Frame Geometry

[jrenaut]

Just thought of this while reading Dasgeh’s thread about picking out a good commuter and didn’t want to threadjack.

What is the benefit of a slanted top tube? My old bike had one, my current doesn’t. I really prefer a flat top tube aesthetically.

Topic

[DismalScientist]

It’s easier when you wear your dress.:rolleyes:

[mstone]

@jrenaut 74102 wrote:

Just thought of this while reading Dasgeh’s thread about picking out a good commuter and didn’t want to threadjack.

What is the benefit of a slanted top tube? My old bike had one, my current doesn’t. I really prefer a flat top tube aesthetically.

You can get a higher head tube without a darwin award.

[DismalScientist]

@mstone 74110 wrote:

You can get a higher head tube without a darwin award.

This only encourages violations of Rule #44.

[dasgeh]

It’s a good question. If I could get a fast bike with a sloping downtube, I’d be all over it. I guess I should say that in my thread.

[vvill]

My understanding was that the sloping downtubes of “compact” frame geometries allow a specific frame size to fit more people (via stem and other adjustments). So a manufacturer might make a bike in 5 sizes to fit the general population, whereas with a traditional geometry they may have made 7 or 8 sizes, for example.

[TwoWheelsDC]

Sloping top tube = more seatpost. The more seatpost you have, the more Pro you look.

[cyclingfool]

@TwoWheelsDC 74315 wrote:

Sloping top tube = more seatpost. The more seatpost you have, the more Pro you look.

Which makes a folding bike ELITE Pro!

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[jrenaut]

So there’s no real advantage to ME and I’m free to find the flat top tube much more aesthetically pleasing? Good to know.

[mstone]

@jrenaut 74317 wrote:

So there’s no real advantage to ME and I’m free to find the flat top tube much more aesthetically pleasing? Good to know.

The advantage is what I said: you can get a higher head tube, meaning that you can get higher handlebars without compromising strength or clearance (other ways to raise the bar relative to the seat are to have a long unsupported steerer or to drop the bottom bracket). If you always ride with the seat much higher than the bars, this would not be an advantage to you. Or, you can stay old school and simply have very little clearance over the top tube, which is risky if you’re putting your feet down a lot.

[jrenaut]

Sure, but I have a bike with a flat top tube that fits me well and I put my feet down all the time and haven’t yet had any unwelcome incidents. So it’s really a solution to a problem I don’t have, and also ugly.

[TwoWheelsDC]

I have two road bikes. One has a straight top tube (Cannondale CAAD) and one has a sloping top tube (Cervelo R3). I can barely tell the difference, but the R3 gives me a slightly more upright position on the hoods and I don’t have to stretch as far to get in the drops. Aesthetically, I’d probably pick a straight top tube bike over a sloped top tube bike, if all other things were equal, but priority-wise, it’s fairly low on my list. Now, no offense to Spesh owners, but *curved* top tubes make me want to vomit.

[vvill]

@jrenaut 74317 wrote:

So there’s no real advantage to ME and I’m free to find the flat top tube much more aesthetically pleasing? Good to know.

The indirect advantages are reduced design/manufacturing/etc costs leading to cheaper bikes, and an increased chance that you’ll find a bike in stock or in the second-hand market that can fit you, or someone you’re shopping for.

For a classic bike look I also prefer a straight level top tube (and round, thinner tubes), but looks aren’t everything. I’m all for innovation and different shapes, tubing, etc. and I’m more than happy with my compact road frame for the bulk of my riding. And I would love to ride an Infinito CV, for example.

[jrenaut]

@vvill 74356 wrote:

but looks aren’t everything.

… says a guy who probably has ugly bikes.

[mstone]

I scoff at people who babble about classic looks and aren’t riding a pennyfarthing. And don’t get me started on pneumatic tires.

[jrenaut]

I don’t really care about classic vs otherwise. I’m just mad that my current bike-object-of-lust, the Pinarello Catena, seems to have traded last year’s flat tube for a slight downward slant.

[Author]

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