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ASK Cub Reporter, Version 07.22.2010- A Weekly Q & A Session

Aha, here we are for yet another week of the ever so scrumptious letters from you, our precious (and ornery) readers.

Hi Cubby
When reading your review of the HPI Blitz you mentioned scrubbing jumps. Can you describe what that is?

Morgan W. Ellis

Cubby– Yo Morgan, thanks for reading. As far as your question goes, let me start with a bit of background on “scrubbing” a jump.

Scrubbing comes from motocross, and riders have been doing it for years. It came into prominence when a rider named James “Bubba” Stewart took the art of scrubbing to a whole new level, so you’ll also hear it called the “Bubba scrub”. You see, a rider can gain time on a track by using the scrub technique. While a normal rider may hit a 60 foot long triple jump and his apogeee (the highest point in flight) is 30 feet in the air, James Stewart might scrub the same triple and only get 20 feet high. Because Stewart was able to stay 10 feet lower, he’s in the air a shorter amount of time, and able to get his tires back on terra firma earlier and get back on the gas sooner. As a rider hits the face of a jump his suspension compresses and the springs on the bike will store that energy. On a normal take off all that energy shoots the bike/rider vertically. When you scrub a jump you lay the bike over and some of that energy is released horizontally, keeping you lower to the ground while still carrying enough speed to make the gap.

True scrubbing in rc does not (and can not) happen, there just isn’t any way for us to lay our buggys horizontally upon initial take off. Scrubbing in rc normally refers to not hitting a jump perfectly square. If you hit a jump perfectly square you will get the maximum amount of vertical rebound, making for the highest arch possible. If you hit the take off face slightly off axis, not all the stored energy in your springs is released at the exact same time upon take off, making for a slightly lower flight, saving you time. When you see an rc racer scrub, they almost always land a bit sideways, which can be an advantage if there is a corner immediately after the landing jump. But landing a bit sideways takes a lot of skill, sometimes a small amount of counter steer, and a good set-up to not traction roll. Currently, Billy Fischer, Ryan Maifield, and Frank Root are some of the best drivers at using this technique. Check out THIS VIDEO of Fish and his Losi 2.0 working on scrubs.

That’s it for this week Cub fans, shoot us your questions, funny stories, taco’ed chassis, and yes, even your questions to cubby at BigSquidRC dot com!

YOUR Cub Reporter

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Posted by in Ask Cubby, cubby on Thursday, July 22nd, 2010 at 10:27 am