# Bullitproof

• Member since Jun 29, 2011
• 69 Followers
• Vancouver , British Columbia
• Male / 19

#lifebehindbars

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## Recent

Bullitproof pinkbikeaudience's article
Sep 1, 2014 at 2:32
2 days
Go Back to School in Sweet New PB Gear
No, we really don't. Sorry to burst your 60's bubble
Bullitproof RichardCunningham's article
Aug 29, 2014 at 2:50
Aug 29, 2014
E-Thirteen Finally Answers the Age-Old Question:
no, @slidways, ( @KUNTHER you too!) the angle of attack difference between a 26 inch wheel and a 29 inch wheel is really negligible. heres a picture to prove what i am saying, this is a relatively large bump, so it should, in principal, show the largest difference in attack angle of the bump with the tangent line of the rim at the contact point. http://www.bike-advisor.com/wp-content/uploads/2013/01/wheel_27_5_650B_1.jpg the difference of less rolling resistance is scientifically correct, but is it effective? without tests, i say a ~1 degree change in attack angle does not constitute a better platform. in response to the inertia comment, it is the LINEAR momentum of the bike that we are concerned about. when a bike impacts a bump, it produces a force that acts 90 degrees to the surface of the wheel (this is actually what makes wheels useful). this does not create any torque on the wheel, which does not affect its rotational speed. what you have to consider is the horizontal and vertical components of that perpendicular force. the vertical component will not interact with the horizontal motion of the bike, and gets stored as gravitational energy/dispersed by the dampers. the horizontal force will change the bikes velocity, regardless of magnitude. the size of the horizontal component is determined by the angle of attack (defined above in the link) that the bump creates with the wheel. to take away: slowing the wheel down has less of an effect on the linear velocity of the bike than the horizontal force acting on the bike as a whole (through the wheel). heres a nifty home experiment (for everyone, at your own risk): try skidding to a stop (a stoppage of the wheels angular momentum), and then hit a brick wall (a horizontal force) at the same speed. :salute:
Bullitproof parisgore's photo
Aug 29, 2014 at 0:04
Aug 29, 2014
the pest control wasn't enough to keep ratboy from winning the overall!

Bullitproof coastphoto's article
Aug 28, 2014 at 20:14
Aug 28, 2014
Being Photographed in the Whistler Mountain Bike Park
we get something for that thousands of dollars we spend, something that continuously gives us enjoyment, getting not even a hard copy for 25 bucks is insane!
Bullitproof RichardCunningham's article
Aug 27, 2014 at 19:17
Aug 27, 2014
E-Thirteen Finally Answers the Age-Old Question:
I think what everyone here needs is a straight to the point physics 101 class from an engineer. I'm going to assume everyone here also has enough IQ's such that you know how to pump your tires up. ;) The torque required to spin a wheel with a certain angular acceleration is equal to the cross product (multiplication for simple cases) of the desired angular acceleration and the moment of inertia. Angular acceleration is just a rotational form of linear velocity. the radius of the wheel multiplied by the angular acceleration is the linear velocity (bike speed). The moment of inertia for a round object is just the total weight of that object (well, mass..) multiplied twice by the radius of the wheel. So, if you consider the torque you apply to the wheel as your effort or "how hard it is to pedal" and assume you want to accelerate at a certain rate, the ONLY way you can argue that a wheel accelerates faster is either that it is lighter, or has a smaller radius. By this we also see that the effort(torque) is way more dependent on the radius of the wheel than it's mass. In laymans terms, the size of the wheel, has a ton more impact on how hard it is to accelerate that how much it weighs. 29ers are waaaay lighter than normal rims, and that's how they compensate for the added radius
Bullitproof coastphoto's article
Aug 27, 2014 at 11:29
Aug 27, 2014
Being Photographed in the Whistler Mountain Bike Park
With the cost of gear they can buy(I'm guessing a cannon mark 3, you can pay for it faster (maybe even a day) on a line with five dollar shots. This is what people don't get, yes the one time cost of a camera is sorta expensive, but it doesn't cost shit to take a picture!
Bullitproof ChrisRicciVideo's article
Aug 27, 2014 at 11:25
Aug 27, 2014
Video: Remy Métailler Burns the Whistler Bike Park
It's more of a fear of having to take the walk down the hill for a tube or a tacod wheel that prevents me from trying something like that
Bullitproof BellBikeHelmets's article
Aug 26, 2014 at 17:14
Aug 26, 2014
Bell Introduces Super 2R Helmet - Press Release
haha might as well just not have the chin guard at all, it is literally just fo' sho'
Bullitproof remy-metailler's photo
Aug 25, 2014 at 15:49
Aug 25, 2014
I cant actually believe how many people dont know what POD stadns for when its stamped to the right of each PHOTO of the day.. hahaha

Bullitproof remy-metailler's photo
Aug 25, 2014 at 15:47
Aug 25, 2014
^that is picture of the year