"I read somewhere that the reach should be higher with my height."

reach? or stack? reach can't be higher. it can be longer or less long. stack can be higher. or less high.

and let's just make sure that when you say stack and reach that you're simply talking about where the head tube top terminates above and in front of the bottom bracket. if you mean pads, or anything else, you have to modify it. if you're talking about your POSITION on the bike, maybe where your hoods are on a road bike or your pads on a tri bike, you have to express this in your statement.

if you said pad rise and run i'd know what you're talking about. or pad x and y. or even pad stack and reach. but with no modifier, just stack and reach, if you said that, you're ONLY talking about a frame measure.

"which is more important? Stack or Reach?"

reach. you fit to reach, mostly, because there is so much adjustment to height. it's easier to adjust height than length.

but it's not even just frame reach, it's also that bike's length as expressed in other measures, such as wheelbase and front/center.

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Dan Empfield
aka Slowman

Ok, I guess I should have said my reach seems short. The number seemed low, could this mean that my position wasn't stretched enough? Will probably change as I get used to the aero position.

Was curious if the size was a little small considering the additional spacing and possible change in position in the future.

Does the fitter usually err on the side that a novice will change positions and therfore their HX/HY numbers change and allow them to grow into the bike?

Thanks for dealing with my questions, I just want to make a purchase that's right and last several years considering the amount of money a bike costs.

"Ok, I guess I should have said my reach seems short."

again, words mean things. if you say reach, that refers to the horizontal distance from the BB to the top of the frame's head tube. are you talking about the distance to the center of the pads? yes, that 450mm to 460mm number is pretty small.

"Does the fitter usually err on the side that a novice will change positions and therfore their HX/HY numbers change and allow them to grow into the bike? "

not me. when i fit you i help you achieve today's best position. now, let's say you have a belly, and your belly keeps you from getting as low as you'd like. and you're adamant that you're going to lose weight. then i'll make sure not to recommend a bike that can't go any lower than your position is today.

but that's the bike i recommend. i'm still going to put you in the best position you can be in.

the biggest mistake fitters make today is they don't work their subjects hard enough during the fit session. road or tri. that often results in positions too high and not stretched out enough.

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Dan Empfield
aka Slowman

Not an elementary question at all.

Both are important, but I actually think that stack is slightly more important than reach. For most frames and most people, you can adjust reach via changes in stem length with little problem or penalty.

However, adjusting stack can be a lot more problematic. If your frame is too big, and you need a lower stack, well, you're s.o.l. (short of extraordinary steps or contortions). And if your frame is too small, and you need a number of steerer spacers to get your effective stack up higher, well, now you've made a change that has added a lot of aero drag to your formerly superbike (and negated thousands of dollars of aero design work). Plus, many bikes (well, the forks of those bikes) are quite limited in how many spacers you can add without venturing into uncharted engineering territory (and the possibility of catastrophic failure).

So I like to get my stack perfect and then see how close I am to my desired reach. Then I adjust reach as needed.

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Advanced Aero TopTube Storage for Road, Gravel, & Tri...ZeroSlip & Direct-mount, made in the USA.
DarkSpeedWorks.com.....Reviews.....Insta.....Facebook
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"Ok, I guess I should have said my reach seems short."

again, words mean things. if you say reach, that refers to the horizontal distance from the BB to the top of the frame's head tube. are you talking about the distance to the center of the pads? yes, that 450mm to 460mm number is pretty small.


Yes that's what I'm meaning to say...using the wrong adjectives.



"Does the fitter usually err on the side that a novice will change positions and therfore their HX/HY numbers change and allow them to grow into the bike? "

not me. when i fit you i help you achieve today's best position. now, let's say you have a belly, and your belly keeps you from getting as low as you'd like. and you're adamant that you're going to lose weight. then i'll make sure not to recommend a bike that can't go any lower than your position is today.

I don't have a belly, but I also haven't been riding aero so I'm sure I'm a bit stiff.





the biggest mistake fitters make today is they don't work their subjects hard enough during the fit session. road or tri. that often results in positions too high and not stretched out enough.

I rode the machine for about 10-15mins....I was asked if anything felt better or worse....only thing that felt worse was when the seat height was changed and knees got cramped or when it got too far and I was on my tip toes. As far as the other adjustments I didn't feel great or bad, however I don't know how long I could maintain of course in those positions.

what saddle were you using? where was the saddle nose v the BB? did you get a picture of the fit?

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Dan Empfield
aka Slowman

The saddle was ISM Adamo Podium, the nose was setback 20mm.

I had a picture somewhere but it was a view from the front....I'll see if I can dig it up and scan it.

Hello - my name is Colby Marple, marketing manager at GURU. Thank you for providing information about your GURU fit session.

We have created a software tool called Bike Discovery that allows you to take the 4 fit coordinates that you provided and convert them into complete bike solutions. You can download a 10-day free trial here: http://www.gurusports.net/software

In regards to the fit data that you provided, I ran your numbers using Bike Discovery which yielded results for more than 30 brands.

Feel free to contact me directly if you have additional questions about Bike Discovery or the results.


Thanks, Colby

Quick question. Let's say I already have a bike and I am not considering buying a new one at this time. Can the Guru fit help me with fitting to my current bike? I'd assume so, at least within the limits of adjustability of my bike / frame size.
Or asked another way: is it possible to limit the dynamic adjustments during the fit to a specific range (e.g. the range that your current bike / frame size allows)?

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Less power, more aero.

Yes, it will definitely work. Your fitter just needs to keep track of where that range is during the process...but, I don't think you can set any sort of limits.

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Mat Steinmetz

51-SPEEDSHOP.com - instagram - @matsteinmetz - facebook

Thanks Mat, that's what I was hoping to hear. I would definitely like to try a dynamic fit and see what kind of position I can achieve. I think my previous static fit was overly conservative. I've been with that fit for 1.5 years now and I think I'm ready for a more aggressive one.

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Less power, more aero.

Hello, I have read up a fair amount on the ST Bike Fit page (trying to follow along on the FIST Tri Bike fit articles), but am still very new to all of this so please be gentle. I recently did a GURU bike fit, and am trying to use the results to find which tri bike frames would fit well me without a ton of adjustment (5'3" female).
Slowman's detailed response was very useful, so now I am trying to use the Bar to Head Tube Calculator to calculate my stack and reach, however, as a bike newbie I am not sure what is a decent range of inputs to try. Here was my first crack at using the calculator, using Slowman's initial inputs for the OP (my entire GURU fit results are posted at the bottom):

Input:
Bar-Bore Y: 575mm
Bar-Bore x: 423mm
Head Tube Angle: 73deg
Stem Length: 90mm
Stem Angle: -17
Stem Clamp Height: 40mm
Spacer Height: 10mm
Headset Topcap: 0mm

Output:
Stack: 546mm
Reach: 342mm

Questions:
Assuming a 45mm pad height, is it correct that I should be looking at frames with approximately 500mm stack (546mm-45mm) and 342mm reach?
I've tried to play around with it a bit, but it seems that the reach I'm calculating is too small for most frames (a few examples below). Am I doing something stupid here?

Specialized Shiv, Size XS
Stack: 495mm
Reach: 365mm

Cervelo P2, Size 45
Stack: 450mm
Reach: 375mm

Cervelo P2, Size 51
Stack: 506mm
Reach: 397mm

FYI, I only have about 1 year of dedicated road bike riding (completed two IM 70.3 distances), and I'm training for a full IM distance next year (IM Vineman). I'm more geared towards comfort on long duration rides and starting the run not being totally exhausted, as opposed to placing.

Thanks for any help that anyone can provide!!

Here are the GURU fit results: ------------
SX: 112
SY: 592
HX: 423
HV: 575

Saddle Height over bottom bracket: 656mm
Saddle Setback: 12mm
Drop from saddle to bars: 56mm
Reach from saddle to bars: 439mm

Equipment Info
Saddle: Tritone
Saddle Thickness: 54mm
Saddle clamp to nose: 100mm

Bar: SL-70
Bar length: 380mm
Pad stack height: 45mm

Crank length: 165mm

Slowman, or anyone else who cares to chime in with some expertise, how would you recommend to go about getting fit before shopping around for a new tri-bike?

I was planning on getting a Guru fit at a local shop, and now after reading this thread I am not sure if it is the best way to go about this.
Im most concerned about this comment:
If the aerobar is so critical to the fit numbers, how do I know what aerobar this initial fit should be done with? Does it matter which bar it is as long as the dimensions are known? Can the fitter assess at the start of the fit or early on in the fit what bar might be suitable to continue the fit on for best results?


Id also ask a similar question of the Guru rep. Does the software yield the same results regardless of which aerobars the 4 fit coordinates were determined on? Is there anything that I should ask the fitter in advance to make sure they are taking the correct approach to the fit in order to give me the best results in terms of getting the most suitable bike for me?



I made a mistake with my first tribike where I had a sales guy on the bikeshop floor do some basic measurements and fit me to a bike. I got properly fit after and was able to make the bike work for me, although Im now hoping to get the right bike from the start this time.

@Test - There are a number of ways you can determine the output of your fit...in the end, your fit is your fit. The aerobar that was used during the fit is important based on how you want to determine which bike fits you best. For example, if you're buying a super bike and are going to use arm pad x/y, then it doesn't really matter... the fitter will simply use the arm pad x/y coordinates to determine which arm pad x/y coordinates best match the super bike. If you're using handlebar or frame x/y, you need to know the arm pad location in reference to the handlebar center and the fitter will record all of this data so they can replicate the exact details.

Update:
Just wanted to thank everyone on this thread. I decided to seek out a more established fitter and I bit the bullet and just got retested. It went great. This guy really was the real deal and excellent to work . It was Tim Ray at Bicycle in St Louis , just to through him a shout out. Anyway, I feel 100% confident in the results and just about ready to make a purchase. So anyway, thanks to all!

The bike I'm hot on right now is a new 2013 Jamis Xentith T at Jenson for like $1200 shipped. I'm also thinking about perhaps getting Flo 60's or 30's to go with it. I figure an aero bike with carbon and 105 and race wheels for under 2k is pretty good.