Advertise on Bikeforums.net



User Tag List

Page 1 of 2 12 LastLast
Results 1 to 25 of 47
BikesDirect.com
  1. #1
    Senior Member
    Join Date
    Jan 2006
    Location
    SF Bay Area
    My Bikes
    Cervelo RS, Langster SP, S-Works Roubaix
    Posts
    66
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    how to change a saddle while maintaining saddle height?

    Guys,

    I'm replacing my old Specialized saddle with an Sella Italia SLR Max gel flow. I want to keep the saddle height exactly the same as before. I think the rail height might be different on the two saddles. So how to do that?

    Thank you!

    AX

  2. #2
    bt
    bt is offline
    Senior Member
    Join Date
    Mar 2008
    Posts
    2,252
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)

  3. #3
    Senior Member
    Join Date
    Dec 2009
    Location
    Houston, TX
    My Bikes
    1990 Romic Reynolds 531, 2009 Giant TCR Advanced custom build, Merlin Works CR Ti custom build
    Posts
    12,748
    Mentioned
    86 Post(s)
    Tagged
    0 Thread(s)
    Can't be done. Oh you can measure from the BB over the top of the saddle and back down to the other side of the BB. That will get you two saddles at the same height. But what about saddle compression? When you get on the two different saddles, the two won't compress the same. Trial and error is the only answer beyond the ball park that the measurement provides.

  4. #4
    bt
    bt is offline
    Senior Member
    Join Date
    Mar 2008
    Posts
    2,252
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by rpenmanparker View Post
    Can't be done. Oh you can measure from the BB over the top of the saddle and back down to the other side of the BB. That will get you two saddles at the same height. But what about saddle compression? When you get on the two different saddles, the two won't compress the same. Trial and error is the only answer beyond the ball park that the measurement provides.
    oh stop it

  5. #5
    Senior Member Drew Eckhardt's Avatar
    Join Date
    Apr 2010
    Location
    Sunnyvale, CA USA
    Posts
    3,773
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Aero-X View Post
    Guys,

    I'm replacing my old Specialized saddle with an Sella Italia SLR Max gel flow. I want to keep the saddle height exactly the same as before. I think the rail height might be different on the two saddles. So how to do that?

    AX
    Approximate with a tape measure (I always measured center of bottom bracket along the seat tube to the center of the saddle, although I'll switch to rpenmanparker's more accurate bb to bb measurement) and fine tune position and tilt until it feels the same.

    Saddle curves and not sitting in exactly the same spot on different ones preclude an exact solution.

    I _hate_ changing saddles and seatposts.

  6. #6
    Senior Member
    Join Date
    Feb 2009
    Posts
    752
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by rpenmanparker View Post
    Can't be done. Oh you can measure from the BB over the top of the saddle and back down to the other side of the BB. That will get you two saddles at the same height. But what about saddle compression? When you get on the two different saddles, the two won't compress the same. Trial and error is the only answer beyond the ball park that the measurement provides.

    Mostly.

    You can get close though.

    Put a straight edge or ruler over the part of the saddle where you actually sit and measure to the BB center from that edge using a tape measure.

    Now put on the new saddle, level it out, then put the ruler over where you will be sitting on the new saddle and match the measurement as best as you can.

  7. #7
    Senior Member
    Join Date
    Dec 2009
    Location
    Houston, TX
    My Bikes
    1990 Romic Reynolds 531, 2009 Giant TCR Advanced custom build, Merlin Works CR Ti custom build
    Posts
    12,748
    Mentioned
    86 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by bt View Post
    oh stop it
    Never.

    I have saddles which have sagged with usage over time and have had to reset their height. Then a new one of the same type and model doesn't fit right at that height. Also I have two saddles of the same model and brand but with different density foam that have to be run at different heights to get the leg extension the same.
    Robert

    My hero: "Tar-Baby ain't sayin' nuthin'..." (Joel Chandler Harris, Uncle Remus")

  8. #8
    Senior Member
    Join Date
    Feb 2015
    Location
    NY NY
    My Bikes
    2003 Merlin Cyrene
    Posts
    247
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Drill a hole thru your bike shorts directly under your sitbone. Run a piece of string out this hole and down to the bottom bracket while sitting on the bike. Measure and replicate with the new saddle. May be easier if the saddles have a cut out.

  9. #9
    I got 99 problems.... thump55's Avatar
    Join Date
    Aug 2008
    Location
    Does anyone know where the love of God goes, when the waves turn the minutes to hours?
    Posts
    1,991
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Place a book on top of the seat and measure to the top of the book on both ends. This will not only give you the height but the angle very close, and the edge of the book is a nice defined place to measure to.

  10. #10
    Stand and Deliver FLvector's Avatar
    Join Date
    Jun 2008
    Location
    Tampa Bay
    My Bikes
    Cannondale R1000, Giant TCR Advanced, Giant TCR Advanced SL
    Posts
    2,505
    Mentioned
    14 Post(s)
    Tagged
    0 Thread(s)
    You should also consider taking some measurements from the old saddle to the stem to get it in the same fore/aft position. The saddle fore aft position will change if the shape of the new saddle is wider or narrower as you settle in at a new spot.

  11. #11
    Senior Member Nachoman's Avatar
    Join Date
    May 2005
    Location
    Point Loma, CA
    My Bikes
    Bill Holland (Road-Ti), Bike Friday (folder), Co-Motion (tandem) & Trek 750 (hybrid)
    Posts
    13,356
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by rpenmanparker View Post
    Never.

    I have saddles which have sagged with usage over time and have had to reset their height. Then a new one of the same type and model doesn't fit right at that height. Also I have two saddles of the same model and brand but with different density foam that have to be run at different heights to get the leg extension the same.
    That's really true. So I would measure everything possible and try and come as close as you can to exact replication. Then do micro adjustments after a few rides.
    .
    .

    Two wheels good. Four wheels bad.

  12. #12
    A Roadie Forever 79pmooney's Avatar
    Join Date
    Oct 2014
    Location
    Portland, OR
    My Bikes
    (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1970 Raleigh Carlton International gravel grinder
    Posts
    1,102
    Mentioned
    11 Post(s)
    Tagged
    0 Thread(s)
    There's an easy way that is "right". And once you know the dimension,, you can set up any bike's seat height fast.

    It's all about getting your hips the right height above the BB and pedals so you have the most natural knee bend. (This test assumes you want the same seat "height" you had before.) So:

    Sit on your old bike next to a wall so you are centered on the bike and seat. Rotate one crank, say the right, all the way down. (Always use the same crank, right or left. Different crank lengths DO put a hitch into this method.) Place your heel on the underside of the pedal so the heel bone is on the spindle with your knee straight. Now bend your knee. Don't rock your hips! If your heel lifts off, put on a thick sock and repeat the test. Still lift off? Try a low heeled cycling shoe. Perhaps a slipper. Keep going until you find that footwear where you can straighten your knee or flex it a bit and your heel does not lift off. There is one very specific point where you can pass that test. For me it is barefoot. I do best with a fair amount of knee bend.

    Now just set up your new bike to pass that same test with the same footwear. And remember the footwear. It will save you a lot of time down the road.

    Ben

  13. #13
    Senior Member RPK79's Avatar
    Join Date
    May 2013
    Location
    SE MN
    My Bikes
    Fuji Roubaix Pro
    Posts
    4,969
    Mentioned
    42 Post(s)
    Tagged
    0 Thread(s)
    Why measure all the way to the BB? Don't you just have to maintain the same distance from the top of the seat to the top of the seat tube? Give or take a few mm based on compression differences.
    Quote Originally Posted by thosebikes View Post
    i know how to write dumb $h!t

  14. #14
    Senior Member
    Join Date
    Dec 2009
    Location
    Houston, TX
    My Bikes
    1990 Romic Reynolds 531, 2009 Giant TCR Advanced custom build, Merlin Works CR Ti custom build
    Posts
    12,748
    Mentioned
    86 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by RPK79 View Post
    Why measure all the way to the BB? Don't you just have to maintain the same distance from the top of the seat to the top of the seat tube? Give or take a few mm based on compression differences.
    You are right for a single bike. Using the BB is standard practice to allow different bikes to be matched.
    Robert

    My hero: "Tar-Baby ain't sayin' nuthin'..." (Joel Chandler Harris, Uncle Remus")

  15. #15
    Senior Member Blue Belly's Avatar
    Join Date
    Aug 2013
    Location
    Vermont
    My Bikes
    Pinarello Montello, Merckx MX Leader, Merckx Corsa Extra, Pinarello Prologo, Tredici Magia Nera, Tredici Cross
    Posts
    879
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    With the pedal in an identical position(both saddles), your knee should also be in same position. Set up a jig to check this.

  16. #16
    Farmer tan f4rrest's Avatar
    Join Date
    May 2008
    Location
    Burbank, CA
    My Bikes
    Allez
    Posts
    1,773
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    I ride the old seat first, then just swap the saddle by eye and take a spin around the block.

    I feel any height difference immediately and adjust.

  17. #17
    Aluminium Crusader :-)
    Join Date
    Apr 2004
    Location
    Melbourne, Australia
    Posts
    9,969
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Use a stick. I use a stick. ... or a rigid ruler. You can get close enough to prevent having to make big changes on your first ride.

    Obviously measure from the BB shell or the pedal, and press on the saddle to see how much it flexesk, then measure. Sure, it ain't a technique NASA would use, but it's not rocket surgery

  18. #18
    Senior Member
    Join Date
    May 2010
    Location
    Bristol, R. I.
    My Bikes
    Specialized Secteur, old Peugeot
    Posts
    1,787
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Don't forget that reading will differ with latitude and altitude, maybe as much as a mm.

  19. #19
    Senior Member RPK79's Avatar
    Join Date
    May 2013
    Location
    SE MN
    My Bikes
    Fuji Roubaix Pro
    Posts
    4,969
    Mentioned
    42 Post(s)
    Tagged
    0 Thread(s)
    Another method would be to tie a string to the ceiling and cut it off where it touches the old seat. Put the new seat on and line it up with the string.
    Quote Originally Posted by thosebikes View Post
    i know how to write dumb $h!t

  20. #20
    Senior Member
    Join Date
    Dec 2009
    Location
    Houston, TX
    My Bikes
    1990 Romic Reynolds 531, 2009 Giant TCR Advanced custom build, Merlin Works CR Ti custom build
    Posts
    12,748
    Mentioned
    86 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Blue Belly View Post
    With the pedal in an identical position(both saddles), your knee should also be in same position. Set up a jig to check this.
    Despite what fitters would tell you, you can't measure body parts with either accuracy or precision. No engraved marks to go by. It is all by gosh and by golly.
    Robert

    My hero: "Tar-Baby ain't sayin' nuthin'..." (Joel Chandler Harris, Uncle Remus")

  21. #21
    Senior Member Blue Belly's Avatar
    Join Date
    Aug 2013
    Location
    Vermont
    My Bikes
    Pinarello Montello, Merckx MX Leader, Merckx Corsa Extra, Pinarello Prologo, Tredici Magia Nera, Tredici Cross
    Posts
    879
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by rpenmanparker View Post
    Despite what fitters would tell you, you can't measure body parts with either accuracy or precision. No engraved marks to go by. It is all by gosh and by golly.
    . It's basic geometry.

  22. #22
    Senior Member
    Join Date
    Dec 2009
    Location
    Houston, TX
    My Bikes
    1990 Romic Reynolds 531, 2009 Giant TCR Advanced custom build, Merlin Works CR Ti custom build
    Posts
    12,748
    Mentioned
    86 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Blue Belly View Post
    . It's basic geometry.
    I don't know what that means in this context. I do know that it would take a metrological "vision system" to get any precision, and you would still not know you were measuring from and to the right points on the body. Where exactly IS that little bone on the knee? Skin and fat further complicate finding the right end points of the measurements. Forget it.
    Robert

    My hero: "Tar-Baby ain't sayin' nuthin'..." (Joel Chandler Harris, Uncle Remus")

  23. #23
    pluralis majestatis redfooj's Avatar
    Join Date
    Feb 2004
    Location
    you rope
    My Bikes
    red. 2 wheels. 1 handlebar
    Posts
    2,665
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Aero-X View Post
    Guys,

    I'm replacing my old Specialized saddle with an Sella Italia SLR Max gel flow. I want to keep the saddle height exactly the same as before. I think the rail height might be different on the two saddles. So how to do that?

    Thank you!

    AX
    move it up and down as needed

  24. #24
    Senior Member Blue Belly's Avatar
    Join Date
    Aug 2013
    Location
    Vermont
    My Bikes
    Pinarello Montello, Merckx MX Leader, Merckx Corsa Extra, Pinarello Prologo, Tredici Magia Nera, Tredici Cross
    Posts
    879
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by rpenmanparker View Post
    I don't know what that means in this context. I do know that it would take a metrological "vision system" to get any precision, and you would still not know you were measuring from and to the right points on the body. Where exactly IS that little bone on the knee? Skin and fat further complicate finding the right end points of the measurements. Forget it.
    you mean, if you put a permanent marker dot on your knee cap, you wouldn't be able to find it?

  25. #25
    Senior Member
    Join Date
    Dec 2009
    Location
    Houston, TX
    My Bikes
    1990 Romic Reynolds 531, 2009 Giant TCR Advanced custom build, Merlin Works CR Ti custom build
    Posts
    12,748
    Mentioned
    86 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Blue Belly View Post
    you mean, if you put a permanent marker dot on your knee cap, you wouldn't be able to find it?
    Where on your knee cap? How far bent? Don't say a particular angle. How would you measure that either? How much muscle flex? It all matters. Some things simply cannot be accurately or precisely measured.
    Robert

    My hero: "Tar-Baby ain't sayin' nuthin'..." (Joel Chandler Harris, Uncle Remus")

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •