justinc5716

Because the low engagement hub will give you a random amount of back-pedal before engagement. It just depends on where the pawls are in between the ramps when the hit comes. The O-chain should always has the same amount to give versus suspension travel.

Beat me to it. Other than the horst linkage, the rest of it is identical.

And in some special cases its cheaper now to buy a dirtbike. If raw material and labor prices are the issue, then how is this true? Yamaha YZ450F, MSRP: $9599. S-Works Enduro, MSRP: $10,500 I mean what gives here? Simply put, one of these has a freaking ENGINE, and the other has pedals...which you have to buy.

@sewer-rat: I was praying for that thing to snap in half the whole time. Unfortunately, this sets a precedent. Now you have to bring slopestyle tricks to win Rampage, because that scores way higher than continuity and technicality. BS

@johncee: YES...I'm thinking the same thing the whole time. Why is he on the panel?

Yes. The bums living under the Colonnade are really eager to lend a hand too. Seattle really has it all when it comes to freeride.

@DaveRobinson81: I invite you to join the discussion on the vital forum, as we've covered a lot of this and I think you'd find it interesting and enlightening. The oscillatory modes of a motorcycle are really strange as they aren't vibrational resonance as we are used to thinking about it. An article I read once described them as "orbits of stability" that arise when dealing with a system that has a high number of degrees of freedom. This gets a bit beyond my mathematical background to explain in detail, I'll admit. Note I did not say that an RSU fork is stiffer, I said stronger for the weight. In terms of fore-aft stiffness a USD fork of equivalent weight will always outperform a RSU design of equivalent weight. The lack of a bridge however, removes a load path present during torsional loading, meaning that the RSU design will prevail in terms of torsional stiffness. In regards to ultimate loads though, the RSU design will always come in lighter if you just want to make something that will survive. Chiefly, this approach compromises fore-aft stiffness, and bushing overlap (hence more friction results). On motorcycles it is common for the mass of the entire machine to rest on the front forks during braking. The fore-aft loading can be quite severe therefore as you can imagine. This happens with bicycles too, but the static loads are about 200 lbf instead of 600 lbf (a typical sportbike with human attached). Add in the much higher dynamic braking loads and all of a sudden you are asking the fork to support a substantially higher load in the fore-aft direction. This drives you to design something much stiffer, that will resist binding, and maintain steering geometry at these load levels. Hence the USD design comes in.

@DaveRobinson81: This is not quite true. Aluminum has a higher stiffness-to-weight ratio than steel so most aluminum structures sharing the same ultimate load as a steel equivalent will come in at a higher stiffness. I've been pondering this issue a lot, along with some other brains over on the Vital forums. I think the best answer we've arrived at so far is that motorcycles place much higher loads on forks than bicycles. These loads are big enough to create deflections that will excite different oscillatory modes (like the "death wobble", or "tank slapper"). Bicycles are not heavy enough, nor do they generate enough tire grip to excite these modes so the main driver for development has been creating enough strength to survive impacts. With that in mind, the RSU fork will always provide the best strength to weight ratio, granted that a bridged lower casting is used.

@JeffreyJim: Exactly! However, motorcycles do have much wider crown spacing which improves torsional and lateral stiffness. There was a great analysis done by Primoz over on the VitalMTB forums. One of the take-homes was that increasing axle diameter beyond 20mm granted only minimal stiffness improvements. On the other hand, increasing spacing helps a lot more because you are increasing the moment of inertia of the entire structure. It'd look silly, but I think an 8 or 9" fork tube spacing on an inverted MTB fork would probably fix all the "problems".

What if e-bike racing is a set of jumps that you have to pedal in order to clear? Kind of like the opposite of what dirt jumping is now. Imagine all the jumps being just a little too long for trail speed, so you have to crank hard out of the corners to make the next one. That'd be exciting...watching guys mess it up and splat into the backside of the next transition. Oops! Guess his battery ran out!