A compact frame (sloping top tube) allows for a smaller triangle in the main frame. Smaller = Stiffer. The smaller frame is compensated for with a longer seatpost. The large sizes of compacts can look really ungainly, as the head tube swells - look, for instance at a 58+cm Specialized Tarmac. They're quite ugly! Due to the nature of compacts, they fit great for normal people, but really shine for people with long torsos and short legs. If you have long legs and a short torso, compacts don't work nearly so well.RyanM said:Some bikes like Trek and Specialized's top tube have a downward slope to the seat while some like Cannondale have a top tube that is pretty horizontal to the ground. is there an advantage to one or the other?
Pure propaganda. Litespeed has released some advertisements of extremely dubious technical merit in the past few years, they've lost a lot of credibility. I say this as a Litespeed owner.skaruda_23 said:I think a lot of it comes down to styling and marketing. But according to Litespeed, the top tube experiences 29% of the frame's stress from a vertical impact. I think that Specialized, Trek, etc. might try to emulate a leaf spring type of design for the top tube (roughly semi-elliptical) in order to create a smoother riding bike...
Notice this curvature is similarly applied to seatstays on many models in order to make a "more compliant ride." Also according to Litespeed, the seatstays take up 32% of a vertical impact's induced stress, so this bent design in theory has merit.
In the real world, I don't really think curving the tubes makes all that much difference in ride quality compared to tire width/pressure, saddle choice, and correct fit, but the engineering is interesting nonetheless.
Check it out http://www.litespeed.com/current/tech_mat.aspx
Do you have articles to back this up? Not trying to be argumentative, I'd just like to see how they came up with those numbers and what others have to say about it.estone2 said:Pure propaganda. Litespeed has released some advertisements of extremely dubious technical merit in the past few years, they've lost a lot of credibility.
With regards to those exact numbers? No, I don't have anything. But assuming exact proportions of stress on each tube are exactly the same on exactly every bike for exactly every weight of rider is dubious, at best. Different geometries will change the stress distribution, different rider positions (saddle vs handlebar)... even different rider styles can change that.f3rg said:Do you have articles to back this up? Not trying to be argumentative, I'd just like to see how they came up with those numbers and what others have to say about it.