Why do Lemond Renos/Tourmalet have sloping top tubes?

[vegasbabee]

I'm a novice hybrid bike owner who may add a road bike in the future for long commutes and a speed fix . I noticed that the alloy Lemonds have a sloping top tube ala a hybrid cycle. Why do most road bikes have a horizontal top tube? Benefits of each?

 

[Walrus]

I'm a novice hybrid bike owner who may add a road bike in the future for long commutes and a speed fix . I noticed that the alloy Lemonds have a sloping top tube ala a hybrid cycle. Why do most road bikes have a horizontal top tube? Benefits of each?

I'd suggest searching the forums for this, as the arguments are many. The sloping top tube (sometimes refered to as a "compact" geometry) is basically just another design option. Some claim that this makes the frame lighter and stiffer, due to the shorter top tube and the change in geometry.

It's a personal thing. Look at the pro peloton and you'll find a mix of teams using both.

 

[biker7]

Benefits are a longer steerer tube relative to seat tube length for higher handle bars and more stand over clearance...a slightly lighter and stiffer frame.
George

 

[lokstah]

...a slightly lighter and stiffer frame.
George

Beg to differ, there. Though the companies which embrace compact designs (like Giant and Specialized) push "lighter and stiffer," it simply can't be illustrated as a valid fact. To my knowledge, it never has been. All in all, it's better to look at compact geometry as just another means to an end--there's nothing wrong with compact frames, but they're not a magic revolution either.

Get one if you like the look, or if the angled top tube gives you a better standover-height option. You should also get one if you couldn't care less, and the compact option comes in a color you like more than the standard geometry option next to it.

 

[boudreaux]

Benefits are a longer steerer tube relative to seat tube length for higher handle bars and more stand over clearance...a slightly lighter and stiffer frame.
George

BS........! Can't you do better than regurgitating and generalizing Georgie?

 

[baj32161]

The compact design yielding a lighter and stiffer frame is the conventional mantra. I have a 2004 Tourmalet and test rode many bikes before buying it. I can honestly say that I didn't notice a difference in ride quality simply due to the sloping top tube. I rode compact frames (Giant, Specialized) and traditional frames (Trek, Cannondale) and once I rode the Lemond I found that I liked the "happy medium." The Lemond, IMHO, is not a true compact frame. The top tube is only slightly sloped and,unlike most companies who use compact frames and only offer 3 or 4 sizes (S, M, L, XL) the Lemonds offer a full range of sizes from 48cm - 61cm. I think, now that I have the bike, I really like the greater standover clearance it offers without being a "true" compact frame.

I hope this helps.

Brian

 

[biker7]

beg to differ back at you lokstah. Its a simple geometry lesson. One could argue comparing same size frames both the seat tube and sloped top tube are shorter for the same sized compact frame hence lower weight. The shorter seat tube of a compact frame is partially but not completely negated by the added weight of the longer seat post but the shorter length of the sloped top tube which creates the same virtual horizontal top tube length of a convention frame from seat tube to steerer tube is not to be denied. Always was and always will be shorter than a level top tubed conventional frame and hence the weight savings.
George

 

[lokstah]

beg to differ back at you lokstah. Its a simple geometry lesson. One could argue comparing same size frames both the seat tube and sloped top tube are shorter for the same sized compact frame hence lower weight. The shorter seat tube of a compact frame is partially but not completely negated by the added weight of the longer seat post but the shorter length of the sloped top tube which creates the same virtual horizontal top tube length of a convention frame from seat tube to steerer tube is not to be denied. Always was and always will be shorter than a level top tubed conventional frame and hence the weight savings.
George

Triple differ ya.

First off, notice that it's impossible to discuss this without bringing in faith-based suggestions, such as compact lightness being "partially but not completely negated by the added weight of the longer seat post." You're wading into massive variables territory here, George. It depends on the seattube height (many supposedly compact frames have tall ones). It depends on the seatpost itself (is the seattube low enough that a comparatively bulky seatpost is required to counter the long extension?). Is the distance between the toptube-seatstay junction and the saddle cutting into stiffness? What frame are we talking about here, anyways? An Airborne Torch? A Specialized Allez Pro? A Giant TCR? A Lemond Tourmalet?

All pointing, of course, to my point that you can't make secure claims about compact geometry benefits--nothing that's meaningful beyond raw, pre-production theory, at least.

I'd also disagree with the suggestion that a sloping toptube necessarily involves less tubing than a classic frame sized for the same rider. Assuming a standard seattube angle, you're looking at a negligible difference only, which may or may not be countered by a difference in the seatstay angle and junction placement. Depending on the angle of the slope and the angle of the seattube, though, you're bound to have instances where the geometry doesn't favor either.

All in all, it's a wash across the board. I've got a 2002 alloy TCR (quite compact) and a 2004 Klein Q-Pro (classic and long), and the latter is both stiffer and lighter. I wouldn't chalk that up to classic versus compact geometry, though; it's just a better frame.

 

[artmichalek]

beg to differ back at you lokstah. Its a simple geometry lesson. One could argue comparing same size frames both the seat tube and sloped top tube are shorter for the same sized compact frame hence lower weight. The shorter seat tube of a compact frame is partially but not completely negated by the added weight of the longer seat post but the shorter length of the sloped top tube which creates the same virtual horizontal top tube length of a convention frame from seat tube to steerer tube is not to be denied. Always was and always will be shorter than a level top tubed conventional frame and hence the weight savings.
George

The shorter seat tube is more than negated by the longer seat post. Inch for inch, seat post tubing is heavier than frame tubing. The top tube also doesn't turn out to be that much shorter. Materials and construction have a much bigger effect on weight than the shape. That said, the only valid reason not to get a compact is if like me, you have to shoulder your bike up stairs every day.

 

[biker7]

There isn't a major weight savings...but no wash equating two frames with the same wheel base and 3 pt contact. I will side with the book on compact frames and we will have to agree to disagree.
George

 

[lokstah]

There isn't a major weight savings...but no wash equating two frames with the same wheel base and 3 pt contact. I will side with the book on compact frames and we will have to agree to disagree.
George

Agreeing to disagree isn't embraced enough around here. I salute us.

 

[biker7]

hehehe. After a while we are all on the same page and argue for argument sake...lol.
Cheers to my brethren.
George

 

[artmichalek]

hehehe. After a while we are all on the same page and argue for argument sake...lol.
Cheers to my brethren.
George

I don't know about you, but I'm arguing for the sake of not getting any real work done.

 

[lokstah]

I don't know about you, but I'm arguing for the sake of not getting any real work done.

Something like that. Well done.

 

[Slider77]

Benefits are a longer steerer tube relative to seat tube length for higher handle bars and more stand over clearance...a slightly lighter and stiffer frame.
George

That depends entirely on the particular frame and whether the individual sets the bike up as intended . Most of my road racing compadres that use compact geometry have as much or more handlebar drop as standard frames available to them.

 

[boudreaux]

Agreeing to disagree isn't embraced enough around here. I salute us.

That can't work. There has to be a moron.

 

[lokstah]

That can't work. There has to be a moron.

And a wiseass.

 

[baj32161]

And a wiseass.

YOU guys oughtta try Bikeforums...you'd fit right in

 

[Insight Driver]

I would like to weigh in with a serious answer. The sloped top tube is current fashion. It does allow a person to get a larger frame because they will have the standover clearance at least near the seat. All manufacturers are not slave to fashion, though in this case I would say they are since there is no particular advantage to either sloped top tube or horizontal top tube.

I think the only important thing is make sure you don't get square wheels. Round ones work better, IMOHO