes with a 76� seat angle and i ride at 79.5�, you're going to have to put that saddle forward to 79.5� and if the saddle can't go that far forward, then, sorry, i can't ride that frame.

but, look, at a certain point, it becomes really tough to jury rig a frame to match your fit coordinates. if your saddle height is 79cm, and your armrest drop is 14cm, you're going to need a bike with a certain "stack" that makes it easy to get your aerobars positioned. if the stack is too low on a particular frame, you're going to need a bunch of headset spacers. if it's too tall, and you take all the spacers out, and you have a downward pointing stem, and you still can't get low enough, that's a problem also.

so, what's important to know is this:

1. your fit coordinates are like your suit coordinates. i'm a 42 long, 15" neck, 34" sleeves, 34" inseam, 32" waist (during a good year). if i buy an armani, or a brooks brothers, or a saville row, does that change my suit coordinates? no. likewise, if i buy a cervelo or a cannondale or a felt, my fit coordinates - where i sit aboard that bike, and where my saddle is relative to the bb, the cockpit distance, the armrest drop - that doesn't change. my fit coordinates are uniquely mine.

2. the bike's geometry ideally should be a good match for my fit coordinates. if it isn't, i'm going to have to strain to get the coordinates to work on that bike. if i buy a 44 regular sport coat, and my "fit coordinates" are 42 long, then the tailor is going to have a time getting that suit to fit me, right? likewise, if my fit coordinates are better suited for a cervelo than a scott, or a scott rather than a felt, or a felt rather than a giant, then, my wise and proper choice of bikes narrows.

3. based on the above, i think you can see that unless you know your suit coordinates it's hard to know what suit you're looking for, and if you don't know your fit coordinates (your PROPER fit coordinates) it's hard to know what bike you best buy next.

one more thing: if a "static" set of body measurements works when determining my suit size, then why not for my bike size? because you don't do the high hurdles for time wearing your business suit. if you did, then you'd need a "dynamic" fit when determining the suit you should wear. you'd need a way to know what sort of suit works for you during the process of high hurdling. because you have to RIDE the bike, not just sit there on a bike, the best process for fitting you to your bike is a dynamic process. for this reason, a lot of footwear stores have you run down the block, or on a treadmill, before you buy a shoe. you want to test ride a bike before you buy it, right? well, you'll want to "test ride" your fit before you determine that this fit is in fact the fit you want to live with, especially because i can't know your saddle height REALLY until i know whether you're a toe pointer or a heel dropper, and i can't know what seat angle you'll be best at until i try you out in a variety of seat angles.

does this help?

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Dan Empfield
aka Slowman

there are values we don't allow to be input into the bike fit manager because we *think* you're putting in cms instead of mms. my guess is that you - short (ahem) of stature! - might have a fit coordinate that, while in mm, falls outside our range. if you can PM jordan with your fit coordinates and ask him whether we need to widen a specific range, i think that might do the trick. this is just my guess, mind you.

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Dan Empfield
aka Slowman

first off, everybody has fit coordinates, just like everybody has suit coordinates. even if you have no suit, you have suit coordinates. you have a neck, ergo, you have a neck size. you have a head, ergo you have a hat size. even if you have no hat.

likewise, you have a proper saddle height, saddle set-back/set-forward, you have a proper distance from the saddle (nose) to the armrest (back); you have a proper distance from the saddle nose to the ends of the extensions (where the shifter's pivot is). your armrests are so many cms or mms below the top of your saddle, and i measure this by placing one end of a 24" level on the top of my saddle, angling it over one of my bike's armrests, and i have a little 15cm long ruler than i place on the top of my armrest. i measure up to the bottom of the level. that's armrest drop.

and that's it, folks! those are the relevant fit coordinates! there are some minor coordinates you might want to consider. for example, if you measure to the midpoint of your saddle (from the bb) and you measure 4cm behind the nose of your saddle, you now have two "saddle heights" and the value of this is that you now have a measure of your saddle tilt as well. you might want to measure the distance between your armrests.

if you look at your forum user profile, you'll see a thing called "bike fit manager". if you visit my user profile, or rappstar's, you'll see our bikes listed, with our fit coordinates listed.

now, getting GOOD fit coordinates is the rub. which fitter do you trust? how do you know whether you're on the right track? subject for another lesson upcoming. first, i want to make sure you understand the three points above, in my initial post in this thread, and understand them thoroughly and unequivocally.

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Dan Empfield
aka Slowman

If I'm understanding this correctly. This picture helped me visualize it.




You go in to get fit. The only items that move during the fitting are the items in blue - the seat and the aero bar.

The origin of the coordinate system is the bottom bracket. it is fixed. it does not move.

During the fit, you move the seat ( up,down, left or right) and move the aerobar (up down left or right ) until you get the perfect fit.

Once this is done, you take measurement A, B, C, D, E, F and G.

Once you have those coordinates, you look for a frame (using stack, reach, seat angle etc.) that allows you to most easily mount the seat and the aerobars in the exact points in space relative to the BB.

Is any of this incorrect?

I have a couple of quick constructive comments about the curricula, and it's order of presentation:

• It might "flow" better in the presentation and for the student's understanding if the explanation of "fit coordinates" and how they are determined and measured are presented prior to the discussion of frame stack and reach. I say this because in the process of either determining a particular bike size or other equipment, the fit coordinates are the starting point, or the inputs. The output can then be either the required frame stack and reach (i.e. choose frame size based on the chosen other equipment) or the other equipment required (i.e. stem and bars) based on a chosen frame, as you've described in your P3C and Slice examples.
• I know we've discussed this in the past, but I still think that "fit coordinates" should use the same frame of reference (i.e. vertical and horizontal measurements from the BB center) as the frame coordinates. This tends to make things clearer from a conceptual standpoint as well...as in how fit coordinates "map" onto frames.
  

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http://bikeblather.blogspot.com/

So this all makes sense and I find your descriptions very thorough. My main questions is, because I'm a perfectionist when it comes to these sorts of things) regarding optimization. I have a good fit on my bike such that im not particularly uncomfortable and I'm also feel fast, but I have a feeling that it could be better. How does one determine if their position is optimal? A computrainer or some other device?

Cheers

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Michael J. Pelechaty
Brewer, Black Box Brewing Co.

"Yeah, I was depressed for a little while, but then I remembered how awesome I am."

"The only items that move during the fitting are the items in blue"

bingo. you understand perfectly. once you go thru that process of determining your fit coordinates, then you're ready to start considering what bikes best match those coordinates. we have a system that matches bikes to fit coordinates. however! if you start with a bad set of fit coordinates, you'll get a faithful match using our system to that bad fit.

so, if a tailor measures you out to be a 44 regular, when in fact our true size is 42 long, then, a suit maker might provide you with a 44 regular faithfully designed to fit a person of that size. but if you're really a 42 long, then the process of matching your "size" to a suit of that size worked perfectly. still, you're in an ill-fitting suit.

so, it's important to know what fit coordinates are, and why they matter. second, however, is the harder task: getting your fit coordinates correct.

a proper fit bike will do two things: it'll be designed to grant adjustability, and adjustability along each important axis, to aid a fitter in easily, quickly determining where your saddle and aerobars should be relative to the bottom bracket. then, second, it'll be able to translate those coordinates to bikes that are for sale. alternatively, those coordinates can be translated to the geometry of a bike that a guru, or an elite, might build for you custom. that, by the way, is also a part of our system, and resides on slowtwitch, and in a future installment i'll show you where.

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Dan Empfield
aka Slowman

"It might "flow" better in the presentation and for the student's understanding if the explanation of "fit coordinates" and how they are determined and measured are presented prior to the discussion of frame stack and reach."

i do as you suggest right now. in my workshops. and in our already-published articles in the bike fit section of slowtwitch. i'm trying a different approach, to see if this works any better.

"I still think that "fit coordinates" should use the same frame of reference"

i do to, theoretically. and i would, if this was all on paper. that's why stack and reach use that same sole reference point. but certain things don't, in practice, lend themselves well to what seems intuitive. for example, saddle height might be best represented as an XY dimension. but it's hard to do that in practice. much easier to take the angular dimension.

accordingly, cockpit length is most easily, in my experience, measure v the saddle, likewise armrest drop. furthermore, what really MATTERS to cyclists is not the spatial relationship between the armrests and the bb, rather the relationship, or interaction, of the armrests, and bar ends, to the saddle. these interactions determine shoulder angle, and hip angle.

for example, if lengthening the cockpit creates discomfort, it's not because the armrests are further in front of the bb, rather because they're further in front of the saddle. this, because if you move the saddle and armrests further forward in tandem, pain in the back or the shoulder largely or entirely disappears. the relevance is not in the front end's placement v the bb, rather its placement v the saddle.

for these two reasons, i'm stickin' wit what i got.

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Dan Empfield
aka Slowman

Hi Dan,

Firstly, thanks for sharing your knowledge on bike fit. I think I understand stack and reach, and I think I understand fit coordinates. I understand how to measure these on my existing bike/s. What I wanted to clarify is this: in order to get your stack and reach, and your fit coordinates, you need a bike which is a very good fit through a process of experimenting. Having tweaked your existing bike and found a comfortable enough position within the limits of what that frame will allow, without a fit bike etc, you may not be able to experiment enough to get your bike to the point of REALLY finding your best position? So the key again is finding someone who is worth their salt as a fitter or having to spend a lot of money on a fit bike or several bikes and parts? Hope this doesn't sound negative as I really appreciate you trying to drum all this into my thick skull!!! :)

Thanks,

Will
Proper fit coordinates.

Dan, thanks a million for taking on all the questions. I've long been a user of the stuff in the fit portions of the website.
Here's a quick one about the +/- conventions in the bike profiles on this site. I'm looking specifically at the three bikes in your profile.
For "B:plumb line, saddle nose to BB", when you prefix a "+", I gather that means your nose is ahead of your BB, and a "-" indicates behind (as on your Davo.)

Similarly, it must be that E:Armrest drop gets a "-" when then armrests are lower than the seat.
But on the road bikes, does "I:Handlebar drop" work the opposite way? You show a 75 there. Based on Ves' nice post of that bike's drawings in the 201 thread (and my assumption that you don't ride like my grandma), it seems you must mean 75 lower as well. I thought it might just be an oversight, but Jordan does it the same way.

Maybe I am not ready for this master's level course, but doesn't crank arm length have an impact on seat height and therefore fit coordinates?

I include this thinking it may be the right time in the conversation, hopefully to add practical illustration of the principle.

These are my fit coordinates from my curent bike, a 56cm Airfoil Pro. As built from the factory it does not fit me well, but through trial and error (4 stems, 2 aerobar combos) I think it does fit me well now. I have been professionally fit twice on it, once by a FIST fitter. As a disclaimer it was a lust purchase in 05 before I found S/R, I would not buy a long low bike now (I don't think).

Stack (Horizontal line from BB center)
BB to Headset Top center 510
BB to Stem Top center 590
BB to Aero Pad Top 650

Reach (Vertical line from BB)
BB to Headset center 450
BB to Stem Top (center) 420
BB to back of Bar 560
BB to back of Pad 510

Other measurements
Seat clamp to stem top center 550
Seat clamp to back of bar 640
BB to seat clamp (direct line) 720

I realize that I am missing a few things here - bb to saddle top, reach to bar end shifters. Also these are tape measure type measurements so may be off a cm or so.


So, realizing that I am riding with wayyy to many spacers, and feeling that my current bike is a little too long for me, I started my search for the next bike. I will likely recycle my front end (syntace CX bar/C2 extensions) which is average tall stack.

So I am looking at the following bikes thinking they might be candidates. (S/R from the table on ST)

Orbea Ordu 57 530 422
Trek Speed Concept L 541 426
Argon 18 E114/112 L 536 428
Trek Equinox 7 56 544 420

But I really like these other bikes as well:
Kestrel 4000 55 536 418
Scott Plasma L 548 416

I would buy the K4k all else equal. Will it fit well with my coordinates as above? Is it too short? Too long? What is the allowable range of "fudge" for stack and reach?

Thanks!

Yes! Ready!

I believe my position is pretty good and rather powerful. It is not the most agressive, but I think better than it looks due to relatively short humerous bones. So, given that, I would like commentary of which high end frame work best with my coordinates. Perhaps that is "401."

Here are my coordinates:
A: Saddle height 738
B: Plumb line, saddle nose to BB +26
C: Cockpit (nose to extension tip) 760
D: Armrests to extension tip 350
E: Armrests drop -100
F: Saddle nose to armrest back 425
G: Armrest width 235

Many thanks,

---

David
* Ironman for Life! (Blog) * IM Everyday Hero Video * Daggett Shuler Law *
Disclaimer: I have personal and professional relationships with many athletes, vendors, and organizations in the triathlon world.

Dan, What a great explanation. I have a much better understanding of fit coordinates and how they play a key role to come up with r&s. Truthfully, it was getting a little hard to comprehend, but as it's been said on here "a picture is worth a thousand words" Your explanation, the diagram posted here by elpete and by actually visiting your profile and seeing how many fit coordinates there are:

A: Saddle height B: Plumb line, saddle nose to BB C: Cockpit (nose to extension tip) D: Armrests to extension tip E: Armrests drop F: Saddle nose to armrest back G: Armrest width

Brought all the pieces of the puzzle together. I now feel comfortable enough to walk into any bike shop and speak to the fitter on a level where I can understand......thank you. Heck, as a matter of fact, if the fitter can't come up with s&r based on my fit coordinates, cause he feels he doesn't need one or two of these measurements......don't walk out of there, RUN!.

Now my questions change some. Moving forward. Let's say I now have all my fit coordinates, know the stack and reach of the frame needed. Find one, build one. I'm aero and comfortable to the point I can ride it miles on end. That's all fine and dandy, but is there a general rule of thumb to come up with maximum power output without compromising the first two? I don't have the gift of gab and typically can't explain myself well, but I hope you understand what I'm getting at here. Basically, I want to go fast without compromising aero+comfort. Would the rule of thumb here be to sit right over the BB, behind it or in front of it? Thanks again, thanks a mil.

respectfully,

-J

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Jehovah and family unity above all.

generating your fit coordinates: there are a few ways to do this.

first, get yourself aboard a fit bike and experiment until you have it nailed. either with or without a fitter to help. the only magic about a fit bike is you can explore endless positions and you can do so quickly, and change from one parameter to another to get more or less instant feedback.

second, you experiment with your current bike, assuming that bike is not entirely out of the ballpark for you, and if you're willing to invest in a few stems, and if you have a frame and/or aerobar that is adjustable enough.

i would guess that most of the pro athletes over the past 10 years haven't had access to a fit bike, yet they've found a way to divine their own best positions.

all that established, nowadays there are some pretty neat fit bikes, and one of these good fit bikes in the hands of somebody who really understands what's going on is going to make it a lot easier. if you pay attention to this series of threads, you'll be able to tell which fitters understand the concepts, and which fitters aren't quite ready yet for prime time.

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Dan Empfield
aka Slowman

"when you prefix a "+", I gather that means your nose is ahead of your BB, and a "-" indicates behind"

yes

"drop gets a "-" when then armrests are lower than the seat."

yes

"does "I:Handlebar drop" work the opposite way?"

it shouldn't. i'll take a look. my h'bar on my road bike is definitely lower than the saddle.

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Dan Empfield
aka Slowman

"doesn't crank arm length have an impact on seat height and therefore fit coordinates?"

yes, it certainly does. when you change crank length, seat height changes, and armrest drop may also change.

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Dan Empfield
aka Slowman

all those metrics you list are great, but they aren't the metrics i use, and are therefore not metrics i'm familiar with. i'm not a lazy guy entirely, but i'm certainly too lazy to try to derive my metrics from yours. so, you have to give me your fit coordinates according to the metrics i use before i can comment.

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Dan Empfield
aka Slowman

how tall are you?

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Dan Empfield
aka Slowman

"if the fitter can't come up with s&r based on my fit coordinates, cause he feels he doesn't need one or two of these measurements......don't walk out of there, RUN!."

;-)

as to your question, that's a few classes ahead.

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Dan Empfield
aka Slowman

I'm not sure if I understand why measuring vertically and horizontally to a point on the saddle is any more difficult than measuring frame stack and reach? Why don't you use measure an angle and length to define the location of the top of the head tube? Measuring seat location "X-Y" should be just as easy as measuring head tube top location "X-Y". Besides, I don't see an angle measurement in this figure:

In Reply To:

accordingly, cockpit length is most easily, in my experience, measure v the saddle, likewise armrest drop. furthermore, what really MATTERS to cyclists is not the spatial relationship between the armrests and the bb, rather the relationship, or interaction, of the armrests, and bar ends, to the saddle. these interactions determine shoulder angle, and hip angle.

I'm looking at it from the standpoint of consistency in measurement. Yes, the saddle to pad location is important, BUT those can be either inputs or outputs. You can either measure them directly off of the bike in "X-Y" and then calculate the cockpit length and drop from those measurement...OR, you can do it like you prefer and then calculate the "X-Y". At some point those locations need to be translated into the "X-Y" coordinates in order to use them. My preference, and I'm coming at this from someone who deals with dimensioning and tolerancing on a daily basis, is to take the measurements directly from the chosen datum. That reduces errors in "setup to setup".

The dimensions you show can still be calculated and displayed as "reference dimensions", and would be the "quick and dirty" dimensions you could check to make sure things are where you think they are.

BTW, I have an idea for a fit bike attachment you could have made which would basically create a "fit bar", in other words, the aerobar version of a "fit bike". You could have made a device which allows you to position the pad locations and shifter locations in the X, Y, and Z coordinates (relative to the headtube top) and then you can directly read those coordinates off of the device and add them directly to the stack and reach coordinates read off of the fit bike. That way, you wouldn't need to actually stock a sample of each bar and stem type. You can merely have measured them once and then set up the "fit bar" to each candidate bar's particular coordinates (including the adjustment ranges). Same thing with particular combinations of stem lengths and angles, along with any spacers or head caps. You could fit someone on one of these fit bikes and be able to specify a complete bike/stem/bar/saddle setup without ever actually mounting any of them on the particular bike. What do you think?

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http://bikeblather.blogspot.com/

Absolutely, which is why crank length (along with the particular pedals, shoes, saddle and bars) should be CLEARLY noted on any fit coordinate sheet. They all affect the specific fit coordinates relative to the BB. They are part of the "assumptions" of the particular fit.

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http://bikeblather.blogspot.com/

"I'm not sure if I understand why measuring vertically and horizontally to a point on the saddle is any more difficult than measuring frame stack and reach?"

it's not. but end users don't ever have to measure stack and reach. they do need to measure their own fit coordinates. if end users had to measure stack and reach themselves, that would be pretty horrible.

the middle part of your post: asked and answered in our previous exchange.

the last part of your post: i welcome all new kinds of fit tools. we don't have a good XY tool yet to measure XY coordinates (like stack and reach). if dealers had a good XY tool, they'd be able to recruit some of their older fit bikes and press them into current service.

one thing, tho, about having various aerobars in stock and set up for use. to me, it's precisely like saddles. the only way to know if you like it is to sit on it. you could say i'm anal about my saddle ;-)

what i'm picky about is every "contact point". so, i want folks to try them, palpate them, not just the aerobar pads, but the extension shape, and the match of the extension height to the pad height, all of it. i want them to ride on that bar on a fit bike before they get sold that bar and that bar gets mounted on a bike.

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Dan Empfield
aka Slowman

"how tall are you? "
-----------------------------------
I'm almost exactly the same size Jurgen Zack :-).....seriously - you may recall we were all together at Paula's camp in the early/mid 90s. You said I looked like Dirk....doesn't say much for my hair do.

5'101/2, 173 lbs.

---

David
* Ironman for Life! (Blog) * IM Everyday Hero Video * Daggett Shuler Law *
Disclaimer: I have personal and professional relationships with many athletes, vendors, and organizations in the triathlon world.

it seems to me you're fairly evenly proportioned. maybe a little long in the torso? which would make your cockpit distance about right. maybe 1cm too long? my only comment, from afar, is that if i were forced to fit you without seeing you, watching your ride, or anything, it's that it seems your armrests are 2cm or so higher than they might otherwise be. and i wonder if that 1cm of tighter cockpit might allow you the correct shoulder angle that might then allow you to drop those aerobars another cm or 2.

then again, as you say, if your humerus is short, that's the explanation for the less than large armrest drop. but, if this is the case, your back is still going to be relatively flatt(ish), and affixing a goniometer to your hip angle while riding should yield an angle typical of a rider with a greater drop.

but even with the flatter back, the short humerus means a taller frame. specialized transition (not shiv), scott plasma, cannondale slice, blue triad. just, if it's a plasma, make sure you can get the saddle nose to +2.5cm.

but, as we shall see in the next installment, as lance says, "it's not about the bike." what it's about is "the bike + the aerobars." that's what will determine what you should be aboard.

---

Dan Empfield
aka Slowman

http://www.youtube.com/watch?v=ESnVoXQwvLk

---

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

harsh. but funny ;-)

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Dan Empfield
aka Slowman

Is there a ratio of stack:reach that says a bike is long/low or tall/narrow.

Back to the picture is worth a thousand words topic -

I "think" this would really drive it home for me:

Same guy. Same day. On these different set ups-
1. Bike that is the perfect set up for him (maybe Rapp)
2. Same model/brand but in the next size up. And next size down. Same fit coordinates
3. A bike that is built the opposite of their style (ie - if Rapp rides Long/Low how would he look on a Narrow/Tall bike with the same fit coordinates?)
AND - if the fit coordinates are the same across each scenario- what is the impact? (aero, power, handling,etc)

Thanks for your reply To my earlier post. Makes sense. Your stack and reach index for tri bikes is a fantastic resource. Talking road bike geometry for a sec, do you know where I can find stack and reach info? Most manufacturers don't list these on there geometry tables?

Thanks,

Will

A great thread. Small detail - I think you mean seat tube in this explanation? Might be confusing...

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Richard Melik | I work for the following companies | Zwift.com | Freespeed Bike Fit (UK)
Manager | David McNamee

"Small detail - I think you mean seat tube in this explanation?"

yup. seat tube.

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Dan Empfield
aka Slowman

"Is there a ratio of stack:reach that says a bike is long/low or tall/narrow."

it's not hard to divine. in very rough terms, if the stack of a bike is more than a third again its reach, it's starting to trend narrow/tall. so:

reach of 36cm x 1.33 = stack of 47.9cm
reach of 38cm x 1.33 = stack of 50.5cm
reach of 40cm x 1.33 = stack of 53.2cm
reach of 42cm x 1.33 = stack of 55.8cm
reach of 44cm x 1.33 = stack of 58.5cm

so, while a ratio of 1.33 or greater means it's trending narrow/tall, i think a ratio of 1.22 or smaller means it's trending long/low.

reach of 36cm x 1.22 = stack of 43.9cm
reach of 38cm x 1.22 = stack of 46.4cm
reach of 40cm x 1.22 = stack of 48.8cm
reach of 42cm x 1.22 = stack of 51.2cm
reach of 44cm x 1.22 = stack of 53.7cm

again, very general numbers. so, you take a bike that's got a reach of 42.0cm, if it's got a stack between 51.2 and 55.8 its a relatively mainstream bike, geometrically, at least as regards fit. let's see how some of these line up. here are bikes with a roughly 42cm reach, with their stack numbers, in order of long/low to narrow/tall:

kestrel airfoil pro size 52 reach 41.5cm stack 48.4cm ---- ratio: 1.17
kuota kueen k size 54 reach 50.3cm stack 42.6cm ---- ratio: 1.18
cervelo p3 size 54 reach 41.9cm stack 49.8cm ---- ratio: 1.19
cervelo p2 size 54 reach 41.8cm stack 51.2cm ---- ratio: 1.22
felt size 56cm reach 42.5cm stack 52.5cm ---- ratio: 1.23
orbea ordu size 57 reach 42.2cm stack 53.0cm ---- ratio: 1.23
argon18 E114 size M: reach 41.9cm stack 51.5cm ---- ratio: 1.23
qr cd0.1 size M reach 42.0cm stack 49.7cm ---- ratio: 1.26
trek speed concept size L reach 42.6 stack 54.1 ---- ratio: 1.27
specialized transition size XL reach 42.1cm stack 54.2cm ---- ratio: 1.29
cannondale slice size 58 reach 41.7cm stack 54.8cm ---- ratio: 1.31
scott plasma size L reach 41.6cm stack 54.8cm ---- ratio: 1.32
BH gc aero reach 42.0cm stack 56.0cm ---- ratio: 1.33
blue triad size ML: reach 41.4cm stack 55.8cm ---- ratio: 1.35

now, there are certain things to remember:

1. these bikes to not necessarily maintain these ratios throughout their size runs. for example, on our home page are write-ups of kestrel's 4000, and with its two tri bikes (the 4000 and the airfoil pro) plotted against trek's speed concept. the speed concept keeps to its ratio. the two kestrels do not. this is not a bad thing, it's just a notable thing, and it gives kestrel's retailers a pair of geometric styles to choose from when fitting their customers. just, neither model keeps to a single style. they're BOTH moderately trending long/low in their two largest sizes. but in their smaller sizes, the 4000 trends narrow/tall to midlin'. the airfoil pro is long/low in its smaller sizes.

2. this is a lead-in to the next class, so, get ready: it's not the BIKE that determines the ratio. it's the BIKE + AEROBAR that determines the ratio. for example, if you take a p2 and put a 3T aura on that bike, and if you take a slice and you put a vision clip atop that bike, and you do this in the sizes listed above with the 42cm reach, you now have two bikes that are almost exactly the same height to length (assuming the stem length and pitch is the same on each bike).

so, don't get too hinky about the FRAME, rather, consider the entire construct aboard which you'll sit.

one more thing: what's the most mainstream bike on that list? trek speed concept. in every size, it's right smack dab in the middle. why? because trek plotted every bike in the market, and designed its geometry with the prime inputs as stack and reach. trek made a wager, that if its bike sat in the middle of the pack geometrically, it would fit as many customers as possible, and it would inoculate itself against any charge that its bikes were geometrically problematic. it wagered that if it simply erased that as a concern for as many people as possible, then it could concentrate on its narrative of superior aerodynamics.

that established, it's now up to bontrager to make aero bars that allow the entire construct to fit as many people as possible. in other words, bontrager has to do what trek did: make a geometrically mainstream bar; or it needs to make two bars: one high profile and one low; or it needs to make one bar that can be adjusted high or low profile. did bontrager do this? this spring we'll be reviewing aerobars and you'll find out. but in the next class, i'll equip you so that you can determine this yourself.

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Dan Empfield
aka Slowman

Do you offer fitting as a service?

Mike

"Do you offer fitting as a service? "

no. our FIST school teaches retailers how to fit, and manufacturers how to design and spec their bikes to make sure they're geometrically correct. i don't fit. but, we have two instructors who teach here with me. one is rappstar, the other is jt lyons at moment cyclesport in san diego. these guys are each very knowledgeable, of course, they're also each university trained engineers, and i chose jt to be one of my two FIST instructors because when he took the course he was the biggest pain in the ass ever to set foot on the compound property. this, because he asked the hardest and the BEST questions. he really got it, to the point where he saw through every flaw and i reckoned that if i just absorbed him into the system he'd help me fix any flaw. likewise jordan, well, you know what a pain in the ass he can be, so, with these two ass pains FIST as a system has continued to gain strength as a protocol that stands up.

i'm am absolutely convinced that if jordan and i each independently fit 10 people, 8 or 9 of those people would end up with fit coordinates within 5mm in every axis. jt likewise is going to be very close, but, jt sees a lot more people on a day to day basis than do jordy and i, because jt owns a retail store and fits people all day long. jt also has a new guru dfu bike, pretty neat.

i don't know if jordy will fit people, other than the pros who go to him. jt of course does. the two people i'd recommend most highly are, of course, these two. i don't know if tom demerly is fitting people over at trisports in tucson. i'd recommend tom. i like colin o'brien at cronometro up in madison, wi. there are plenty of good fitters out there.

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Dan Empfield
aka Slowman

I'm wondering if Jordan and JT appreciate you using the term "ass pain" and the acronym "FIST" in the same sentence in reference to them.... ;-)

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http://bikeblather.blogspot.com/

Kevin Riseborough - flying wombat here on ST - is in the Phoenix area. Has taken the FIST workshop at least twice and every time is a major pain in the ass (in a good way) and also demonstrates over and over that he "gets it." I've sent several folks to him, and they've all been happy. I'd add him to Dan's list of top notch fitters who've been through the FIST program and really buy into it and fit according to the methodology we teach.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

I'm a little late to class and I hope I'm in the right room...

How does saddle choice play into the "saddle nose to extension"? Specifically, I sit differently on different saddles. My hip angle changes based on which saddle I am using therefore changes my coordinates.

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******************************************************
Well I believe in God, and the only thing that scares me is Keyser Soze

Rappstar,

Is there anyone you would highly recommend in Texas. Closer to Austin, San Antonio, Corpus Christi, preferably South Padre Island or Rio Grande Valley. Thank you.

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Jehovah and family unity above all.

"How does saddle choice play into the "saddle nose to extension"? My hip angle changes based on which saddle I am using therefore changes my coordinates."

then, your fit coordinate is tied to a particular saddle, just as it's tied to a particular crank length, and maybe a particular cycling shoe.

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Dan Empfield
aka Slowman

I know that ATC has sent four folks to the FIST workshops, but I do not have any personal experience with them beyond that.

I really don't want this thread to turn into a "who do Dan & I recommend for fitters." That's largely why we added the additional field for "fit methodology followed" to the bike shop database. And that's why we put up details about exactly what the FIST process entails. And THAT is why we are having this thread. We want you to be educated about what a fit should entail. Then you can go ask the person who wants to sell you a bike what the process means to them. When those two things are in agreement, THAT is the fitter I would highly recommend.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Rappstar,

Point well taken and I apologize if you feel I in some way put you on the spot. My reasons for asking were a bit selfish. Obviously, Dan and you are well respected in the community for numerous reasons. So it stands to say that your opinions around here carry a lot of weight. But you're right, that is why we're having this thread. Hopefully, to educate us well enough to ask the important questions and form our own opinion about the fitter's knowledge.

I feel Dan has helped us achieve this already. A great deal of thanks.


-J

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Jehovah and family unity above all.

Thanks Dan....If Herbert ever gets his Scott finished, and since he is just a few minutes away, maybe I'll get to try it!

Thanks!

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David
* Ironman for Life! (Blog) * IM Everyday Hero Video * Daggett Shuler Law *
Disclaimer: I have personal and professional relationships with many athletes, vendors, and organizations in the triathlon world.

The one question in this thread I most wanted to see an answer to is Cheddar's - I have a position that is pretty comfortable and seems to work pretty well, but I suspect that perhaps it could be "better". How do you know when your position is optimized, rather than just acceptable? I recognize that this requires striking a balance between different factors, namely comfort, power output, and aerodynamics, and that the appropriate balance is going to vary between individuals. I also recognize that aerodynamics is going to be somewhat difficult to determine on a fit bike (beyond the "eyeball windtunnel"). But if I assume that there is a small range for each measurement within which I will be equally comfortable, what is the protocol for figuring out which position is the "best"?

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__________________________________________________
The plural of anecdote is not data. :-)
- Andrew Coggan

My biggest issue now with S&R now is how to figure out the STA.

If I understand everything well for a given individual, a steeper STA means forwarding and lowering the arm cups. However, it seems to me that the TT position is one that you grow into, and as you get more miles in the position you can go lower and steeper. It was certainly true for me and my road position where I was able to get into a more aggressive road position after many miles.

So say one person starts a 76deg STA but grow comfortable into a 78-80deg STA. That means changing the cockpit contact points, but can you accommodate this without needing a new frame, since S&R is now different? If you can achieve that with just changing the cockpit components (lower aerobars) without an extremely long stem, how do you choose the optimal frame that will allow you to slide forward over time?

OK, so I get S&R, and I get its relationship to fit coordinates (my body on the bike). I also get that the common sense end result is a frame whose S&R matched with their 'right' aerobars provides that 'best match' form me (and the right crank size, stem within tolerance, seat adjustment within tolerance, etc). Here's a potentially irrelevant question: If my frame is too small and my setup is beyond reasonable tolerance in order to make it work for me, do I gain comfort and speed with a larger frame (assuming the coordinates are correct). Does the larger frame, with its longer (apples vs apples) wheelbase provide a fundamentally faster platform per watt? Just bitch slap me if this is way too off-topic or random, but this relates to my specific issue with my current frame. I also love my saddle, and it's the only component I'm not willing to swap out.

Dan all this confusion must be causing you to pull out what hair you have left ;-) I recall years ago pretty much figuring this out intuitively. I think I called reach "effective top tube length" in my little spread sheet file. I bought my first two tri bikes totally sight unseen just off the geometry charts and it worked fine. I think folks are getting way too worked up over this...it is not that complicated.

When will you have your bike selection data base available with links to the manufactures sites with "Doubleclick" counters giving you some nice revenue for all this work? That would actually be a great service. Thanks!

"How do you know when your position is optimized, rather than just acceptable?"

in broad strokes, the answer is: do you find yourself constantly urged toward a change? for example, do you find yourself moving forward on the saddle, or wanting to, but you can't, because the saddle won't adjust further forward? if so, then, you probably aren't optimized. however, this doesn't necessarily mean that your seat angle is too shallow. it might mean that your cockpit is too long - you're too stretched out, and moving forward on the saddle might simply be a ploy to adopt a correct cockpit. the point is, if you feel like there's something about your position that you feel needs to be different, then - just like anything else in life - your instincts are probably right. if you feel you need a change in your life, you probably do.

that's in broad strokes. if we drill down a little closer - for example, if i had you up on a fit bike and i was able to execute changes right then - my answer is this: what's the LEAST comfortable thing about your position? this takes a bit of "body-awareness". you have to reflect, and adopt as best you can some sensitivity into your approach. have you ever laid in bed, at night, and relaxed yourself, one body part at a time? likewise, when you're aboard your bike riding, think about every body part, and ask yourself what's least comfortable about your bike. that's what needs to get fixed first. fix it. then, ask yourself what's next. fix that. eventually, you'll run out of things to fix. you're optimized

that's how pros have achieved their positions over a period of riding their bikes for a few years. the reason they got there in a HURRY is that you're riding 75 miles a week and you can suffer thru a bad position. they're riding 400 miles a week, and they can't.

obviously, there are tools that help accelerate this. a good fit bike. several different saddles. several different aerobars. a selection of stems. a selection of aerobar extensions. even if you simply found a bike shop with a good fit bike and hopped aboard and played around until you thought you had a good position, and then checked here on this forum to see of the resulting fit coordinates made intuitive sense, then you could make changes to your existing bike to adopt the new reality you achieved on the fit bike. it would be worth that bike shop's while. you'd certainly have to buy stuff to make your new reality happen.

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Dan Empfield
aka Slowman

Dan, I a follow up to your response just above....

If I'm uncomfortable on my bike, then I get on a fit bike and it 'feels better' while I'm on it, that isn't necessarily a reflection of how I'd feel after 90' with that new fit. So, how is the fitting 'in your world/how you teach it' take that into account? It might feel better for the 3-5 minutes on the fit bike, but it may not be 'better' long term. Hope this makes sense.....

Sorry if this isn't a 301 level question.

i don't think:

a) your optimized tri position has to evolve a lot over time;
b) you need a lot of time to adapt to your optimized position;
c) your best 15 minute position is very different from your best 5 hour position.

i do think:

a) you'll never be comfortable, for 30sec, 30min, or 3hr, on a saddle that you don't like;
b) likewise on aerobars you don't like;
c) likewise in a position that isn't right.

it's like of like meeting the "right" gal. a part of what makes her right is that you know what you're looking for; that you're looking for the right sorts of things in a gal; that you have your priorities right; and that you've done what you need to do to be the right guy. if all that is in place, the right gal will be right, right away, and for a long time after.

likewise, if you're a fit, trim triathlete, and you know everything a good position consists of in theory, then you'll what to look for in practice, and you're likely to find it.

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Dan Empfield
aka Slowman

So, know your coordinates, then match those up to the right bike. Once you hop on, with the right help (trained fitter), you'll just know the fit works, (somewhat) irregardless of how long you're on your new fitting bike.

Is that about right?

Please come to Tampa.....

Hey Dan,

How do you account for 2 position seat posts. Meaning a manufacture offers bike X and the geometry information published is for the bike at 76*, but the post can also be placed at 78*. Now I am speaking strictly from the point of numbers for the bike, not what the customer will or will not need.

I realize this does not change the stack or reach of the frame, but does influence frame selection.

Cheers,

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Richard Nixon, Fit2Tri Multisport Inc.
Fit2Tri,
rich@fit2tri.com
Discount code, slowtwithch

"How do you account for 2 position seat posts."

let's take rupaul as an example. sometimes he dresses like a guy. sometimes he dressed like a gal. but if you look lower down, you'll know the truth.

same thing with a bike sporting a 2-position seat post. is it a 75� bike? or a 79� bike? look lower down, and you'll know the truth.

the "lower down" is to be found in two places: the bike's stack and reach, and, lower down yet: the bike's front/center (the distance between the bottom bracket and the front wheel axle.

let's take two bikes as an example: kestrel's talon and cervelo's p3. each has a 2-position post. but if you look down at the bikes' stack and reach, one is very narrow/tall, the other is moderately long/low. and if you look at their front/centers, the talon's is short, the p3's is long.

the talon is so narrow/tall it's really not even a tri bike, it's a road race bike. it's meant to be ridden in the shallow seat post config. the p3, because it's long/low, can't be ridden in the shallow seat post config. that bike won't fit anybody if ridden that way, except perhaps by somebody who's riding mid-steep and rides with the saddle in the rearward hole with the saddle slid all the way forward on its rails.

during the media event surrounding the unveiling of felt's DA, one road bike journalist asked, "i notice you don't have the two position post, i suppose that's available for those who ride in the conventional position?"

the answer, from felt's dave koesel (superdave here): "this is the new convention. when we took all the garmin riders into the tunnel, every one of them was better off in the forward position. so, if road racers won't ride the rearward position - even when encumbered by UCI regs - why would we continue to make bikes with that position on the seat post?"

or if these weren't his exact words, they were fairly close.

the only reason for the rearward position in most well made tri bikes is for dealers encumbered by backward thinking. but occasionally you find a bike, like the talon, that needs to be ridden with the saddle rearward. that bike shouldn't, in my mind, have a forward position any more than the felt DA needed to have a rearward position.

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Dan Empfield
aka Slowman

On this:



Why did you make F the distance to the arm pads, and not the distance to the place you grip onto the aero bars? I find that the pads can move around a little bit, especially as pads now come in a variety of shapes, but where my hands are (on the shifters or right by them) is not affected by the pads.

"Why did you make F the distance to the arm pads, and not the distance to the place you grip onto the aero bars?"

we have both. look at C. we list D as well because of the difference in where folks like their aerobar pads to sit under their forearms.

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Dan Empfield
aka Slowman

That pretty well covers it, but we still make 3 different seatposts for the new DA. We have a "slack" seatpost for those that ride a conventional saddle with a relatively low hieght that must remain behind the BB by 5cm. That seatpost is an aftermarket item. We've got the "team" version of the seatpost with the Di2 battery mount and a much more forward position. This version is still designed to abide by the 5cm rule but not every saddle and every seat height can manage to stay legal with this post. At ~78 degrees it also may not be steep enough. The production seatpost is further forward yet. As yet unseen, this seatpost will come with the OEM bicycle as it suits 95% of the consumers buying the bike. It can be set up north of 80 degrees for most configurations and has the battery location back underneath the BB shell on the downtube with the aero cover over the battery.

-SD

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https://www.kickstarter.com/...bike-for-the-new-era

"That pretty well covers it"

especially the part about rupaul, who, as i understand it, rides a felt. or if he doesn't, he probably should.

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Dan Empfield
aka Slowman

How about posting some pictures of bikes with the riders on them showing correct frame size and correct overall fit (saddle height, aerobar setup, etc.)?

Is there a database of aerobar geometries we could see? It doesn't seem that manufacturers publish that information.

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________________________________________________________
Ben Waite | Zipp Senior Design Engineer | The Power of Bicycles: Please contribute to World Bicycle Relief | Zipp | SRAM | Quarq |