how to change a saddle while maintaining saddle height?
#1
Junior Member
Thread Starter
Join Date: Jan 2006
Location: Austin TX
Posts: 139
Bikes: Factor 02, Canyon Ultimate, CAAD12, Langster SP
Likes: 0
Liked 2 Times
in
2 Posts
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
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
#3
Senior Member
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,682
Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build
Likes: 0
Liked 58 Times
in
36 Posts
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
Banned
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.
#5
Senior Member
Join Date: Apr 2010
Location: Mountain View, CA USA and Golden, CO USA
Posts: 6,341
Bikes: 97 Litespeed, 50-39-30x13-26 10 cogs, Campagnolo Ultrashift, retroreflective rims on SON28/PowerTap hubs
Liked 326 Times
in
226 Posts
Saddle curves and not sitting in exactly the same spot on different ones preclude an exact solution.
I _hate_ changing saddles and seatposts.
#6
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
Senior Member
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,682
Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build
Likes: 0
Liked 58 Times
in
36 Posts
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.
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.
#8
Advocatus Diaboli
Join Date: Feb 2015
Location: Wherever I am
Posts: 8,860
Bikes: Merlin Cyrene, Nashbar steel CX
Liked 1,613 Times
in
1,061 Posts
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
I got 99 problems....
Join Date: Aug 2008
Location: Does anyone know where the love of God goes, when the waves turn the minutes to hours?
Posts: 2,087
Likes: 0
Liked 3 Times
in
2 Posts
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
Stand and Deliver
Join Date: Jun 2008
Location: Tampa Bay
Posts: 3,340
Bikes: Cannondale R1000, Giant TCR Advanced, Giant TCR Advanced SL
Likes: 0
Liked 1 Time
in
1 Post
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
well hello there
Join Date: May 2005
Location: Point Loma, CA
Posts: 15,435
Bikes: Bill Holland (Road-Ti), Fuji Roubaix Pro (back-up), Bike Friday (folder), Co-Motion (tandem) & Trek 750 (hybrid)
Liked 343 Times
in
211 Posts
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.
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.
__________________
.
.
Two wheels good. Four wheels bad.
.
.
Two wheels good. Four wheels bad.
#12
Senior Member
Join Date: Oct 2014
Location: Portland, OR
Posts: 13,353
Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder
Liked 4,364 Times
in
2,806 Posts
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
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
Custom User Title
Join Date: May 2013
Location: SE MN
Posts: 11,239
Bikes: Fuji Roubaix Pro & Quintana Roo Kilo
Likes: 0
Liked 31 Times
in
14 Posts
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.
#14
Senior Member
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,682
Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build
Likes: 0
Liked 58 Times
in
36 Posts
You are right for a single bike. Using the BB is standard practice to allow different bikes to be matched.
#15
Senior Member
Join Date: Aug 2013
Location: Vermont
Posts: 1,200
Bikes: Pinarello Montello, Merckx MX Leader, Merckx Corsa Extra, Pinarello Prologo, Tredici Magia Nera, Tredici Cross
Likes: 0
Liked 5 Times
in
3 Posts
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
Farmer tan
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.
I feel any height difference immediately and adjust.
#17
Aluminium Crusader :-)
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
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
#19
Custom User Title
Join Date: May 2013
Location: SE MN
Posts: 11,239
Bikes: Fuji Roubaix Pro & Quintana Roo Kilo
Likes: 0
Liked 31 Times
in
14 Posts
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.
#20
Senior Member
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,682
Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build
Likes: 0
Liked 58 Times
in
36 Posts
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.
#22
Senior Member
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,682
Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build
Likes: 0
Liked 58 Times
in
36 Posts
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.
#24
Senior Member
Join Date: Aug 2013
Location: Vermont
Posts: 1,200
Bikes: Pinarello Montello, Merckx MX Leader, Merckx Corsa Extra, Pinarello Prologo, Tredici Magia Nera, Tredici Cross
Likes: 0
Liked 5 Times
in
3 Posts
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.
#25
Senior Member
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,682
Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build
Likes: 0
Liked 58 Times
in
36 Posts
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.