How big a difference do I need to worry about for stack and reach?
Looking at several bikes for my first road bike. Aiming for under $1200 here. Primarily for commuting(tired of fighting a 10+mph average headwind on an upright 'sport comfort' bike), but fun/long fitness rides are a priority. So is trying to get faster.
I'm looking at several bikes, most new, one used. I'm wondering how wide a range of stack/reach measurements have to be until they become significant enough for a bike to not fit.
At a LBS, I spent about 30 minutes total across two bikes. I honestly couldn't tell the difference between the two. Both were surprisingly comfortable, for completely unfamiliar positions. I suspect I would adjust pretty quickly and easily to a more aggressive riding position. I doubt I could tell a difference between the two, barring pain schemes.
For the ones that list stack/reach:
Bike #1 is a 58cm: Reach of 39.1cm, Stack of 59.8cm. 58cm frame.
Bike #2 is a 60cm: Reach of 39.5cm, Stack of 61.5cm. 60cm frame.
I recently saw a Bike #3 I would potentially buy used. It's also a 58, with a Reach of 40.3cm and a Stack of 58cm. Top tube length right in the middle between #1 &2, lower stand over than both-which appeals to me. It's a higher quality bike with much higher quality components, but lightly used and 4 years old. 8-12mm doesn't seem like much. Easily fixed with a different stem, if necessary, right? And the shorter stack would just mean a more aggressive fit? Or are the differences of #3 vs 1 or 2 severe enough to not be comfortable?
Several other bikes I found enjoyable to ride felt different than 1&2, but didn't have any stack/reach listed, so I expect that I'm not too picky/discerning. Just don't want a case of buyer's remorse.
Terraferma 650b, Mondonico SL and ELOS, Masi Gran Criterium, Trek 610, Breezer Liberty, Georgena Terry Classic
The stack of 58 cm means your handlebars will be at least 2 cm lower than on the two new bikes, and the reach 1 cm longer means you will reach out farther. You can adjust actual hbar reach by putting on a shorter stem, and you can adjust actual hbar drop by adding spacers under the stem or using a more angled stem in the "sticking up" position. Some people think a stem sticking up looks ugly on a road bike, but YMMV! Another degree of freedom is a narrower bar or one with shorter reach.
You might or might not be able to get a stem that will achieve the fit adjustments you might want. Unfortunately I don't think I could analyze this for myself without buying the bike and trying it out.