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  1. #1
    Senior Member biker7's Avatar
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    Sit Bone spacing relative to Saddle Width...

    Got around to measuring my sit bone spacing and think I now have an accurate measurement. I am considering a Specialized Alias saddle and wonder for those that have been measured if you can explain how sit bone spacing actually correlates to the three saddle widths offered as I presume there are ranges of spacing that work for the three saddles? I poked around their website and couldn't find this information.
    Thanks for any advice,
    George

  2. #2
    Senior Member rule's Avatar
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    Hmmm...okay. I can tell you how it has worked out for me. God only knows if this applies to you and yours though.

    The idea of the sit bone measurement is to match you up with a saddle width that allows for your sit bones to be adequately supported by the width of the saddle. If you use too narrow of a saddle, your sit bones will be placed towards the outer edges and may not leave you adequately supported. This is especially true as you slide forward along the saddle during a ride. If you get too big of a saddle, your sit bones can be placed too far inwards towards the cutouts, which may not leave you adequately supported. And sitting too close along the cutout portion actually can cause more comfort problems for the typical rider than anything else with a cutout saddle.

    What has worked best for me is to get the width that allows me to center my sit bones on padded ovals. That way I can move forward or backwards along the length of the saddle as needed and have the best range of sit positions, while still being adequately supported.

    Something like 70% of riders will fit nicely on the middle sized (143mm) saddle, according to the Specialized rep I bumped into at my LBS. Your LBS should have a sit bone measurement pad. You sit on it and compare the impressions from your sit bones to the dimensions of the three saddles and go from there.

    I ride both the Alias and the Avatar and have no complaints at all. The key though is to get the proper fit. Without it, they won't work out as well.

    Hope this helps.

  3. #3
    Senior Member biker7's Avatar
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    Quote Originally Posted by rule
    Hmmm...okay. I can tell you how it has worked out for me. God only knows if this applies to you and yours though.

    The idea of the sit bone measurement is to match you up with a saddle width that allows for your sit bones to be adequately supported by the width of the saddle. If you use too narrow of a saddle, your sit bones will be placed towards the outer edges and may not leave you adequately supported. This is especially true as you slide forward along the saddle during a ride. If you get too big of a saddle, your sit bones can be placed too far inwards towards the cutouts, which may not leave you adequately supported. And sitting too close along the cutout portion actually can cause more comfort problems for the typical rider than anything else with a cutout saddle.

    What has worked best for me is to get the width that allows me to center my sit bones on padded ovals. That way I can move forward or backwards along the length of the saddle as needed and have the best range of sit positions, while still being adequately supported.

    Something like 70% of riders will fit nicely on the middle sized (143mm) saddle, according to the Specialized rep I bumped into at my LBS. Your LBS should have a sit bone measurement pad. You sit on it and compare the impressions from your sit bones to the dimensions of the three saddles and go from there.

    I ride both the Alias and the Avatar and have no complaints at all. The key though is to get the proper fit. Without it, they won't work out as well.

    Hope this helps.
    I am not a little guy and without getting too personal , my sit bone spacing from center to center is 113mm. I understand the Specialized chart if I could find the dam thing...heard it is on their site but can't find it...cross references riding tendencies which makes sense as when riding in the drops one's pelvis rotates forward and sit bone spacing physically decreases with seat contact point. I presume I need the 143mm saddle width as 143 = 113 + 2X where X is the distance from the sit bone to the perimeter/edge of the saddle at its widest part = 15mm or so or a bit over 1/2" from sit bone to saddle edge which seems to center the sit bone in my case between the cutout in the center and saddle perimeter edge as you suggest.
    If someone has a link to the Specialized Saddle Chart, it would be a big help.
    Thanks for your comments rule,
    George

  4. #4
    Senior Member gpelpel's Avatar
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    All Specialized dealers should have the chart on the back of the "Assometer". That's what they call their measuring pad. According to your seatbone spacing the chart recommends the proper saddle depending of your riding position, the straighter you are on the saddle the wider you need.
    I tried the Alias 143, it's one of the best saddle I have used but I found it very hard and very unforgiving. My weight was really on my seatbones, I have no discomfort in the soft tissues area and no numbness. The problem was that my seatbones were hurting during long rides.
    I now have a San Marco Rever, it is as wide as the Alias, has little padding, doesn't have the perineum cut, but absorb the shocks a lot better. It has a dampening system where the rails attach to the seat. It is very comfortable and much lighter and thinner than the Alias.

  5. #5
    DocRay
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    Go to Specialized dealer.

    They will measure you on the assometer and apply a formula to seat bone width, and seating position.

    The Toupe saddle has more flexy rails and is lighter than the alias.

  6. #6
    Senior Member biker7's Avatar
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    Quote Originally Posted by DocRay
    Go to Specialized dealer.

    They will measure you on the assometer and apply a formula to seat bone width, and seating position.

    The Toupe saddle has more flexy rails and is lighter than the alias.
    Thanks guys. Gpelpel...read your saddle trials on another thread and appreciate your good input as you have tried them all. If there is a knock on the Alias..it is as you say...beaucoup pressure on the sit bones. Ironically, some shared weight distribution on the perineum as with the Arione for example may lessen the load on the sit bones....a tradeoff but some have reported hating the Arione for this tendency...remember Doc you being in the anti-Arione camp if I recall correctly. And Doc...may seek out a Specialized dealer if I can find one nearby. Is that your present saddle of choice? I am wondering about the Toupe if indeed it would be more forgiving then the Alias...the Toupe being relatively new with few reviews with target market directed toward racers who are known to endure some pain to save a few grams.
    Thanks again,
    George

  7. #7
    Cycle for life... woodcycl's Avatar
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    Good thread ...

    I did the same thing ... I went to a Specialized dealer and was measured and fit the 143mm (medium) width the best. I ended up with the Avatar saddle for my needs and did get used to it. However, on longer rides, it was a little hard. I have fairly narrow sit bones ... and the 130mm may have worked, but the 143mm was a little more viable.

    Now, however, .... I have tried the ARIONE and LOVE it in a big way. I have over 1000 miles on it ... on both my road bike and my tandem and it rocks. Yes, it is a personal thing ... as we all know. But, don't take my word for it or someone's word who it didn't work for. My recommendation, because of how much I do like the Arione ... is to get it and try it ... give it at least 200 miles and see what you think.
    -\Brian
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  8. #8
    Senior Member gpelpel's Avatar
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    Pressure on the seatbone is not wrong, that's where the pressure should be. Pressure on the soft tissues will definetly result into pain on long rides and numbness, mainly because it compresses blood vessels. So the Alias is perfect in that regard. The problem I had with it was that it felt very, very hard. May be the Avatar is better or the new Toupe.
    But, again, this is my personal feeling according to my own anatomy. Yours could be different. If it was wider the Arione would have been great as well. One thing to be cautious about is the angle of the saddle, it can make a huge difference. Start testing a saddle in the flat, horizontal position.

  9. #9
    DocRay
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    there is an answer to all this.
    If any one from a bike store is reading this thread, here's an idea:

    Saddle rental. Allow riders to rent any saddle you sell for $5/day, with the option of buying and keeping the saddle. Any store that does this will get more $$ than those that don't. And you will likely sell more expensive saddles.

    Airione will never work for someone my size, i'm picking up a Toupe in NY next weekend.
    Oh...despite the assometer, its seems that everyone I know is 143 mm.

  10. #10
    Senior Member biker7's Avatar
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    Thanks guys for all the good input. To let you know, I contacted Specialized customer support and mentioned my sit bone spacing and they promptly responded that for std. road bike riding the 143mm is the right size but if riding upright...say a hybrid...155mm would be the ticket which seems to satisfy intuition. I think I may be on the brink of the Arione being a bit too narrow as it was for you Doc but may give one a try at some point. I am inclined to try the Specialized first however. Doc be sure to post your review of the Toupe. I love the no frills minimalist design of the Toupe but $150 a copy is steep but presume the price will fall when supply catches up with demand in a few months.
    Look forward to hearing what you think.
    George

  11. #11
    Lawman
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    The code on the back of the assometer specifies a 130 saddle for a sitbone center to center width of 100 mm or less, a 143 saddle for a sitbone center to center of 100 mm to 130mm and a 155 for a sitbone center to center of 130 or more.

  12. #12
    Hiracer
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    Quote Originally Posted by jhglaw
    The code on the back of the assometer specifies a 130 saddle for a sitbone center to center width of 100 mm or less, a 143 saddle for a sitbone center to center of 100 mm to 130mm and a 155 for a sitbone center to center of 130 or more.
    Great thread. Any chance this information relates to other makes, albeit imperfectly?

  13. #13
    Senior Member biker7's Avatar
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    Quote Originally Posted by hiracer
    Great thread. Any chance this information relates to other makes, albeit imperfectly?
    Of course it does but sit bone spacing is only one ingredient in the sea of data one would need to deduce the right saddle parametrically...ain't gonna happen with certainty. Saddles are topigraphical and so are anatomies with different levels of compliance so sit bone spacing will only help as a discriminator to know if a saddle won't work if your sit bones completely miss the mark which they many times do. Saddle width is perhaps most important however so not a bad idea IMO to know your spacing and you can simply measure a saddle to see where your sit bones would contact. Rear top of seat side to side curvature... front to back curvature and seat deflection under load is huge for comfort. So is the seat edge radii for your thighs how they blend rearward which affects where you end up sitting on a saddle. So is your riding tendency...which Specializes makes a rough inference from...if you ride in the drops...you are more rotated forward and need support with sit bones a bit closer together. I want to try the Alias but would like to hear Doc's input on the Toupe before pulling the trigger.
    George
    Last edited by biker7; 09-24-05 at 05:49 AM.

  14. #14
    Senior Member biker7's Avatar
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    Quote Originally Posted by jhglaw
    The code on the back of the assometer specifies a 130 saddle for a sitbone center to center width of 100 mm or less, a 143 saddle for a sitbone center to center of 100 mm to 130mm and a 155 for a sitbone center to center of 130 or more.
    Thank you jhglaw.
    George

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    Does the assometer take into account the triangulation of the two sit bones with that of the sack load midpoint? Some seats are longer than others. In addition, some sacks are centered, while others list one way or the other.

  16. #16
    Senior Member gpelpel's Avatar
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    This is a follow-up from my previous posts.
    Yesterday I rode my Selle San Marco Rever for the first time on a long ride (century). I confirm my first impressions about this saddle; fantastic. For the first time I didn't experience major saddle pain during a century. My sitbones were a bit sore at the end of the ride but nothing bad. I never experienced any pain or numbness anywhere else.
    If you have wide sitbones and require a 143-145mm saddle I recommend you give a try to the Rever. It really comfortable yet quite light at 190gr and beautiful.

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