# How does one choose the seatpost with the proper offset on the new Madones?



## the sky above tar below (Mar 31, 2004)

Hi. If I understand correctly, the new 08 Madones come with a choice of three seatposts, each offered with a different offset: 20mm rearward, 10 mm rearward, and 05 mm forward.

How does one choose the proper one? I have a very short torso and always have to go with a very short stem and if given a choice, a short top tube.

Does this mean I should go with the seatpost with the 05 mm forward? Or not? How is this choice made?


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## PJ352 (Dec 5, 2007)

the sky above said:


> Hi. If I understand correctly, the new 08 Madones come with a choice of three seatposts, each offered with a different offset: 20mm rearward, 10 mm rearward, and 05 mm forward.
> 
> How does one choose the proper one? I have a very short torso and always have to go with a very short stem and if given a choice, a short top tube.
> 
> Does this mean I should go with the seatpost with the 05 mm forward? Or not? How is this choice made?


https://trekroad.typepad.com/photos/uncategorized/2007/06/05/2008_trek_new_mdaone_seat_height__2.gif

I'm skeptical the attached link will help you because it deals primarily with saddle height, but if you know yours, it's a start.

Trek publishes frame reach/ stack with their geometry. The performance versions seem to have shorter reach than the pro's, so you'd probably go that route. Because of your (relatively) short torso you'd go with a smaller frame (thus, shorter TT). 

I'd be careful of using a non standard seatmast, because it may put your knees too far forward/ back from pedal axle. But my starting point is knee over pedal axle, it may not be yours - or other forum members.


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## the sky above tar below (Mar 31, 2004)

So what you're saying is that the choice of seatmast has nothing to do with torso size or reach?


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## PJ352 (Dec 5, 2007)

the sky above said:


> So what you're saying is that the choice of seatmast has nothing to do with torso size or reach?


Sorry for the confusion. Seatmasts with different offsets will definitely affect reach because they move you forward or back on the frame, but they also affect where your knees are in relation to the pedal axle. My starting point is dead center, meaning that if you drop a line from your knee down to the pedal, the line intersects through the axle.

I only brought this up because you mentioned possibly using a non standard seatmast. I don't know your dimensions, but it's possible if you use the chart and pick the smallest frame you can ride, the reach with a smaller stem will meet your needs. I'd guess it would be the performance fit, as opposed to the pro.


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## the sky above tar below (Mar 31, 2004)

I'm definitely going for the performance fit. However, I'm confused about which seatmast to go for. Which one is the standard: 20 mm rear, 10 mm rear, or 05 mm forward?


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## PJ352 (Dec 5, 2007)

the sky above said:


> I'm definitely going for the performance fit. However, I'm confused about which seatmast to go for. Which one is the standard: 20 mm rear, 10 mm rear, or 05 mm forward?


From Trek's 'up the road' website:

Seat caps and masts. There are two different seat cap lengths and three different offset options. The standard cap is 120mm x 20mm (length x offset). The offset options are 20mm rearward, 5mm rearward and 10mm forward. The tall cap is 160mm and comes in the same offsets. We are shipping 160mm x 20mm caps this week with the other options available ASAP. So far we are happily impressed with how little the cap scars or scrapes the mast so if you are having to raise and lower your cap to find the right seat height, they seem to be fairly resistant to maring. And there's no cutting so you don't have to worry about making a really big mistake.

Here's the link if you want to read more:

http://trekroad.typepad.com/trekroad/faq_2008_madone/index.html


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## 08Madone5.2 (Dec 25, 2007)

Sky, the very simple answer to all your questions is to get over to your local Trek Dealer and let him fit you. I'm 5'9", ride a Performance 54cm frame. My seatpost is 120 mm with the 20mm offset. I have yet to see an 08 Madone with anything different. The rails are adjustable so whatever offest you get can probably be adjusted for you so you're fitted properly. Seems to me that the forward 5mm offset would be good for someone who wants to set their bike up with aero bars for Tri's. Hope this helps.


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