# Domane Offset Seat mast



## Srode (Aug 19, 2012)

The LBS I ordered my Domane 5.2 from said they would rather replace the seat mast / post with one that has a different offset to adjust me on the bike rather than move the seat from center - why would that be a better way to set up a bike that just moving the seat forward or backward? Is it Domane specific or in general?


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## davidka (Dec 12, 2001)

The Domane and Madone seat mast (they share the same parts) come in two lengths and two offsets. All sizes have the same amount of fore-aft seat rail adjustment but the alternate offset is 5mm (stock is 20mm on most sizes).


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## cxwrench (Nov 9, 2004)

they don't want to clamp the saddle rails all the way to the rear of the rails, that's all. smart move on their part to use the correct mast for your fit needs.


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## Srode (Aug 19, 2012)

Thanks guys, so the alternate mast would put the saddle 15mm forwards? But why would this be preferable to moving the seat forward without the mast change? Is there an advantage to keeping the saddle mounted on the center of the rails instead of toward the front or rear? The balance of the bike wouldn't be any different, correct? Do the rails provide some additional ride cushion which is lost if moved off center by much?


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## brianb21 (Jul 21, 2010)

I would think it gives you more adjustment for future fit issues if you need them.


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## cxwrench (Nov 9, 2004)

the real reason is so you don't break the rails. if your saddle is clamped at one end of the rails, all of the leverage created by you sitting and bouncing on the saddle can cause problems w/ the rails breaking.
and the obvious...it allows the saddle to be positioned in the correct spot and still have some adjustability.


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## Srode (Aug 19, 2012)

cxwrench said:


> the real reason is so you don't break the rails. if your saddle is clamped at one end of the rails, all of the leverage created by you sitting and bouncing on the saddle can cause problems w/ the rails breaking.
> and the obvious...it allows the saddle to be positioned in the correct spot and still have some adjustability.


That makes sense - I was just reading about how the side clamp on Selle SMP saddles doesn't work well if the seat is pushed back due to lack of clamping pressure. Makes sense the extra leverage on the rails might break them at the extreme positions, but more so pushed back than forward since most of the weight will typically be on the back not the front. Thanks folks!


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## dekindy (Jul 7, 2006)

Srode said:


> That makes sense - I was just reading about how the side clamp on Selle SMP saddles doesn't work well if the seat is pushed back due to lack of clamping pressure. Makes sense the extra leverage on the rails might break them at the extreme positions, but more so pushed back than forward since most of the weight will typically be on the back not the front. Thanks folks!


I have no experience but have researched Selle SMP saddles. They are very specific in the type of seat post support they require:
http://www.sellesmp.com/smp4bike/en/support/assemble-and-adjust-saddle. 
Scroll down the page to seat post recommendations. I found that of the major seat post manufacturers that I reviewed, Thompson seemed to be the only that satisfied the requirement. There is a seat post handbook somewhere but I cannot remember where it is.


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