Sloping/Horizontal top tube?

Good evening, people of LFGSS.

I have UTFS, but the threads have been about top tubes sloping downwards towards headtube, such as Lo-Pro frames.. But i'm talking about the ones sloping upwards, such as the one on the Langster.

I was wondering, what are the advantages and/ or disadvantages of sloping (upwards) and horizontal top tubes? I've just been told that the horizontal top tubes are supposed to be more race orientated aren't really for touring/ long distance - I don't see how?
Someone also told me that bikes with horizontal top tubes don't handle as well as those with sloping? HOOOWWW?!

Anyone who can enlighten me about this will be mucho appreciated! :)

more standover height.

It's known as 'Compact' geometry

Lighter, cheaper manufacturing costs and theoretically stiffer.

more here:
http://www.bikeforums.net/showthread.php?49639-compact-vs.-tradtional-geometry

Someone also told me that bikes with horizontal top tubes don't handle as well as those with sloping? HOOOWWW?!

don't listen to Ed that's just hearsay regurgitated from the interweb.

pifko said it. thread over.

It's known as 'Compact' geometry

Lighter, cheaper manufacturing costs and theoretically stiffer.

more here:
http://www.bikeforums.net/showthread.php?49639-compact-vs.-tradtional-geometry

This.

Here's my next steed (just got to get the cash together :-) )

It's known as 'Compact' geometry

Lighter, cheaper manufacturing costs and theoretically stiffer.

more here:
http://www.bikeforums.net/showthread.php?49639-compact-vs.-tradtional-geometry

marginally stiffer, yes but a diagonal line is longer than a horizontal line therefore more material -> marginally heavier, no? Plus you end up having heaps of seat post, too, which also = more weight.

Here's my next steed (just got to get the cash together :-) )

That's just hideous!!!

The compact frame idea was pioneered by Mike Burrows and commercialised by Giant with their TCR frame. The idea is that by having a rearward sloping top tube, you have a smaller frame (for a given size) therefore lighter and stiffer.

For manufacturers, the advantage is that you don't have to make as many different frame sizes. With traditional horizontal top tubes, frame size is mainly governed by seat tube length. With a compact design, seat tube length is irrelevant - you just compensate for lack of seat tube with a longer saddle post.

Interesting bike - but so many questions

Why curve the seat tube and not mirror the curve of the wheel?
Why not close up the clearances to shorten the wheel base?
Why disk brakes?
How does the belt tension work?
Is that a derailleur hanger?
Why biaxial ovalise the downtube?
What's with the Rohloff cable routing standoff o the head tube?
Does that seat tube flex a lot?

Actually - is that a Rohloff?

i just came into this section about to ask a similar question.

what is the advantage of having a curved seat tube?

I'm considering starting another project and want to have a new frame built for me. On a purely aesthetical level, i love the look of a curved seat tube, so i'm hoping that the purpose of them is going to benefit me.

Is it again to further compact the frame size?

Like this:

and i too UTFS

;)

The curved seat tube can allow the rear wheel to be taken closer to the BB and give the shortest possible chain-stay length for maximum stiffness. How much difference it makes who knows and the one in the picture is probably more for show than performance.

to shorten the wheelbase to make it more responsive.

marginally stiffer, yes but a diagonal line is longer than a horizontal line therefore more material -> marginally heavier, no? Plus you end up having heaps of seat post, too, which also = more weight.

But a compact frame will have shorter seat tube and chainstays.

How many people actually cut down the excess seatpost material when used on traditional frames?...

@ Dynamical

It's made by a spanish company called Jeronimo.

Frame shaping is quirky absolutely - totally personal but I love it.

Disc brakes? Well I run a single Dura-Ace on my current bike, but I'm a motorcyclist (and an engineer) and taking your braking surface as far away as possible from the sh1t makes a hell of a lot of sense to me.

It's Ti so I guess the integrated seat tube should be quite compliant. Comfy ride rather than a ball rattler.

Belt tensioning is a p o p, I ride a District based fixie and it would take a lot to convince me to move back to chain.

Clearances etc? Don't know, just love the look. For the sort of commuter hammering I do I can't imagine that track geometry would make that much difference.

As with everything it's personal aesthetics - I just like this, don't know why but I do.

there is a severe amount of InternetTheoryBullshit™ around here.

^more of it.

But a compact frame will have shorter seat tube and chainstays.

How many people actually cut down the excess seatpost material when used on traditional frames?...

Dunno but you end up buying a much longer seat post than what you'd normally need + plus a longer top tube.

marginally stiffer, yes but a diagonal line is longer than a horizontal line therefore more material -> marginally heavier, no? Plus you end up having heaps of seat post, too, which also = more weight.

The shortest top tube possible would be where the top tube is perpedicular to the seat tube, hence being the lightest also. The design is always going to be a compromise between a short top tube and one that give the frame maximum stiffness.

^more of it.

you want more?
here's my favorite: "nippy in traffic"

don't listen to Ed that's just hearsay regurgitated from the interweb.

Actually I heard it from the guy at the LBS.. But hey, thanks for all the help guys. Laff you all :)
One more little theoretical question: So would, lets say, a 52cm frame with a sloping TT of around 7 deg, have the approximate same fit of a ~55cm frame with a horizontal TT, assuming ceteris paribus (All other things equal, eg head tube length etc etc)?

Or is this not the case?

Do you mean a compact frame with a 52cm seat tube?

Well, the question isn't really very relevant as on a compact, the seat tube length is immaterial as you can have whatever virtual seat tube length you want by using different seat post lengths.

What is relevant is what is the virtual top tube length on a compact frame. By virtual, I mean what the top tube length would be if the top tube was horizontal. That determines the size of compact frame more than the seat tube length.

Any frame with a sloping top-tube is stiffer and generally far superior to a frame with a horizontal top-tube the only real disadvantage is that due to the extra forces on the seat-tube you can't fit a negative shim to your seat-post should you need one.

the forum has gone full circle into n00bery again.

ask edscoble, he believes in all that red herring shit