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I have a Trek Madone 5.2 and recently had a professional fit on it. I also own an old (very old) Trek 1200 that I use as a beater bike and want to use that one on my trainer instead of the Madone.

I want to adjust the fit of the 1200 so that it matches the Madone, but am a bit lost on how to do that. For example, I assume the place I want to start is saddle height and set back, but since the geometries of the bikes are different I am not sure how to measure. For saddle height do I measure from top of saddle to center of bottom bracket? If so do I measure along the seat tube or do I measure perpendicular to the ground? For set back should I measure from front of saddle to bars? From position of knee relative to pedal spindle?

I guess what I really need to know is whether there is a "how to" somewhere for this.

Thanks.
 

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gazing from the shadows
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Measure the horizontal distance between your bar and the back of your saddle, and the distance from the BB to the top of your saddle following the seat tube. Make the old bike match as close as you can to these two measurements.

That will likely get things close to the same. Fine tune from there as needed.
 

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More cowbell!
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Assuming you have the same saddle for both bikes, here are the critical dimensions in matching one bike to another:

Top of saddle to center of BB along seat tube
Saddle setback from BB (use either a level or a plumb bob and a measuring tape)
Saddle angle
Saddle to bars horizontal
Saddle to bars vertical

It also helps if you have the same bars. Short and shallow bars vs. standard ones would put the brake hoods closer to your saddle and throw off the dimensions a bit.
 

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Assuming you have the same saddle for both bikes, here are the critical dimensions in matching one bike to another:

Top of saddle to center of BB along seat tube
Saddle setback from BB (use either a level or a plumb bob and a measuring tape)
Saddle angle
Saddle to bars horizontal
Saddle to bars vertical

It also helps if you have the same bars. Short and shallow bars vs. standard ones would put the brake hoods closer to your saddle and throw off the dimensions a bit.
@OP
The only thing I will add to this is the concept.
You want to create an anchor point, for this the anchor point is the saddle in regards to the BB (horizontally and vertically), once you set this point you can set the bar position to the saddle.
 
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A couple of other things. Make sure the bikes are perfectly level when measuring so your plumb line measurement for setback will be consistent.
Also When measuring setback, ideally you will have the same saddle on both bikes.
If not, you have to take into account that some saddles have a longer nose (or back) than others. I try to match up different saddles at their widest point on the premise that will be a consistent sit point when riding. Depending on shape, front and back can easily be different for essentially the same setback.
 

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I measure height along the seat tube, from the center of the BB to the top of the saddle.

If I'm using the same saddle, I tend to compare setback by dropping a plumb line from the front bend in the saddle rails. It's mere coincidence, but for me it hits a repeatable spot on a horizontal crankarm. If not, it's relatively easy to find a spot to measure from.
 

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Thanks for the assistance. Turns out that the saddle height on both bikes is about the same. I guess I shouldn't be surprised because both bikes were fitted by the same guy, albeit 3 years apart. At least he's consistent. Reach to bars and bar drop will be an issue. I was less flexible when I got the older bike fitted and the bars are higher and closer. Looks like I'll need a new stem.
 

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Thanks for the assistance. Turns out that the saddle height on both bikes is about the same. I guess I shouldn't be surprised because both bikes were fitted by the same guy, albeit 3 years apart. At least he's consistent. Reach to bars and bar drop will be an issue. I was less flexible when I got the older bike fitted and the bars are higher and closer. Looks like I'll need a new stem.
If both cranks are the same length then measuring from the BB to the top of the saddle is fine. If the cranks are different lengths on the two bikes, measure from the pedal axle to the top of the saddle, but recognize that you won't have identical fit with different length cranks.
 
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