Rappstar wrote:
There's no elastomer on the Dimond. The suspension is built in through the carbon layup. The mistake that you are making is thinking that you can tell how rigid - or not - a carbon frame is simply by looking at it. What's clear is that the Softride design was flawed. There was WAY too much deflection in the beam, such that your saddle height changed too much during the pedal stroke. The "smooth" pedal stroke required on a Softride was the only way to keep the beam from bouncing.
The Dimond does allow the beam to separate from the lower "triangle" - unlike the Falco - but that actually doesn't necessarily affect the suspension (or lack thereof). You could build a beam bike with a more rigid interface and still have plenty of deflection in the beam. The Dimond process has much more to do with manufacturing tolerances than it does to building in suspension; there's virtually no flex of any kind until you get to the cantilevered portion; the separate beam/lower may allow for better distribution of forces when the beam deflects, but that'd be likely to show up in terms of longevity of the frame.
In all cases, the deflection of the beam has everything to do with layup, ply orientation, etc. The REAP bike could easily have almost no suspension or it could have more than the Dimond. It's flawed to think that looking at the bike you can tell whether it has suspension or not. As evidenced by your misunderstanding of how the Dimond is able to build suspension into the design.
A cantilevered beam will ALWAYS have SOME deflection. The question is how much is desirable for riding. And there's no clear answer there. But the Dimond seems to have it right with a deflection that's about (it depends on beam size) 0.065mm/kgf.
First things first. Jordan is correct here, and there's just no argument to be made to the contrary.
Flexibility and shape have a connection, but especially in the case of carbon fiber layup, you can't tell anything from the outside. Orientation, layers, modulus of the fabric, epoxy %, etc all have a huge impact on the outcome.
However, I'm going to have to defend Softride a bit here, since I am probably the only person who has put extensive miles on all of these frames. I have a Classic with a 240lb max beam, a Rocket TT, a Dimond, a Pearson, a Falco, and also rode a Zipp for several years.
The Classic with the stiffest beam has about 3/8" of deflection when loaded with my weight. I ride very far forward, but try very hard to maintain the balance between my shoulders and perineum. It can be made to bounce at high cadence until you learn to "pedal in circles". It does take awhile, and I'm not at all sure it isn't actually a positive thing to learn.
The Rocket TT has about 1/4" of deflection when loaded with my weight. I consider it to be the best balance of comfort and suspension. It's an amazing machine, and design flaw (delamination of the beam) aside, it's really a very good machine.
The Dimond is a spectacular machine. It has some deflection, but never bounces. It's comfortable for all day riding, but not at the same level as the Rocket.
The Pearson is a bit stiffer in the beam, but more flexible in the seatpost. At low cadence you can see the seat post flex more than seems acceptable. I have been planning on improving the shape of this while adding some lateral strength.
I don't really have anything bad to say about the Falco. I believe it falls short of the Dimond and Pearson aerodynamically, but not by a long way, and it varies by angle of attack. The stock adjustable stem is great for getting the front end dialed in.
