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Old 05-06-2012, 04:50 AM   #16
jadavis
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Physics

Sometimes thinking about the physics behind something helps.

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Here the rider going around a corner is a mass on a stick because it's easier to draw. Their weight (W) acts downwards from their center of mass. N is the normal force. The normal force is always perpendicular to the ground and is always equal to the sum of the other forces perpendicular to the ground, so in this case N=W. The centripetal force, which does exist, is the velocity of the rider squared times the mass of the rider divided by the radius of the turn they are making. A way you could think of this force is that it is how badly the bike wants to no longer travel on a curved path. Lastly, the frictional force is equal to µ*N, where µ is the coefficient of friction ( this would depend on your tires and the surface you are on). The angle your bike is at is essentially just so that you can keep yourself upright going through the turn and exiting it. To determine if the bike will slide or not you just have to see if µN is greater than F_c, if it is then the bike won't slide.

If you look at a berm, you will see that the normal force contains components of the weight as well as the centripetal force, so long story short, berm=more traction.
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Old 05-06-2012, 04:57 AM   #17
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Old 05-08-2012, 07:08 PM   #18
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That was great - can't wait for the next one!
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Old 05-13-2012, 08:26 PM   #19
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Quote:
Originally Posted by C.C. View Post
Great video. Thanks for posting it.

Can you elaborate on the process of preloading suspension to gain more traction on flat and bermed turns?
Sorry for delayed response, I've been on road last couple of weeks.

Riders can use 'pressure control' to weight or un-weight the bike for a variety of uses. A rider can weight the bike to gain traction (corners) or momentum (pump track) or un-weight the bike to momentarily reduce traction (drifting) or absorb the forces created by the oncoming terrain (pumptrack).

If a rider pushes down into the bike evenly (hands & feet) and perpendicular to the terrain, we can add traction through corners. Timing the release of this energy is key (un-weighting), could result in rider accelerating out of corner or losing traction and drifting. Berms give us additional support, making the weighting and unweighting of the bike a bit easier to execute. See the cool physics a few posts earlier if you need...

Sometimes we use Pressure Control quickly & explosively in tight corners, other times a very slow load/release (giant bike park berm), depends on corner and situation.

i hope it helps clear up your question.

How is the Lazer Pecker working out for everyone? lol

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