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Added 6 photos to PMBI-Association
Jan 22, 2017 at 14:00
8 hours
zeptechniques enduromtbtrainer's article
Oct 7, 2016 at 16:12
Oct 7, 2016
End of Season Fixes: Part 1 - Lower Back Pain and Hip Care
Great info and presentation Dee... thanks!
zeptechniques vittoria's article
May 31, 2016 at 14:16
May 31, 2016
How To Climb With Lindsey Voreis - Video
Good job Lindsey! Nice focus on the core skill of Position & Balance and highlighting the fundamental concept of constant adjustments (balance) to maintain traction, as the terrain changes. Good to see a video like this that doesn't over simplify things too much and make people think, "if I do 'x' and 'y', I can climb any trail". Making people think as they ride, to constantly react as they feel they need to, is great. Again, great stuff.
Apr 28, 2016 at 13:30
Apr 28, 2016


Mar 31, 2016 at 23:39
Mar 31, 2016
zeptechniques zeptechniques's article
Feb 11, 2016 at 14:31
Feb 11, 2016
Zep's How-To Mythbusters: Body Position for Descending and Corners
I like the passion and interest here WAKI, but can I ask you to please try to be careful. There's some pretty misleading information in your comments that is potentially dangerous for people learning... especially with the jumps and drops. I get where you are coming from but it all stems from a slight misunderstanding of the physics, and how things work when moving vs being stationary. It's also worth mentioning again that each picture you highlight is a moment in time... and photographers naturally like taking pictures when something cool is happening, like rolling over a drop. They don't tell the whole story. In the case of a drop, riders often need to absorb the pressure on the rear wheel to avoid being pushed OTB, and this naturally results in the bike moving ahead underneath them and their hips moving vertically over the BB. But again, they were able to do this because they were most likely centred, and from this "default" position on the bike, they were then able to make the adjustments they need. This is key... as the article explains, the neutral and ready positions are places to move and react from, not where you should stay all the time. For example, rocks and roots often act to "slow" the bike down, so moving the hips slightly back (so they are vertically above the BB, on a downhill slope), can put the rider in a stronger position to "brace" against the forces from the bumps, that are trying to slow the bike down and through the rider OTB (over the bars). The rider is in this position because of the rough terrain, not because it's a downhill slope. Using one of your examples... www.pinkbike.com/photo/5626815 ... Sam's COM is pretty much vertically aligned over the bottom bracket, in this rock garden. However, if this was smooth, his chin would be more over his stem and his COM would be more aligned over the BB at a perpendicular angle. Here's a couple of examples of this http://www.pinkbike.com/photo/13105612/ http://www.pinkbike.com/photo/12487643/ Another good analogy or example is skateboarders dropping into a half pipe. It's a steep slope that's smooth. And you can bet their COM is not vertically above their skateboard. They are "tipped" into the pipe, with their body more perpendicular to the slope. Look at some BMX'ers in a halfpipe and you'll see the same thing. Keep studying and it will make more sense. By the way, this idea is a little newer in mountain biking, but's it's been around in the ski and snowboard teaching world for literally decades. The physics on this are solid. As for now, I appreciate the discussion as I can geek out on this stuff quite easily! As the article also mentions, we'll talk more about this in the next blog and hopefully this will answer some more of your questions... if I put everything in one blog, it would have been way too long! Cheers, Paul
zeptechniques zeptechniques's article
Feb 10, 2016 at 17:50
Feb 10, 2016
Zep's How-To Mythbusters: Body Position for Descending and Corners
Hi WAKI. I like that you bought this up as your conclusion can be quite a common misconception. Without going vastly into detailed physics of different components of gravity on a slope and how this affects an object on a slope when it's moving rather than stationary, I'll highlight another brief example to hopefully explain further. You say, "in that drawing you would be putting pressure on bars...". If the rider was stationary, this would be true. However, and again I'll highlight the article: "Technically speaking, resisting gravity involves very different forces acting on the rider when compared to going with gravity. Similarly, the physics of when the rider is stationary compared to moving, are also different." To relate to your specific comment you can discover the answer to this yourself... as can anyone reading this. Neither the Neutral or Ready positions will make the rider put pressure on the bars, when they are coasting (little to no brakes), down a slope. Why? Try this: Find a slope with a level surface that transitions down, into a short slope. Ride along, relaxed in a Neutral or Ready position from the top to the bottom. If you coast all the way, the only additional pressures you may feel is at the very bottom of the slope, as the terrain flattens out (this is mostly due to the natural "compression" you would feel, rather like in a berm). You should notice that on the slope itself, as long as you are keeping your chin over the stem, your hands didn't suddenly get heavy. You can also try this: Ride slowly onto the slope and stop halfway down. As you brake and as you are stationary, you will notice more pressure on your hands*. Stop only for a brief moment, let the brakes off and roll down the rest of the slope.** You'll notice the pressure in your hands when you are stopped, should disappear as soon as you let the brakes off. I like your drawings (wish I could draw like that!) and the idea of keeping the COM vertically aligned over the BB when you are stationary, does makes sense. However, the physics change when you are moving. As the article explains... what is true when stationary is not necessarily true when moving. If you're keen to learn more about the physics, here's one of our many references that I would recommend. I like it because it does a great job of explaining the physics clearly, in a way most of us can understand (physics papers and articles have a habit of completely making things way too complicated!). It's obviously tailored to skiing, but the research and underlying physics in this book are fantastic, and remain true to any downhill sport. Ultimate Skiing - Master the Techniques of Great Skiing: Ron LeMaster, 2010, BlueSky Inc. *Because if you still have your chin over the stem, you COM will be slightly forward - horizontally speaking - of the BB. If you were to remain stationary on the slope and wanted to be more stable, you would indeed need to align you COM vertically over the BB. Rather like standing still and "upright" on a slope. **As you let the brakes off, if you did have your COM aligned vertically over the BB (your chin would be a little behind the stem, most likely) you would end up even further "in the back seat", as the bike would accelerate away from you. Instead, keeping your chin over the stem and your COM aligned perpendicularly over the BB (when compared to the surface of the slope), would result in you staying centred and balanced as the bike accelerates. Hope that helps. Cheers, Paul
zeptechniques zeptechniques's article
Feb 10, 2016 at 17:22
Feb 10, 2016
Zep's How-To Mythbusters: Body Position for Descending and Corners
Nice reply @TheR, spot on. Yes, the first two skiers are pretty much centred over the ski's, despite how the picture may look to the average person. Plus, if they were a little over the back of the ski, ski racers often use this at certain times in a run (again, these pictures are freeze frames) to help glide and even generate speed. Professional ski racers vs. average joes... this is a very important distinction.
zeptechniques zeptechniques's article
Feb 10, 2016 at 17:14
Feb 10, 2016
THE BALANCE AXIS... tipping "down" the hill, to stay centred.
This is a common misconception. Yes, gravity is always vertical, but how it affects an object on a slope involves some physics that most people aren't aware of. Especially if they have never studied physics. Again, common misconceptions causing myths. Here's just one of many links we've used as a reference in our materials over the years. http://www.tulane.edu/~sanelson/Natural_Disasters/slopestability.htm In a nutshell, Gravity on a slope can be resolved into two components... one that keeps the object on the ground and one that pulls the object down the slope. Similarly, the opposing Ground Reaction force is also a sum of different components. Either way, keeping the COM vertically above the BB will make the rider unbalanced, if they are coasting (no brakes are on). And you can feel and see this in your own rider. The fact that you have your chin over the stem when you are coasting down a hill, is you doing exactly this.
zeptechniques zeptechniques's article
Feb 10, 2016 at 1:50
Feb 10, 2016
Zep's How-To Mythbusters: Body Position for Descending and Corners
There's some good thoughts on this thread. Our next article will have some more info to answer/explain some of the questions and comments. Cheers everyone.
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