34" (pant size)

56cm Miyata 610
58cm Mercier Serpens
58cm Trek 2120

Az

30" inseam, 54cm. I would have preferred a 53cm frame but I couldn't find one in my price range at the time but the 54 feels really comfortable.

Same size as mollusk. Just bought a Cannondale Synapse... 60cm. The fit appears to be just right using a short stem.

+1 I switched to a 110mm stem with 6 degree rise and it fits perfectly. Of course, this is a prime example of what is wrong with this thread. You have to go to the specs of every bike to find out how the seatpost is measured. The center to center measurement on my bike is actually 60cm. On the other hand, I have a steel bike that is a size 60, but the actual length is 59cm. I am convinced that the seattube measurement is pretty worthless, by itself. The virtual toptube and standover height have a lot more relevence. I wish I knew why the manufacturers on one hand use this as the main measurement and then make it as confusing as possible. Trek and Lemond are made by the same company but they measure their bikes differently. Why?

I'm still a bit confused.

I based my measurements on this page: http://www.coloradocyclist.com/BikeFit/index.cfm
My inseam is 32-inches or 81.28cm. Multiply that by 0.67 for "C-T" and I get 54.45cm. (call it "54cm")

Here's where I've got questions.

What that number basically tells me is, if I buy a frame labelled "54cm", the manufacturer will PROBABLY have spec'd the geometry such that I, with a 32inch inseam, can reach the pedals.

Similarly, if I tried, say, a 65cm frame, I would, in all likelihood, NOT be able to reach the pedals. (and the top tube would be long enough I'd probably feel pretty stretched out anyway)

Really though, I could probably get away with, say, a 50 or 52cm frame and raise the seat so I had proper extension or a 56cm frame with the seat appropriately low. The smaller frame would have a shorter top tube so I'd be less stretched out, the opposite being true of the larger frame.

Missing anything?

EDIT: with ANY bike, using "0.883 * inseam" my 32inch/81.28cm inseam tells me to make sure the distance between the top of my saddle and the center of the bottom bracket is 28.25in or 71.77cm (call it 72cm)

As long as I can get that distance out of a given bike, I'll have appropriate leg extension to not be causing me knee problems...?

EDIT2: Mollusk, if you had, say, a 54cm frame as your inseam suggests, I understand how it would be too "cramped" for you.

Could this be alleviated with a HUGE stem or are there other issues I'm missing? These ones from Yellow Jersey seem like they add 4 inches of rise and extension: http://www.yellowjersey.org/photosfr...t/823STEMZ.JPG

Yes. One of the reasons for proper frame sizing is to place the handlebars at the correct height in relation to the seat. If you buy a frame that's too small and raise the seat way up, the bars will be far too low. Most racer wannabes do this on purpose to get a racier look, (and a smaller frame will theoretically be lighter) but it's not really a good idea for a general purpose rider. I see a lot of people riding frames that are way too small and the easy way to spot them is that gigantic seat post and/or flipped stem.

Az

Inseam - 29"

Bianchi - 53cm
Schwinn - 21" (53.5cm)
Nishiki MTB - 16" (40cm)

- Wil

Exactly right. Some of the bike books published during the 1970 to 1975 "Bike Boom" have been accused of making bike fit "too simple", but some of that "too simple" advice actually works well for many riders. For example, it was often suggested that a buyer start by finding out what is the largest size bike he could stand over flat-footed without discomfort.

Using the "stand-over" method, I find that my 35 inch long legs let me stand over a bike where the top tube is 33 inches above the floor without discomfort. (There is contact between my jeans and the top tube, but I can raise the front wheel of the bike about two inches before the contact is uncomfortable.)

Because different companies measure bike sizes differently, and because many 2006 road bikes have a sloping top tube, a bike that has a 33 inch standover (measured from just behind the stem) could be labeled as a size 54, 56, 58, or 60 by four different companies. But, odds are, all four bikes would have a "true" top tube measurement of around 56cm to 58cm, measured from the center of the seatpost, horizontally to the center of the stem insert post. And that means, with the bars set at the height of the saddle, any of those four bikes is likely to provide me with a good fit (after the saddle and stem are adjusted to fit me).

So, in the "modern" world, fitting bikes by referring to the seat tube length may no longer be very helpful. A more useful way to start is by finding the tallest bike you can stand over without discomfort, when standing as close to the stem as possible. That is the size that will make it easiest to set the bars at the correct level, even with the top of the saddle. Of course, it is never possible to be sure how a particular bike will fit until you take a test ride...but it is good to have a way to know WHICH bikes to test ride.

32.5" Inseam

57 cm (c-t) Colnago
56 cm (c-c) Fuji Cyclo-cross
56 cm (c-c) 80's Giant Kronos

If I use the .67 x inseam (for c-t) I get 56.1 cm. My 'nago is a 57 cm which is 55cm c-c and 55 cm top tube length.

Seat tube length is a heck of a lot easier to mess with a bit (adjust the seat height). I'm leaning that buy a bike based on a reasonable "size" or seat tube lenght....but really pay attention to the top-tube length.

I bought my colnago used, the "size" or seat tube length is spot-on.... but I am not too sure about the top-tube lenght the more I ride it. The bike has a threadless CF fork and spacers....therefore no adjustment up (isn't new technology great?). I think the bars a bit low (I just need to get in better shape).

There used to be a rule of thumb about when you are in the drops if you look down, the horzontal part of the bar should obscure the front hub. Is that still true?? (as a gauge of TT + stem length)

I know where you're coming from. It seems common to find steerer tubes cut too short "because they look goofy on store shelves" when they're uncut, ridiculous as that is.

You can raise the bars on a threadless stem with one of these:
http://www.sheldonbrown.com/harris/i...iserSM2787.jpg

Works great. Harris Cyclery has them: http://www.sheldonbrown.com/harris/stems/index.html
I have one on my bike - rock solid.

af895, would you mind posting a pic of your bike with that Zoom extender? I'm wanting to raise the steerer on mine, and was going to replace the fork, but this could be a good interim/cheaper solution. Thanks! -d42

Here are some links:

http://www.ncf.ca/~af895/bike/misc/F...ar_quarter.jpg
http://www.ncf.ca/~af895/bike/big/F20_52T_side.jpg
http://www.ncf.ca/~af895/bike/big/jay_feather.jpg

...perhaps not what you're expecting though. ;)
It's a 20" wheeled (406mm) folding bike. Though it's fully suspended, I'm exclusively a roadie/urban cyclist and the suspension is short-travel, making the small wheels feel like big wheels. The bike's adjusted for a perfect fit. I'm 6'0" with a 32" inseam.

af895, How much does that puppy weight?

Oye. Stock bike was 29#. I'd like to say I've cut that down but every time I add a light part (Salsa seat post, road crank) I add a heavy one (Brook B67 ;). Probably still in the 28# range. :)

30" pants inseam, 5' 8", Orbea Dauphine 54cm with 175mm cranks

http://www.orbea.com/upload/cuadros_...ias/line_g.gif

83cm inseam riding a 57. Next bike will be a 55-56 with 175 cranks

Same pants inseam and height, ride a 60cm R1000 with a 120 stem.

Fits perfect and I have almost no stand over clearance, but I bought it to ride, not stand over it.

How are all of you measuring your inseam? I see a lot of talk about pants size, but if understand correctly, your inseam (at least for bike fitting purposes) should be measured from the floor to your crotch. You should be barefoot for this. Am I correct in this?

Anyway, my inseam is about 35.25 inches, I'm 6'-1/2" tall (to be precise) and I ride a 60cm Trek.

Anyone else between 6'-0" and 6'-1" riding a 60cm or larger frame?

Here is another sizing site that has nifty charts:

http://www.cbss.ca/Custom.htm

80 cm cycling inseam 54cm c-t frame

I am a shade under 6'2" in my stocking feet and I am riding a Cannondale Synapse that has a 60cm frame. I only have 100 miles on the bike but it seems to fit me just fine. However, I do have a fork that has an extended steerer tube that allows me to raise my handle bars above the seat. I needed the bars raised because I had neck surgery a few years back. The bike rides like a dream.

I measured my inseam while standing in my stocking feet, from the floor to my crotch. The measurement turned out to be 32".