I'm replacing my old commuter frame and am buying a new frame. I am tall, just over 6'3" but my inseam is 34.5 and my boys aren't exactly hanging free at that point. From my measurments I'm told a 58-59 would be around prime for me, but my top tube would need to be around 59-59.5cm. The frame I'm looking at has either a 57cm with 57.5cm top tube and 33 inch stand over or a 60cm with a 60.5cm top tube and a 34 inch stand over. My current stem would work in length with the 60cm but i fear the stand over may be a little too high? Although with shoes on my legs would gain maybe half an inch. Or would the 57cm work better for me if i purchased a longer stem like a 120mm or 130mm?

Try to find a frame with a sloping top tube. Although many people don't like the sloping top tubes that are so common now, it seems that that sort of bike would be perfect for you - you could get a 59cm frame and still have lots of standover clearance.

I have recommended this site before as a good starting place to determine frame sizing, https://www.ebicycles.com/article/bic...ze-charts.html. There are links on this page to various frame styles and sizing. They have a calculator allowing you to input height, inseam and sex and it outputs an optimizes frame size along with crank length.

I'm about 6'2 with a 32" pants inseam and I have a 60cm road bike. I think it fits me well. I also have a 58cm road bike and I think it's just a tiny bit too small, but usable. The calculator above came up with a 60-61cm size with 175 cranks for me. Give it a try!

It sounds like you have already decided on a frame and are stuck in a frame size decision.

You may want to step back a bit and consider the larger frame geometry decision. I, for example, have long legs and a short upper body so I look for a frame that has a relatively shorter top tube. There's a good bit of variation across models. Use the calculator or another one and then look at the frame geometry online to hone in on models worthy of test driving or size options within models. The relatively longer top tube on the Surly Cross-Check is the reason I sized down to a non-XL bike for the first time since puberty.

I honestly can't believe at 6'3" you're going to have a standover problem on even an XL frame. On my L Cross-Check it is a 34" standover w/ 700c wheels and 700x35 tires and I have a good 3+ inches (35.5 pants inseam). -- CORRECTION: 4+ inches in bare feet, measured it just now.

Actual crotch height >> pants inseam. Shoe thickness, cuffs aren't dragging, you're not garotting the jewels, etc.

You're an inch taller than my partner. Your inseam is 2.5" longer. And the suggested top tube measurement is a lot shorter than his ideal measure... if we had gone just by top tube, he should be on something in the 62cm range. Problem is that'd put the top tube trying to go 2-3 cm through his pelvic bone in an emergency stop situation... and on the routes he rides most often, it's not unusual to have an emergency stop every few miles. So he's on a too small, 58cm bike, tho it is a hair taller than he'd really feel comfortable on in an emergency stop situation.

I really don't see why you're worried. Like most people, you're built fairly "square", and many mass market frames will work fine. As long as the frame isn't trying to go through bone, it is relatively workable. You may find that it feels safer to angle the bike slightly at stops. You'll have a lot more options about how upright or flat you want to be on the bike... my partner has one choice: bolt upright.

I am 6'2" with a 32" Inseam, and I ride a 58 cm Madone! I road the 60cm and it felt larger then it needed to be!

I am also certain that different sizes by different manufactures will feel different to you. So use the 58 - 60 cm as a starting point and purchase the bike that when you ride it, you feel like you are part of the bike, not the other way around!