Growing up I always had shoes a half size or more too big, on the theory I'd grow into 'em. Now that I buy my own shoes, and my feet aren't growing, I buy them a little on the small size, and they stretch to fit. So... yes, I do. But it's a bad analogy; bike frames don't stretch.

Yeah, yeah. In the last year I've put over 3000 miles on a folding bike with frame that measures about 31 cm c-t. It has a looooooong seat post, and it fits me fine.

I've been 6' tall since some time in the late 70's, and my first ten speed, a Raleigh Record, was a 25 1/2" frame. This was soon replaced by a Grand Prix, same size. But a couple years later, when I bought my Raleigh Pro in '80, and my Trek 720 in '83, the "correct" size for me was 24" or 24 1/2," and to my surprise they fit about the same; the seat post was just set a little higher. I later switched to a 23" Cannondale touring bike, and a few years ago, when looking at buying a new road bike, the shop sized me for a 56 cm frame; and that, too, fit just fine. Recently I've started riding my Trek again... and it's nice. I'm not saying they all fit the same; but they all fit within acceptable parameters.

Part of this equation is that before the Mountain Bike craze began in the mid 80's, seat posts were all quite short. There was no way I could ride a 22" frame back then; now, with a longer seatpost, I can.

Another part of this equation is that there's more than one way to measure frames. Ideally all measurements should be labeled, c-c for center to center, c-t for center to top, etc.

And then there's crank arm length. If you prefer shorter crank arms, you will want a larger frame, and vice-versa.

That said, Luke, I see no reason why you can't be perfectly happy on a 60 cm c-c frame if you find one you like. Put a few hundreds, or thousands, of miles on it; and if you still want a bigger frame, keep looking; sooner or later you'll find a good frame in the size you want at the price you want; I've seen quite a few 62 cm frames for sale on Craigs List in the last half year. Be sure to check NJ and Philadelphia.

One or both of you is going to wind up unhappy with this arrangement IMO. BBM is right; a 63 is way big for your dad unless he has no torso, and even then the top tube will be too long.

Wear shoes, now measure from crotch to floor.

~Bike size = inseam * 0.65 (from Brown's page).

It isn't the thread that is so much an annoyance as it is a case of whether the person asking the question wishes to listen to the advice given or ignore it. Have a look at the frame damage from bicycle repair stand thread in the Mechanics section for a truly revolting example.

-Kurt

*megiggles

+1 on that. I'm 5'6" with long legs for my size, ride 56's and 58's, which everyone says are too big. They probably are. I sell a bike from time to time, and no one yet my height has been comfortable on a 58. You put that poor guy on a 61-63 and he will not be "confident."

I am 6'3" and I ride a 25" Miyata frame. After an absurd amount of reading and fidgeting (three stems, two seatposts, two sets of bars), I have dialed it in so that it is very comfortable. However, I will buy a larger frame one day because it is about 1" or so too small.

A few things that I found out.
1. Measuring PBH (pubic bone height) per the instructions on the Rivendell site was actually pretty useful. It allowed me to calculate the proper seat height off of the center of the bottom bracket. I lowered it just a touch over time, but it was pretty spot on.
2. You can get modern mountain bike seatposts that can put your seat at the right height for basically any frame. You might have trouble with the fore-aft positioning, but this is likely solvable. Unfortunately, vintage seatposts are more limited in their minimum insertion. Pretty much a fistful above the insert line and you are at the limit. If you are gonzo over old Campy or SR or whatever, then you may want a frame that doesn't demand 6" of seatpost out of the frame.
3. The real pisser is the stem. If you get the seat too high off the frame, then you get some unattractive options for stems that have enough rise. I like having my bars just a tad below the seat, but Grant P and others say even with the seat. With a 25" (63cm) frame, that meant that I needed about 5" of stem above the headset. That meant I could either use the Nitto Technomic or the Nitto Dirt Drop (I bought both). In the end, the Dirt Drop functions better, but it just looks strange on a vintage bike. The Technomic, however, can get comical. The more you expose the stem, the further back it pulls the bars. In order to get proper reach, you have to get a relatively long model. At 5.25" exposed stem and 13cm stem size, it looked like I had brazed an anemic cobra onto the frame. Further, with wide bars, it had all of the torsional stability of cold pasta. I decided to just go with the Nitto Technomic Deluxe, lower the bars, and do more pilates.

Under no circumstances would I buy an undersized frame that is not completely standard at least by early 1980's standards (don't buy the French bike). You don't need a threadless steerer, but at least have an English threaded BB and a standard headset. It is just too hard and too expensive to buy big-guy parts for freaky threadings and diameters.

None of this may apply to you. I had a 94 cm PBH, and it means I need a big bike. But you should take it seriously. A cool vintage bike that you don't ride is really just a novelty.

Matt

Frame size isn't as cut and dry as saying that someone of a certain heighth should ride a frame of a certain size.

For example, I am 6"2.5 and I ride a 60cm frame. The guy that used to own the frame is 6"0. Last week I met a guy that is exactly my heighth and inseam size and he rides a 64cm frame. I know a guy that is 6'5" and rides a 62cm frame.

The only way to know for sure is to do a bike fit. Even with my 60cm frame, I have a 100mm stem. I like to sit upright and not stretch out much when I ride.

I'm likewise a 6'3" newb (35" inseam/PBH) trying to sort out the whole fit issue.

I think it'd be great to be able to borrow a bike, or maybe even a few, and take them out for a longish test ride but of the handful of people I know with bikes, none of them are all that close to being my size. So I feel like I'm going to be kind of stuck making an educated guess.

The two articles I've found most helpful so far have been the competitivecyclist.com's Fit Calculator and this handy essay on Choosing a Frame Size (mentioned above). And browse around sheldonbrown.com (start here).

The Competitive Cyclist's calculator offers me three different fit styles (and explains them in detail) that range from about 58 cm to about 61 cm. Rivendell's PBH chart puts me in the neighborhood of 60 to 62 cm for a 700c wheel. CC's fit styles are smaller for racers and larger for a more relaxed riding style. The Rivendell guy seems to think most people are riding on bikes that are too small for them and he makes a case for his ideas about frame size. I think that Sheldon's site mentioned both inseam *.65 and inseam *.67 but I can't find the link at the moment. Those put me in the 58 to 60 range.

If I were you I'd read through those and take some measurements. After looking at those three sources I'm getting an idea with a centerpoint and a bit of space around it. I'm looking at 58 to 62 and figuring that if anything, I probably belong towards the higher end of that range. You might be built very differently than I am or 63 cm might be at the larger end of what you'd want. A bit smaller might be workable or maybe even more appropriate.

If you're firmly attached to the idea of sharing the bike, run both of your measurements through and see if there's any overlap… maybe it'd be possible to meet in the middle in a way that's not too uncomfortable for either of you. Zonatandem's analogy to sharing shoes is probably still worth considering, but then again what sort of riding are you planning on doing? Is this for long distance rides or shorter hops around town?

OK enuff of all of your life experiences already. OF COURSE it's not etched in stone, but it's a starting point, a base-line, a rule of thumb, a number to start from. People here are just startled at the disparate choices the OP proposes.

So please no more, but I'm 5' and ride a 62cm (and work at a circus) OK

Beg pardon? These "life experiences" that you condescendingly refer to were posted here by individuals who are interested in helping the OP.

I hope you don't mind me mentioning this, but it is not at your discretion whether the subject is closed to discussion or not.

-Kurt

Sorry, I missed this point before my first reply.

If you're still interested in that idea, though, you should probably consider a bike that's really designed as a one-size-fits-all, which is fine, but it won't be vintage. But as I said before, most modern folding bikes do fit a wide range of sizes, though not usually up to your height. One that does, and which might be worth a look on your part, is the Swift-- advertised to fit anyone 5' 2" to 6' 4." I don't ride one (because it doesn't fold up small enough for my needs), but I took one for a test ride once, and it's a pretty sweet bike.

https://www.xootr.com/xootr/swift/bikes.shtml