Saddle Adjustment
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  1. #1
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    Saddle Adjustment

    I recently lowered my saddle 5mm and it feels better.
    Now I just read that if you move your saddle back it raises the saddle height, and forward lowers the saddle height. I was wondering if after lowering it as I did, how much if any would it effect the fore & aft.

  2. #2
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    Quote Originally Posted by Stew View Post
    I recently lowered my saddle 5mm and it feels better.
    Now I just read that if you move your saddle back it raises the saddle height, and forward lowers the saddle height. I was wondering if after lowering it as I did, how much if any would it effect the fore & aft.
    If you think about it,
    if your seat tube was 90degree vertical from the bottom bracket center, then lowering it would simply lower the seat directly down.

    But it's not vertical. By lowering the seat the center of the seat/seatpost central point to the center of the Bottom bracket would move it slightly forward too. This dependent upon the angle of the seat tube.

    If you simply pick a center point in your seat tube somewhere half way down. Then place a dot there. Then another dot 5mm down in the center of the seat tube, you'll know how far forward the seat moved by measuring the horizontal difference of the two points.

  3. #3
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    To expand on that thought, just check your bike build seat tube angle. U can use that to exactly calculate the horizontal offset to any vertical movement of the seat.
    You will need to determine if your vertical movement u are using is vertical with the earth or the seat tube.
    Simple trigonometry.
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  4. #4
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    If it feels better, who cares? 5mm is A LOT! But hey, you put some miles on it and itís working well, what else matters...
    To date, philosophers have merely interpreted the world in various ways. The point however is to change it.

  5. #5
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    Quote Originally Posted by PBL450 View Post
    If it feels better, who cares? 5mm is A LOT! But hey, you put some miles on it and itís working well, what else matters...
    Bingo! The 5 mm drop in seat height was not determined by hours of calculation on a quantum computer, but rather by a "let's try this and see if it works better." If the OP wants to move his seat forward or backward to see if it works better, fine. If that desire is driven by some perceived need to preserve the very exact reach to the bars, just keep in mind "If it works better, fine. If not, move it the other way."

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    Oh, god, not ANOTHER saddle adjustment thread! FWIW, here's my method: Carry the tools you need to adjust it, then go for a ride and see how it feels. Stop to adjust it up, down, forward, back, or tilt as you see fit. Ride it a bit further. Stop to fine-tune the adjustment. Simple as that. Within 5 miles, you should have it adjusted the way that works for you.
    "L'enfer, c'est les autres"

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    Quote Originally Posted by No Time Toulouse View Post
    Oh, god, not ANOTHER saddle adjustment thread! FWIW, here's my method: Carry the tools you need to adjust it, then go for a ride and see how it feels. Stop to adjust it up, down, forward, back, or tilt as you see fit. Ride it a bit further. Stop to fine-tune the adjustment. Simple as that. Within 5 miles, you should have it adjusted the way that works for you.
    Agree.

  8. #8
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    It is a very exact science, requiring hours of study and an astrophysics doctorate is helpful... He moved it a whole 5mm, what is that like a 1/16" of an inch?
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  9. #9
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    Quote Originally Posted by duriel View Post
    It is a very exact science, requiring hours of study and an astrophysics doctorate is helpful... He moved it a whole 5mm, what is that like a 1/16" of an inch?
    Not familiar with the metric system? 5 mm is 0.2 inches (25.4 mm per inch).

  10. #10
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    Quote Originally Posted by No Time Toulouse View Post
    Oh, god, not ANOTHER saddle adjustment thread! FWIW, here's my method: Carry the tools you need to adjust it, then go for a ride and see how it feels. Stop to adjust it up, down, forward, back, or tilt as you see fit. Ride it a bit further. Stop to fine-tune the adjustment. Simple as that. Within 5 miles, you should have it adjusted the way that works for you.
    Except that if often takes more than 100 miles to adapt to changes, and things that "feel good" immediately after a change may not really be improvements that last. So someone who wants to get this right records all their changes so that they can go back to a previous adjustment, and they give time to adapt to determine whether they have a long term improvement. But I agree completely that each rider needs to use a "try it" approach to finding what works for them.

  11. #11
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    Quote Originally Posted by duriel View Post
    It is a very exact science, requiring hours of study and an astrophysics doctorate is helpful... He moved it a whole 5mm, what is that like a 1/16" of an inch?
    Not sure if you are serious or being sarcastic, but talk to any bike fitter or anyone who knows about bike fitting and they will most likely tell you that 5mm makes a difference when it comes to bike fitting. You can see for yourself by either raising or lowering your saddle or handlebar by 5mm.

    I recently had a bike fit for my new build, which put me within the "optimal" fitting range (dead center), but I was getting numb at the Perineum. I moved the saddle down 3mm (an amount that is just enough to make a difference, but not enough to throw things all out of wack) and I no longer experience that numbing feeling, but still within the "optimal" range. The bike fit got me 99% there (if you will), but sometimes I have to make very small adjustments, which keeps me within the "optimal" range, but gives me more comfort.

    Anyone making adjustments should always take measurements and mark your movements.

  12. #12
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    Quote Originally Posted by Kerry Irons View Post
    Not familiar with the metric system? 5 mm is 0.2 inches (25.4 mm per inch).
    See my reply to Duriel above.

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    Well, originally the question was... how much horiz diff was there when he moved his seat vertically. He hasn't been back to comment. If you move your seat 5mm (.2") vertically, just how much is that horizontally.... say .05mm.
    Can you tell if someone moved your seat .05mm rear ward?

    Don't move my seat, yes, sarcastic.~
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  14. #14
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    Quote Originally Posted by duriel View Post
    It is a very exact science, requiring hours of study and an astrophysics doctorate is helpful... He moved it a whole 5mm, what is that like a 1/16" of an inch?
    5mm = .195". 1/16" = .063".
    "L'enfer, c'est les autres"

  15. #15
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    Quote Originally Posted by Kerry Irons View Post
    Except that if often takes more than 100 miles to adapt to changes, and things that "feel good" immediately after a change may not really be improvements that last. So someone who wants to get this right records all their changes so that they can go back to a previous adjustment, and they give time to adapt to determine whether they have a long term improvement. But I agree completely that each rider needs to use a "try it" approach to finding what works for them.
    This has always been my experience. It takes some time and very small well documented changes to get it dialed in, at least it does for me. My right knee has the magical ability to feel just a few mms and it tells me so. I have leeway in every other measurement, but saddle height is something that I need to have perfect or else.
    To date, philosophers have merely interpreted the world in various ways. The point however is to change it.

  16. #16
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    We don't know his bike, let's assume he has a 73.5deg seat post.
    Cosine of 73.5deg is .32 something. 5mmx.32=1.6mm=.0699"
    .0699" = 1/16 of an INCH!
    Last edited by duriel; 4 Weeks Ago at 05:09 PM.
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  17. #17
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    Quote Originally Posted by duriel View Post
    We don't know his bike, let's assume he has a 73.5deg seat post.
    Cosine of 73.5deg is .32 something. 5mmx.32=1.6mm=.125"
    .125" = 1/80 of an INCH!
    Oh, c'mon....EVERYBODY knows that .125"=1/8".
    "L'enfer, c'est les autres"

  18. #18
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    I re-did the math, that was difficult! ..and embarrassing, you're as bad as CXW!
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  19. #19
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    Quote Originally Posted by duriel View Post
    I re-did the math, that was difficult! ..and embarrassing, you're as bad as CXW!
    Well, metrology is a big part of my profession....
    "L'enfer, c'est les autres"

  20. #20
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    One must also not forget that by lowering (or raising) your seat with all else kept the same, you also have lowered your seat to the handlebar height which now seems higher .. of course minute adjustments might not be felt.

    But this also changes your upper body angle to the handlebar, and may change your feel when you are on the hoods, etc. Of course, the more a change, the more it may be felt. Others may not feel or notice anything on minor changes though.

    The OP was online 18 hours ago according to their profile. So maybe they just haven't replied for various reasons.

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