newbie101

I'm sizing myself for a bike, and have two sets of figures to work with.

I did a fit kit sizing years ago, and it gave me a figure of 66 cm of reach: top tube + stem length; that is, about a 56 cm top tube + 10 cm stem.

More recently, I crunched some numbers via the competitive cyclist web site, and it recommended a 53.5 cm top tube and a 10 cm stem (approximate figures).

I have a specific bike in mind via mail order and two sizes are available:

51 cm size: 54 cm top tube, 10 cm stem, 30" standover

53 cm size: 55 top tube, 10 cm stem, 30.6" standover.

So, the two sizing systems recommend two different sizes.

I turned to rivendell as the tie breaker, and it recommends using pubic bone height. Using their formula

Learn About Bikes with Rivendell Bicycle Works

I should actually buy a 54 or 55 cm sized bike. With their roadeo bike, this translates into a 55.5 cm top tube.

In other words, I should size up and get the 53 cm bike.

Do you agree with rivendell that most bikes sold in bike shops are undersized?

Machka 

Fit the top tube and the standover height will take care of itself.

Campag4life

Rivendell's fit philosophy is the precursor to modern genre of endurance bikes which are overwhelmingly popular to average cyclists who don't want to bend over in a full out racing position for mile after mile. This is also why the vast majority of bikes...most of which are not drop bar have the handlebars positioned above and not below the saddle. With larger sizing aka taller head tubes which get the bars up higher, modern bikes solve the stand over issue with a sloping top tube. Rivendell bikes can be compromising is this manner with their horizontal top tubes.

Rivendell sizing has been debated and put down on this forum many times. To me Grant is right about sizing for average cyclists..for those that don't competitively race. But a quirk of human nature is average guys don't want to be average and so they model their bike selection and geometry after the stars on TV and they end up paying the price for it. Better cyclists who have owned at least 5 framesets will develop a preference for size because they have evaluated the margins if they have done their homework. A top skinny racer will want to size down and an older average guy will generally feel more comfortable on a bigger bike because the head tube is taller. This is a fact lost on the vast majority but Rivendell explains it on their site. If you size up to a larger frame with a taller head tube to increase the height of the bars, you need a longer top tube...which fits into what a larger frame is...taller head tube and a longer top tube. You need a longer top tube because as the handlebars come up in height they get closer to the shoulder joints and since your arms don't change length, you need a longer top tube to compensate.
My favorite tenant of bike fit which I coined when many I suppose don't understand is...reach much be conserved...no matter what stack/reach ratio.
Above is in fact why a given rider can ride different frame sizes.

Frame size isn't about right or wrong, it is about your riding objectives, fitness level and flexibility. It is preference which you can only hone after owning several bikes. Most of us learn from trial and error.

A last note about Rivendell is, I personally wouldn't own one. To me, you just don't get enough bike for your money.
If spending that kind of money, purchase a frameset from any top steel builder with a better pedigree of steel and exactly what you want. Then buy the components and wheelset. Even if you can't build a bike you can pay somebody to put it together. You will end up with a much finer bike.

Campag4life

Sorry but that is flat wrong.
A short legged rider with long torso, if they fit the top tube correctly, then standover can be a big problem unless they choose a frame with sloping top tube.

Machka 

I knew it.

rpenmanparker 

Come on, Machka. Making a sport out of disputing C4l's generally spot-on information is getting a little silly around here. How could what he said be wrong? Let's face it, sloping top tubes were at least in part introduced to obviate the standover problem that crops up with short-legged, long torsoed cyclists.

Machka 

No idea what this means ^^

I just knew that someone would come along with some exception. Too funny!!

bikemig 

Unless the OP is racing, it's generally a good idea to have the handlebar level with the saddle. It's a more comfortable position for most rider and it will be easier to do that with the larger of the 2 bikes. If the OP is buying a complete bike mail order, then the steerer will be cut and handlebar height could be an issue.

bbattle

With Rivendell bikes, if you get the seat height set, the reach to the bars will take care of itself. That's the way it was with traditional frames. Yes, there are certain people with very short legs and long torsos and vice versa, but for most folks, that worked for many decades.

Today, with seatposts of freakish lengths possible, racers can get the smallest frame possible and make it work for them. The stem length on many of their bikes is also very long. If you like that look, go with the smaller frame.

I bought my first road bike based on the fact that I cleared the top tube but because I have longer legs/shorter torso, I had to shorten the stem from 120 to 90mm. When looking at the Domane, I test rode their 54cm bikes, then the 52cm. The 52cm fit me better. My old bike and the Domane have different geometries so it's like comparing apples and oranges; test rides help sort things out.

If you like the Rivendell, discuss your fit questions with them via e-mail. They are friendly and will write you back. I've considered buying a couple of their frames in the past; their bikes are much better looking in person than on their website. They are a bit pricey but good quality bikes.

jaxgtr

Even if the top tube is a little long, you can always go with a shorter stem to account for that. My CrossRip has a long top tube and I bought a smaller size to account for that, but use a 70mm stem to produce a more comfortable reach for me. Same on the Synapse, the sloping top tube was a tad bit longer for my short arms, so I got a shorter stem to account for the reach issue, but, leg wise, both frames were perfect height even though one was a 52cm and the other is a 54cm.

BillyD

Differing opinions are human nature, as sure as night follows day. It's all good.

fa63

You were wrong (when you said "fit the top tube and the standover height will take care of itself"), and someone pointed it out. Why is that funny?

To the OP - I am not sure I would trust the Competitive Cyclist fit calculator very much (for me, it is off by quite a bit). What is your height and inseam? I am just curious.

Machka 

It just is.

And it gets more funny as we go along here.

Machka 

I used to believe all that hoo-ey about standover height and that I could shorten my stem if the top tube happened to be too long. And I ended up with awkward teensy-tiny stems and bicycles that didn't feel quite right.

Then I realised, if I get the top tube right, the rest of the bicycle feels right. It was a revelation that lead to comfortable bicycles.

The thing is, we're all different shapes and sizes. All these calculators and things are based on some sort of average.

If you've got a short torso and long legs like I do, it might be important to you to be able to ride on the hoods without having to resort to a teensy-tiny stem. Then get the top tube measurement right.

If you've got a long torso and short legs, maybe the standover height is your important measurement because you'll have no problem reaching the hoods.

First determine what you're working with ... your body shape. Then go to a calculator that makes sense for your shape. And it helps to ride bicycles and determine for yourself what you think is important.

fa63

In this day and age, with as many options as there out there, there is no reason why one can't find a frame that has both the appropriate top tube length and standover height. Those two things are not mutually exclusive.

StanSeven

This is something an inexperienced rider might find. Most people with average flexibility and experience find a drop position (bars lower than saddle) is comfortable and effective. It's really all about your cycling objectives. An upright position dramatically increases the required effort to got a set speed.

bikemig 

I'm skeptical that most people find a position with the bars lower than the saddle "comfortable and effective." It's like anything else to do with bikes, there are trade-offs. When I raced, I set my bars lower than my saddle and my bike size went down a bit from where I started. I don't race anymore and I've slowly raised my bars as well.

My guess is that Peterson's observation that most riders are better off with bars set around the height of the saddle is probably right. That is clearly not the best position for everyone (and it may not be the best for the OP depending on his or her goals as you point out) but for most people that is a good rule of thumb to start with.

rpenmanparker 

Machka, you keep focusing on which measurement should be most important, standover height or top tube, and you are dissecting the question by a rider's dimensions, worrying about the effect that making the wrong choice will have on stem length and so on. The message that C4l and I would impart is that it does not have to be one or the other. The message is that compact frames allow one to avoid any problems with standover height on a bike that has the right length top tube for the short legged, long torsoed rider. And of course they work for the opposite extreme as well given the availability of long seat posts. One should always look first at top tube and head tube lengths and then check last that the seat tube won't be too long. One has the luxury of assessing bike fit in this order nowadays, because compact frames will almost never be a standover problem. So that issue can just be checked off at the end of the process to be safe.

tarwheel 

Back to the OPs original questions. He/she needs to provide more information to get meaningful advice. Such as:

- What size frame do you ride now and does it fit you comfortably?
- How do you position your handlebars? Lower, even with, or higher than the saddle? Is the position comfortable?
- What kind of riding do you do? Racing, fast recreational, touring, commuting, putzing on bike paths?
- why are you getting a new bike? N+1 or because your current bike doesn't fit? Do you want to go faster? Ride more comfortably?

Machka is right to a point about top tube length. It is arguably the most important dimension. However, depending on the rider, head tube length might be just as important. IMHO, stand over is the least important. Not irrelevant but the last one to consider.

Fit formulas can be very misleading. Years ago when I got back into cycling after laying off for many years, all of the on-line fit formulas suggested that I needed a smaller frame. Several misfitting bikes later, I was back to riding a frame the same size as my original bike from 20 years earlier -- that is, much larger than what the fit formulas recommended.

RJM

OP, how tall are you and what is your Pubic Bone Height using Riv's method of measurment?

I am 5'6" tall and have a pubic bone height of 79 cm using their measurment method and they put me on a 53cm Roadeo. It fits well using a 9cm quill stem. Just remember that you will not be seeing huge amounts of seatpost sticking out and the standover will be quite a bit less than compact frames from somebody like Trek. I have about an inch, maybe even less of space when I stand on the ground. The bike fits me very well when riding and is really comfortable.

I bought a 48cm Sam Hillborne from them too and that also fits well. That bike seems to have a longer top tube than the Roadeo and I have it set up completely different...it also has a top tube that slopes a little bit more than the Roadeo. I think the difference is 6 degree slope for the Sam and 2 degree for the Roadeo.

If you are thinking about buying a Riv, the best thing you can do is follow their measurment advice and call and talk to them. They will get you on the right frame by talking to you and using your PBH.

Also, I think that using Riv's sizing as a guide will make it a bit difficult to translate into another manufacturer's sizing. Riv likes to put you on a bike that is a bit bigger than others. It works, but just realize that if and when you talk to them to get a size, you will think it is too big for you. I really thought they would stick me on a 51cm Roadeo but they said no, the 53 was the one. They were right.

WhyFi

+1

Many, myself included, have a hard time buying a non-custom frame, with a level and appropriately long top tube, without standover being a problem (aka putting the reproductive system in mortal danger).

WhyFi

It's the least important when you have enough. When you don't have enough, it moves up the list considerably.

RJM

How much standover do you require, WhyFi?

tarwheel 

The thing about stand over height is why is this so important? When have ever had to straddle a top tube? Who has ever crunched their crotch on a top tube? In 40+ years of cycling these have never been problems for me, and my legs are on the short side for my height. However, I have owned a number of bikes that were uncomfortable because the top tubes were too long or handlebars too low.

RollCNY

Is having your pelvis 13" over your head uncomfortable?