Magic Spring

WhipMeister wrote:

This whole bruhaha that inevitably ends up with personal attacks and shit-stirring (and more traffic for Vital) always centers on one, single, core point: Can the...

This whole bruhaha that inevitably ends up with personal attacks and shit-stirring (and more traffic for Vital) always centers on one, single, core point: Can the suspension influence vertical trajectory of a bike/rider leaving the ground or not? That's where the battle line always gets drawn. One faction says suspension is no factor, the other says it must be. And then the fun starts.


It seems to me it would be pretty simple to settle that question to everyone's satisfaction once and for all. If you take the single-table-table question I'm fond of positing,


if the suspension is completely null and void in the equation, then this sequence:




should not have materially different trajectory results than this:




A (good) rider should be able to jump the gap with an equivalent trajectory, either way. Wheelie, sit down, stand up, bounce around, make a face before you launch, whatever. One should be as good as the other all other things being equal (takeoff velocity and acceleration, bike/rider mass, 'divots', etc). Leave from one spot and land in pretty much in the same spot without regard of whether you jumped into first table or just rode across it.


It would be relatively easy to set it up, to control the variables, etc, and measure the results (video it). (My lawyer's caution: I would make some test passes slightly off-line from the face of the 2nd table in the flat drop-off scenario before trying it straight on. You know. Just in case the resident engineers need a refresher in physics?)


Set up the single-table-table so that a rider is able to comfortably mimic Grant's Bercy S-T-T leaps (in the vid below). Once that's been run, go back with the dozer and fill in all but the final gap. Then try to jump the same gap again at the same speed without the first jump.


If the rider is able to clear the single-table-table gap without mayhem (doesn't need to be 30 feet; that's just for illustration), but can't clear the flat-to-table (with the same trajectory, i.e. smooth comfort) without jumping into the first table, the argument is settled. If he can, the argument is settled the other way. The only physical difference between the two would be a decompressing versus a relaxed suspension.


With as much fervent attention as this subject always draws, I think it would make a really good magazine article.


Oh, and here's my magic spring video for reference (again):

Void Main wrote:

I think whether you jump in to the first table or you start on the first table it is possible to get the same amount of...

I think whether you jump in to the first table or you start on the first table it is possible to get the same amount of upward help over the gap to the next table. That is "if" you have enough body mass to fully compress the suspension just by rapidly going from a standing to crouched position. These pro riders are pretty light and they run a stiff suspension so it's possibly they can't do it in which case I would agree that jumping into the first table would get you better lift into the second table because you have both the rider weight and the bike weight to use to compress the suspension.

Void Main wrote:

I already know the answer because I basically already perform the test when I hop puddles in the woods, but I have an easier time loading...

I already know the answer because I basically already perform the test when I hop puddles in the woods, but I have an easier time loading up my suspension than most of these pro riders (if you know what I mean). I rode this weekend and made a conscious effort to play around with both scenarios. It's definitely easier if you start when coming in from a jump though, much less effort required to load the suspension when you have gravity plus the mass of you and your bike helping you.