Hey, I'm about 5'10, would a 61cm bike be too big for me? The one I'm looking at is:https://www.bikesdirect.com/products/windsor/thehour.htm

Thx for any help.

Way too big unless you have freakish body measurements. For comparisons, I'm 5'8" and ride a 51 or 52 for a track bike.

I'm 6'4" and ride a 61 cm. I have pretty evenly proportioned legs and torso. Go to a bike shop and try out different sized bikes to get an idea of what you need. Or, measure your inseam from crotch (all the way up) to floor and search for a website with a fit calculator.

It's probably too big but that depends on the fit you like. I'm 6'1" and like a 60 or 61cm

I'm 6' and ride a 58cm tourer.

Sorry for my oblivion, but how are the bikes measured?

....with a tape measurer or a ruler

okay, at what point on the bike.

the old standard of measuring that's still dominant is the length of the seattube from the center of the bottom bracket to either the top of the seatube (way old school-still in use sometimes) or the center of the toptube. nowadays with sloping top tubes of all sort this measurement is arguably less important than top tube length. the top tube defines to some extent how stretched out you'll be on a bike and should probably be the first measurement you look at. top tubes are measured from the center of the seat tube to the center of the headtube.
nightfall a 61cm is gonna be too big. i'm 5'10" and ride 54-56cm frames. you could probably get away with a 57-58cm but i doubt bigger would work well. the best thing to do is ride a bunch of bikes and see what feels good.

The old and simple way to size for a level top tube road frame was to measure your inseam and subtract 9" (23 cm). A 61 cm frame would be for someone with a minimum 33" inseam length

An interesting question.

The frame size that is most frequently qouted is seat tube length. It's most commonly measured from the center of the bottom bracket shell to the top of the top tube but there are at least a couple more different ways that it's sometimes measured.

The really crazy thing is that knowing the seat tube length isn't really all that helpful. Saddle height is the easiest adjustment to make on a bike. Many riders feel that top tube length is a more useful dimension for determining what size bike to buy. Since tall people tend to be tall all over, bike frames tend to get longer as the seat tubes get taller.

That's a long way of saying that, although you may physically be able to straddle a 61cm frame, the handlebars will likely be too far away from the seat and you'll never be able to adjust the bike so that it's comfortable for you to ride.

Your fit on a road bike will affect your comfort, efficiency and performance every minute that you're on the bike. Nothing else comes close in importance.

Actually, it's not just about the seat tube length - a more important consideration would be the effective top tube length. Which varies amongst bikes of the same "size".

Thanks for the answers!

There is no unimportant dimension in sizing a bike .
Seat tube length is not all about seat height, on a level top tube frame it also determines the drop to the handlebars. A recreational, older or touring rider is most likely going to want the top of his handle bar within a couple of centimeters of his saddle height. That gives a rider a more upright relaxed position for cruising while still having the drops within a useful range for an aerodynamic position. Seat tube length (or effective seat tube length) is even more important now that nearly all new bicycles have threadless headsets which offer very little stem height adjustment. Top tube lengths can be adjusted by stem lengths that range from 60mm to 150mm. and by handle bar reach.

Agreed, with the additional notes that bottom bracket drop can affect standover (thus the maximum size a rider can safely fit) and frame angles also have an affect on fit and comfort.

You need to know the precise standover measurement of the bike, and your precise leg length, crotch to the ground. I'm a bit shorter than you, with a 34 inch inch leg length. With a bike with traditional geometry, my preferred size bike has a standover measurement of about 33 inches (just behind the stem), which yields a size of 57 to 61, depending on which method of sizing is used.

One of the advantages of buying from a good bike shop is a careful fitting before you buy. Buying mail order is advertised as a means to save money. Yet, it often results in a very unhappy customer, who has wasted a bunch of money. A bike that fits you perfectly, from a shop that provides service before and after the sale is the "best buy" in the long run.