Road bikes with sloping top tubes

[febikes]

I don't see very many road bikes with sloping top tubes. Some "compact" frames like the Giant TCR exist but they are pretty rare plus usually the slope is not very much. Especially with handmade microbuild type guys it seems the level top tube style road bikes are much more popular but this is also true of the big brands.

For reference, the following is a basic view of the approach. Modern seat tubes are available with 350mm length so why not build bikes with top tubes that slope down as much as possible while still allowing the rider to fit? It seems logical to assume that the smaller front triangle would increase lateral stiffness and the longer seat tube mast would provide more favorable vertical compliance.



In any case, what are your thoughts as a builder. Do you feel there is a structural reason for level top tubes on road bikes?

[zank]

Nope. I just like the way they look.

[John Winston]

agree. road bikes look right with level tubes.

[David Tollefson]

I haven't made a level-top-tube bike yet. Unless the customer really wants it for aesthetic reasons, I just don't see the point. But I also don't do lugged construction, and they seem to go together.

[Jonathan]

On smaller bikes I prefer to slope the TT a few degrees. Aesthetically it bothers me to see a seat post with its logo disappearing into the seat tube and not much post showing. A little extra stand over never hurts smaller frames either. On larger bikes I prefer level top tubes.

[Crowemagnon]

in my mind, i dont want the saddle changing relationship from the BB or handlebars (riding a worn-out saddle which bounces alot can be very bad) so lots of exposed seatpost isnt where i look to get compliance to absorb bumps in the road.

i try and build the front triangle (including whatever holds the saddle) stiff, and float, or suspend it between the wheels using a supple fork and stays, like suspension.

thus the toptube-seattube junction stays up pretty high, and the tube stays pretty flat, and the seat doesnt move around too much.

[Amaro Bikes]

Well, I guess no one builds road bicycles with sloped top tubes because then they would not be road bicycles anymore...
Also, if Dario said he does not build any road frame with sloping it becomes a holy Commandment for all apostles!

Although Tyler likes to do some slightly sloped top tube in the road Fireflies, so I guess he founded the protestant church!

Man, is amazing how much metaphysical discussion a simple tube angle can create, we're so fucked...

[Mark Kelly]

Client decides.

[Amaro Bikes]

client decides.

never!

[fastupslowdown]

I'm not a builder, but am surprised to hear votes in favor of sloping or aesthetic reasons. I have two bikes one sloping, one not(the frames are not large 50cm & 4cm sloping), and the sloping at least for me , lacks a certain symmetry. -Mike G

[Andrew R Stewart]

To slope or not to- That is the question.

I try to let the fit of the bike, including stand over, determine the TT slope if any. Most of the bikes I build are rather small so many get some slope. Andy.

[Rody]

The performance and design objectives define the ultimate shape of the bike, the aesthetic comes after. If not constrained by materials (traditional lugs), I've rarely found a physical rationale for building with horizontal top tubes.

This one was built compact to fit into a S&S case...

small headbadge road bike.jpg

This one was built with a sloping top tube to maximize rigidity/power transfer using very thin butted titanium tubing...

zombie1.jpg

Though customer input certainly has it's place, utlimately, it is the builders resonsibility to create a design that is the culmination of the vehicles performance/fit requirements.

[abbeyQ]

never!

Always.

[Dazza]

Snipped for clarity

The performance and design objectives define the ultimate shape of the bike, the aesthetic comes after.If not constrained by materials (traditional lugs), I've rarely found a physical rationale for building with horizontal top tubes.

I agree with Rody, "design objectives are defining", but I also would include that aesthetic can be a design objective as long as it does impact negatively on the design objectives.

"constrained by materials (traditional lugs)"
to a certain degree, yes, but for road bikes there are two sizes of round tube sets sloping top tube lug sets which cater for lugged building, giving the lugged builder more freedom in design. Which is my own flavour with lugs.

A road bike lug set for a round XL tube size has been around since 2004.





Read more here

The Framebuilders' Collective | Llewellyn – XL Compact

These tubing sizes are marketed by some as Uber or double over size etc but have been available from Columbus and other makers since at least the mid 1990's.
By selective omission of facts it is marketed as a new offering, sigh!
(Direct fitting 30.60mm seat posts into 31.7mm .7/.5 or .8/.5mm seat tubes have been available since 2004)

A road bike lug set for OS tube sizes has been around since 2006. (I have since been informed there was an Italian Builder who had a OS sloping lug set but kept supply in house)





read more here
The Framebuilders' Collective | Llewellyn – OS Compact

Aesthetic bias is allowable and is just fine and dandy.
However sloping top tube frame designs have merit for aesthetic reasons and for good design reasons when selected and designed correctly for small frames, high handle bars or because the punter likes it.

[SteveP]

Reluctant at first... now my 2 favorite bikes have sloping ttubes. ( 2 times )
I thk, long run, the level top tube will disappear.

Relegated to classic lugged steel bikes. Which some people like.
Nothing modern.

[fpavao]

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.

[Mark Kelly]

Client decides.

never!

Never a sloping top tube or never let a client decide such a thing?

If the latter: why not?

[Curt Goodrich]

I like 'em level (road bikes) because it's my name on the down tube and that's what looks proper to me. Sometimes I'll put a small slope (1-2 degrees) if I need a longer head tube but even that keeps the traditional look that I like. I've built lots of bikes with sloping top tubes but none with my name on the down tube.

[Dallas Tex]

IMHO, both are great.

But I prefer straight blade forks on sloping TT bikes and curved on horizontal TT. Not a rule or a 'have to'.

[febikes]

However sloping top tube frame designs have merit for aesthetic reasons and for good design reasons when selected and designed correctly for small frames, high handle bars or because the punter likes it.

I like form follows function an can't see any function for the level top tubes so they simply look ugly to me. This may also be related to the fact that I spend a lot of time riding 29er style mountain bike. On mountain bikes level top tubes are pretty rare. My road/cx bike does not look "traditional" but the mix works for me and the logic makes sense.

I also like mounting the stem to slope upwards because it provides a logical way to get the bars where they need to be.


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