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  1. #1
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    Question about stem length and frame size.

    I am currently riding a 54cm frame but use a 130mm stem.

    It seems to be the right length of stem (ie the handlebar blocks out the wheel hub).

    But recently have checked online and suggestions seem to be (after rough/approx self measurements) that I might be better with a 56cm frame.

    Would this seem logical and be the reason why I am currently using a reasonably long stem on my current bike?

  2. #2
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    First, the hub reference thing doesn't really work because it doesn't factor in whether you have a deep or shallow bar. And stems have been trending shorter because of the reach to shifters. So we can't say that 130 is the right stem, and it isn't the universal length depending on other factors.

    However, 130 might be a reasonable length stem if you happen to have longish arms and/or torso. The "average" stem is 110mm (the old typical range is 90 to 130, though there are much longer and shorter nowadays. So I don't think a 130 stem is all that crazy for someone who belongs on a 54. It's only 2 extra centimeters.

    There are all sorts of ways of calculating frame size, and one company's 54 may be like another company's 56. As a rule of thumb I find height to be the most useful guide to seizing frames because it factors both leg and torso length. Generally, 54s are good for people around 5'8", and a 56 is better for people at 5'10".
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    Quote Originally Posted by Kontact View Post
    Generally, 54s are good for people around 5'8", and a 56 is better for people at 5'10".
    I am about 5'10" so that would mean 56 for me.

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    Quote Originally Posted by Greatwhite7 View Post
    (ie the handlebar blocks out the wheel hub).
    That's as general as KOPS (knee over pedal spindle). It would be accurate if everyone in the world has same body measurements, flexibility, all bicycle fork rake and head tube angles are the same.

    But recently have checked online and suggestions seem to be (after rough/approx self measurements) that I might be better with a 56cm frame.
    As mentioned already, it depends on the brand. You want to compare more on the stack and reach dimensions.

  5. #5
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    Quote Originally Posted by Greatwhite7 View Post
    I am about 5'10" so that would mean 56 for me.
    Maybe. For example I'm 5'8" and ride a 52 w/ a 120mm stem. It's dependent on lots of variables. You can't just say I'm X'XX" therefore I should ride a XXcm frame. That's ridiculous. Flexibility, body proportions, and who makes the frame all come into play. Add to that the intended use (race, endurance, gravel, cx)
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  6. #6
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    Quote Originally Posted by cxwrench View Post
    Maybe. For example I'm 5'8" and ride a 52 w/ a 120mm stem. It's dependent on lots of variables. You can't just say I'm X'XX" therefore I should ride a XXcm frame. That's ridiculous. Flexibility, body proportions, and who makes the frame all come into play. Add to that the intended use (race, endurance, gravel, cx)
    And that's why I said that the geometry of the frame matters because one company's 54 might be like another company's 56. But on "typical" old school American C-T frame sizing, height provides a more reliable starting point than inseam.

    Over the last 25 years, I've observed this connection between height and frame size. It cuts both ways - my guesses for frame size based on height have been very accurate, and my guesses on customer height based on seeing their well-fit bikes have been very accurate.

    At 5'8", a typical 52 seems pretty small. After all, what would someone 5'4" be riding if people 4" taller are near the bottom of the range? I'm not saying you're sized wrong, I'm saying that there are likely factors in why a "52" fits someone of your height, and I suspect it might be the specific frame's geometry or a fit preference for extra set back or a hood-centric position.


    I am about 5'10" so that would mean 56 for me.
    The question for the you is whether your 54 with a 130mm stem is a poor fit, since that's the bike you has. Nothing better than a bike you're riding to figure out what size works for you. Are you comfortable? Is the handling reasonable? Aside from the stem length making you wonder, what's wrong with your current fit?
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  7. #7
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    Quote Originally Posted by Kontact View Post
    At 5'8", a typical 52 seems pretty small. After all, what would someone 5'4" be riding if people 4" taller are near the bottom of the range? I'm not saying you're sized wrong, I'm saying that there are likely factors in why a "52" fits someone of your height, and I suspect it might be the specific frame's geometry or a fit preference for extra set back or a hood-centric position.
    Or maybe cx is fitting the HT. Just guessing; good flexibility, shorter inseam but longer upper body proportions. Perhaps the 54 was too tall up front is my guess...

  8. #8
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    Quote Originally Posted by Kontact View Post
    And that's why I said that the geometry of the frame matters because one company's 54 might be like another company's 56. But on "typical" old school American C-T frame sizing, height provides a more reliable starting point than inseam.

    Over the last 25 years, I've observed this connection between height and frame size. It cuts both ways - my guesses for frame size based on height have been very accurate, and my guesses on customer height based on seeing their well-fit bikes have been very accurate.

    At 5'8", a typical 52 seems pretty small. After all, what would someone 5'4" be riding if people 4" taller are near the bottom of the range? I'm not saying you're sized wrong, I'm saying that there are likely factors in why a "52" fits someone of your height, and I suspect it might be the specific frame's geometry or a fit preference for extra set back or a hood-centric position.



    The question for the you is whether your 54 with a 130mm stem is a poor fit, since that's the bike you has. Nothing better than a bike you're riding to figure out what size works for you. Are you comfortable? Is the handling reasonable? Aside from the stem length making you wonder, what's wrong with your current fit?
    All good stuff, for sure. Regarding my fit I'm probably on the tall side for that geometry but it works great for my particular dimensions. I would put someone w/ less flexibility, longer legs and shorter torso/arms on a 54, and something w/ a taller head tube for sure. Another 'for example'...Cav is a little taller than I am and has ridden a 49 Tarmac/Venge w/ a 140 stem. His prime reason is to get as low as possible. Works for him.
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    Quote Originally Posted by cxwrench View Post
    All good stuff, for sure. Regarding my fit I'm probably on the tall side for that geometry but it works great for my particular dimensions. I would put someone w/ less flexibility, longer legs and shorter torso/arms on a 54, and something w/ a taller head tube for sure. Another 'for example'...Cav is a little taller than I am and has ridden a 49 Tarmac/Venge w/ a 140 stem. His prime reason is to get as low as possible. Works for him.
    Given the Tarmac's awful geometry, this isn't too surprising. The 49 has a 75.5 seat tube angle, so the top tube is effectively very long - longer than a Cervelo 51cm. Pros have been handicapped for several years with head tubes that are simply too high for an aero position and have had to resort to negative sloping stems and crazy sizes to get the bars in an appropriate spot.
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    Quote Originally Posted by cxwrench View Post
    Add to that the intended use (race, endurance, gravel, cx)
    Just general racing.

    Might be a good idea to get measured up by some "expert" then?!

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    Quote Originally Posted by Kontact View Post
    And that's why I said that the geometry of the frame matters because one company's 54 might be like another company's 56.
    Ok so get the dimensions of the frame first, and then measure, and then ask someone?!

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    Before spending money on fit, try this link and see what numbers come out. https://www.competitivecyclist.com/S...ulatorBike.jsp

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    Quote Originally Posted by Greatwhite7 View Post
    Ok so get the dimensions of the frame first, and then measure, and then ask someone?!
    Well, maybe. But I would ask yourself first what's wrong with your current bike? Do you feel cramped or have handling problems? If not, don't fix what's not broken. You could go through a lot of testing and fitting just to end up confirming you bike fits you fine right now.
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    Quote Originally Posted by bvber View Post
    Before spending money on fit, try this link and see what numbers come out. https://www.competitivecyclist.com/S...ulatorBike.jsp
    Ok thanks mate, will try it.

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    Quote Originally Posted by Kontact View Post
    Well, maybe. But I would ask yourself first what's wrong with your current bike? Do you feel cramped or have handling problems? If not, don't fix what's not broken. You could go through a lot of testing and fitting just to end up confirming you bike fits you fine right now.
    My current bike it 12 years old and 9 speed.
    Was going to use it mostly indoor or for training and get a new bike for racing.

  16. #16
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    Quote Originally Posted by Greatwhite7 View Post
    My current bike it 12 years old and 9 speed.
    Was going to use it mostly indoor or for training and get a new bike for racing.
    If you buy from a shop, they will size you if they are reputable.
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  17. #17
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    Quote Originally Posted by woodys737 View Post
    Or maybe cx is fitting the HT. Just guessing; good flexibility, shorter inseam but longer upper body proportions. Perhaps the 54 was too tall up front is my guess...
    And I want a lot of weight on the front end. I can't stand the vague feeling I've had before from bikes w/ top tubes that are too long for me and head tubes that are too tall, taking weight off the front end.
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  18. #18
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    Quote Originally Posted by Kontact View Post
    Given the Tarmac's awful geometry, this isn't too surprising. The 49 has a 75.5 seat tube angle, so the top tube is effectively very long - longer than a Cervelo 51cm. Pros have been handicapped for several years with head tubes that are simply too high for an aero position and have had to resort to negative sloping stems and crazy sizes to get the bars in an appropriate spot.
    being aero on a road bike does not necessarily mean get a frame with short head tube and slam that stem. The best aero position on a road bike is a position that will allow you to get your arms parallel to the ground, and with back as horizontal as possible. Many pros are riding undersized frames and slamming their stems thinking that would get them into an aero position, but... what really happens is that they cannot sustain a position I have described above and they end up stretching their arms out as they place them in the drops as they sit up as their back has now fatigued out.

    A low bike only makes the bike aero, but when the bike plus rider are taken as a package, where the rider now accounts for most of the aero drag, then a low bike does not equate to more aero for this bike plus rider package if the rider ends up breaking form (ie., arms straighten out on the drops as the rider fatigue and cannot hold the arm-parallel position anymore).

  19. #19
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    Quote Originally Posted by aclinjury View Post
    being aero on a road bike does not necessarily mean get a frame with short head tube and slam that stem. The best aero position on a road bike is a position that will allow you to get your arms parallel to the ground, and with back as horizontal as possible. Many pros are riding undersized frames and slamming their stems thinking that would get them into an aero position, but... what really happens is that they cannot sustain a position I have described above and they end up stretching their arms out as they place them in the drops as they sit up as their back has now fatigued out.

    A low bike only makes the bike aero, but when the bike plus rider are taken as a package, where the rider now accounts for most of the aero drag, then a low bike does not equate to more aero for this bike plus rider package if the rider ends up breaking form (ie., arms straighten out on the drops as the rider fatigue and cannot hold the arm-parallel position anymore).
    I wasn't aware that pros, their coaches and managers were all such bungling idiots when it comes to bike fit, but that doesn't change my point that head tubes have grown by at least 50% on most production race bikes, limiting the lower range of stem positions. This was not done for the benefit of pro riders but for the 50+ year olds that have the money for a $10,000 bike that would normally be maxed out on headset spacers.

    I'm an old punter, and my stem would be slammed if I was riding a Madone or Tarmac.
    Last edited by Kontact; 2 Weeks Ago at 12:34 AM.
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    Quote Originally Posted by Kontact View Post
    If you buy from a shop, they will size you if they are reputable.
    Was going to build it myself like I did last time.

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    Quote Originally Posted by Kontact View Post
    Given the Tarmac's awful geometry, this isn't too surprising. The 49 has a 75.5 seat tube angle, so the top tube is effectively very long - longer than a Cervelo 51cm. Pros have been handicapped for several years with head tubes that are simply too high for an aero position and have had to resort to negative sloping stems and crazy sizes to get the bars in an appropriate spot.
    I'm not sure how "different from years past" is a handicap. Yes, they do use negative slopes and what years ago would have been called a size too small but where is the handicap in that?

    Sloping top tubes and higher head tubes (to a certain point) just add versatility from what I can tell. As long as the the supposed smaller size and negative stem doesn't f up the handling I don't see the harm or handicap there.

  22. #22
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    25+ years ago, the only time anybody used a 130mm stem would be if they bought a frame that was too small. Times sure have changed..
    "L'enfer, c'est les autres"

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    Quote Originally Posted by No Time Toulouse View Post
    25+ years ago, the only time anybody used a 130mm stem would be if they bought a frame that was too small. Times sure have changed..
    My experience is exactly the opposite. Years ago we always had lots of 120 and 130mm stems around. Now the sales guys and fitters rarely seem to ever go over 110mm. Every time they see my bike they're surprised I'm on a 120. I've got 25 years in the business, most of the sales guys under 3, rarely 5years. The important thing is that my fits ME very well and handles great.
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    I am a little over six feet tall, oddly proportioned, overweight, inflexible, with a couple shoulder injuries.

    Everyone tries to stick me on a 58, but almost every 58 is too long in the top tube, forcing me to compensate with a micro-stem.

    I generally fit on a 56 but need some odd combos of stem angle and spacer stacks.

    But ... I just finished a 3.5 hour ride on my Dawes, which is a 50---Yes Fifty---cm frame.

    Everyone everywhere would laugh at my clown bike with a foot of exposed seat-post, 35 mm of spacers, and a 120-mm 17-degree stem.

    Thing is, it is the most comfortable bike I own. Not by much, and part of it is the $11 Vader saddle .... but even with rock-hard 23-mm tires it is the bike for the miles.

    I don't care what the "experts" say. I listen to them, because some of them are pretty knowledgeable and experienced (that is, they have actually learned from their experience.) I take into consideration what experienced, intelligent people say ... but ultimately it is Me out there on the bike on the road 25 miles from home and it is Me who either does or does not feel pain.

    On my various bikes I have swapped bars, saddles, stems, seat posts, spacers ... fine-tuned each of them so that I can enjoy riding them. No generic "expert opinion" counts for the miles of real-life testing I have done.

    If your bike works for you and you can ride it without discomfort for a few hours .... sure, test different things if you like. But never forget that the baseline, the bike you have now, seems to be meeting all your needs. Don't let some "expert" talk you into doing something the "Right" way if it is wrong for you.

    Also .... Measure your contact points on your current bike as it is currently set up. If that set-up works for you, you would likely want to export it to other frames.

    Learn to read geometry charts. Plug in your current bike's dimensions. Compare and contrast.

    Go to the Dollar Store and get a cheap "drafting kit"--- usually you can find a cheap plastic ruler, protractor, a 30-60-90 and 45-45-90 triangle and a compass for a buck, particularly at back-to-school time.

    Get a sheet of graph paper and lay out your frame. Get the geometry chart online from the manufacturer, start at the BB shell, measure up for BB drop, draw a line parallel to the horizon, measure front/center and rear/center, make your marks, measure, and that should be the wheelbase. If not, refine your method.

    Whether or not you have the wheels located you can do the seat tube, because you should have seat tube angle and length. You should also have virtual or effective top tube length, measured from the seat tube, which locates the top of the head tube. You have your head tube angle and length, so draw that in. Extends that down, and add trail at the base where it hits the wheelbase line, and that double-checks the front wheel position.

    Also you can draw in the actual top tube and see if its scale length corresponds to the listed actual TT.

    Take saddle set back and BB-to-saddle-center from your current bike and sketch in where the seat would be. Sketch in your stem (you know its dimensions) and then measure saddle-center to stem-clamp center on the drawing and see if it corresponds.

    If you are a little careful it isn't hard to create a side elevation engineering drawing (a view of your bike from the side that shows the important aspects) which actually corresponds to the real bike. This is like a sixth-grade shop class assignment ... which means it was really hard for me, but I found it worthwhile.

    Once I had the sketch, I could trace it onto another sheet, and change it to suit different frames. This way I could lay out a frame I was thinking of buying and see what I would need to make it fit the contact points I needed. I was able to calculate the seat post length, offset, stem length and angle, and spacer stack for my Workswell so I knew what parts to buy before the frame even arrived. It fit exactly as it was supposed to fit.

    You can do this.

    It matters because not every frame is the same ... as others have mentioned, head- and seat-tube angles vary, BB drop varies, and head tube length varies disproportionately with different sizes of the same frame..

    I have found that a lot of frames don't gain a lot of top tube between 56 and 58 but gain a bunch of head tube, which increases stack and reach more than you'd imagine 2 cm of top tube would do.

    I find all frames use different angles for head- and seat tubes throughout the size range, which means raising the seat a little on one size might mean moving it back more, which means changing saddle offset---if you didn't notice that, you might find your weigh too far back and your bars too far away compared to n the same frame in a larger size.

    Also, if, like me, you have an other-than-standard body ... everyone will do their very best and still give you horrible advice. It just happens. They mean well ... bless their souls.

    If your 54 frame with a 130 stem suits you ... end of topic.
    Last edited by Maelochs; 2 Weeks Ago at 09:44 AM.

  25. #25
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    Quote Originally Posted by Jay Strongbow View Post
    I'm not sure how "different from years past" is a handicap. Yes, they do use negative slopes and what years ago would have been called a size too small but where is the handicap in that?

    Sloping top tubes and higher head tubes (to a certain point) just add versatility from what I can tell. As long as the the supposed smaller size and negative stem doesn't f up the handling I don't see the harm or handicap there.
    They add versatility to fitting non-pros while making it harder to fit young racers. For a racer, a negative slopping stem is just another bit of aero drag and something to get injured against - and it makes team bikes look kind of stupid.

    But it definitely has been a boon to amateur cyclists with guts and stiff backs allowing them to put their bars at saddle heights without the awkward looking handlebar set ups the pros have had to resort to.

    I appreciate the some companies, like Cannondale, have kept to the middle ground.

    25+ years ago, the only time anybody used a 130mm stem would be if they bought a frame that was too small. Times sure have changed.
    I've had at least one bike that needed a 130 over the last 25 years.
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