Road bikes with sloping top tubes

[David Tollefson]

The next question is how people feel about level top tubes for cross bikes?

See my previous reply on this thread.

[e-RICHIE]

I've been sloping the top tubes on my smaller lugged frames since the mid 1970s. All of my cx frames have sloping top tubes, and have since the mid 1990s. Regarding facts atmo, pipe sizes outside the traditional "old school" one inch top tube frame dims been available since (and even in) that era. And OS sizes weren't new when they crept into the mainstream in the 1980s. The simply weren't what people were used to, until they finally were. The same is true for UOS, XL, and double OS sizes. None of this is new; it simply takes a generation or more for some of these changes to supplant what can before them. However, some of the actual sets and pipes that comprise them are new (or were when they were introduced) even though the diameters weren't.

[Sean Hennessy]

Just a side note to this discussion. It obviously doesn't apply to all custom builders, but the UCI has design rules in place regarding sloping top tubes amongst other things. So as a result the extreme sloping top tubes that we saw on the early Giant TCR haven't been built by the large manufacturers since 2000. It wouldn't make business sense for them to manufacture bikes that can't be raced.

[abbeyQ]

However, some of the actual sets and pipes that comprise them are new (or were when they were introduced) even though the diameters weren't.

Do you dimension your signature parts off of the ID, like pipe is?

[e-RICHIE]

Do you dimension your signature parts off of the ID, like pipe is?

What doe that mean?

[Dazza]

What doe that mean?

Using the term pipe sounds hip or a trendy but can lead to confusion as the same dimension pipe is a very size to the same dimension tube.

Difference between Pipes and Tubes

A quick way to remember is that pipes have fluids flow inside them so the internal size is the important one for flow rates and volumes etc.
Tubes are structural so it starts with the outside inwards.

[Dazza]

Am I the only one that likes both?

I've made for myself a singlespeed frame with a level top tube and a road bike with 8º slope. I like both equally.

I like them both, and have two sizes of tube diameters with my lugged offerings with level top tubes and sloping top tubes. (about 6 degrees is the slope I settled on)
I do think that slopping top tube frames like sweetest with a straight blade fork only
and level top tubes are fine with both
that is my aesthetic bias

[abbeyQ]

What doe that mean?

Like Daza pointed out, Pipe is dimensioned off of the inside dimension because it has something flowing through it and that's the dimension that matters. The pipe size (ID) stays constant even as wall thickness (also referred to as "schedule" IE sch 40, 80, 120 and so on) increases. That keeps the flow constant regardless of wall. Tube on the other hand is tooled and dimensioned off of the OD and the ID is what changes with wall thickness. You use the term pipe on a somewhat regular basis and it incorrectly describes what you're talking about. Others are following suite and I figured I would attempt to straighten it out before people start thinking the two terms are interchangeable.

[Dave Thompson]

I've always regarded the term 'pipes', when used by fbuilders, as slang for tubes.

I like, and have both level and sloping top tube bikes. I like both aesthetics. I build level topped bikes more 'traditionally' and sloped less so.

[e-RICHIE]

Using the term pipe sounds hip or a trendy but can lead to confusion as the same dimension pipe is a very size to the same dimension tube.

Like Daza pointed out, Pipe is dimensioned off of the inside dimension because it has something flowing through it and that's the dimension that matters. The pipe size (ID) stays constant even as wall thickness (also referred to as "schedule" IE sch 40, 80, 120 and so on) increases. That keeps the flow constant regardless of wall. Tube on the other hand is tooled and dimensioned off of the OD and the ID is what changes with wall thickness. You use the term pipe on a somewhat regular basis and it incorrectly describes what you're talking about. Others are following suite and I figured I would attempt to straighten it out before people start thinking the two terms are interchangeable.

Oh - I use the terms interchangeably. I probably still will.

[Eric Estlund]

Pipetubebrassbronzejigfixture

It's short hand. I'm guilty.

[EricKeller]

wow, that took a turn toward pedantry that I never would have expected.

My time in the Air Force pretty much removed the impulse to say 'jig' as opposed to 'fixture'. Not PC enough

[steve garro]

wow, that took a turn toward pedantry that I never would have expected.

It actually has an important distinction if you order benders or dies

- Garro.

[EricKeller]

well, yeah, but you probably would never order a pipe bender. Is there such a thing? I have, on 2 separate occasions, ordered 3" pipe clamps only to find out that they are some random (much larger) size that fits a 3" pipe. Grrr.

[Mark Kelly]

371a-500x500.jpg

Yep, generally hydraulic.

I used to design food and beverage processing equipment, mostly in stainless. Mixing up tube and pipe could get very expensive.

[Jeffrey Borisch]

wow, that took a turn toward pedantry that I never would have expected.

My time in the Air Force pretty much removed the impulse to say 'jig' as opposed to 'fixture'. Not PC enough

On takeoff, George's trademark would be to call the tower. "The jig is up"

A great man I was lucky to know.

[Eric Estlund]

If this distinction is one misapplied in the construction of a bicycle there are larger issues at play than the angle of the offending top pipe.

[e-RICHIE]

If this distinction is one misapplied in the construction of a bicycle there are larger issues at play than the angle of the offending top pipe.

Agreed atmo.
God forbid others may follow suite and wreck the conversation about sloping top tubes atmo.

[Peter Polack]

When I ordered my custom Soulcraft I asked for a sloped top tube with an angle to match the common -6 degree stem. Aesthetically it just looks right to me for the stem and top tube to have the same angle. Sean was kind enough to oblige me.

What I DIDN'T want was an extreme slope because the smaller front triangle can make it difficult to insert/remove seat tube mounted waterbottles, especially since I wanted a pump mounted under the top tube. Something for framebuilders to consider.

[Mark Kelly]

Does that mean the tube is sloped at 11 degrees (assuming 73 degree head angle)?