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  #16  
Old 09-11-2021, 06:29 PM
ducati2 ducati2 is offline
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Or, just ride them and forget about it since they feel the same to you and it’s only 1/5th of an inch.
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  #17  
Old 09-12-2021, 07:59 PM
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jimmy-moots jimmy-moots is offline
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I think the first thing is you're not measuring to the same point on the saddle. I measure midpoint but you could use the nose.

I have noticed that if you measure along the ST from BB to top of saddle, the differences in saddle height can be substantial.

Fixed point controls for STA.
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  #18  
Old 09-13-2021, 06:35 AM
merckx merckx is offline
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If the saddle angle is different between the two saddles, the saddle height will feel different. Even if the angle is different by a fraction of a degree, it will feel different. Nose up feels like a higher saddle height, and nose down feels like a lower saddle height even when the saddles are measured to the same height. I use a wixey angle gauge to set my saddle angles to dboa agreement.
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  #19  
Old 09-14-2021, 11:52 PM
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jimmy-moots jimmy-moots is offline
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Quote:
Originally Posted by merckx View Post
If the saddle angle is different between the two saddles, the saddle height will feel different. Even if the angle is different by a fraction of a degree, it will feel different. Nose up feels like a higher saddle height, and nose down feels like a lower saddle height even when the saddles are measured to the same height. I use a wixey angle gauge to set my saddle angles to dboa agreement.
Laser level is also pretty good for this sort of stuff as it allow you get the axles level.

Once you know the axles are level, you can use a spirit level app on your smartphone - I typically grab a book and put it across the saddle so you capture the overall saddle angle (rules out any differences in placement of the phone on the saddle).
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  #20  
Old 09-15-2021, 07:40 PM
auto_rock auto_rock is online now
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Quote:
Originally Posted by rustychisel View Post
Bingo!!! Also shoutout to Wakatel Luum.

Measuring from BB centre to saddle will tell you essentially nothing except that the bottom bracket is higher or lower.

Rotate cranks to parallel the seattube. Measure from saddle top (level) to centre of pedal spindle on lowest crank.

Repeat this exercise on the other bike.

Adjust accordingly. Consider how seattube angle may affect setback and reach.
Could someone help me understand this one? Shouldn't measuring from BB to saddle versus measuring from spindle to saddle be equivalent, except one is offset by the crank arm length? OP has the same size cranks on both bikes.

I understand the error reducing merits of measuring along the seat post and then using trigonometry to figure out the rest, but the part where saddle to BB reveals BB drop has me stumped.
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  #21  
Old 09-18-2021, 08:48 PM
Wakatel_Luum Wakatel_Luum is offline
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Quote:
Originally Posted by auto_rock View Post
Could someone help me understand this one? Shouldn't measuring from BB to saddle versus measuring from spindle to saddle be equivalent, except one is offset by the crank arm length? OP has the same size cranks on both bikes.

I understand the error reducing merits of measuring along the seat post and then using trigonometry to figure out the rest, but the part where saddle to BB reveals BB drop has me stumped.
Yes they are the same if both bikes have the same crank arm lengths, what effects the position is the seat tube angle and the bottom bracket drop. If these two are different between both frames then neither will match using the above seat height measuring method.
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