I am 5' 9 1/2" inches tall, 32 inseam. Been looking at road bikes, size calculators say 55cm frame. I have tested some Cannondales at the LBS, 56 seemed decent, but the 54 did too.

I am real tempted by a used Allez Comp, but it's a 56. It's not nearby, so test rides are out. Some here say smaller is better, others the reverse. Would being slightly too big be a mistake?

Need some opinions before pulling the trigger.

My first bike was a 56. If I knew what I know now, I'd have gotten a 54. Take from that what you will.

I'm your same height but .5" longer inseam.

Depends on the geometry as well. I'm 5'8" and find some 54s on the small side for me.

If you are that close in size then either should work for you. A Slightly shorter stem or slightly longer stem, a few adjustments, and you're there. A 52 or 58 may be stretching it, but 2cm in either direction can be made up for.

Btw, it's easier to make a small bike bigger than to make a big bike smaller.

54.

+1 go for the 54.

+1

I am your exact height and inseem. I ride a cannondale supersix 54

I'm also supposed to be at 55cm, 5 10 and 33" seam. I have a 54 and a 56 Allez. The 54 gets you lower with its shorter top tube. I've a 100mm stem on one, and a 90mm on the bigger bike. So it depends what/how you get the bike to fit you. Between the two, I concur with everyone on the 54cm.

And I'm 5'8, very comfortable on my 54 Trek...but yes, geometry matters!

Look at the different manufacturers carefully, some state a 56 has a 56 top tube (specialized) others state a 56 means it has a 56 seat tube (colnago for example) so a 56 might have a 56 top tube or a 58 top tube, it just depends.

specialised and cannondale both state top tube length so are roughly comparable.

That said I would guess at a 54 spesh fitting you quite well

I'm 5'9" with a 32" cycling inseam (30" pant inseam) and ride a 54 with a 550mm top tube. I could probably fit a 56 if I was willing to run a 70-80mm stem. The 54 will definitely allow more saddle-to-bar drop if that matters.

54

I'm the opposite. Roughly same height. My first bike was a 54, but I also have a 55 and just bought a 56 that I'm building up.

You've got to determine if you're more leg or torso to really figure it out, I think.

Don't guess.

https://www.competitivecyclist.com/za...LCULATOR_INTRO

fify

rather oxymoronic.

Let me just add to my OP- due to neck injuries, I will likely need to run a fairly tall bar stem if I want to ride a roadie at all. Would this impact sizing?

That depends on how sensitive you are to a dorky-looking high rise stem angle. Nearly every brand now sells a model with a 2cm taller head tube that will raise the bars and reduce the need for a steeply angled stem. Don't buy a short head tube racing model if you need the bars set high.

A steeply angled stem will also be significantly shorter in it's horizontal length, that the advertised "length". If you select the larger size to get even more head tube length, then stick with a sloping TT, or you'll run out of standover clearance.

A 54cm Synapse would be a good choice. The 165mm head tube would allow you to get a very small saddle to bar drop of only around 3cm, with a common 84 (-6) degree stem and about 2cm of spacer.

It would help if you posted and actual saddle height, but it should be in the 71-73cm range, with the inseam you've posted.

If you have neck issues and may need the bars higher, get a size 54 bike, but in a relaxed geometry frame. The Allez you mentioned in the OP is a race frame meant to be ridden aggressively.

I agree with Dave. A 54 Synapse has more relaxed geometry but is still closer to the correct size for you. If your flexibility increases over time, you can always make the Synapse a little more aggressive while still remaining comfortable to you. If you went with an Allez, you could make it slightly more relaxed but you'd be fighting the frames' purpose at that point.

Look at Specialized Secteurs.

Much more relaxed geometry, same price point.

I agree dont buy a racing bike. Race bikes can be setup like comfort bikes... They are still TOO stiff for back injured riders, and could be even be too much for most riders.

For someone with neck issues I'm guessing you want the seat to be level or slightly lower than the bars. If that's the case I'd consider getting a 56cm frame in relaxed geometry and run a shorter 70-80mm stem. The will get you a fairly tall ~190mm head tube and won't force you to run a dorky high rise stem to get the bar position you're seeking. This assumes 32" is your cycling inseam and not your pant inseam.

This is absolutely correct. On my hybrid, I had to get a higher stem which puts seat and bars at about the same height. This was not done on a whim, but rather a pro fit to help with comfort. I am hopeful that a similar setup on a road bike will help me ease into being more at home on the drops. I have tested a couple of Synapses, but the stock (lower) bar height makes it tough for me to determine if it's the way to go.

32 is pants inseam, please educate me on the difference to cycling inseam.

BTW, the Allez sold, so it probably was for the best.