Swap seatpost without affecting saddle position

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Lightweenie
Posts: 199
Joined: Sun Aug 03, 2014 1:00 pm

by Lightweenie

Hello,

title already says it. I am swapping to a lighter carbon seatpost, and was wondering whether there are there any tricks to get the exact same saddle position. It had taken me about a week of micro adjustments to figure out the exact position.

by Weenie


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Broady
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Joined: Thu Jan 03, 2013 5:02 pm

by Broady

Measure tip of saddle to stem and rear of saddle to seatclamp or something along those lines.

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Lightweenie
Posts: 199
Joined: Sun Aug 03, 2014 1:00 pm

by Lightweenie

I don't think this is sufficient. Even if the saddle is parallel to the ground, one could achieve the same two measurements with the saddle being higher and more forward... Perhaps clamp to rails and then have a string with something heavy hanging off the front and measure the offset of the string to the BB or something? Sounds complicated and not very accurate though.

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Rick
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Joined: Sat Aug 29, 2009 4:30 pm

by Rick

Using a large carpenter's square and a level:
1. Lay the level on you existing saddle and shim it (the level itself) to level (I use whatever coins I have in my pocket). Remember how you leveled to and how many of what coins you used.
2. Lay the carpenter's square on the top tube and slide it back until it just touches the nose of your saddle. Mark the place on the top tube (I use a piece of tape.) Also mark the intersection of the level with the square with a pencil/tape, etc. You now have a fore-aft and height reference. I use a plastic square so that it doesn't scratch my paint. They are available at Home Depot.
3. Remove and replace seatpost and saddle.
4 Reproduce the old saddle "level" (or tilt of the saddle) using the same coins and level placement as before.
5. Adjust fore-aft and height of the saddle until it matches the marks on top tube and square.

It may take a little iteration to get perfect.

This works best when continuing to use exactly the same saddle, of course; but I have used it to get a good starting approximating when going to a new saddle of different kind also. In that case it usually requires a final adjustment by feel, since you might tend to sit a little further forward or back, or prefer a different tilt of a new saddle. Different saddles sag more or less than others too.

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Lightweenie
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by Lightweenie

Hey Rick, this sounds great and should work! Thanks - I only need to buy a carpenters level. Saddle will remain the same, yes.

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ms6073
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Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

Alternate approach: :mrgreen:
1. Support bike on level floor
2. Place a digital level on top of the saddle, aligning front of level with nose of saddle and record angle of saddle as indicated by digital level.
3. Use measuring tape (metric of course) to measure distance from floor to the bottom/base of level and record measurement.
4. Measure distance from gap in front of stem where face plate clamps handlebar to nose of saddle/front of level and record measurement.
5. Repeat steps 3 & 4 to verify accuracy of measurements.
6. Replace seatpost
7. Referencing data from measurements, use digital level and tape measure to replicate saddle position with new seat post.

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- Michael
"People should stop expecting normal from me... seriously, we all know it's never going to happen"

AJS914
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Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I've never done it so scientifically. I measure from the center of the BB to the top of the saddle. I drop a line from the tip o the saddle to the top tube and mark it with a piece of tape. I put it back the same way and do the tilt by eye. I seem to have a good eye for knowing how I like my saddle.

eric
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by eric

I also measure from the BB and use a plumb line to measure setback. But I use a digital level to set the angle.

BikeAnon
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Joined: Sun Mar 02, 2014 6:36 pm
Location: NY USA

by BikeAnon

A bit like this: http://velonews.competitor.com/2012/05/ ... ano_219260

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^^^Not my pic ^^^

Essentially, I use a drywall square (and I don't use the level), and take pictures with my cell-phone.

A couple of measurements from known locations (I reference the vertical line of the T-square with things like the chainrings and rear derailleur).

This works for replacing the saddle or seatpost. And you don't need to make sure you are on level ground, or level the saddle. Just replicate your measurements. And you have the pics right there in your hand to get it right (I don't write the measurements down).

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ms6073
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Location: Houston, Texas

by ms6073

AJS914 wrote:I've never done it so scientifically.

Not really necessary to go to that extent unless, you have a wife with knees that can detect ~1-2mm difference in saddle position after replicating bike fit from road to cross bike, which usually has me thinking I need to purchase the tool below: :lol:

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- Michael
"People should stop expecting normal from me... seriously, we all know it's never going to happen"

jgilesband
Posts: 10
Joined: Thu Jul 16, 2015 8:58 pm

by jgilesband

ms6073 wrote:
AJS914 wrote:I've never done it so scientifically.

Not really necessary to go to that extent unless, you have a wife with knees that can detect ~1-2mm difference in saddle position after replicating bike fit from road to cross bike, which usually has me thinking I need to purchase the tool below: :lol:

Image


Anyone know the cost of that contraption - I love it!

BikeAnon
Posts: 399
Joined: Sun Mar 02, 2014 6:36 pm
Location: NY USA

by BikeAnon

jgilesband wrote:...Anyone know the cost of that contraption - I love it!
I'm confident you could make one for under $40 with a trip to Lowes or Harbor Freight Tools.



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Follow this guy: http://www.timetriallingforum.co.uk/ind ... &p=1252228
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dmulligan
Posts: 314
Joined: Wed Jul 23, 2014 6:16 pm

by dmulligan

There are digital level apps for Android and IOS that do a good job for saddle angle. Use your phone like the digital spirit level above.

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by Weenie


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ms6073
Posts: 4288
Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

jgilesband wrote:Anyone know the cost of that contraption - I love it!

About 3-years ago, I think they could be obtained for US ~$495, but then BMC and and a couple other WT teams got press using the jig and the now the price has jumped to US $1000 to $1400. :roll:
- Michael
"People should stop expecting normal from me... seriously, we all know it's never going to happen"

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