BroadSTPhilly

I am looking at buying a Giant OCR 1 but I am unfamiliar with the geometry. I have never owned a road bike that didn't have a traditional diamond frame with a top tube that is parallel to the ground. Can you tell me what difference in feel is with this type of frame?

dysFTP

Search for threads on "compact geometry".

johnny99

Better manufacturers will vary tube sizing so that there is no difference in frame stiffness. The only differences will be in sizing and fit (e.g., stand-over clearance and handlebar height).

dcvelo

Why would fit be different? Whether the top tube slopes or not, you'd still want your three contact points in the same relation to each other. I have both geometries and all the dimensions between saddle, bar and bottom bracket are the same.

There is more standover clearance on the compact frame, I'll give you that.

dysFTP

Sloping top tube


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 /əˌbɒməˈneɪʃən/ [uh-bom-uh-ney-shuhn]

–noun
1. anything abominable; anything greatly disliked or abhorred.
2. intense aversion or loathing; detestation: He regarded lying with abomination.
3. a vile, shameful, or detestable action, condition, habit, etc.

Val23708

stiffer triangles

umd

If you read the post you are replying to, he said standover clearance

johnny99

Stand over clearance is a huge part of fit for shorter people. More clearance gives a cyclist the option to choose a bigger frame size and get a longer top tube and/or higher handlebar. Also, some compact frames (like the Giant OCR mentioned by the original poster) have a taller head tube to allow an even higher handlebar position.

BroadSTPhilly

Maybe I just need to ride it before I get the answer but what I need to know is how does it feel and respond differently. Is it less aggressive? Does it lead to a more upright riding position. Am I sacrificing performance for comfort?

CastIron

They're ugly, but for those like me with simian proportions, they fit better for reasons Johnny has mentioned.

johnny99

Relaxed-fit bikes like the Giant OCR are designed to be less aggressive and more comfortable at slower speeds than race geometry bikes (like the Giant TCR). This is a different issue than just compact vs. standard geometry, since compact frames can have either relaxed or race geometry. Relaxed geometry frame will have a taller head tube or shorter top tube or less steep seat tube or some combination of these.

bitterken

You can argue that a compact frame can be lighter and stiffer, but there are usually so many other variables involved that it won't be a good argument.

These days, a bike seems to be considered relaxed if it has a longer head tube.

dstrong 

Good candidate for Compact Geometry frame.

CastIron

^^ Close, but I'm a blonde.

BroadSTPhilly

So if I like aggressive geometry this is not the bike for me?

stapfam

How aggressive? What do you ride now?

The feel of a compact frame in comparison to a conventional version- is not going to differ. As dcvelo Stated- it is the 3 contact points that are going to concern you. How the frame is set up- as comfort or race geometry will though. OCR is comfort- TCR is more race orientated. Both are Compact frames.

bitterken

For what it's worth, the TCR bikes are considered the "aggressive" ones in the Giant lineup, but the OCR may be plenty aggressive for you. Test ride?

dcvelo

Well, actually, he said "standover clearance and handlebar height". Handlebar height is certainly an element of fit, and not one that has a damned thing to do with whether the top tube's sloped or not.

dcvelo

Okay, point taken....

grahny

Although the bike's geometry may not be considered "aggressive", depending on your personal measurements/fit, it could be more than aggressive for you. The fact that it's 'compact' does not make it more or less aggressive though... all of Cervelo's road frames are compact for instance, and considered aggressive.

It's a misnomer IMO that a taller headtube means less aggressive. Some people need taller headtubes than others, but are still put in an aggressive position. The absence of quill stems as the norm these days makes people think that spacers are bad, and they need to have their face in their front wheel all the time and it will make them faster. Me thinks it's using mild aerodynamic advantages to compensate for poor fit which affects power output (in most cases - some of you f'ers are just powerful and can get obscenely low).

The generally agreed upon reasoning for compact frame design (sloping top tube) is that it allows manufacturer's to produce a fewer amount of sizes to fit a wider market of riders. For instance a traditional frame may be made in a 48,50,52,54,56,57,58,60,62,63... while a compact frame could fit all those riders in a 50,54,56,58,60, or S,M,L,XL... less sizes means less cost to the manufacturer. Some will argue it makes a stiffer frame. I don't know about that.

The take away here should be that when you're sitting on top of the bike, whether or not the frame is compact or of traditional geometry won't be the deciding factor on it's overall ride quality. The material, quality of craftsmanship, components, wheels, tires, etc... and most importantly fit... will be what dictates if your bike suits your needs.

bidaci

^^^^ What he said!

I had an OCR that was plenty aggressive for my needs at the time, group rides. Read stable instead of comfortable or less aggressive. It really depends on what your expectations are and what type of riding you are going to be doing.

scirocco

Your wallet will feel lighter due to the successful marketing exercise.

Seriously, though, as an engineer I can buy the idea that a compact frame can be made stiffer than a traditional design. But as has been pointed out, a multitude of other factors come into play, and you never really get to compare apples with apples.