Seat post diameter for new titanium Audax bike
#1
Donnie Jonhson
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Join Date: Mar 2014
Location: Australia
Posts: 70
Bikes: Many, mostly old, steel, heavy and beautiful + one titanium bike; pretty much the complete opposite of my other bikes.
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Seat post diameter for new titanium Audax bike
Hi Everyone,
I am in the process of building a high end titanium Audax/ultra distance bike. The bike has been assembled and riding perfectly, beyond what I ever expected.
In the process of building the bike I borrowed the 27.2 diameter Ritchie seat post form my mountain bike and installed it with a 27.2-30.9 Crane Creek shim. The frame requires a 30.9 diameter seat post. I did this as a the frame geometry (seat tube angles) are different to my usual bike and I was unsure what set back I would require.
Now that the bike a assembled and being ridden, it is time to purchase a new seat post. I am primarily considering an aluminium seat post however will consider a carbon one.
My questions are;
• Should I purchase a 30.9 diameter seat post or continue to use the 27.2-30.9 shim and a 27.2 seat post?
• Will there be any noticeable difference between a 27.2 and 30.9 seat post?
• Have people experienced any problems with their frame when using a shim and a smaller seat post?
Kind Regards
Donnie Johnson
I am in the process of building a high end titanium Audax/ultra distance bike. The bike has been assembled and riding perfectly, beyond what I ever expected.
In the process of building the bike I borrowed the 27.2 diameter Ritchie seat post form my mountain bike and installed it with a 27.2-30.9 Crane Creek shim. The frame requires a 30.9 diameter seat post. I did this as a the frame geometry (seat tube angles) are different to my usual bike and I was unsure what set back I would require.
Now that the bike a assembled and being ridden, it is time to purchase a new seat post. I am primarily considering an aluminium seat post however will consider a carbon one.
My questions are;
• Should I purchase a 30.9 diameter seat post or continue to use the 27.2-30.9 shim and a 27.2 seat post?
• Will there be any noticeable difference between a 27.2 and 30.9 seat post?
• Have people experienced any problems with their frame when using a shim and a smaller seat post?
Kind Regards
Donnie Johnson
#2
Senior Member
Join Date: Aug 2007
Location: NorCal
Posts: 546
Bikes: 2009 Surly Cross Check Frankenbike
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I predict the consensus will be that:
1. There is no advantage to your current arrangement, and maybe some mild disadvantages.
2. You need to buy a new seatpost anyway, it doesn't really make sense to buy anything but the right part to put on a high-end bike you just had built.
Of course, it's your bike, so you can do what you want.
1. There is no advantage to your current arrangement, and maybe some mild disadvantages.
2. You need to buy a new seatpost anyway, it doesn't really make sense to buy anything but the right part to put on a high-end bike you just had built.
Of course, it's your bike, so you can do what you want.
#3
Senior Member
A larger diameter post may be stiffer than your current arrangement.