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  1. #1
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    Fit between two bikes "same" but pain on one

    I took my road and CX bikes to the local university cycling team's fitter and asked him to fit me right and duplicate the fit between both bikes. I'll go back to him if I have to but I'd rather fix this now than wait a month for his next opening if I can on my own.

    After riding EASY for 3 weeks, I am starting to ramp up the power and see how it feels. I rode my CX bike on Saturday on a 20 mile loop and had done 877kJ of work. I had pain behind my knee or maybe burning hamstrings until I started consciously sitting forward on the saddle compared to where I would usually sit. I rode the same loop on my road bike yesterday and my perceived exertion was MUCH higher and yet I only did 724kJ of work.

    This loop (before my fitting) usually gets me 800-850 on an average day, 900-950 on a good day, and 950-1000 on a great day so 724 was very disappointing especially considering how hard I was pushing.

    Anyway, I put both bikes in the trainer and measured saddle height relative to bottom bracket (both bikes have same exact saddle) and fore/aft relative to the pedal spindle in the 9 o'clock position. The CX bike was about 1cm further back (I dropped a plumb bob off the nose of the saddle). I got the fitting to eliminate knee pain and it's completely gone on my road bike, and gone on my CX bike if I sit forward on the saddle, but power is way lower on road. Should I make any changes?

    Cliffs - pain behind knee on CX, low power on road, saddle height same with same saddle, CX saddle appears to be 1cm further forward on CX. Keep riding on road to see if I acclimate and power rises or adjust fit?

  2. #2
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    yes, it's a very crucial setting.

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    Saddle position relative to BB should be the same, as it’s almost completely a function of your leg and femur length. This means your saddle height and your saddle setback should be the same.

    1cm of difference would be very noticeable for me.

    The fact that your fitter set up the saddles this far apart does not speak well to his abilities. I would recommend you confirm your stack and reach numbers on the two bikes.

  4. #4
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    Saddle height doesn't necessarily match set ups if you are using different shoes and pedals with different stacks. The difference between SPDs and SPD-SLs can throw off a fit match if it's not adjusted for in the set up, you can't just use the distance from the center of the crank to duplicate it.
    Last edited by Srode; 1 Week Ago at 03:32 AM.
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  5. #5
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    Scientists have learned the linkage between pain and psychosomatic illness induced by bodily processes and perception of the environment. This is akin to picking up a piece of fresh dog $h!t with your bare hands and believing it can be harmful when in actual fact its good for you aside from the smell.

    Take away is, the color of they bike that is causing you pain is likely the root cause and not fit or setup. Even on a conscious level you may believe you like the way the bike looks but probably deep in your subconscious through previous lives you were repelled by such a shape or color and why it haunts you to this day.


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    I have many number of bicycles that I built from frame up and over the last ten years the saddle to crank relation has become the thing I’m most concerned about between all of them.

    If the saddle is too forward on one I notice immediately. Thank the good lord above setback seatposts were invented!

    10mm is a distance I would correct for sure but as said earlier, different pedals and cleat position can also play a part in this experiment we like to call cycling.


    And then finally color, yes color is huge!

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    Quote Originally Posted by factory feel View Post
    I have many number of bicycles that I built from frame up and over the last ten years the saddle to crank relation has become the thing I’m most concerned about between all of them.

    If the saddle is too forward on one I notice immediately. Thank the good lord above setback seatposts were invented!

    10mm is a distance I would correct for sure but as said earlier, different pedals and cleat position can also play a part in this experiment we like to call cycling.


    And then finally color, yes color is huge!
    In bold above FF, you should really delegate this activity. Replace with having Jeeves bring the limo around and take you for a nice stroll...maybe do some shopping and stop for a spot of tea. You can call the lbs from your cell phone to check on frame build status.

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    Correct, I did not build the frames.

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    Quote Originally Posted by factory feel View Post
    Correct, I did not build the frames.
    Give Jeeves your three pts. of contact and have him get back to you.
    You have bigger fish to fry.

  10. #10
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    Quote Originally Posted by factory feel View Post
    I have many number of bicycles that I built from frame up and over the last ten years the saddle to crank relation has become the thing I’m most concerned about between all of them.

    If the saddle is too forward on one I notice immediately. Thank the good lord above setback seatposts were invented!

    10mm is a distance I would correct for sure but as said earlier, different pedals and cleat position can also play a part in this experiment we like to call cycling.


    And then finally color, yes color is huge!
    Same shoes for both bikes

    It's like one feels great but gets me low power and the other gives me great power but hurts. Maybe 5mm forward on the one that gives me pain and 5mm back on the one that gives me low power?
    Last edited by thisisthebeave; 1 Week Ago at 02:06 PM.

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    Quote Originally Posted by thisisthebeave View Post
    Same shoes for both bikes

    It's like one feels great but gets me low power and the other gives me great power but hurts. Maybe 5mm forward on the one that gives me pain and 5mm back on the one that gives me low power?
    If crank and saddle are nearly identical the only other factor is their relationship to the handlebars.

    Reach is measured from the crank, but you could measure saddle to bar reach as well.

    Also bar drop from the saddle.

    It seems as though your saddle to crank is pretty close, I’d like to see that measurement close to exact.

    I presume crank arms are same length as well ?

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    Gearing? Crank Length? What are you doing riding a CX bike on the road?

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    Quote Originally Posted by factory feel View Post
    If crank and saddle are nearly identical the only other factor is their relationship to the handlebars.

    Reach is measured from the crank, but you could measure saddle to bar reach as well.

    Also bar drop from the saddle.

    It seems as though your saddle to crank is pretty close, I’d like to see that measurement close to exact.

    I presume crank arms are same length as well ?
    Reach is different on the frames but I imagine that would impact my back/shoulders/hands more than my knees. The saddle is the exact same model (bought 2 at the same time), I use the same shoes on both bikes, same crank length, etc. If I hook a tape measure in the same spot on the saddle rail, it's the same exact measurement to the center of the crank. I realize that a different fore/aft position could result in the same height measurement, and I think that's my issue.

    But are there any other factors I'm not thinking of? If height is the same and I know fore/aft is different, should I move the saddle forward 2-3mm and up 1-2mm at a time until my knee pain goes away? Knee pain is non-existent on road but it's there on the posterior on my CX bike.

  14. #14
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    Quote Originally Posted by thisisthebeave View Post
    Reach is different on the frames but I imagine that would impact my back/shoulders/hands more than my knees. The saddle is the exact same model (bought 2 at the same time), I use the same shoes on both bikes, same crank length, etc. If I hook a tape measure in the same spot on the saddle rail, it's the same exact measurement to the center of the crank. I realize that a different fore/aft position could result in the same height measurement, and I think that's my issue.

    But are there any other factors I'm not thinking of? If height is the same and I know fore/aft is different, should I move the saddle forward 2-3mm and up 1-2mm at a time until my knee pain goes away? Knee pain is non-existent on road but it's there on the posterior on my CX bike.
    If it's the same saddle type on both bikes and you are sitting in the same place on the saddle then saddled position should be the same. Drop a plumb bob from the nose and measure how far it is in front of the crank center on each bike and see if they are the same. Adjust them to be the same (but that should have already been done when the fitter matched the bikes) and then re-adjust height to match the saddle height measuring from the crank center to the same point on both saddles (assuming both saddles are at the same angle).

    Pain behind the knee typically means the saddle is too high, so if all else fails lower it a couple MM at a time until the pain goes away. You need to do this before you hurt yourself....
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  15. #15
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    Quote Originally Posted by 11spd View Post
    Scientists have learned the linkage between pain and psychosomatic illness induced by bodily processes and perception of the environment. This is akin to picking up a piece of fresh dog $h!t with your bare hands and believing it can be harmful when in actual fact its good for you aside from the smell.

    Take away is, the color of they bike that is causing you pain is likely the root cause and not fit or setup. Even on a conscious level you may believe you like the way the bike looks but probably deep in your subconscious through previous lives you were repelled by such a shape or color and why it haunts you to this day.
    And you accuse ME of trolling? Really?
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



  16. #16
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    Quote Originally Posted by fronesis View Post
    Saddle position relative to BB should be the same, as it’s almost completely a function of your leg and femur length. This means your saddle height and your saddle setback should be the same.

    1cm of difference would be very noticeable for me.

    The fact that your fitter set up the saddles this far apart does not speak well to his abilities. I would recommend you confirm your stack and reach numbers on the two bikes.
    Quote Originally Posted by Srode View Post
    Saddle height doesn't necessarily match set ups if you are using different shoes and pedals with different stacks. The difference between SPDs and SPD-SLs can throw off a fit match if it's not adjusted for in the set up, you can't just use the distance from the center of the crank to duplicate it.
    Good food for thought here. The important takeaway is that unless everything about these two bikes is the same, you're really comparing apples to oranges. It is unlikely that these two bikes have exactly the same geometry which in itself can affect your position on the bike. 1cm is quite a lot in the world of bike fit.

    I don't know how old you are Beave, but knee pain is not to be ignored regardless. Losing a few watts of power is a small price to pay for being pain-free IMO.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



  17. #17
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    Pain behind the knee as mentioned is the saddle is too high. Lower it 2-3 mm at a time until pain goes away and nothing else occurs, that will be your proper saddle height.

    Now as you said your power output is lower on the road bike you will need to duplicate your CX measurements to your road bike.

    Center of crank spindle to top of saddle
    Nose of saddle to center of handlebars
    From the ground to the bottom of the handlebars.

    These measurements can make 2 different bikes fit very similar without going to a professional fitter.

    If any of these measurements from your road bike do not match your CX bike, make adjustments accordingly.
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  18. #18
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    Quote Originally Posted by Srode View Post
    If it's the same saddle type on both bikes and you are sitting in the same place on the saddle then saddled position should be the same. Drop a plumb bob from the nose and measure how far it is in front of the crank center on each bike and see if they are the same. Adjust them to be the same (but that should have already been done when the fitter matched the bikes) and then re-adjust height to match the saddle height measuring from the crank center to the same point on both saddles (assuming both saddles are at the same angle).

    Pain behind the knee typically means the saddle is too high, so if all else fails lower it a couple MM at a time until the pain goes away. You need to do this before you hurt yourself....
    I moved it forward 3mm and up 1mm since making this thread. Front of knees hurt a little bit. I re-measured and now I'm 1-2mm forward compared to the other bike. It's really obnoxious that I am getting pain when I'm a max of 1-2mm off in either direction. How you sit on the saddle is a bigger factor than 1-2mm....

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