I need some help from the forum. I have basically only ridden tri bikes. I am looking into buying a road bike for the winter group rides, training, etc/
I realize compact frames are lighter but what are the general pros and cons of buying compact vs. non-compact frames?
Thanks for any info.
Compact=longer seatpost
Non compact=shorter seatpost
I have ridden both and I dont believe that there is much difference, certainly less than the difference between individual frames. If you have short legs and a long torso you might find it easier to get the correct top tube length on a compact.
Are compacts supposed to be lighter than frames having horizontal top tubes? First time I’ve heard this. If it is so, why so?
Some say compacts are better for putting the power down in hill climbs. I have my doubts cuz again I don’t see how so?
My current perception is that the compact frame is just another frame design not giving any diff in performance. It is convenient for women athletes who want more modesty is all.
Compact frames I think are a good thing, especially if you are looking in the realms of Ti or Steel. I’ve owned both types of frames and have to say that I prefer compact. They’re lighter (whoop’d E doo), but more importantly, theyre stiffer and their center of gravity is lower. All this makes for a very fast climbing bike. If you happen to be tall, like me, the weight savings and stifness advantages are amplified compared to the larger bike you would otherwise be riding.
Comparitively, a compact frame will be very slightly lighter, but noticeably stiffer because of the tighter, smaller, more efficient back end. They make great climbing bikes and I like to climb, so it’s a good idea for me. I am also very tall, so the minor weight savings and especiallly the stiffness advantages help me out.
HOWEVER, the compact frames that I’ve ridden seem do not handle well on descents. Maybe this is coincidence because I see no real reason for it.
“So what is the real deal with the sloping top tubes? Is it just to make the frame lighter? More responsive on the rear triangle?”
Short and sweet - simple economics. The bike manufacturer can try to please everybody while diluting revenues due to the costs of producing/maintaining frame jigs/molds for as many as 6-10 differrent frame sizes or the company can adopt a one size fits many philosophy which allows that manufacturer to reduce manufacturing costs by producing only 3-4 sizes.
Most smart bike companies (not Giant) still make compact frames in 2cm intervals. Fancy companies like Colnago do it every cm if I remember correctly.
Depends what you mean by “smart.” Since Giant sells more compacts than anyone else they’re doing pretty smart business.
I absolutely adore my TCR, but the geometry is sort of odd and I wish they’d make a size between the small and the medium, but without elongating the reach of the small, which already has a virtual top tube length of 53.5 cm.
I’ve also found that compact frames (I ride a Soloist more often than the TCR these days) descent differently. I wouldn’t say poorly, but they don’t track around corners the same way as a traditional frame. The older model TCRs, from 1998 to 2001, were definitely pretty twitchy in the rear triangle, but Giant seemed to address that with the 2002 model alloy TCR and since then with the rest of their road bike line.
As another poster pointed out, compact frames can be a good solution for someone like me who has a long torso relative to legs. I need a long top-tube, but to get that, on a conventional frame, I have to have a frame that’s so tall I can’t get other fit parameters to work. I own a Trek 5500 and ride it with a stem that’s a mile long. It sucks on descents and I suspect that long stem and the weight-forward position is a factor. Conversely, the fit for me on my two compacts is much better. But that’s all a unique benefit for a person of my unique build.
As far as relative performance, my compacts both have shorter chainstays. That puts more weight over the rear wheel and adds stiffness. They accelerate and climb well. They’re also both harsh as hell. 40 miles and my ass can feel the beating. (I live where there are lots of tar and gravel roads.) Also, if you have to have a smaller frame size, it’s hard to fit water bottles inside the small front triangle.
It should be obvious that when you put two smaller triangles together, you’re going to get a more rigid structure. Hence, a compact frame is going to tend to be stiffer. As for it being lighter … well, there are too many variables in materials and components for that to be much of a factor, but obviously, a compact frame of the same material will be lighter than a conventional frame to some degree.
My Trek 5500 conventional carbon frame is my all-day ride bike and century bike. My compacts are my Tues./Thurs. fast club ride bikes.
As for the economics of manufacture determining the penetration of compacts into the marketplace … that’s probably part of it. With set-back seatposts and various stem lengths, you can fit a wider range of riders on a smaller selection of compact frames. But there are compromises.
Bob C.
It should be obvious that when you put two smaller triangles together, you’re going to get a more rigid structure. Hence, a compact frame is going to tend to be stiffer. As for it being lighter … well, there are too many variables in materials and components for that to be much of a factor, but obviously, a compact frame of the same material will be lighter than a conventional frame to some degree.
It should be obvious, but I’ve yet to see any empirical data confirming this theory.
As far as lighter, yes, the frame is lighter. but then there’s the **seatpost **issue. The fact that you need one is the issue. After you add the extra length of the seatpost needed you’re just about at the same weight. The difference, if combined with a famous-Canadian-bike-company’s SL series, may add up to 1/4 pound…or a little more water in that bottle.
it’s about manufacturing costs and inventory…not much else proven.