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Slack Randoms: Triangle Wheels, Gee Atherton's Backcountry Ride & More

May 28, 2023 at 11:06
by Ed Spratt  
We use Slack as our workplace communication tool at Pinkbike and we have a #randoms channel that we use to share an assortment of videos and stories from all corners of the cycling world and beyond... We thought a couple of the moments from the past week were too good not to share with a wider audience, so here are some of the highlights.

Who Said Wheels Have to be Round?

bigquotesTriangle wheels can be comfortable! Actually, with this type of suspension almost any wheels shape would feel like normal round ones. The Q

Gee Atherton Takes on Brother Dan’s Enduro Loop

bigquotesJoin Gee Atherton on an almighty mission as he takes on brother Dan’s Enduro loop

These natural Dyfi tracks offer big climbs, fast single track sections, and super-tech, steep downhills - when Gee says a trail is "pretty spicy" you know it's an understatement :-)

Join Gee on board the Atherton AM.150 for six minutes of leg burning, foot-off, all mountain mayhem.
The Athertons

Behind the Scenes of One of Fabio Wibmer's Biggest Urban Freeride Sends

Downhill Race Carnage from Dirt Masters

bigquotesGnarly day watching the downhill! This week has been sick. Thanks to the YT Mob for the good times, and all the crazy German fans! Jack Moir

Vinny T's Blizzard Ride

bigquotesEver gone mountain biking? What about on a trail that is fully snowed out? Well, Vincent Tupin has, and he went full send down the entire trail. GoPro

World Record Nose Manual

bigquotesWhat a good day to make a world record LOL … I’m soooooo stoked to present “400m”, our new project based on a nose manual world record produced and managed by @encouragedprod - .Well to be honest , I don’t really have words to describe how tough was this one. I know it may look easy and simple but for sure 100% this is one of the most difficult challenges I have ever faced. It was so hard for the body but even harder for my mind. Thanks to this project, I’ve developed a new level of perseverance and consistency in the face of purposes. I'm glad there's a making-Of-ViD coming soon to describe how intense it was. Thank you all for the support as always and I just want to say that:

“Consistency is the new key to Balance”
Courage Adams

Man Paralyzed by a Cycling Accident Walks Again Using Bluetooth to Connect his Brain & Spine

bigquotesA man paralyzed by a cycling accident is able to walk again after an experimental operation by neuroscientists and surgeons in Switzerland. Associated Press

Author Info:
edspratt avatar

Member since Mar 16, 2017
3,298 articles

  • 66 3
 "No Strava" = best sign you could ever see at the start of a trail!
  • 9 1
 My mate built a secret trail called ‘No Strava’ but people eventually do, and even if they don’t you get the Strava heat map so the tail can be found. ‘Only Nokia 3310’s’ will be the name of my next tail…. Smile
  • 8 1
 @notphaedrus: see I always thought ‘no Strava’ was more about having fun on the trail over trying to be KOM / QOM rather than about keeping the trail a secret. Hmm…
  • 2 1
 No social media was the only rule when we built the local trails. We now have a locked gate at the end of the street because of idiots who wanted internet glory (IG), make believe trophy's (Strava) or a dumbass who didn't have time to touch a shovel. Ugh.
  • 29 1
 ...Triangle ain't Dead \m/
  • 28 0
 Them’s ain’t triangles, they look more like Wankel rotors.
  • 7 0
 @Karlos97: Almost, but actually it's a reuleaux triangle
  • 2 0
 I'm done with the industry forcing us to adopt the new standard of equilateral triangles. #isoscelesneverdie
  • 16 1
 So, nobody is going to comment about how insane that Wibmer backflip was? The margin of error was tiny and they didn't even have crowd control stopping people from walking across the landing area. I'm super glad it worked out and he stuck it. I know all of his stunts could potentially be career ending but that one would have been so awful to watch if it had gone wrong. Congratulations Fabio on another amazing feat. I can't believe anyone would even thing about trying that, never mind having the skills and the balls to pull it off.
  • 14 1
 Imagine your legs start lagging
  • 45 1
 Imagine? My legs have been lagging for years.
  • 17 1
 You wake up, and your neighbor has his keyboard connected to your spine...again!
  • 3 0
 @thomasjkenney1024: I have a spinal stimulator that has a Bluetooth remote that controls the electrical stimulator wired into my spine ...it's called a spinal stimulator and it really helps alot with pain and gain movement in limbs that have paralysis
  • 12 0
 I can't decide if I like the sound of the triangle bike, or if it should be destroyed immediately.
  • 27 1
 If you cut the corners off the triangle wheels it would ride smoother.
  • 3 1
 @kingbike2: next up: "Hexagon wheels. Almost round."
  • 5 0
 I always wanted to try playing an engineer on PB, but alas, I don't have an engineering background.

So I ask: why the roller bearing fenders with the pseudo triangle wheels? Is it to smooth out the transition off the points? Or some other reason I'm failing to see?
  • 7 0
 The corners of the triangle are the central point for the radius of the curved opposing edge, so the length from side of the triangle to the other is always consistent, so it behaves like a circle, but only with a floating axle. I hope that makes sense!
  • 3 0
 From Wikipedia: The most basic property of the Reuleaux triangle is that it has constant width, meaning that for every pair of parallel supporting lines (two lines of the same slope that both touch the shape without crossing through it) the two lines have the same Euclidean distance from each other, regardless of the orientation of these lines.

There's a diagram alongside that text in the article that I think makes it easier to understand. It's not for smoothing the apices, the overall shape simply requires it, since (obviously) the radius is variable.
  • 2 0
 I played at 0.25 speed to see what was happening, kinda make sense with the above explanations.
  • 1 0
 Shapes of constant width can also be generalised to 3D. For the interested, the book “How round is your circle?” discusses these shapes as well as other topics at the intersection of engineering and mathematics. Linkages galore too.
  • 4 0
 This was puzzling me too . . I took @kingbike2's suggestion and slowed the video down, then re-read the explanations from lucaj and boozed. Seems like the key other piece of info, watching the video, is that the roller bearing fenders keep the top of the wheels/triangles at the same height relative to frame main triangle.
With that happening, then what lucaj says make sense of it all: the top and bottom of the wheel are always at the same distance apart, but the hub floats up and down (and so the seat, cranks and handlebars stays at the same height relative to the ground). Must be weird to ride though.
  • 2 0
 @ernestozed: The other key takeaway is that I now know why I'm not an engineer.
  • 2 0
 @iammarkstewart: I'm no engineer either, but I've always been a sucker for a linkage fork.
  • 5 1
 @iammarkstewart The entire weight of the bike is running on those roller bearing fenders. Without the bearings in the fender rollers, the wheel would be unable to turn as the tyre would grip the underside of the fender.
The hub on this design isnt carrying any weight at all.
  • 1 0
 If you look at his other videos, he's been experimenting with loads of non-circular wheels. The frame and fork connection of these racks (for lack of a better word) which support the wheel from the top seem a bit sketchy. Good enough for this experiment but I do think they are being subject to some vibrations as the center of mass of the wheel (at the hub) and obviously the linkage does go up and down. Seems like a PITA (pun intended) if it fails. There is a lot to be said for round wheels though of course, there is a lot to be said for trying something different too! Trying something different gets you thinking about what you'd otherwise take for granted and might eventually help you come up with something that really is better than what you had. And if not, you still had fun Smile .
  • 1 0
 @gabriel-mission9: I don't think my now-older mind is plastic enough anymore but I do think I get the "two supporting parallel lines" reference in the Wikipedia article. Basically it works because the "wheel" is running in a "track" formed by the ground and the "fenders". And at .25 speed the linkages and lack of weight-bearing in the hub becomes more apparent.

Thanks for helping out. Completely unrelated, is this reuleaux triangle the basis for the rotary element in the Wankel/Mazda rotary engine?
  • 1 0
 just excited that the dude chose a URT bike for this
  • 4 0
 @iammarkstewart: Nope, although this is a commonly asked question. In diagrams, wankel rotors look very similar to reuleaux triangles, but are not the same. In practice, rotors can be any shape as long as the three "tips" are the highest points, by enough that none of the rest of the rotor comes into contact with the cylinder walls at any point in the rotation (they could be perfect triangles if you wanted). Although this isn't generally shown in diagrams, wankel rotors often have quite complex shapes in order to provide an efficient combustion chamber.
  • 1 0
 @gabiusmaximus: No mechanic but as soon as you said combustion chamber I thought of course you must tweak the sides for displacement and/or performance. Then I watched a quick vid on a rotary engine and makes total sense about the tips. Sorry for all the commoner questions.
  • 1 0
 I was confused at first as well....

That rear triangle is missing the shock that would normally keep the wheel from "bottoming out" against the seat tube. That fender is stopping the wheel from travelling further up and bottoming out against the seat tube.

It's the same idea with the front wheel.
  • 5 0
 I'm fairly certain the Q would be a serial killer if he didn't do what he does with bikes.
  • 6 0
 Courage Adams nose manual was nearly as long as the Gee back country ride.
  • 3 0
 Seems like he could have held the manual for a few more meters thus extending his record to 400+ metres.
  • 2 0
 @kingbike2: Got to save something for episode 2.
  • 4 0
 That brake squeel on the Atherton vid is annoying but the trail looks awesome!
  • 3 0
 I am sorry, but any trail that Gee Atherton calls 'spicy' on a 150 mm bike is a no thank you from me...
  • 4 1
 Pick a tire shape and be a d!ck about it.
  • 3 0
 If Felix Wankel made a bicycle!
  • 2 0
 imagine pairing your legs to an xbox controller
  • 8 0
 Imagine pairing your legs to my xbox controller
  • 6 0
 @boozed: imagine pairing your xbox controller to my xbox controller
  • 1 2
 @Joseph866: imagine controlling your legs to xbox pairing
  • 1 0
 Imagine the two pairs of you pair your pairs of legs. That would make for a pair of horses.
  • 4 1
 Are those triangles 26"?
  • 1 0
 Anybody see the video of a
Kid who does it about 50 times longer (No fn BS) ?
  • 1 1
 What was the previous world record for nose manual? And is it mandatory to use a bike with no front brake?
  • 1 0
 Front brakes give a general advantage to maintaining balance, but to set a record having no breaks is always going to win, assuming all else is equal and the rider is skilled. Using the breaks to maintain balance is always going to slow you down.
  • 1 1
 @jackfunk: But it's not a speed record, it's a distance record. With brakes you could use a steeper road maybe? I can't hold a nose manual for more than 2 seconds so I don't have a clue honestly.
  • 2 0
 @ak-77: That was my point, its about how far you can go, so if two riders are going the same speed on level ground, the one that uses brakes to balance will be at a disadvantage, using the brakes takes away speed/potential distance.

I dont know if this is a bmx specific record, but if it is I'm assuming it is supposed to be on level ground without front brakes, as that is what a modern BMX nose manual is.
  • 2 14
flag Snowytrail (May 28, 2023 at 16:33) (Below Threshold)
 IMO...no helmet, no record.
  • 8 2
 A manual by definition is pure balance, i.e. no braking or accelerating allowed, compared to wheelies which use both. Otherwise it would be a nose wheelie, stoppie, or endo.
  • 1 0
 Addendum. Although it’s not quite true as some riders still use rear brakes for manuals, Chase Hawk being the one that comes to mind.

Oh well, at least it’s less messy than the cross-sport definitions for switch/oppo/fakie!
  • 1 0
 @dirtyburger: thanks for the clarification. I wasn't aware that the terms 'nose manua' and 'nose wheelie' had separate meanings.
  • 1 0
 @dirtyburger: You can add me to the list of people that use rear brakes for manuals :-)
  • 2 0
 @ak-77: The etymology and definitions of these technical terms are recent, regional and rapidly evolving. There’s no organised body that governs them either, so they just mean whatever a sufficiently large group wants them to mean.

  • 1 0
 @jackfunk: pretty sure it has to be flat, or very close to it. The rear manual record was set by a young guy near here on an airplane runway.

  • 1 0
 @plyawn: It must have some slope I guess? I think you would need a serious tailwind to beat 400 m on a truly flat road.
  • 1 0
 that fella has been spray painting indoors too much!
  • 1 0
 Triangle wheels for a pre-installed pinch flat. Brilliant!
  • 1 0
 Just no on the tri-hoop thanks
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