Will a smaller frame put me further behind bb?

[Michael]

If it is the same model?

Like, say I had to choose between a 55 and a 54 Homer.

I think the answer would be no, because they are proportionately the same. But not sure. Thought I'd ask you all.

I like shoving the saddle all the way back and wish it could go back more.

[Jim Thill - Hiawatha Cyclery]

No. If anything, a smaller frame is likely to put you farther forward.

[David Yu Greenblatt]

http://www.rivbike.com/product-p/sp3.htm

On Tue, Jan 8, 2013 at 10:07 PM, Michael <john1...@gmail.com> wrote:

<snip>

[Jay in Tel Aviv]

Or this
http://store.velo-orange.com/index.php/components/seatposts/vo-grand-cru-seat-post-long-setback.html

On Jan 9, 8:42 am, David Yu Greenblatt <david.yu.greenbl...@gmail.com>
wrote:

[iamkeith]

Someone can correct me if I'm wrong, but I think you're over-thinking
this. The frame size shouldn't have anything to do with how fore or
aft your saddle is, relative to the bottom bracket. Assuming the seat
tube angles are identical, the only thing that will change is the
amount of seat post extension. Trigonometry says it's still the same
overall triangle. On either frame, you can (should) put the saddle
where it fits you and/or where you want it. So the seatposts
recommended above are relevant either way. The difference between
making the two different frames fit would be in chosing compensating
stem length and height. As per riv philosophy, I'd go with the
biggest one that fits.

[Kenneth Stagg]

The key thing here is "Assuming the seat tube angles are
identical...." Typically smaller frames have steeper seat tube
angles, though I don't know about the AHH. That will, once again
'typically', mean that smaller frames will put you further forward.
In my case it's one of the reasons I'm so happy with my custom frame
(non-Rivendell) - the seat tube angle is much shallower than most 53cm
frames (72 degrees) which allows me to get a good saddle position even
though I'm using a B17.

-Ken

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[Phil Brown]

It will be a bit forward but unless you are very, very picky you won't
notice the difference after 5 minutes.
And about the seat post try a Campy 2 bolt. It will get a saddle about
as far back as you can get it.
Phil Brown

[Garth]

You are correct iamkeith,

Yes, the Homer seat tube angle is the same for the 54, 56 , 72 degrees. TT difference is 1 cm.  I use TT length and bar height as my major criteria for frame size. PBH alone is incomplete.

[Philip Williamson]

Nope. Unless your seatpost extension is greater than the difference in seat tube length...

This doesn't apply in this instance, since the two frames are from the same model, but it might be fun to wrap your brain around. http://www.biketinker.com/2011/bike-resources/bike-fit-geometry-relationships/

Philip

www.biketinker.com

[Jeremy Till]

There's a lot of conflicting things being said, so just to reinforce: No.  Assuming seat tube angle, seatpost, and saddle are all the same, then frame size makes no difference as to saddle setback (the common term for the horizontal distance from the bb centerline to the saddle nose).  As others have said, it is common that seat tube angle gets steeper (i.e., less setback) on smaller frames, although one of the nice things about Grant's frames is that they do not get as steep as in some other bikes, thanks in part to the use of smaller wheels such as 26" or 650b in the smaller sizes. 

The most effective way to achieve more setback is changing your seatpost to something with more offset like the VO Grand Cru or the Nitto S-84 (my personal favorite).  However, since such a seatpost moves your seat away from your handlebars, you will be increasing your reach, and if you already feel like you're a bit too stretched out (I think you may have mentioned this before), then this will only be worse with a large offset seatpost.  In this case, a smaller frame (with the same seat tube angle), having a shorter top tube, may help you achieve both a rearward saddle position and a comfortable reach to the handlebars, assuming you can get the handlebars high enough with the smaller frame (shorter headtube).  

Bike fit's tricky because it's very holistic--changing one thing affects all of the other variables in question.  

On Tuesday, January 8, 2013 10:07:28 PM UTC-8, Michael wrote: