Slopey top tubes

I don't like how slopey top tubes look.  But, I see them everywhere these days.  Why do they exist?  Does anyone actually think they look cool? (I KNOW THATS PROBABLY NOT THE POINT, I'm guessing they have some practical value)  It seems they were not used on the top tubes of the eighties and nineties.  I have four frames of the eighties and all top tubes are parallel to the floor.  So what's the deal with these things yall? 

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Permalink Reply by Drewbacca on March 27, 2014 at 6:28am

Taller head tubes result in a more upright riding posture, which is desirable... they require a sloping top tube or else you get an incredibly tall stand over height. 

Permalink Reply by Kevin Mulcky on March 27, 2014 at 6:31am

On hybrids the sloping top tube give the bike a lower standover height, a higher top tube, and is better suited for non-exact S/M/L sizing.

On racing bikes, the sloping top tube style is referred to as a compact frame. There's less distance between the frame joints on the front triangle. This benefits racing bikes by leading to a lighter, stiffer frame. 

Permalink Reply by Skip Montanaro 0mi on March 27, 2014 at 7:02am

Following up on Kevin's response, I think it was originally done as a cost-saving measure. Manufacturers could get away with fewer distinct frame sizes. This is especially important for carbon fiber frames which laid up in molds.

I don't like the way they look either. But I'm an old fart (what's your excuse? <wink>) While I do have one bike with a sloping top tube, it's nearly headed out the door. All my other bikes (mostly 70s/80s road bikes, even my old Schwinn Speedster beater) have traditional triangular "safety bicycle" dimensions.

Permalink Reply by Robert Underwood on March 27, 2014 at 8:53am

hmmm... interesting.  I guess it would save them money in production costs, one setup to produce multiple results.  I only owned one with a sloping t.t., a Raleigh Sojourn(er?) from 2010 and sold it couple yrs after I bought it.  I may be more concerned with asthetics on bikes than most, but it just bothered me so much every time I looked at it.  also the wheel would hit my toe when I turned while pedaling.

I wonder if it will last, or become the norm or just fade away.

Permalink Reply by Skip Montanaro 0mi on March 27, 2014 at 9:05am

Overlap of your shoe with the front wheel isn't affected by the slope of the top tube. In theory, the seat tube and head tube angles could be the same.

I doubt it will fade away. It's not often that companies voluntarily increase their costs. :-)

Robert Underwood said:

hmmm... interesting.  I guess it would save them money in production costs, one setup to produce multiple results.  I only owned one with a sloping t.t., a Raleigh Sojourn(er?) from 2010 and sold it couple yrs after I bought it.  I may be more concerned with asthetics on bikes than most, but it just bothered me so much every time I looked at it.  also the wheel would hit my toe when I turned while pedaling.

I wonder if it will last, or become the norm or just fade away.

Permalink Reply by Robert Underwood on March 27, 2014 at 9:52am

I just meant that was another reason, the overlap of the front wheel. 

probably wont fade away, your right.  At least there are still some flat... traditional... whatever you call it, safety triangle, options.  I was looking briefly for some cross bikes with flat tubes and couldn't find any. 


Skip Montanaro 12mi said:

Overlap of your shoe with the front wheel isn't affected by the slope of the top tube.

I doubt it will fade away. It's not often that companies voluntarily increase their costs. :-)

Permalink Reply by Gecko on March 27, 2014 at 11:45am

The 'safety bicycle' has nothing to do with sloping top tubes.  It means any diamond-frame or similar with freewheeling front wheel attached to forks connected to steerable handlebars, and chain or belt-driven rear wheel drive, with the rider's weight distributed as evenly as possible between the two wheels.  The only technically non-safety bicycle is a pennyfarthing.

Back on topic, the big selling points for sloping top tubes as I remember from working in a shop were 1) better standover height while keeping proper leg and arm extension, and 2) taller headtube for more upright riding position if desired, without using tons of stem spacers or having a super long fork.  Everyone at that time agreed (without any scientific evidence, mind you) that sloping top tubes weren't aero enough for "serious" racers but could be very effective for cyclocross or epic touring rides.

Permalink Reply by Legacy Frameworks on March 27, 2014 at 11:57am

As a framebuilder, who builds with 8 degree sloping top tube in my diamond frames, I do it as a way to get the rider more upright and to maximize the range of heights that can fit on one size. 

The real issues come in on the smaller range of the frame sizes. If you want a 700c bike with room for larger tires and fenders, that is going to mean a longer fork and higher bottom of the head tube. 

Take my small frame for example. As it is now - with 8 degrees of slope in the top tube and the head tube 10cm (shortest I  want it for a couple of reasons) I can have a 48.5cm (19in) Seat tube and 74.5cm (29.25in) Standover. If I wanted to make it a horizontal top tube and keep the head tube length, it would have to be a 53.5cm (21in) seat tube and a 78.5cm (31in) Standover. That extra couple of inches, could mean getting someone on the bike that wouldn't otherwise be able to.

Now you've got me going....

Permalink Reply by Skip Montanaro 0mi on March 27, 2014 at 12:11pm

Yeah, isn't that kind of weird? I like mixtes, hate the modern sloping top tube...

Jeff Schneider said:

OTOH, the mixte frame is a thing of beauty...

Permalink Reply by Lanterne Rouge on March 27, 2014 at 1:57pm

I have been on an anti-sloping kick for a couple of years, but now I'm over it. I'm probably going to add a second bike to my quiver, and I want it to be brand spankin' new. 

Sizing is much different on sloping top tubes as well. Whereas I ride a 57-58 cm on a traditional frame, I have rode 52-54 cm on a compact frame, with no issues whatsoever. 

Permalink Reply by Robert Underwood on March 28, 2014 at 5:19am

I don't understand (just saying... I might research this farther), how it adds stiffness.  not that I don't believe it, just curious.  aesthetically speaking, I will always dislike the look of a slanted tube.  I tend to go with the vintage look over modern, generally speaking.  (However, if slanted was vintage, and level was modern, Id go with modern in this case.)    

    

Permalink Reply by Ryan Stahlman on March 28, 2014 at 5:28am

I am also a fan of the nearly horizontal top tube, hence I ride an 80's era touring bike. Rivendell just posted about a new custom frame they built for a short customer. I really enjoy the creativity and care they put into the frame design that allowed the top tube to remain horizontal.

http://rivbike.tumblr.com/post/80720787036/heres-the-story-of-our-l...

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