It seems to me that lightweight climbing bikes made a bit of a comeback in the recent years (to my delight). I noticed that many of them have a very similar frame design – no dropped seatstays, round tubes, light top tube sloping and often a round seatpost with an exposed clamp (exception is the R5 which does not have a round seatpost).
I am wondering why? I am assuming that the frame might feel stiffer under heavy load when climbing with the non-dropped seatstays, and that the round tubes might also be stiffer than aero-shaped ones, but I do not understand the benefit of a round seatpost, considering that the weight of a carbon seatpost is pretty much the same (if it is not a deep aero shape of course).
We have also seen with the new Addict RC that the bike can get below the UCI weight limit even with some aerodynamic tube shapes and dropped seat stays, and apparently it is also a great climbing bike?
by imperius99
5 Comments
Wdym a comeback? i don’t think lightweight frames ever went away
A round seat post has more compliance.
Absence of dropped seat stays allows for a larger triangle (stiffer). Mostly round tubes are used because it’s the most efficient use of material to get desired strength in all planes of stress. There’s some exceptions, Orbea for example uses a flat top tube to offer a bit of ride compliance with a part of the diamond that doesn’t bear significant load. Large round down tubes allow for very wide and stiff bottom bracket shells. The overall compact diamond shape was optimized back in the ‘90s for stiffness-to-weight. Round seatpost is for stiffness. The other commenter is incorrect in that regard. Flattened tube shapes offer compliance in the direction perpendicular to the flattened face (usually intentional by design).
I got an Orbea Orca OMX because I wanted a more compliant bike for long training rides. Aero bikes aren’t nearly as harsh as they were 10 years ago, but slow’ish 5-6 hour rides are just a little more comfortable on the Orca than on the Madone. But, yes, besides a little extra comfort there’s no point to these bikes. They’re rarely used in racing because faster aero bikes are barely heavier and comfortable enough.
Because you can easily get a seatpost that is a lot lighter, there is no standard for aeroseatpost so almost each company has it’s own seatpost so if you wanted to get a lighter one you are kinda screwed. I would also guess that it has more compliance in general.