kirke

I think this fits best in the Mechanics section, but if not feel free to move this:

This deals not so much with measuring the standover of a bicyle, but measuring (what Rivendell Bicycle Works calls) your "floor-to-pubic-bone" height. In other words, YOUR standover height.

Most instructions suggest taking this measurement "in your stocking feet." However, shouldnt you measure from the floor to your crotch while wearing whatever shoes you typically cycle in? No one, as far as I know rides in their socks. It wont be much of a difference, but if you wear MTB shoes, it could be almost an inch couldnt it?

Thoughts on this?

DannoXYZ 

The difference in shoe thickness is usually offset by the similar pedal height above the spindle. So it evens out in the end.

bikinfool

So what's the point? You gonna just hit your pubic bone? Frankly standover is way overrated, not really a concern except for those fearing the boys getting hurt...

Panthers007

Nah! You are supposed to carry 2 ballpean-hammers and ride no-hands. And then beat the "boys" with the hammers - like a galley-ship - as you reach your cadence! Boom! <ow!> Boom! <ow!> Boom! <ow!>...

Proper beating is done with 1 inch of room above the cross-tube.

HillRider

The "floor to pubic bone" distance isn't measured to determine stand over height but as a guide to frame sizing and saddle height. There are several formulas that take the ftpb distance and multiply it by some factor (which varies depending on who is making the recommendation) to calculate your recommended frame size and saddle to bb spindle distance. For example, Greg LeMond's book recommends a factor of .65 for frame size and .883 for saddle height.

These are interesting formulas but tend to discount top tube length which is every bit as important in bike fit.

The recommendation for stand over height is a comfort and safety consideration and a VERY rough guide to frame size choice.

LarDasse74

+1

Retro Grouch 

After you determine the measurement, what are you going to do with it?

Assuming your intention is to plug it into some formula, why wouldn't you take the measurement however the formula specifies?

Road Fan

If you measure this in your stocking feet, and you buy a bike that matches this number, you'll just get a little extra clearance with your shoes on.

I haven't bought a Riv, but people I know who have say it's a great buying experience. I'd suggest talking to them about how you want it to fit, and see what they recommend. Rivendell has really thought their method through. I would just talk to them.

The measurement in bare feet is much more standard, and has other uses, such as setting saddle height, choosing crank length, and seeing if you are suited to an off the rack frame or a custom design.

Road Fan

Hey guys, check out the Rivendell site. They use this number to key you to their sizing system. It's unconventional, but that's what they do. And customers usually say it works.

Yes, we're all correct about the equations, the other uses, and the importance of top tube, and the seeming arbitrariness of it all. But the question is about using Rivendell's method.

Longfemur

If you follow the standard methods of road bike frame size selection, multiplying your "inseam" length (or pubic bone height, if you like) by that .883 number will give you a level top tube height that is just enough to clear the top tube while hanging your stuff over it. The thickness of your shoes give you that much more clearance, but keep in mind that any road frame sizing methods were not developed with mountain bike shoes in mind. So, you can take that extra thickness into account if you want. It won't matter as long as the bike is not too long for you.

But when you stop to think about it, while shoe sole thicknesses vary, and you may not always wear the same cycling shoes in the future, you will always have the same thickness of feet. So, it probably makes more sense to keep measuring inseam in bare feet and go from there.

kirke

Thanks for all the responses. Great discussion here.

Garthr

I find there is no "formula" for fitting a bike. It comes from knowing your body and the position you want to be in. But, you gotta start somewhere.

Does your crotch clear the frame? I don't know too many who'd NOT like to clear it.

Where do you like your bars in relation to the seat?

What kind of bars do you use?

What is your best riding position, straight up, bent over 60,45, 30 degrees?


All this help you choose the length of the top tube. Being tall and having ridden on short TT's for most of my life until the last 10 years. . . I can say I would absolutely take a frame with a longer TT, and use a shorter stem rather than throw a long stem on a too short TT frame. The feel is totally different, from being "with" the bike, as opposed to being on top of the front end. It's a matter of balance.

Top tube length and head tube length(the ability to get the bars where you want them), are often under considered when getting a new frame, then they scramble after the fact to get the bars up or out or in.

Give it a lot of consideration. The actual frame size will likely be in the ballpark if those two factors fit you. If not, go custom

Camilo

You're mixing up two terms that aren't interchangable and don't have to do with the same fit issues.

The floor-pubic bone measurement is called "cycling inseam" and is indeed taken in stocking feet. It is used to get in the realm of "doable" with frame size, crank length, seat height, etc.

"Standover" is simply the measurement of the BIKE (not the person) from the floor to the top of the top tube about midline on the top tube. You then straddle the top tube - in your normal cycling shoes and see if you have enough clearance to feel comfortable. Then, as you look at frames, you limit your search to frames with a standover you feel comfortable with.

You can't determine your preferred standove based on the cycling inseam for a couple of reasons. First, the anatomical bits that dangle below the pubic bone used for the cycling inseam measurement are what concerns you ... and then only when you're wearing yoru normal cycling shoes, not barefooted.

second, everyone has a personal comfort level with that. Traditional road bike fitting didnt' require a lot of space betwen the top tube and the crotch because whenever you dismount a road bike, you naturally tip it to the side of the foot that's on the ground, therefore the straight on vertical distance is not relevant. People coming from mountain bikes think they need a lot more standover than they do. I'm happy with 1/2 inch of good clearance, but always have several inches when I'm actually stopped on my road bike.

Al1943

It's kind of a worthless measurement unless you have a level top tube. The top tube length is more important.

Al

Delano

Given all this great info, how much does a centimeter actually matter? a 56 cm bike might be perfect, but would a 58 cm bike be so far from comfortable as to be unrideable? Shouldn't there be a spread in the "range" of bike fit? Why so exact?

Al1943

No, fit is very important. And advertised sizes are not consistent from brand to brand. You need to know how each frame is measured. My some had a Specialized Alize 52cm that had the same standover height as my 56cm Trek 5500, and both had level top tubes. The top tube lengths were very different.