Fifty Plus (50+) - According to Rivendell my bike should be 63

My Pubic Bone Height is 35" or 88.9 cm
Subtract 10 cm and get 78.9 cm for saddle height.
Subtract 15 from 78.9 and get 63 to 64 size bike.

Wow!

What do you think? I would think I'd be too stretched forward, wouldn't you?

Time for Maddmax to post his Sizing measurements. I didn't use his system for my bikes- but it was spot on.

Keep in mind that Rivendell bikes kind of assume you will ride with high handlebars. That brings them back and so shortens the reach a bit. They also suggest that their bottom brackets are lower. I don't know, I've never measured one, but assuming that's true, it would mean you could get the same standover clearance as you normally would on a slightly smaller frame. Personally, if it was me, and I was in that position once, I would stick with the inside leg measurement (same as "inseam" or "pubic bone height"), and multiply it by .065 (centre-to-centre frame sizing, or the equivalent for centre-to-top), unless you actually are buying a Rivendell and you want high handlebars. Also keep in mind that that kind of bike rides more towards the touring bike end of the spectrum than the racing bike end. So it depends what you want. Just because you're over 50 doesn't mean you can't appreciate the ride of a fine road bike set up moderately racing style. There was a time when I was approachig 50 that I assumed I would be more comfortable higher and more laid-back and with fatter tires, but it turned out I really missed the racing bike feel (fast curves, fast downhills). Maybe when I'm 60, I'll get the bars back up, but not right now.

On cue:

Basic bike size=.67 times your true inseam height (use book pushed up there uncomfortably for measurement guide against wall, measure to top of book)

Top tube length modifier is a ratio of overall height divided by true inseam height. If it is greater than 2.2 then a longer top tube (maybe larger bike) is indicated. If it is less than 2.0 then a shorter top tube (smaller bike?) is indicated. This measurement corrects for long or short legs/short or long torso.

These are approximate starting points as different styles of bikes vary in their frame dimension ratios and riders have differing tastes.

I think for Tony it worked out to 57/58 for a basic size with a modifier toward a shorter bike. I believe that he got and likes a 55/56.

My Pubic Bone Height is 35" or 88.9 cm
Subtract 10 cm and get 78.9 cm for saddle height.
Subtract 15 from 78.9 and get 63 to 64 size bike.

Wow!

What do you think? I would think I'd be too stretched forward, wouldn't you?

My PBH is 81. My Atlantis is a 56 cm. It's a good fit for the torso, but pretty high in the top tube, but I don't really care. If I was a guy I'd care more. But I'm long waisted, so what's a good stretch for me might not be for you. I don't know how anyone* can ride a bike based on the seat tube measurement unless you have a very normal body type.

And Rivendell, who prides itself on being rational about bikes, measures by the seat tube. What difference does that make to the ride? FWI, the bottom bracket is low on my Atlantis.

This is what is so nice about this site. . . . great people taking the time to help others. Thanks for all of your help. When I tried a Giant tr pro or whatever it was (carbon) it was a 58 and I felt like I was stretched out too far to the horns. But maybe I was not just broken into it having gone from my 53.5 trek to that.

Well, this should end my curiosity about if I should have gotten a bigger bike.

Tonight I go into the Trek store with my bike and they are going to fit me out and do all the fancy shmancy adjustments so I will be a little faster than that guy whose last name is Armstrong (nyuk nyuk nyuk!). (In my dreams).

Thanks again folks!

Tony

Keep in mind that Rivendell's sizing recommendations are for Rivendell bikes. Their 63 may not be dimensioned similar to other makers. Grant's sizing philosophy leans toward fitting riders on the tallest frame possible and working with bar height and stem length to work out the reach. I would not think of using Riv suggestions for another brand, but I would think hard about going against their recommendations on one of their bikes.

If you went by Rivendell's measurements you would have to buy there bike, because hardly anybody makes them that big.

It would probably be a good idea to go to a bike shop and try some bikes on for size. You may be surprised that you can fit on a 60cm, with no problem.

O.K. I went to the Trek fitting thing tonight and the guy there, after measuring me and running everything through their computer told me I should be on a 58 road bike. However, he said that LeMond Poprad is different and that my 55 is O.K. for me.
He was very good and adjusted some of my teckniques, seat height, etc. It was a good experience.

Tony

OK, I don't mean to start trouble here, but being of normal size I really don't know the answer to this. How many 60-64 cm bikes do they stock at an LBS? Would they tell him that he needed a special order frame, or just try to make one that they had work?

Depends on the LBS. A reputable LBS would advise a buyer to get the right sized bike, even if it isn't in stock. I've known LBS's that wouldn't hesitate to do that.

But there are certainly many that will push whatever it is that they have to sell.

O.K. I went to the Trek fitting thing tonight and the guy there, after measuring me and running everything through their computer told me I should be on a 58 road bike. However, he said that LeMond Poprad is different and that my 55 is O.K. for me.
He was very good and adjusted some of my teckniques, seat height, etc. It was a good experience.


While it is true that one can adjust a bike to achieve a better fit, and that expertise in this area can be very helpful, I'm not buying the statement that the Poprad is different, because it isn't.

The LeMond Poprad is a typical traditional geometry bike. It is true that their sizing is a bit smaller than what Trek uses on their other lines ... that is, a 55cm Lemond is essentially the size as a 56cm Trek.

Consider the effectively length of the top tube: A 55cm Poprad is 56.1cm, a 56cm Trek 1500 is 55.7cm, likewise for a 56cm Madone. A 56cm Trek Portland has a TT of 56.5cm.

Meanwhile a 58cm Trek 1500 is 57.2cm and a 58cm Trek Portland is 57.5cm

Thus one can make the case that a 55cm Poprad is the equivalent of a 56cm Trek. But it is smaller than a 58cm Trek. If your perfect fit road bike is a 58cm, then it goes that your perfect fit Poprad would be the 57cm size.

But that doesn't mean you would like the 57 better. Some people like a bike that is a bit larger or smaller than the formula suggests. However I think the LBS should try to put you on the best fit first and do their best to make that work, rather than put you on a less optimal fit and then make adjustments.

FWIW, all my bikes are not dialed in to one exact specification, they're close, but all feel slightly different. When I switch bikes occasionally, the "new" bike feels weird for the first few miles but not uncomfortable. I've done long rides on all of them with no problems. Perhaps I am lucky that my body seems to conform to a number of slightly different adjustments, or I'm such a fred that nothing matters.

56 cm = 22 inches
58 cm = 22.8 inches

I wonder if it makes all that much difference to push the steering tube about 1/2 to 3/4 inch further from the seat to attain the 58 cm distance as opposed to my current bike size?

I know I'd be reaching further. Would reaching 1/2 to 3/4 inch further be as comfortable for 100 miles than what I am now? I don't know. I just don't know.

I did ride a 58cm Giant and the reach did not feel as comfortable to me as the LeMond. But maybe it all comes down to getting used to a longer frame and bypassing the discomfort for a couple hundred miles?

Keep in mind that Rivendell's sizing recommendations are for Rivendell bikes. Their 63 may not be dimensioned similar to other makers. Grant's sizing philosophy leans toward fitting riders on the tallest frame possible and working with bar height and stem length to work out the reach. I would not think of using Riv suggestions for another brand, but I would think hard about going against their recommendations on one of their bikes.



Against the advice of my LBS I did exactly that, and bought a 56cm Soma instead of a 54cm model.

It is a great bike but too large and I have had trouble getting it to fit.

Having learned an expensive lesson I will always take any potential new ride for a looooong ride.............

I have a 35" inseam and I ride a 64, a 63, and a 62. All different makers, all different length top tubes. The 64cm frame actually has the shortest top tube of the three. I have long arms, btw.

I sent Rivendell my measurements in 2001, including a 87 cm PBH, they built me a touring frame with a 58 cm seat tube. I don't remember the other measurements, but comfort has never been a problem on that bike, even after some long days in the saddle. I do ride with my bars lower than they advocate, which I told them when we were discussing how to build the bike. My other bikes are a 1988 Marinoni w/ a 57 cm seat tube and a 2001 Marinoni Piuma w/ a 58 cm seat tube, both very comfy. Get in touch with Rivendell and talk to them before you buy a bike based on what their website says. They're not nearly as dogmatic as some people would have you believe.

Tony, here's something to think about. It takes a while for the muscles in the back to get used to stretching. I don't know about others, but I can ride anything for a little while, but when it gets over 10 miles I start to really need to stretch out a bit. If I had to chose between a bike that was too big and a bike that was too small, I'd chose too big, because I really hate the feeling of being cramped up in that cockpit. I would try some more bikes before you get one that is so much smaller than the numbers add up to. A centimeter doesn't seem big, but you'll feel it on a long ride.

For those who want to learn a little more about what sort of stuff goes into a bike fit, here is an article (moderate length and may leave you gasping for air about technical jargon) about fitting a race TT bike for a rider who already knows some very specific knowledge about the measurements of a bike that works for him.

http://www.slowtwitch.com/Bike_Fit/Finding_the_right_bike_from_the_bars_back_290.html

Slowtwitch.com by the way has a whole series of articles on the sizing and fitting of TT bikes. TT fitting is a little more of a science than the average bike shop fit. It is much more akin to fitting a pro racer to a bike. It has the advantage of being in the public domain however (which I doubt is the case for many of the pro teams).

Although its TT related, the science is interesting for those willing to pick through it.

By the way, a change from 22 to 22.8" on a top tube is a 3.6% change. That change also effects many other things about the bike including how much weight will be supported by the riders hands. For some manufacturers, the head tube may not change in length resulting in bars that are closer to the ground relative to the saddle on a larger bike. Other manufacturers change the angle of the head or seat tube as the bikes get bigger.

Years ago we used the seat tube length to measure bicycles for "standover height". We are getting a little smarter today as we understand that a proper top tube length is necessary to get a good "reach" for us. Tube angles, head tube length, center-front and center-rear are all dimensions that are part of the "proper fit".

After all of that science, it is the riders perception of fit (or for racers, the stopwatch) that determines what is right.

I don't see any problem with their recommendations. Their bikes are essentially refined versions of older regular road bikes from the 1960s & 1970s. Their fit is essentially the "big = comfortable" high bar touring approach from the same time period. The puffing is really great, though!

But it's different from a racing fit, and folks seem to have forgotten how things used to be. Racers with smaller tight frames and regular folks with bigger comfortable bikes. Roads were generally pretty bad compared to today, too. So we always had a 73 parallel light fun bike with Campy NR and tubulars, fit pretty small (55 for me) and a utility touring bike fit bigger (57 perhaps). Now the utility road bikes have generally gone away at the high end, although they're around in the less expensive models. Have to look, many low end models are imitation performance bikes.

From Dave Moulton, I'd run a 55 x 55.25 w/ about a 118 mm stem ideally. TT + stem of about 67 cm. Can think of that as 55 square because todays seat tubes are a little steeper. Another chart of his, 55 has a reach of 67.5 and drop of 8.7. I actually run 54.5 + 12.5 = 67 cm, and 8 cm drop. Which is OK, because my head tube angle is a little shallow, so longer stem shorter TT is the way to go.

My fit by a real master in 1974 gave me 21.5" TT = 54.6 cm and I ran a 100 mm stem. 64.6 cm. Was always a little cramped on that one.

My touring bikes at the time were generally 23" frames, so that would be about 22.5 or a bit less ctc, 57 cm ctc say. TT were probably 57 cm and I'd run a 90 mm stem jacked up level with the saddle, reach of 57+9 = 66. I'd run the saddle back and these were probably 72 parallel frames. I'd set one up and sell it to the first guy who liked it, but they were all about the same. Nice British touring rigs. Bikecenntennial got folks interested in touring and I could do a bike up well, so the market was there. They all rode about the same, too. I'd forget what I was on!

"Rivendell" would put me on (low end of their scale) a 59. I'll look at a Bleriot. 72 x 71 w/ 5 cm rake and WAIT - this is for 650 tires!! Will never do. Let's find a 700C. OK. Homer Hilson, 72 x 72, 59 x 58 with an 85 cm standover. That's WAY up in the air for me! And very far out. Put a 90 mm stem on it and I've got a reach of 67. Hold on, that's just right. I could actually ride that setup! With the bars up high, I'd be tempted to put a 100 or even 110 stem on it.

But would I like a Hilson? It's just a little bitty bit bigger than I used to tour on. The geometry is nice. I bet I'd like it. I think a 58 or larger would just be a bit huge.

But wait, that's about the same geometry I used to tour on, but a little undersquare to get the bars up. And many people used to ride big frames back in the day. Is there really any difference?

Old British touring. 72 square 50 to 55 mm fork rake, 43 cm + chainstays, 57 x 57.

57 cm Hilson: 72 square, 52 cm rake, 45 cm stay, 57 x 57

Hmmm. Nothing new under the sun. Except for fitting perhaps 1 size large to get the bars up and back.

I imagine I could ride a Hilson loaded with bags no hands on the level and put on a jacket.

What would I get from their line?

Looking at geometry, Legolas in 55 appeals. 73 x 72.5, 55 x 55.5, 45 mm rake, 43 cm stay. Quickbeam 56 is a bit slacker in the seat, low and long rear end. That's cool, too. Most of them seem to have reasonable geometry for smooth handling road bikes.

I think the big deal is the way big sizing. Everything else looks like standard dated road bike design - which doesn't feel nearly as dated on the road!

This is fun now. Let's see what they would want to put me on. Two types of riding. First, fast recreational with smooth handling, lots of hills, light loads at the most. Second, mid-weight short tours, commuting, utility. 170 lb for me, 30 for the bike on the first one. Add 30 for the second. So 200 to 230 lbs. Looks like they'd put me on a Hilson. I'll look at it. I like. Wonder if my old Campy sidepulls would fit.


OK, much discussion about very pedestrian, well thought out bikes with lots of puffing. "Big bike = comfortable" - funny, I used to tell people that in 1973 when I was selling bikes! Old stuff in new package. I'd probably compromise and go slightly big, but below rivbike's recommendations.

Would be quite a contrast with my tiny carbon compact, which is very dinky and tight and very Italian, with my bars and saddle out from the center, wheels tucked under. That one screams GO GO GO GO GO all the time. A mellower ride might be fun.

I just got off the phone with a sales rep from the LBS I purchased my Poprad from. As it turns out I purchased the last Poprad of my type (no disc brakes) the company has. They do have a size 57 which is basically a 57.8cm TT (in disc brakes). But it is at another store and they don't want to ship it to their store where I purchased my bike and take the chance of me not liking the fit.

So they want me to bring my bike down and see if they can either make some adjustments to it or just have me try out a completely different bike.

This is what stinks about a bike shop making me buy a bike first and then going to another store with that bike to be fitted. Had they taken all my measurements first and told me the ideal bike to get I would not have purchased the 55cm Poprad.

Thanks for letting me vent a little. There, now I feel a little better.

Sorry to keep dragging this through the mud. I spoke with the guy that measured me. He told me the bike I now have fits me very well. He said it is just not meant to be a road bike. It is more of a comfort style. If I were getting an actual road bike then a 58 would be what I would want. He said whether by hapinstance or whatever, my current new bike fits me well and I should be comfortable doing centuries.

Thus ends the saga. It is just that after paying so much for a bike I just want to make sure I am getting exactly what I need.

Tony

Sorry to keep dragging this through the mud. I spoke with the guy that measured me. He told me the bike I now have fits me very well. He said it is just not meant to be a road bike. It is more of a comfort style. If I were getting an actual road bike then a 58 would be what I would want. He said whether by hapinstance or whatever, my current new bike fits me well and I should be comfortable doing centuries.

You may indeed be comfortable doing centuries on it. However, as much as I hate to say it, the Poprad's design is not a comfort style bike. He is either lying or misinformed.

Take a look at this bike:
http://www.lemondbikes.com/bikes/cross/poprad.php

The head tube is low, the top tube is horizontal. There is no "comfort style" aspect to it, outside of it having a bit of an upturned stem.

FWIW: Last year I test rode a few LeMonds. Two different Trek dealerships told me that my best fit on a Lemond was a 53cm bike. I'm 5' 7.5", my inseam is only 28.25", and my Rivendell pubic bone height is 75.

Hey, are the Poprads on big sales yet at Trek dealerships? As Trek & LeMond are locked in a heated lawsuit, what I've heard from Trek dealers is that they expect the two companies to go their separate ways and thus Trek will be dropping the LeMond bikes, supposedly replacing them by bringing back their Klein line from Japan and Europe.

Sorry to keep dragging this through the mud. I spoke with the guy that measured me. He told me the bike I now have fits me very well. He said it is just not meant to be a road bike. It is more of a comfort style. If I were getting an actual road bike then a 58 would be what I would want. He said whether by hapinstance or whatever, my current new bike fits me well and I should be comfortable doing centuries.

Thus ends the saga. It is just that after paying so much for a bike I just want to make sure I am getting exactly what I need.

Tony

I ride compact frames and only went road a couple of years ago. Mountain bikes look wierd to most roadies as the frames seem overly small for the sizing. This is made worse as a lot of riders also take a smaller frame than they would naturrally fit- to be able to get it to handle better for them. See attachment of the Bianchi to see what I mean.

When I went road- I stayed compact frame and I fitted right between the XS frame and the S frame. I got the XS. This was not a mistake- but I did change the stem to give me a bit more height and Reach. That initial OCR bike fits. The XS frame fits a sizing equivalent to a standard frame in 49 to 51. Next bike- was something special and is a 51 cm frame. That also fits well and is a full race geometry frame. THEN- Another Giant- A TCR C and I went to the S sizing- to fit 51 to 54 in standard frame. That fits well- but possibly ought to shorten the stem by about 10mm to get a better fit.

There is no set size for a particular rider with an inside leg measurement of "X". Bikes are adjustable and you just have to set them up right-----FOR YOU. Inside leg measurement means nothing on bike fit. Reach to the bars does- and a frame that is TOO large will be noticable aswell.




http://www.giant-bicycles.com/en-US/technology/compactroad_new/

The head tube is low, the top tube is horizontal. There is no "comfort style" aspect to it, outside of it having a bit of an upturned stem.

Tom, why would a horizontal top tube be not "comfort" style? Aren't all touring bikes made with flat top tubes?

I'm no expert on touring bikes. My take on why they are more comfortable, and others can correct me and add to my knowledge, is as follows:

- Tend to have steel frames, and usually a bit heavier steel, and a ride that is more forgiving.
- Tend to have longer wheelbases which also smooth the ride at a compromise in quick handling.
- Tend to have relaxed head tube angles.
- Many tend to have larger tires & more clearance in the forks. The Trek 520 and Fuji touring bikes come with 700x32 tires as standard.

The Poprad is not a touring design. It does have a steel frame, which strikes me as a positive for riding cross, but it's a light one. It is a bit longer, but not as long as touring frame. It's head tube is a bit relaxed, but again not like a tourer.

The Poprad is a racing bike and I just don't see where it comes off as a comfort bike in its geometry. Perhaps it is a bit more comfortable than a road racing bike. But I don't see where it would be so much so that it would have a substantial impact on the sizing.

Personally, I think that given what the OP said about his measurements, that the best Poprad size for him would be the 59 cm. But I could be wrong. I also base this upon my experience in riding a LeMond 53 and finding it a reasonable fit ... and I'm much smaller than the OP. His Rivendell PB measurement is 5" longer than mine. The Popard 55 has a standover of 80cm, and his PB is 88, so that puts him 3" over the top tube. Usually that is a bit small. But if he has a shorter torso & arm length than would be typical for his inseam, then he may better fit the smaller frame.

If one has a traditional geometry bike, and the buyer is a normally proportioned man (which isn't all that normal), a 55cm bike is fitted to a man who is around 5'8". As the LeMond 55 is really a 56, as most companies would size it, then I'd expect it to fit a "normally proportioned male" who is 5'9" to 5'10".

The Poprad is a cyclocross bike. It is not unusual to go a size smaller on a cyclocross bike than a roadracing bike. The bottom brackets are usually higher and you need a lower top tube on a bike that will be ridden offroad sometimes. As long as a comfortable and functional cockpit can be arranged with the correct stem and seat post, I wouldn't worry at all about the low top tube.

I'm suspicious of ALL fitting formulas, because we're not all proportioned the same and don't all have the same degree of flexibility. A friend and are are the same height within an eighth of an inch, both 6'4", and his pants inseam is two inches longer than mine and his sleeve length an inch shorter. How can we fit the same bike?
Having said that, though, Rivendell's sizing worked perfectly for me on two bikes. I was really reluctant to order the 65cm Atlantis they recommended, but I went for it and it couldn't be better. Makes all my other bikes feel too small.

The Poprad is a cyclocross bike. It is not unusual to go a size smaller on a cyclocross bike than a roadracing bike. The bottom brackets are usually higher and you need a lower top tube on a bike that will be ridden offroad sometimes. As long as a comfortable and functional cockpit can be arranged with the correct stem and seat post, I wouldn't worry at all about the low top tube.

I know that it is true for some cross bikes to have a higher bottom bracket. I don't believe this is true for the LeMond Poprad. In fact, I believe the Poprad has a lower bottom bracket than do the LeMond road bikes.

The BB drop on the Poprad is 74mm
http://www.lemondbikes.com/bikes/cross/poprad.php?tab=2

The BB drop on the LeMond Tourmalet (55cm) road bike is 67.5mm
http://www.lemondbikes.com/bikes/road_racing/ac_dc/tourmalet.php?tab=2

And for the LeMond Reno (55cm) it is 67.5mm.
http://www.lemondbikes.com/bikes/road_racing/performance_aluminum/reno.php?tab=2

Why it is lower, I have no idea. I'd guess it has something to do with handling characteristics.

I'm suspicious of ALL fitting formulas, because we're not all proportioned the same

Which is exactly why I made a point of stating that the sizes I referred to were applicable only when one was of normal proportions.

Being a person not of normal proportions, I would never use a simple fitting algorithm.

My Pubic Bone Height is 35" or 88.9 cm
Subtract 10 cm and get 78.9 cm for saddle height.
Subtract 15 from 78.9 and get 63 to 64 size bike.

Wow!

What do you think? I would think I'd be too stretched forward, wouldn't you?

A 54 cm Rossin Record fit me well. By the Riv method I was between a 55 and 57 and I went with a 55 Bleriot. I really like the bike and the size is perfect. It rides great and handles just fine. It is far from being boring. But it is not available in a size to fit you. The BB is lower so I bet a 61 or 62 cm frame from another maker would be the right size for you. Tony, you are a tall guy.

Is all this bike "fitting" size stuff only for expensive bikes. I bought a Giant FCR 1 and all I had to choose from was the size (XS, S, M, L). The small felt the best but I wonder now if I should have been looking at something else. I went with Gian rather than Trek because the Giant LBS is SAFE riding distance from my house, rather than the Trek LBSt

Is all this bike "fitting" size stuff only for expensive bikes. I bought a Giant FCR 1 and all I had to choose from was the size (XS, S, M, L). The small felt the best but I wonder now if I should have been looking at something else. I went with Gian rather than Trek because the Giant LBS is SAFE riding distance from my house, rather than the Trek LBSt

No, any bike has the potential for adjustments to the way it fits you. This doesn't mean your bike might not fit you fine the way it is. Some people need a pro fitting more than others do.

Proper fitting is not just for expensive bikes. You want to have good saddle position and handlebar position on any bike. This is not something that just comes from the size of the bike. But, people with more expensive bike may be more finicky about it.

Is all this bike "fitting" size stuff only for expensive bikes. I bought a Giant FCR 1 and all I had to choose from was the size (XS, S, M, L). The small felt the best but I wonder now if I should have been looking at something else. I went with Gian rather than Trek because the Giant LBS is SAFE riding distance from my house, rather than the Trek LBSt

No, it applies to all bikes. If you can ride your bike a few hours, feel good when you are finished and ,IMHO, want to ride again the next day you are there or very close.

Keep in mind that Rivendell's sizing recommendations are for Rivendell bikes. Their 63 may not be dimensioned similar to other makers. Grant's sizing philosophy leans toward fitting riders on the tallest frame possible and working with bar height and stem length to work out the reach. I would not think of using Riv suggestions for another brand, but I would think hard about going against their recommendations on one of their bikes.

Yes, Riv's bikes are designed a bit different and the sizing method does work well. I was between a 55 and 57 and went with the 55 Bleriot. Worked out perfectly.

Tony, check this out. http://cgi.ebay.com/Heron-Road-99-by-Waterford-Reynolds-531-Lugged-Frame_W0QQitemZ190230342992QQihZ009QQcategoryZ98084QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

There is a NOS Rivendell Atlantis for sale on eBay that I was interested in. It's 61cm, usually what I think of as close to "my size" (I'm about 6' 2-1/2" tall).

To figure out whether I wanted to bid on it, I carefully measured myself "the Rivendell Way" and they are saying I should take a 67 cm frame. I was shocked. I know that Rivendell says on their website that they expect folks to be surprised and confused, but even with that warning I was surprised and confused.

O.K. I went to the Trek fitting thing tonight and the guy there, after measuring me and running everything through their computer told me I should be on a 58 road bike. However, he said that LeMond Poprad is different and that my 55 is O.K. for me.

My experience with my two Trek bikes is the same. My road bike is a 58cm '00 Trek 1000. My commuter is a 56cm '06 Trek Portland (a first cousin to the LeMond Poprad.) Both bikes fit really well. Its the difference in the geometry of the front end that makes the sizing difference between them.

FWIW, MM's formulae work out to 57.62 and 2.01 for me, which indicates a 57 or 58, but the top tube modifier puts me on the cusp of sizing-down. Seems to jibe with reality.

Edit: After having read a little further down, Tony, I agree that the smaller Poprad would be the better century bike. My 1000 is a great fun ride bike and I love it dearly, but I become uncomfortable on it at around 50 miles, and at 70 miles I just plain want off the thing. The Portland, a relaxed front end like the Poprad, is still comfortable after 105 miles (my longest ride to date.)

As for the brakes, if you're not constantly riding in the rain, the slush of winter, or down mountainous descents, then don't worry about disc brakes. I do all of these things and disc brakes are one of the reasons I bought the Portland.

IMO, rivendell measurements put riders at the extreme upper end of what might provide a workable bike fit.
If thats what a rider wants, great.
But for me, a road bike with or without luggage has to be comfortably handleable, riding a 63 wouldn;t do it for me.
I've listed my specs below, along with comments I made on BF, back in 2005. Only things different now is that my saddle to bar stretch has gone out a further 1 cm (saddle is now 6.5cm behind BB). That being mostly becuasse I was recovering from some serious upper body injuries back then and couldn't load the shoulders and arms as much as I feel is best. But slowly getting back to a better fit. Also the 9 cm bar drop now works fine and is very comfortable.
I've also gone almost completely to 57 and some 56 (ctr BB to top) for any new bikes I get. I still have some of my old race machines from the 70's and 80's and they went from 60 to 59 and finally to 58 cm (in '80). The 59 (crit specs) and 58s are still very nice, the 60s were all sold, thankfully.
Maddmaxx's basic formula is a good one as a start. And going a bit smaller is no biggie if one allows for more extension with a longer stem. What I see a lot of these days is very confined and shortened upper body positions. Makes for back,shoulder and neck problems. Stretch out a bit more and a lot of those issues go away. And that's all considering I have a very short torso. Riders with average and longer torsos will feel even more comfortable with a longer stretch to bar.
my .02

my post/ my specs from 2005:
"For further comparo, my numbers:
height - 180 cm ( 5' 10.8")
erect barefoot inseam to sitzbones using the 'book' method - 88.2 cm (34.75 in.)
sitzbones behind BB plumb = 28 cm (11 in)
seat nose to BB plumb = 5.2 cm (2.125 in)
seat nose to bar center = 55.9 cm (22 in)
sitzbones to bar center = 78.7 cm (31 in)
wristbone to neckbone = 74.9 cm (29.5 in)
172.5 to 175 cranks
bar drop from saddle top = mostly 9.5 to 10 cm (>4in) but recently went to 9 cm to try a slighty more upright position, no verdict yet...
I prefer a 57 to 57.5 cm TT, and usually find that on frames 58 cm and can also do 57 cm if no shorter than 56.5 TT (usually means a 110-120-130 stem length for the 57.5, 57, 56.5cm TTs)."
;)

You can always modify the fit of the top tube some by changing the stem. You must have stand over height in my opinion. In my case, I have a long torso compared to my inseam, though I have large feet compared to my hieght. My size came in OK from Rivendell system. I have a an old C-dale touring bike. Due to a shoulder injury I later got a new stem and moved the effective length and hieght of the top tube so I am slightly more upright.

I'm still of the opinion that standover height is one of the most overrated numbers in cycling history. With the exception of MTB riders who come to sudden stops and are propelled violently off the saddle, very few riders need to stand over a bike with both feet flat on the ground. The tradeoff for that flat footed standover height is in frames that are poorly proportioned for riders doing what they should be doing on a bike............riding.

Saddle position in relation to the bottom bracket and to the pedals.
Bar position in relation to the position of the saddle.
Bar drop.

Those are rider specific dimensions to concentrate on.
Seat posts can be made longer or shorter, saddles can move for and aft and stem lengths and angles can be changed to adjust these dimensions to some extent.

With that in mind, the length of the top tube (or the virtual top tube for compact designs) is much more important than the standover height. If it turns out that when the bike is sized for the proper rider performance, there is insufficient standover height, then the rider needs to lean over on one foot when stopped or a compact sloping top tube disign needs to be looked at.

By the way, the approximate sizing formula given near the begining of this thread is primarily intended for a standard road bike. For compact designs, use the virtual top tube length and for mountain bikes go smaller. One has to work at getting a virtual top tube length for many MTB's as they are almost universally sized by seat tube length. They almost always (for modern bikes) have a much longer virtual top tube that seat tube.

I'm not sure why Rivendale measures people for such large bikes but I'm pretty sure that their measurements do not work for other brands of frames.

In most cases you can lean over when stopped but now and then, not often, stand over hieght can save your boys. I think Rivendell works for me. I am 5-10. I have the handfull of seat post with a leather brooks seat. I got rid of stock C-dale (it was torture device). I am on a 58 cm frame, which was the medium size for the 96 C-dale touring bikes.

What do you think? I would think I'd be too stretched forward, wouldn't you?
That would depend on your overall height, no?

Our company transfers bikes between stores 5 days a week. The truck is going there anyway so we're happy to throw another bike on if it means getting it sold. And if the customer changes his mind, well, we can sell it just as well as the other store. That's our philosophy, anyway. Get the customer happily riding his new bike ASAP, so he'll ride back in for tires and accessories (where the real margin is).

By the way we have a few '07 Poprads with disc brakes in 57, if you're interested.

FWIW.....I've always ridden (and still do) 54 cm seat tubes with around 55cm horizontal top tubes. I ordered a Riv Romulus in 03 on a whim over the phone. They insisted, given my 5'8" height, 32" inseam, that I ride their 57. I was dubious, but what-the-hey.

The Romulus, in fact, fits like a glove with its 56.5 tt and not-so-slack 73 degree head tube (Seat tube leans back at 72 degrees.) I ride with my bar tops about 1.5 inches below my saddle. I use a 10cm conventional stem. The head tube is Rivendellian longish at 15cm.

The bike fits well and handles like what it is....a sport tourer good for long rides, sweeping stable descents, no-hands. Like their Rambouillet, this is a "long & low" bike: low bb height and long wheelbase. For riding on someone's wheel, I prefer a "quicker" frame of mine which is a bit less comfortable over long miles.

All in all, the bike looks and measures "big", but handles and feels well matched to my size. A Rivendellian, practical bike not meant for competitive riding.

It tends to stand out among tighter wheelbase, carbon bikes and, on organized rides, people comment on it...thinking I've restored some older 70's bike.

Repeat after me, " Rivendell sizing instructions are are designed for and intended to to be used for Rivendell frames." They are not intended to be applied to other brands of bike frames. In fact, different models of Rivendell frames sometimes have their own individual sizing instructions and should not even be applied to other Rivendell models. Rivendell uses different relationships between frame dimensions and angles than other frame builders use. There is no reason to think that because Rivendell recommends that you ride a 59cm size A. Homer Hilsen, that they would also recommend that you should ride a 59cm Cannondale.

Repeat after me, " Rivendell sizing instructions are are designed for and intended to to be used for Rivendell frames." They are not intended to be applied to other brands of bike frames....

not to get into your face, since your statement regarding Riv sizing is certainly more agreeable than how 'they' put it.
pls check their site...
here's a small excerpt.
"Us versus Them
Most bikes are sold too small. We see it all the time: bars way below the saddle, the rider leaned over 35-degrees with arms straight out as his hands are on the brake hoods. If he took his hands off the bar he'd flop down and smack his nose on the stem. It's not comfortable or correct.

When you come to us for a bike, we'll ask what size you ride now, and invariably put you on a bike that's two to five centimenters bigger. You'll still have crotch clearance, but your bar will be higher, you'll lean over less, and you'll be a lot more comfortable.".

clearly, they intent to define their correctness over other ways to 'fit' a rider. There's little doubt left as to their 'correctness'.
one starts within general guidelines and then the rider adjusts how they see fit. Which means ultimately the rider has to determine what works best for them and their time on the bike.
Now some riders will luv an upright position, others may not find it as pleasing.
Like everything in life, position, over time, is not a static thing. We all change and so does how we approach things. Bike fit certainly 'changes' for all of us.
And you gotta start somewhere... Maybe the Riv startpoint is as good as any, and maybe not.
However, my exposure to life leads me to the obvious, that Dogma often leads to poop.
the 'Riv' thang is as fashionista as anything else... there I've said it, shame on me.
we're all slaves of some fashion in some way, its just human

Take anything on the riv site with a grain of salt would be my advice. I do like their fit system and use it with a recalibration of just going 3 sizes (that's sizes not cm) smaller than they recommend.

Does the seat tube length have much effect on how stretched out you are? That's a function of the TT and the stem, not what we usually refer to as frame size.
As for Rivendell, though, Grant knows what he's doing. I bought an Atlantis five years ago, and Riv's sizing chart put me on a 65cm (I'm 6'4" with a 34-inch pants inseam; can't remember my PBH offhand). I'd ridden mostly 62s for 15 years, and I had real doubts. I finally decided that if I wanted one of Grant's bikes, I should trust him to know how big it should be. As it turned out, they were out of 65s, so I ordered a 64 frame w/fork.
I built it up mostly with parts I had around, and it was instantly wonderful. It took about three minutes to fine-tune the bar and saddle height, and I haven't changed anything in 12,000 miles. On the first ride, I could go at least 25 percent longer without being uncomfortable, and there's no disadvantage (but many advantages) to having the bars about level with the saddle. I can't think of one thing about the bike, setup or fit that I'd change.
Last year I found a used Rambouillet in the same size at a take-it-and-run price, so I bought that, too. Looking at them now, I think Grant was right--I'm completely comfortable on both, but there's a little more seatpost showing than there should be: I belong on a 65. All those bike shops over all those years were selling me smaller bikes because that's what they had in stock ("No problem--we'll give you a longer seat post").
FWIW, I've found that most people who criticize Riv haven't ridden, and certainly haven't owned, one of the bikes. I've been riding as an adult for more than 30 years, and I've grown especially leery of one-size-fits-all formulas that cite a lot of percentages and decimals and go on the assumption that what works for Lance works for everybody. If Grant says you need a 63, buy a 63.