Fitting Your Bike Are you confused about how you should fit a bike to your particular body dimensions? Have you been reading, found the terms Merxx or French Fit, and don’t know what you need? Every style of riding is different- in how you fit the bike to you, and the sizing of the bike itself. It’s more than just measuring your height, reach and inseam. With the help of Bike Fitting, you’ll be able to find the right fit for your frame size, style of riding, and your particular dimensions. Here ya’ go…..the location for everything fit related.

Conflicting fit advice

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Old 04-15-18, 04:20 PM
  #26  
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Originally Posted by wphamilton View Post
51 to 54 is more than 1cm. Frame reach and stack gets a little funny on small bikes because the HT stops shrinking. But it does move the bars relative to saddle height. Regardless, I didn't get the impression that anyone changed the stems and handlebars for OP's test ride.

If you believe that 51 and 54 sized bikes are identical, then there's not much left to discuss. I can tell you though that between my 54 and 56, there is a huge difference in the way I sit, and it's mainly because of the setup, differences of less than 2 inches.

I think you must have missed the part where I said "could be made to fit identically", even though you responded to it as if you had.


You're saying two different stock bikes in different sizes are going to fit differently. Not the 3cm you initially stated, but they will be different.

I was saying that the difference between the two bikes is so small that it can be corrected for with stem selection, and your responses don't seem to make it clear that you read that or understood what I was pointing out.
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Old 04-15-18, 05:21 PM
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Originally Posted by DianetS View Post
Thank you all for the great advice and information. I'm going to put a little more faith in the fit I received - but go armed with a little more knowledge to ask the right questions and maybe not take "no" for an answer. Comments about riding position and posture do make me think. During the fitting, he was correcting my posture - so even though I was trying to be conscious of it during the test ride - perhaps I got lazy and returned to bad habits.

I'm not a speedster, but I do ride long distances. I've never been able to do more than 65 in a day because I'm completely spent by that time (and I'm also a runner so cardio isn't the problem - I just ache all over by that time). My current bike is a 10 year old entry-level Trek that I just walked into the bike store, rode in a circle in the parking lot, and bought. It has served me well but it's time for an upgrade.

Thank you all again. I feel a little less confused and a little better informed.
I would say that if you have ridden a 65 mile day recently with reasonable comfort, you already have a pretty decent reference point for correct fit. A better fit should be based on that fitment. Do you know how to record your contact points so you can reverse any changes you make?
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Old 04-15-18, 05:33 PM
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Originally Posted by Kontact View Post
I think you must have missed the part where I said "could be made to fit identically", even though you responded to it as if you had.
On the contrary, I don't think it's particularly relevant, because likely no one swapped stems and handlebars and moved the seat around for OP's test ride on the BMC Roadmachine 54cm. Most likely, someone moved the seat down, and that's it.

I'm speaking to OP, not arguing with someone who thinks that different sizes of bikes can be made to handle identically. In some cases that's true, in other cases not, and not at issue in this question.

OP's fit on the 54, and by "fit" I mean how she sits on the bike not distance between the contact points (which doesn't fully describe the geometry btw), and I suggest that her "fit" was along the lines of the so-called French Fit which has some of the characteristics she described. I don't see any pictures, so I don't know for sure. However, it's usually achieved by starting with a slightly larger frame (such as a 54 in her case). It could explain why it "felt good".

I hope that OP followed it better than you have, because I suggested that being a difference in how she's sitting, which could be achieved on either bike, means that she should try the smaller bike as well. Would I have suggested that, were I so concerned about her having the "right" frame determined by some exacting "fitting"? Of course not ... somewhere in all of this, you have misinterpreted things. I only hope that I've been more clear to OP.

I was saying that the difference between the two bikes is so small that it can be corrected for with stem selection, and your responses don't seem to make it clear that you read that or understood what I was pointing out.
You seem to have an issue with people who disagree with you.
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Old 04-15-18, 05:38 PM
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Originally Posted by wphamilton View Post
On the contrary, I don't think it's particularly relevant, because likely no one swapped stems and handlebars and moved the seat around for OP's test ride on the BMC Roadmachine 54cm. Most likely, someone moved the seat down, and that's it.

I'm speaking to OP, not arguing with someone who thinks that different sizes of bikes can be made to handle identically. In some cases that's true, in other cases not, and not at issue in this question.

OP's fit on the 54, and by "fit" I mean how she sits on the bike not distance between the contact points (which doesn't fully describe the geometry btw), and I suggest that her "fit" was along the lines of the so-called French Fit which has some of the characteristics she described. I don't see any pictures, so I don't know for sure. However, it's usually achieved by starting with a slightly larger frame (such as a 54 in her case). It could explain why it "felt good".

I hope that OP followed it better than you have, because I suggested that being a difference in how she's sitting, which could be achieved on either bike, means that she should try the smaller bike as well. Would I have suggested that, were I so concerned about her having the "right" frame determined by some exacting "fitting"? Of course not ... somewhere in all of this, you have misinterpreted things. I only hope that I've been more clear to OP.


You seem to have an issue with people who disagree with you.
I don't have an issue with any disagreeing with me, and you don't appear to be disagreeing with me. You just respond to my posts like you are reading something different than what I wrote.

For instance, is it really unclear to you that I know the OP tried the 54 without a stem swap? You're just not reading what I wrote, and then making it personal. I wish you would not do that.
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Old 04-16-18, 03:58 AM
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Originally Posted by wphamilton View Post
On the contrary, I don't think it's particularly relevant, because likely no one swapped stems and handlebars and moved the seat around for OP's test ride on the BMC Roadmachine 54cm. Most likely, someone moved the seat down, and that's it.

I'm speaking to OP, not arguing with someone who thinks that different sizes of bikes can be made to handle identically. In some cases that's true, in other cases not, and not at issue in this question.

OP's fit on the 54, and by "fit" I mean how she sits on the bike not distance between the contact points (which doesn't fully describe the geometry btw), and I suggest that her "fit" was along the lines of the so-called French Fit which has some of the characteristics she described. I don't see any pictures, so I don't know for sure. However, it's usually achieved by starting with a slightly larger frame (such as a 54 in her case). It could explain why it "felt good".

I hope that OP followed it better than you have, because I suggested that being a difference in how she's sitting, which could be achieved on either bike, means that she should try the smaller bike as well. Would I have suggested that, were I so concerned about her having the "right" frame determined by some exacting "fitting"? Of course not ... somewhere in all of this, you have misinterpreted things. I only hope that I've been more clear to OP.


You seem to have an issue with people who disagree with you.
I have no issue with French fit. Just a handful of seat post and that's it. That's all that's needed. It isn't any faster, it isn't any slower it just is. Pro's have been riding French fit for years, and then Giant introduced compact geometry in the 90s and we're here now with everyone thinking its better. It isn't a French fit bike is more comfortable and it comes a point where your geometry is so aggressive (handle bars slammed and arse in the air) that it is actually less aero.

We came to a point of testing this theory and Froome was actually slower than Pantani in descending. Work that one out if there is a benefit to aggressive fitment. There isn't one. It's life, I ride what I preach. All of my bikes are "French fit" I prefer it. But if you want to ride a more aggressive fitment that is going to be less comfortable and perhaps worse for your back in the long run then you're welcome to ride like that also. It's a matter of choice.

Neither option is wrong, it just seems that the OP was not explained what the difference was, nor did they have enough adjustments done to get a comfortable fit on both bikes. The net aim of the game is to get your back as horizontal and in connection with your aero helmet as possible to reduce drag. The below also includes the UCI illegal superman position. The extreme aero position that some people ride is 2% slower, and sitting on the top tube in a safe position while not being able to pedal 3% faster. A french fit like Pantani riding off the back of the bike is actually in the middle.

None of the more traditional positions including Pantani's will make you significantly slower to the point where you would lose a race. As the professor concluded who studied Froome's descend while pedaling technique. His conclusion was actually not to descend like Froome. Position top tube safe I believe was Sagan. I grew up in the peak of cycling during the early 90s and until the mid to late 2000s. I preach french fit. It was the Once team with riders Alex Zülle, Laurent Jalabert, and Alberto Contador that suggested otherwise by riding the Once TCR. I've always wanted to try one, but I've never been able to find one in good condition to see what the fuss was about and given I was 13 in 1997 I never had the chance to ride one new.

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Old 04-16-18, 08:44 AM
  #31  
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Get the 54. You felt the wonderful thing about a bike that that - fun! That's the critical thing. The upper back thing can be fixed with fit and fitness. That's the tiny, fixable thing IMO. The big thing is to love how the bike goes for you. I was out with a woman on her new BMC yesterday. The bunch came to a short, steep hill and she got down in her drops and was just gone. That's the feeling. It might take a year to get the fit just the way you want it. That's normal. My fit evolved for years.
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Old 04-16-18, 12:13 PM
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No one seems to have questioned which stem/stack configuration was on the Road machine! (The carbon version comes with a convertible bit at the head that lets you change it. if you look at the geometry chart you can see it reflected there.)

I would ask the OP if she could find a way to try out the RM in a 51. It might be as much about the fact that the RM is a more fun bike for her tastes than the Gran Fondo, and is less about the fit/reach. (I didn't like the gran fondo when I tried it.)

Now, at 5'8" with a 32" inseam, I can see either bike fitting her well, depending on things like arm length and waist length. However, I usually counsel going smaller, because it's easier to make a bike fit "larger" than the other way around.

OP: Try and find a road machine in the smaller size!
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Old 04-19-18, 02:26 PM
  #33  
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Neck and shoulder pain along with numb hands are indications of too much reach and/or too high bars. I would would be wary of getting too large a frame because of what Wheever mentions above. Too high a stack and too long a reach is difficult to correct, whereas a longer stem on a smaller frame improves weight distribution, stability, and general handling. I think it's better to err on a smaller size. What size is your old Trek? To my mind a 54cm frame fits someone 5'10"ish. It seems to me the bike fitter was about right.

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Old 04-19-18, 03:04 PM
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The first bike I bought didn't feel comfortable at all even though I used it for a long time. I am 1.8 meters (5 feet 9 inch) and 125 kg (275 pounds) and used a mountain bike that felt too small and caused problems for my back, now I am looking into getting another bike (I left my old one back in my country, actually gave it away to my uncle, when I moved).
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Old 04-22-18, 06:39 AM
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Originally Posted by 1500SLR View Post
The first thing I do with imperial sockets and wrenches is throw them out the window.
Then what do you use for imperial bolts and nuts? You will not be able to tighten\unloose anything properly.
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Old 04-22-18, 06:40 AM
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Originally Posted by Gconan View Post
Then what do you use for imperial bolts and nuts? You will not be able to tighten\unloose anything properly.
I don't live in an imperial country.
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Old 04-22-18, 09:35 AM
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Originally Posted by 1500SLR View Post
Fitting from a fit chart is a terribly pessimistic and narrow way of looking at things. At best with some brands they will give you 2 or 3 frame sizes that will fit a person in the modern McDonalds bike sense (small, medium or large and would you like fries with that) but then there are some manufacturers that still measure accurately per centimeter (using the metric system). This is why bike shops have professional fitters and no its not really a personal thing either if you want to do it properly. A good fitter will be able to fit you within the sizes that suit your body. Of course there are nuances in the human body that are specific to each person. These must be taken into account by the fitter if they're doing their job properly.

But then maybe its just your American thing. In a nation that still has to measure in quarters and thirds of whatever in some measurement I've never heard of you don't really wonder where this kind of thinking comes from. But the majority of the world uses the metric system and if given the right set of opportunities then a fitter can measure your body down to the millimeter.
Big assumption here: my US fitter did all measurements in metric. And when I ordered my custom US made Bike Friday, I sent them my measurements in mm not inches. But they could have easily produced the bike to my exact specs using inches and fractional measurements - it may be different than what you're used to but it can also be extremely accurate.
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Old 04-22-18, 10:21 AM
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Originally Posted by linberl View Post
Big assumption here: my US fitter did all measurements in metric. And when I ordered my custom US made Bike Friday, I sent them my measurements in mm not inches. But they could have easily produced the bike to my exact specs using inches and fractional measurements - it may be different than what you're used to but it can also be extremely accurate.
Can you think what 3/8ths of an inch looks like? I have a fairly decent idea what a millimeter, centimeter, meter and kilometer looks like because they are standard units of measurement. 3/8ths of an inch however... First I need to know what a singlee inch looks like, then I need to know what an eighth of a inch looks like, and then I need to think about what 3 of those looks like. This is a cluster bomb of a situation.
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Old 04-22-18, 10:43 AM
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Almost everything with bikes in the US is done in metric, including fitting. There's nothing wrong with using Imperial to do something like figure out saddle height, or cubits if that's what you have handy. Most Americans are fine using either system without confusion.
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Old 04-22-18, 11:14 AM
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Originally Posted by 1500SLR View Post
Can you think what 3/8ths of an inch looks like? I have a fairly decent idea what a millimeter, centimeter, meter and kilometer looks like because they are standard units of measurement. 3/8ths of an inch however... First I need to know what a singlee inch looks like, then I need to know what an eighth of a inch looks like, and then I need to think about what 3 of those looks like. This is a cluster bomb of a situation.
If you had grown up with imperial measurements, YES you would know exactly what they look like. It's a question of familiarity. In the US, we actually use both imperial and metric in different situations. It's not that difficult, really. They are both arbitrarily assigned and adopted for popular use. You have a fairly decent idea of what a mm, cm etc. look like because you have been exposed to them your entire life, not because they are actually any better at measuring, lol. If you grow up speaking only one language, is that language somehow superior to all others?
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Old 04-22-18, 11:19 AM
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Originally Posted by linberl View Post
If you had grown up with imperial measurements, YES you would know exactly what they look like. It's a question of familiarity. In the US, we actually use both imperial and metric in different situations. It's not that difficult, really. They are both arbitrarily assigned and adopted for popular use. You have a fairly decent idea of what a mm, cm etc. look like because you have been exposed to them your entire life, not because they are actually any better at measuring, lol. If you grow up speaking only one language, is that language somehow superior to all others?
Due to the world we grew up in and the fact that our worlds are connected regardless of distance in the modern world I understand both systems quite fine. I have not had to deal with fractions regularly since I was in high school. The thing with the metric system is that it is a standard measurement. Not 3/8ths or 2/5ths or 1/7th of something else. Everyone knows even if you're over there that a millimeter is 1/1000th of a meter a centimeter is 1/100th. They can never be anything more in a base 100 system that is confusing to nobody.
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Old 04-22-18, 11:41 AM
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Originally Posted by 1500SLR View Post
Due to the world we grew up in and the fact that our worlds are connected regardless of distance in the modern world I understand both systems quite fine. I have not had to deal with fractions regularly since I was in high school. The thing with the metric system is that it is a standard measurement. Not 3/8ths or 2/5ths or 1/7th of something else. Everyone knows even if you're over there that a millimeter is 1/1000th of a meter a centimeter is 1/100th. They can never be anything more in a base 100 system that is confusing to nobody.
If fractions are too hard for you, that's all right
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Old 04-23-18, 04:59 PM
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Originally Posted by linberl View Post
If you had grown up with imperial measurements, YES you would know exactly what they look like. It's a question of familiarity. In the US, we actually use both imperial and metric in different situations. It's not that difficult, really. They are both arbitrarily assigned and adopted for popular use. You have a fairly decent idea of what a mm, cm etc. look like because you have been exposed to them your entire life, not because they are actually any better at measuring, lol. If you grow up speaking only one language, is that language somehow superior to all others?
That's funny. We gave a written test and a manual test to those who were applying for employment. One of the questions on the written test was, "How long is this line?" there being a solid black line on the page. They were not allowed to measure it. The correct answer was 2-9/16". Over the years, there were a few very experienced applicants who got it right.
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Old 05-21-18, 05:37 AM
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Originally Posted by DianetS View Post
My inseam is 32.

I wish I could tell you exactly what I loved about the Roadmachine. The second I started pedaling it just felt right - responsive - fun - I didn't want to get off. But then after 10 - 15 minutes that old familiar ache between my shoulder blades set in.

I'm glad I didn't order it in the 51 - I just don't want to spend the money without actually giving it a test ride. And thanks for the info about the way the different bikes fit. I'm trying to make an educated decision and I guess this is part of the process.
Not to get too personal, but is that your trouser inseam? There is a specific way to measure cycling inseam: from the floor to the top of a book pressed up between the thighs with pressure, with bare feet. It's usually measured to the millimeter.

Another point: probably the most modern way to talk about frame sizing is to quote stack and reach, with seat tube angle. Stack is the vertical distance from the center of the bottom bracket (also the center of rotation of the crank) and the top of the head tube. Reach (in this context) is the horizontal distance from a vertical (aka plumb) line through the center of the bottom bracket and the center of the top of the head tube. The seat tube angle controls how far back from the vertical plumb line your saddle could be located (also known as saddle setback).

Why are these key? The BB location controls where your feet will be, the stack controls (with the cockpit dimensions) how high relative to feet your hands and arms can be, the reach controls (with the cockpit dimensions) how far ahead of the BB your hands can be, and the saddle setback controls how far your butt can be behind your feet. Choosing a frame involves consideration of your center of gravity (butt forward or backward, how much you want to bend (handlebar height relative to saddle and reach) and how far out you will comfortably reach.

Those are the basis of the insights a good fitter should be giving you.

Just working the arithmetic, if 32 " is your cycling inseam, it translates to a range from 80.0 cm to 82.6 cm. Mine is 81.6 cm and I do best on a 54 cm frame with the saddle set back "pretty far."
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