Originally Posted by
pdedes
interesting that you pose the question after you've already made your purchase.
Yeah... well I wasn't seconding guessing it at all until my buddy told me it was too big. But I still think this size is a fine choice.
Originally Posted by
Drew Eckhardt
As long as you can get the same position it doesn't matter - you'll make the same power either way. In most cases either of two consecutive sizes will work fine.
If you need a very high position, the shorter head tube on small frame might preclude using enough spacers.
If you need a very low position like professional cyclists, the large frame may limit stem options due to the extreme negative rise needed.
Seat tubes get steeper on smaller frames; too steep plus short saddle rails can make it more difficult to find a seat post allowing enough setback.
Fortunately I fall between "high" position and "pro" position so I'm guessing a slammed stem will be in order. And I don't mind riding in the drops either.
Originally Posted by
rpenmanparker
Actually the larger frame is better for you, because most stems only come in whole sizes. So the 90 mm stem will fix everything. You would have been 5 mm off either high or low with the shorter top tube.
Of course this is all hypothetical. If the frames are not the same brand and model, the numbers just give you an approximate fit idea. You don't know exactly how the dimensions were measured. Don't worry about it until you get it all put together, then do what you need to do to make it right. Be sure to have full measurements from your old bike before you start. Make six measurements with the bike perpendicular to a wall, perfectly upright and the inflated rear tire touching the wall: (A) wall to center of the bottom bracket horizontally, (B) floor to center of the bottom bracket vertically, (C) wall to front tip of the saddle horizontally, (D) floor to bottom of the front tip of the saddle vertically, (E) wall to back of the bars horizontally and (F) floor to top of the bars vertically. With these measurements you can get a near perfect match between the two bikes in saddle setback (C-A), saddle height from the BB (D-B), bar height (F-B), saddle to bar drop (f-D), etc. If you want the saddle top height, substitute that for the saddle front bottom. But everything is relative, so it really doesn't make much difference, and the saddle tip bottom is easier to measure precisely and accurately.
Very good notes, I appreciate that.
I would be more concerned about power loss on a too small frame. Assuming same ST angle, your set up on the new frame should work fine.
I think so too. My current frame just barely worked for me because the head tube is so short that I had to bring the stem all way up to the top of the steerer tube. I'm thinking with the Foil's taller head tube this won't be an issue.