We have seen that rearward axle path tangents at equilibrium should offer some advantage while pedaling over smooth terrain and during shock absorption while coasting. However, this will also produce bump feedback while pedaling over bumps. Many riders say that they are very sensitive to this trade off, even to the point where differences of less then an inch in main pivot locations are noticeable. Some prefer the generally efficient rearward tangents, while others want the smoother pedaling vertical tangents. So we have a compromise with which to deal.
We have also noted that tight curves above equilibrium, whether circular or varying, may help reduce the bump feedback of a rearward tangent. However, curves tight enough to make a significant difference in the shallow regions of travel where riders are likely to be pedaling may produce inferior bump performance deeper into the travel, since wide curvature should be best for shock absorption. Though again, designs with rearward paths through travel, such as the The Rocky Mountain ETS-X70 and, for the most part, the Giant NRS, may mitigate this compromise to one degree or another.
Furthermore, while variable curvature has its allure, the potential for a bigger tradeoff between weight and durability in comparison to conventional 4-bars, due to closely spaced pivots near the bottom bracket, shows that variable curvature designs may not be without their compromises (this in addition to the compromises noted above involving tight curvature).
This furthers a theme that we revisit throughout this work – there are no “right paths” or “right pivot points”. We have seen this in the mass distribution considerations of having riders with different body types. We have seen this in the fact that no geometry can be completely non-reactive through a pedal stroke, without the help of friction. And now we see it again in the fact that there are choices that must be made, depending on what type of suspension performance one wants.
Human beings can be surprisingly sensitive to physical situations. The author finds that a difference of just two millimeters in the height of a road bike seat gives the feel of a completely different bike. So we are not surprised to find that some people hold small geometric differences as important and we must assume these positions to be legitimate.
However, we must note that some people experience “have-it-all” performance in some designs from manufacturers that claim such performance (though this is certainly not the case with most experienced riders that this author has encountered). Since we have seen that have-it-all performance is impossible, we must conclude that either the powerful psychosomatic phenomenon is at work or that some of the considerations that we have been exploring are not all that discernable to some people, or perhaps it is a little of both.
All of this makes the question of suspension performance largely philosophical. So to continue another theme, we again suggest that test riding be done to determine what performance characteristics are right or even discernable for each person, even if it is just a parking lot test (you can get a lot from a parking lot test).
In the final analysis, none of the major suspension types has a clear advantage over the others. There are lots of happy mono-pivot owners out there (including those with mono-pivot-like Ventanas and Rocky Elements) and there are lots of happy 4-bar owners out there. This pretty much says it all.