I would like to get some feedback to help understand the stack and reach numbers that were measured during a recent bike fit. My coach is a FIST certified fitter, and has several years of bike fitting experience. Several of us are scratching our heads to explain the numbers we measured. We even went back over it several times to make sure it wasn’t just an anomaly. This was a fitting for a tri/TT bike setup, done in advance of looking to buy a new tri bike so we could find the best bike for me. Here are the numbers we got:
Stack - 575mm
Reach - 530mm
These were measured with a seat angle of 80 deg. and a simulated 90mm stem length. He uses a Retul fit bike.
The stack number measured is not too far off from the “normal” range, but the reach number appears to be way off the chart. Even in some of the biggest frame sizes out there, it’s hard to find a bike with a reach measurement higher than 440 - 450.
I am a male, 6’ 1" tall and my torso is pretty long in proportion to the length of my legs. I also have above average flexibility (yay me!) and my coach has been working with me on flattening my back as opposed to riding with a rounded back position. The only explanation we can come up with to achieve that reach number is that a combination of all these factors are what is putting me in that category with a reach measurement anywhere from 500 - 540 mm.
I would like to hear feedback from anyone who might have any thoughts, suggestions, or if I need to provide more info? Thanks in advance.
A large Shiv (or similar frame) with a 100-110mm stem seems inline with this, unless I am missing something. I am assuming your measurement of 530mm includes the 90mm stem.
I do not believe the stem length is used in calculating reach, if I am not mistaken. I only included it for reference.
do you have the fit report? does it specifically say frame reach or arm pad reach? it just seems odd, if you back out the 90mm stem, the measurement seems perfectly in line.
I don’t have the report handy, but the reach measurement is supposed to correlate to “frame reach” measured from the center of the bottom bracket to the center of the head tube.
I’m going back on Friday, and we’re going to look at everything again. In addition to the fit bike, he’s going to put me on an actual TT bike (2014 Scott Plasma 30) just to see how that correlates to the measurements we’re getting on the fit bike.
I have a sneaking suspicion that the 530mm measurement is actually including the stem length and going out to where the bar clamps onto the end of the stem, but I’ll come back to the thread and follow up with what we find out Friday.
That number is most likely a HX/HY or PadX/PadY… Either way, super long and low. Assuming it’s HX/HY if you input those numbers with a -6 110 stem, you end up with a pretty good match on the old P3/P4 geometry or a ML Ilicito. There’s a number of other alternatives as well if you change things around or know what your actual PadX/PadY is.
Following up on this thread after I went back to validate my fit numbers, I have a question that I need help to clear up my understanding (or mis-understanding as the case may be) of the stack and reach measurements in general. Please tell me if the statements below are correct or incorrect.
Stack - on the fit bike, we measured my ideal stack height to be 575mm. Since the fit bike represents an abstract bike frame, in the real world if we found a bike with a stack measurement somewhere around 540mm we could add the appropriate amount of spacers to the stem to raise the headtube up to the appropriate height. Correct or incorrect?
Reach - this one confuses me the most. Reach appears to be defined as the horizontal distance from the center of the BB to the center of the headtube. I hear people talking about adding a longer stem to achieve the correct reach, but if that’s the case shouldn’t reach (on the fit bike) be defined as the distance to the bar clamp at the end of the stem? Put a different way, if my ideal reach on the fit bike was measured to be 530mm with a simulated 90mm stem, should I be looking for a frame with reach somewhere around 430-440mm, then I can add the appropriate 90-100mm stem to get to the ideal 530mm reach measurement?
I understand that there are other variables, and some trigonometry would be required to get the most accurate numbers but I’m hoping for the sake of this discussion we could assume the other variables remained constant.
Following up on this thread after I went back to validate my fit numbers, I have a question that I need help to clear up my understanding (or mis-understanding as the case may be) of the stack and reach measurements in general. Please tell me if the statements below are correct or incorrect.
Stack - on the fit bike, we measured my ideal stack height to be 575mm. Since the fit bike represents an abstract bike frame, in the real world if we found a bike with a stack measurement somewhere around 540mm we could add the appropriate amount of spacers to the stem to raise the headtube up to the appropriate height. Correct or incorrect?
Reach - this one confuses me the most. Reach appears to be defined as the horizontal distance from the center of the BB to the center of the headtube. I hear people talking about adding a longer stem to achieve the correct reach, but if that’s the case shouldn’t reach (on the fit bike) be defined as the distance to the bar clamp at the end of the stem? Put a different way, if my ideal reach on the fit bike was measured to be 530mm with a simulated 90mm stem, should I be looking for a frame with reach somewhere around 430-440mm, then I can add the appropriate 90-100mm stem to get to the ideal 530mm reach measurement?
I understand that there are other variables, and some trigonometry would be required to get the most accurate numbers but I’m hoping for the sake of this discussion we could assume the other variables remained constant.
Thanks again in advance.
Do you have the fit report?
To answer your first question I’ll first ask you a question: how did you determine 575 to be the ideal stack height? What makes it the ideal stack height for you? It’s going to be really tough to find something in that neighborhood with as short of a reach as you need. Did you try using aerobars that pedestal? That would allow for you to find something with a lower stack most likely to have a reach in your neighborhood.
Look up Dan’s article’s on Stack and Reach, should have a good explanation of what each of them mean. It appears you have a general idea of what they each mean You’re confusing a couple of metrics, but you’ll understand it better after reading up on what Slowman has written in the past.
Also, DM me your fit report and I can take a look a closer look at it. Or I guess you can also post it to the thread.
AndresLD - thanks again, I’m sure you are right I am likely misunderstanding the terminology. Here are links to the bike fit worksheets. One is for the Tri Bike fit I am referring to in this post, and the other is for a Road Bike fit I had about a month prior.
I’m including the Road Bike fit for reference only. I ride a 2012 Cannondale Synapse Carbon 5 size 58, which if I could do it all over might not be the best bike for me but it was my first bike and I didn’t get “pre-fit” for a road bike before I made the purchase. The posted stack and reach for that bike is 60.1cm stack x 39.6cm reach. I have a FSA Gossamer 130mm stem inverted on that bike, and it feels pretty comfortable to ride.
That stack just seems way off. I’m 6’-2" tall and I have a stack of 592mm and a reach of 435mm based on a Retul fit. You’re an inch shorter and have a stack of less than one inch shorter than mine but a reach of almost 4 inches more? Seems off to me. Maybe a typo and the reach is 430mm.