Sitbones Width & your saddle width
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  1. #1
    btc
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    Sitbones Width & your saddle width

    To all members, if you know your sitbone width, please post your sitbones width along with your saddle width. For example; sitbones = 110mm, saddle (brand) = 130mm. I did a search and find alot of saddle width mentions here but no sitbones width mention anywhere. Can someone please explane how do they measure a saddle width? For example; 130mm saddle width, is that measure outside face to outside face? If that is the case, you only have 10mm on each side, than it is too narrow. Thanks!

  2. #2
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    You want the saddle width to be a little wider than your sitbone width (by ~10mm). As narrow as you are, you have a lot of options.

    Edit- just noticed your request for measurements... my sitbones are 144mm and my saddle is 155mm wide
    Last edited by Andrea138; 05-19-2008 at 06:01 AM.
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  3. #3
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    I have no idea what my sitbone width is. But I was measured with the Bontrager device and fell within the "Medium" zone.

    Bontrager's medium saddle is advertised 146 mm.

    I never tried one, but bought a E3 Form Titanium from Performance and it's advertised at 133 mm which corresponds to Bontrager narrow.

    It seems to fit fine and has been very comfortable for 200 miles, max ride 30 miles (2 hrs).

    I might try the bontrager just for grins because they have a comfort guarantee. But so far I'm not sure how that sitbone measurement actually plays out in practice.

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    How do you measure your sit bones?

  5. #5
    wim
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    Doesn't correlate directly.

    How do you measure your sit bones?
    The "sitbone" is actually an inverted arch called the pubic arch. The measurement one is supposed to take is the horizontal distance between the lowest points of that arch, marked by the dots in the top illustration.

    The bottom illustration shows the forward-rotated pelvis of a road bike rider. As you can see, the lowest points of the pubic arch are no longer the only points in contact with the saddle. Some of the rider weight has shifted onto the narrower, middle part of the arch. That's why "sitbone" width doesn't directly translate into required saddle width. The only time it does is when you sit bolt upright on a so-called comfort bike with high handlebars, with all your weight on the lowest points of the pubic arch.

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    Quote Originally Posted by wim
    The "sitbone" is actually an inverted arch called the pubic arch. The measurement one is supposed to take is the horizontal distance between the lowest points of that arch, marked by the dots in the top illustration.

    The bottom illustration shows the forward-rotated pelvis of a road bike rider. As you can see, the lowest points of the pubic arch are no longer the only points in contact with the saddle. Some of the rider weight has shifted onto the narrower, middle part of the arch. That's why "sitbone" width doesn't directly translate into required saddle width. The only time it does is when you sit bolt upright on a so-called comfort bike with high handlebars, with all your weight on the lowest points of the pubic arch.

    Well, when being measured (ex. Specialized's sitbone heat sensitive tool), couldn't one just sit in the typical riding position to get a more accurate read out?

    What I don't understand is why high end Italian saddle manufactures, like Selle Italia, don't have different seat widths for their saddles. They seem to stick with 131 mm, and I know not everyone has the same sitbone width.

  7. #7
    wim
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    Quote Originally Posted by semaj
    Well, when being measured (ex. Specialized's sitbone heat sensitive tool), couldn't one just sit in the typical riding position to get a more accurate read out?

    What I don't understand is why high end Italian saddle manufactures, like Selle Italia, don't have different seat widths for their saddles. They seem to stick with 131 mm, and I know not everyone has the same sitbone width.
    Yes, being in your typical riding postion would be good if you're going to get measured for a saddle. But as far as I know, all current measuring devices have you sit on a flat surface, with your upper body vertical. So all you're going to get is the distance between the lowest points of the pubic arch, with these points commonly called "sitbones."

    High-end Italian saddles are for racers. If you race, you lean forward and rotate your pelvis forward to get a flat back. If your bars are also well below your saddle, your "sitbones" don't bear much weight at all. Much of your weight is shifted onto your perineum. Also, you put a lot of force onto the pedals all the time when you race—and the more force on the pedals, the less weight on your saddle. In short, "sitbone" width doesn't matter a whole lot to racers.

    /w
    Last edited by wim; 05-19-2008 at 05:58 PM.

  8. #8
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    If you look at Specialized sit-bone tool you'll notice that you have to sit on the pad and put your foot on something to put your thighs up. Then you take the measurement and then flip the pad over and then choose the seat width depending on the type of riding/position you normally ride in. For a given measured width 2 different style of riders may need to go with 2 different width seats.

    My Specialized Toupe 143 is almost exactly 143mm from edge to edge.

    If my sitbones were 143mm then obviously if I was on a hybrid sitting straight up I'd need the 155mm seat. Since I'm recreational to racer-boy position my 135mm butt fits just great when hunched over riding.

    @wim - that 2nd diagram is not anatomically correct. Look at the relationship and angles between the ASIS, symphysis pubis, coccyx, acetabulum, etc... They don't make sense.
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  9. #9
    wim
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    Quote Originally Posted by Bontrager
    that 2nd diagram is not anatomically correct. Look at the relationship and angles between the ASIS, symphysis pubis, coccyx, acetabulum, etc... They don't make sense.
    I see what you're saying. The diagram above is one of two used to support a text passage about narrow saddles. The diagram below purports to show "a saddle too narrow, rider too upright, coccyx hitting the rear of the saddle." I think there were some creative changes made to better support the text.

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    Sitbone/pain-related question

    Hi, guys, don't mean to steal the thread or anything, but I have a question/problem directly related to this issue, and hopefully someone may have a solution or suggestion.

    Thing is, I have been having trouble sitting comfortably (if at all) due to severe pain in the area where the forwardmost part of the pubic bone makes contact with the saddle. Not a "sitbone" issue, but more of a "pain in the perineal area" issue. To be more specific, pain and swellings at the two points where the pubic bone hits the saddle. The pain is worse during/after racing and high intensity training, such as timetrialing intervals. I ride 200-300 kms/week, race once a week, and have been having this issue for some time (actually, since doing a 540km long distance race two years ago). I have tried numerous seats (Arione, SLR, Rolls, Fizik Pavé, San Marco Concor, and now I have returned to the San Marco Regal).

    As wim writes in his first post, this has to do with the forward-leaning racing position, and the fact that i ride with a fair amount of saddle-bar drop (12-14 cm). This is actually less than on the bike I rode last year, but the problem perseveres. I'm a tall guy, and due to anatomy, bike sizing and the fact that I am otherwise comfortable with this position, I can't reduce the drop more. Saddle height is also an issue, but I have lowered it as much as I think i can (99cm inseam, 87cm crank-saddle height).

    I'd appreciate any thoughts on this.

    sE

  11. #11
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    Quote Originally Posted by wim
    I see what you're saying. The diagram above is one of two used to support a text passage about narrow saddles. The diagram below purports to show "a saddle too narrow, rider too upright, coccyx hitting the rear of the saddle." I think there were some creative changes made to better support the text.
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  12. #12
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    Quote Originally Posted by sEirik
    I'd appreciate any thoughts on this.

    sE
    How about trying saddles with cutouts? What about tilting the saddle nose down? Moving the seat forward slightly?
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  13. #13
    wim
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    Quote Originally Posted by Bontrager
    Definately not Netter
    Drawing isn't better, agree. But I was talking about how an author sometimes insists to have an illustration redrawn to better support his point—pictorial accuracy be damned. I did some map work a few years ago and actually had a customer demand that a road be moved over a few inches so the map would "look nicer."

  14. #14
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    thanks for the suggestions. I have been through most of the routine, but not systematically enough, perhaps. The saddle tilt seems like the most obvious think to re-try, but it is a tradeoff of between saddle pain and too much weight on the arms.

    The cutout saddle I have not tried, but to me it seems like it could worsen things, since the cutouts would amplify the amonut of pressure to the front parts of the pubic bone - the problem areas are located on either side of the perineum. But I would be happy to hear if anyone have had success with cutout saddles and this problem.

    And, eh, any kind of problem located to these parts of the body is notoriously difficult to discuss, so bear over with me if the descriptions nauseate you. But hey, i can't talk to my wife about this (she couldn't care less), so who else to share one's private parts with than anonymous cyclists online?

  15. #15
    wim
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    All good advice from everyone, and I understand about the problem of weight on the arms. I'd rather have my perineum scream in agony than than my hands, wrists or arms, so I've always tilted my saddle nose slightly up. I found that my pain in the nether region can be diminished by regular out-of-the-saddle pedaling; pain in my hands, wrists and arms only by sitting up and letting go of the bars for a few seconds.

    Anyhow, on a different tack: have you checked yourself for subcutaneous nodules, also called biker's nodules? These painful (but often not very visible) knots are closely tied to high-mileage, long-time riding. Here are two links:

    http://cat.inist.fr/?aModele=afficheN&cpsidt=1517840

    http://www.cyclingnews.com/fitness/?...8/letters04-08
    Last edited by wim; 05-20-2008 at 08:19 AM.

  16. #16
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    Quote Originally Posted by sEirik
    The cutout saddle I have not tried, but to me it seems like it could worsen things, since the cutouts would amplify the amonut of pressure to the front parts of the pubic bone - the problem areas are located on either side of the perineum. But I would be happy to hear if anyone have had success with cutout saddles and this problem.

    And, eh, any kind of problem located to these parts of the body is notoriously difficult to discuss, so bear over with me if the descriptions nauseate you. But hey, i can't talk to my wife about this (she couldn't care less), so who else to share one's private parts with than anonymous cyclists online?
    If you find a cutout that extends far enough forward, you should not have a problem with extra pressure up front. You could also look for something that's got a channel (rather than a hole) or a lower density foam running through the middle. I've had a horrible time finding a saddle that works decently, and the only thing you can do it just keep trying different ones.

    And most serious cyclists don't care about discussing crotch-related issues. Sorry to hear that your wife doesn't care about yours... Personally, I'm pretty damn concerned if my man even mentions something going numb/etc.
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  17. #17
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    I love my new saddle.. I picked up a Specialized Alias 143mm before spring while I was still spinning on my trainer. Now that I'm on the road I'm far more comfortable. It's not really padded but it flexes enough to absorb some of the harsher impacts. The 143mm width was a guess on my part when I ordered and I think I guessed correctly because I love the saddle. I'm in the 195ish or so and the saddle hasn't bent or flexed or anything for being a light weight saddle. Hell.. I think my bike is half a pound lighter with this saddle compared to my old Selle.. Oh.. and my crotch likes the saddle too.. No more serious pressure!
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    The "racer position" does not mean you're riding on your perineum.. if you've got the right saddle your weight should still be on your sitbones... the sitbones narrow as you lean forward.. the more agressive the position is the more you will ride on the narrower part of the sitbones, but you should not be on the perineum. For example if you're currently riding a saddle that is too narrow for your sitbones and have a relatively upright position you may notice that the saddle is more comfortable if you go out and ride in the drops the whole time. That's cause the portion of the saddle you use when sitting upright is too narrow for your particular sitbones, but when you get down into the drops the portion of the saddle you use then is wide enough.

    Selle Italia, etc.. does make different widths. They just give each width a different name rather then the same name + widths.

    Plus the same saddle shape may not work in 130, 140, 150mm sizes.. the Italian manufacturers have been making saddles a lot longer then Specialized & Bontrager have been outsourcing saddles to China.. I'm not convinced the Italians have it wrong.

    Selle Italia for example has even more options for width then Specialized... all the Specialized saddles come in 130, 143, and 155. SI has lots of in between widths... 127, 130, 135, 140, 142, 150, 155, etc.. they just don't stick the same name/shape/graphics/rails on their 130 saddle as they do on their 140 or 150 saddle like Specialized or Bontrager do.

  19. #19
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    Everyones arse has a different saddle that goes with it. No saddle is better than another in that regard.
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  20. #20
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    What?

    Sorry, what was the question? I stopped paying attention after Andrea's first post.

    Mmmmm... sit-bones.

    ;^ )
    Looking for a certain ratio...
    Oh-oh, nothing there this time

  21. #21
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    Thanks for the replies. I realize this is a personal issue on a lot of levels, and, well, I will keep trying different changes, one at a time. I don't think I ride enough to qualify for a "third ball syndrome", but you never know.

    Quote Originally Posted by Andrea138
    And most serious cyclists don't care about discussing crotch-related issues.
    Yeah, I know. It's like all riding discomfort-related discussions are sublimated into equipment-related chitchat (which I'm also very much into). That could possibly also explain the actual amount of the latter.

    And back to sitbone width: I agree on the Specialized measuring "instrument": I'm having some trouble finding the relevance of the measurement taken (sitting upright) to the actual riding position – and the idea of a "sitbone" with a fixed measurement seems also a tad off. But I'm sure hip-, pubic- and sitbones come in all sorts and fashions, and that experimenting with different saddles and positions is the only way out of (some of) the discomfort. Time to try a new saddle?

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    Sorry to bump this, but I was curious - I was measured at 143mm on a specialized measuring tool. Currently testing out a 143 Specialized power saddle. Hopefully I will know after a week how it works for me, but on paper doesn't it make more sense to get the 155? Unfortunately the 155 is not available to demo at the LBS.

    I ride in a fairly aggressive position. Not constantly in the drops but leaned forward and arms bent a lot. Interested in the common thinking here as I have not really demoed saddles until now.

  23. #23
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    Quote Originally Posted by HammerIt View Post
    Sorry to bump this, but I was curious - I was measured at 143mm on a specialized measuring tool. Currently testing out a 143 Specialized power saddle. Hopefully I will know after a week how it works for me, but on paper doesn't it make more sense to get the 155? Unfortunately the 155 is not available to demo at the LBS.

    I ride in a fairly aggressive position. Not constantly in the drops but leaned forward and arms bent a lot. Interested in the common thinking here as I have not really demoed saddles until now.
    You measured 143...why would it make more sense 'on paper'...whatever that means...to ride a 155?
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  24. #24
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    Quote Originally Posted by cxwrench View Post
    You measured 143...why would it make more sense 'on paper'...whatever that means...to ride a 155?
    Did you not read this thread? Many posters here insinuated that if you were 143 that 155 was a better fit. That's all I meant. Is there a reason for snark here? It's a thread about a bike seat.

    The 2nd post literally says "You want the saddle width to be a little wider than your sitbone width (by ~10mm)"



  25. #25
    'brifter' is a lame word.
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    Quote Originally Posted by HammerIt View Post
    Did you not read this thread? Many posters here insinuated that if you were 143 that 155 was a better fit. That's all I meant. Is there a reason for snark here? It's a thread about a bike seat.

    The 2nd post literally says "You want the saddle width to be a little wider than your sitbone width (by ~10mm)"


    The 2nd post...from 10 years ago?
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