Educate me on sloping top tubes - or is it just marketing hype?

[gary_a_gooner]

Originally Posted by ntkt10

You're correct. Some people like to see 12 inches of seatpost sticking out of the frame instead of 3 inches.

I prefer the average amount of seatpost--about 6 inches.

[Mark McM]

Originally Posted by wallymann

how does this work?

for me, top-tube height is irrelevant within "normal" limits. i swing my leg over the saddle from the back or handlebars from the front, both are much higher than any top-tube will ever be...so you actually step over the top-tube?

For most of the people here, top tube slope has no affect on the ability to mount/dismount a bike*. But if you look at less experienced and/or more casual cyclists, you'll see that a common way to mount is to first swing their leg over the saddle and straddle the top tube with both feet flat on the ground, and then step on a pedal and push off, before rising up to sit on the saddle. A little extra room to play with while straddling the bike can make this mounting style easier.

*The exception is cyclocross racers, who generally prefer a more "traditional" horizontal top tube, which makes it easier to pickup and shoulder a bike while running.

[Mark McM]

Originally Posted by DfCas

Also in a sloping frame the seatstays are less vertical which allows for more compliance.

While that is true, it is not because the rear triangle flexes more. The frame and rear triangle is essentially a truss, and has very little vertical flex. Even making the rear seat stays less vertical won't add any significant compliance. In contrast, the seat post is a cantilevered bending beam, and can have significant amount of flex. Lowering the seat stay/seat tube junction makes the seat post longer, increasing the flex even more (cantilever beam flex increases with the cube of length).

[OtayBW]

Originally Posted by tv_vt

Read this blog entry by Tom Kellogg for another data point...

https://www.spectrum-cycles.com/geometry.php#compact

Yep.

With that now off my chest, I'll follow up by saying that I like the traditional (level TT) look best...

[pobrien]

And I will pay more attention to the classifieds to scoop up orphan Colnagos with a horizontal top tube. Size 59 particularly.

[pdmtong]

Originally Posted by Butch

When threadless headsets came out steer tubes were steel or ti so you could stack the same as a quill stem with a threaded headset. With carbon steerers the max stack height is limited. Headtube lengths have gotten pretty long in the past few years in order to fit most riders better. When we designed stock bikes with sloping top tubes it allows a customer to be more likely to dial in top tube length without having to go to custom in order to have standover. This is assuming there are many stock sizes to chose from. Balancing aesthetics and function is always a challenge, it is handy people are used to seeing long seatposts.

this is very insightful and obvious once considered.

you can also see the benefit of slope when it comes to the smaller frame sizes.

slope allowed my then 10yo daughter to be on a 44cm specialized dolce with 700c wheels

[Ken Robb]

Originally Posted by Jaybee

I have a friend, not a serious rider, who mounts the bike by standing on the NDS pedal, scooter style push starting, and then swinging his leg over. Every dismount is cyclocross style.

When I was a kid we all used this technique because we were all riding full-size bikes with 26" balloon tires and none of us had any clearance at the top tube. In fact we didn't push off, we got the pedal at the 11 o'clock position, stepped on it to get the bike moving and swung our other leg over the saddle and rode off. To dismount we stood on one pedal as we slowed and swung the other leg over the saddle to the same side BEFORE we stopped to prevent banging our privates on the top tube. I had a Schwinn Traveler with caliper brakes which was better for this than a bike with just a coaster brake for obvious reasons. :-)

[oldpotatoe]

Originally Posted by gary_a_gooner

I prefer the average amount of seatpost--about 6 inches.

a 'fist'...any less and the frames too big(paging weisan-'pal'...)..

[SPOKE]

Sloping yet on a road bike is ok as long as it’s less than 4 degrees. Any more than that just ruins the look IMO.