terry b

That's how I've come along too. Didn't like them at first and now I'm a fan. The biggest unexpected byproduct - a little slope in the frame allows me to clamp the post in my stand without raising the seatpost. A nit for sure, but a nice nit that will certainly increase the life of the bolt in the seat clamp while allowing me the nicety of never having to mess with the setup of my saddle height once the bike is built. An overlooked benefit.

I think a bit of slope imparts a racier look as well.

dekalbSTEEL

I fr!gg!n' HATE my sloping top tube bike! Will some please buy the d@mn thing from me already**********

terry b

Change the bar tape to white and you'll fall back in love with it.

coleadam

are you sereous? what size is it? how much? and why do you hate is so much?

dekalbSTEEL

check the link in my sig for all the details

I don't really hate it, I just have 2 many bikes, and this one is the odd man out.

coleadam

not a bad deal, but i really just need a new frame and fork plus its to small for me and i think i'm leaning tward a LeMond

DrPete 

I'm not understanding the argument that a long seatpost negates the stiffness of the bike. Isn't the goal of a compact frame to create a stiffer BB and rear triangle, neither of which has anything at all to do with the seatpost?

habbit

ive got a felt with similar geometry. just feels a lot like a MTB to me. not bad, just different.

DannoXYZ 

Yeah, people don't realize that your butt is pushing off the seat. A LONG cantilevered arm is gonna flex a lot more than a triangulated part. Also the equivalent length of bike-tubing is gonna weigh a lot less than thick seatpost tubing. So whatever weight you save by chopping 6" off the seat-tube is gonna pile back on much more with 6" of seatpost... Not to mention the longer top-tube will be heavier as well.

If lateral-stiffness of the frame is your concern, there are various other design ideas that work a lot better than compact. Laterally ovalizing the seat & down tubes increases stiffness tremendously. As with increasing their diameter as they go to the BB like in Serottas. Same with using round instead of ovalized chainstays (think track bike). A wider axle-spacing and shorter chainstays would create a wider included-angle of the chainstays as well and brace it laterally.

Compact is all about marketing, there's no performance advantages, at least not significant enough to be quantified.

blackjack51

What a load of bollocks

The reach to the bars and the riding position is completely independent of whether the bike has a sloping top tube or not.

scirocco

I agree.

Earlier in the thread someone said that compacts make it hard to access the bottle cage on the seatpost. Not always the case - I have a compact with a steeply sloped top tube and I have absolutely no problems getting the bottle in and out. Maybe it depends on the style of the cage.

StanSeven

There are two competitive advantages to sloping top tubes. One is that the frame is more rigid for out of seat efforts as in climbing or standing sprints. The other is weight to the extent that the seatpost can be lighter than the frame material. In some cases, a weight savings result; in others, it's insignificant.

If you check the Tour de France team bikes, all but 4 teams had sloping top tubes. Many were built to specific riders wants and there's considerable differences in slope among the same bikes on a team. This reflects personal preferences.

bonelesschicken

Hey Cole, its Ross. Living in SF now? PM me.

Garfield Cat

Bike frame engineering is one of Cervelo's strong points. Their road racing frames are all sloping compact frames. Their web site goes into detail as to why they did what they did.

khuon

But you have to remember that the sloping top-tube is just one design element of a bike. You have to also realise why one uses it. You can achieve nearly identical outcomes with and without sloping top-tubes depending on what it is you're trying to achieve and how the rest of the bike is engineered.

Just because F1 racing cars have spoilers and are fast does not mean that sticking a spoiler on a Toyota Camry will inherently make it fast.

Paulus

I have one of each and to be honest can't feel any difference. As long as the steerer, BB and seat end up in the same place I don't suppose it matters much. The differences in weight and flex are minimal (IMHO). One thing though - I by far prefer the look of the traditional (level top tube) frame. My compact looks like some form of bastardised MTB and I dislike it. Others will no doubt disagree.

grahny

I gave my sloped top tube cervelo solist seat post some viagra so it would be as stiff as a traditional frame

531Aussie

compacts aren't always stiffer. My BMC streetfire is flexier than my traditonal frames.

Compacts aren't really lighter, either, especially if you have an alu seatpost, because 2 inches of seatpost is heavier tham 2 inches of seat-tube.

As others have said, it's mostly about fashion, and some people like the standover room.

As was mentioned, checking out the effective top-tube measurement is crucial, and some of the geometry charts are tricky to read for the uninitiated.

bellweatherman

Why do we even need a top tube?

531Aussie

a bike obviously needs either a top-tube or a down-tube to function, so take your pick



I think UCI rules state that bikes in sanctioned races must be the basic "diamond", or "double triangle" design, which is why bikes like these were banned.......
...but someone might wanna correct me; I'm not 100% sure on the latest ruling.
I gather they were worried that bikes were starting to not look like bikes at all

c4s6

This is a great example of the type of advice that shows you rarely get more than you pay for...

I'm agnostic on the aesthetics of compact geometry. Form follows function. There's a reason most of the pro tour riders are on compact geometry frames as mentioned above.

When I decided to get into the 1 kg frame market, I was fairly analytical about it and decided first on frame material and concluded titanium was where I wanted to be. The only real alternative then was the Magia. Clearly, I was able to get it to fit. I have the Easton EC90 CNT seatpost which is claimed to weigh 190 grams. So I guess I don't buy you put on more in seatpost than you save in seat tube, plus the stiffer rear triangle.

Al1943

Seven out of eight of the last TdF winners were on traditional frames.

dekindy

Here is what the Cervelo website says.

Answer - Traditional, sloping & compact frames
A sloping frame is a frame that has the toptube higher and the headtube than at the seattube, as opposed to a traditional frame that has a horizontal toptube. It really doesn't change anything important in the geometry, the headtube, bottom bracket and saddle, the only points you connect with on a bike, are still in the same spot.

There are however some small differences between sloping and traditional frames that can be exploited in design. If you have two frames that are made identically except for the sloping vs. horizontal toptube, then the following can be observed:

1) slightly higher bottom bracket stiffness for the sloping frame
2) slightly higher torsional stiffness for the horizontal toptube frame
3) slightly lighter frame with the sloping toptube
4) slightly lighter seatpost with the horizontal toptube frame
5) slightly more seatpost compliance with the sloping frame.

Issues 3 and 4 are a wash, and for us at Cervélo the choice between sloping and horizontal depends on what combination we are looking for out of 1, 2 and 5. For our Road bikes, which have plenty of bb and torsional stiffness anyway, we go with a sloping toptube (or a dropped toptube on the tri bikes which has the same effect) to get a bit more seatpost compliance.

Compact geometry is the use of a sloping toptube to convince people you only need to make 3-4 sizes. As is obvious from the above, nothing changes in the way a bike fits when you make the toptube sloping. So if you need six sizes in a traditional geometry, then you still need six if it is sloping. Henceforth we're not big believers in compact geometry. But the terms compact and sloping are really used interchangeably by many people, so make sure you understand what they mean.