BikesComments Off on Magpie Attacks, Stompies and Evolution
Aug102012
I have a great deal of respect for all the things in Australia that can kill you. I have to admit, though, I wouldn’t have guessed even the birds attack you. According to an article on the BrisbaneTimes.com.au, cyclists trying to ride through a place called Manly, near Sydney’s northern beaches, are routinely violently attacked by magpies this time each year.
I’m not sure what to be more impressed with: the fact that even the birds are dangerous in Australia, or that fact that they have towns with names like “Manly.”
Luckily, when the birds finally mount their all-out Hitchcockian assault, we’ll all be traveling in giant robots.
“Stompy” picks up where Kuratas left off, and adds the magic of Kickstarter, which is really how all giant killer robots should be funded.
I’m starting to think building a giant robot might be faster than this latest round of revisions to Danzig. My friend Josh pointed out a potential clearance issue yesterday (and thanks for the shock files!) which got me thinking about some ways to improve all kinds of other details. So here’s the snap shot du jour, but this weekend is going to be a big chance to tackle a bunch of details I want to work out.
According to BoyGeniusReport.com, Woz is predicting cloud computing tragedy as the world slowly realizes they no longer own anything–that they’ve basically ceded ownership of all of their digital stuff.
While I’m sure Woz knows more than most of us, I have to wonder what it was we used to own anyway. Apparently I’ve already drunk the Cloud Kool-Aid, but I can’t think of anything I now store online that would’ve been better confined to a single hard drive. Maybe it’s just that the pace of things has accelerated to the point where nothing we “have” is of any value any more.
“Ownership” has been on my mind since the Danzig patent and the various chaos surrounding patents in the bike industry these days. Intellectual real estate certainly seems to be tightening up in some industries. I’ve been storing backups of all my Solidworks files online, and I still think of those as mine. But even though I’m pretty fond of this suspension system right now–sort of all-consuming–I can still see it as an evolution. What it is right now, isn’t what it’ll be in the future.
I think that’s the weirdest thing about designing something. Whether it’s a little computer code or this bike frame, you have to be completely invested in it. At the same time, you have to realize it’s only a moment in time. Put a little more simply, for me the hardest thing about designing something is stopping.
Case in point: in the process of reshaping the crankcase that houses the lower link, I started to notice a few more things I could do with the lower link. I’ve lowered the pivot locations again, and shortened the link, forcing a reset of the system that I believe–at the other end of a bunch of additional hours–will be better. Here’s where it sat as of last night.
I’m pretty committed to the idea of the even shorter lower link, and I’m liking what it lets me do with everything else. That’s what I’m working on right now.
The biggest design challenge ahead for prototyping Project Danzig is the piece I’ve dubbed the “crankcase.” It isn’t the busiest pivot location I’ve seen, but I still want this piece to be as clean and simple as possible.
To that end I keep refining this section, and probably always will. This most recent iteration is an attempt to make things even simpler and lighter. When it comes to Solidworks, I’m ten levels below “amateur,” but I’m constantly blown away by how quickly Solidworks lets you create. Here’s the quick 2D redraw of the crankcase.
And just exiting the drawing recreates the extruded 3D piece.
It’s pretty incredible, how quickly revisions can be made to pieces. The question is how streamlined can this piece possibly become. That’s what I’m working on this week.
I’ve lost track of the hours I’ve put into Project Danzig, and probably best I did. But just when you think you’ve designed something pretty cool, a company in Japan comes along and releases giant robot that shoots people when you smile.
Lest that shot past you, let me just clarify that last sentence. One feature of the giant new armed robot being sold by Japanese killer robot makers, Suidobashi Heavy Industry–I mean aside from the fact that you can control it with an iPad–is that it shoots people in the face when you smile. Smiling operates the dual Gatling guns that fire BBs, so the funnier and funnier you find it that you’re using a giant robot to shoot your friend in the face, the more Kuratas shoots him in the face.
What type of insurance does a company like this buy?
Did I mention you can operate it from your smartphone? Of course you can.
Nothing I write about can possibly compare to the promotional video, though. Until you’ve watched an adorable Japanese girl’s demure giggles cause a robot to shoot someone in the face, you’ve never met the 21st Century.
My suspension design, in contrast, might one day make people smile, but that smiling won’t be able to put anyone’s eye out. At least not yet.
Clearly I have a lot of design work to do.
To that end, today we wrap up axle path–or the “versus propulsion” side of it. Here’s the drawing from yesterday.
The red dots mark three key stages of the axle path. If you look at the green vertical line along which the red dots are arranged, you’ll notice the lowest dot–which represents the bike sitting there with no weight on it–begins on the right hand side of the vertical line. As the bike moves up to its sag point, the axle moves to the left of the vertical line. The key is that the axle path continues to move rearward for 10mm of vertical travel beyond the sag point.
The idea is that chain tension continues to counteract the suspension’s movement until you’re 10-15mm beyond the sag point. The sag point is where the suspension stays when you’re riding around. Chain force hinders suspension movement until you’re 10-15mm beyond the sag point. Once you compress the suspension beyond that point chain tension no longer tries to control the suspension.
So that’s the idea. Almost all suspension bikes work this way, so I’ve not created anything unique there. What I did try to do, though, is develop a platform that will allow a huge range of options with all of these points. The system makes it easy to fine tune every aspect of the axle path.
So that’s what we’re going to do.
Responses to my “How much more would you pay for U.S.-made carbon fiber?” question keep coming in, but at this point the clear winner is $250-$500 more. The majority of respondents would pay up to $500 more for a carbon fiber frame if it were made in the U.S. Impossible to say how accurate that admittedly highly unscientific analysis really is, those are the results. I’ll keep an eye on incoming responses, though, because these things can change.
And maybe next week we ask how much more you’d pay for a giant killer robot that was made in the U.S. Makes me smile just thinking about it.
BikesComments Off on Short-listing Adam Craig for a Pulitzer then Back to Axle Paths
Aug022012
That photo’s from Adam Craig’s blog. He just posted about his inaugural Megavalanche race–that insane DH race with an eight-thousand plus foot descent, 350 rider mass start on snow, and genuine chance of dying. A lot of my work involves reading, writing, and patching up code for posts. I end up reading a lot, and Adam’s posts always stand out. You have to like phrases like, “I overtook dozens of people, mostly in a safe manner,” and “a 4m wide ‘road’ made up of fist to lawnmower-sized rocks.” Most professional riders lead incredibly interesting lives, but the ones capable of actually describing those lives are few and far between. Adam’s one of those great riders who can write about it.
Anyway, Danzig: so I’m thinking the best possible scenario for version 1 is this: 29er, 125-130mm of travel, 17.35-inch chainstays.
Version 2? Well, that’s something else entirely.
I suspect the last time I tried to articulate what was going on with the axle path made little to no sense, so I’ve been meaning to double back to that for some more detail. For starters, here’s the general axle path of Danzig:
Here’s that same deal, only zoomed in and with highlights on the sag line (where the suspension should be when the rider’s weight is on the bike) and dots to emphasize the horizontal orientation of the axle relative to that sag line and a hypothetical straight vertical line. I came damn close to using “vis a vis” instead of “relative to,” but I fought it off there.
What the hell’s all that, then? At this point, most of you probably already know, but let’s wrap it up with a final detailed explanation of chain and axle path tomorrow.
How great was Marianne Vos’s Olympic Gold? First Wiggins hauls some major sideburn action into Paris and then Vos takes a brutal-looking rain-soaked women’s race in–if I’m not mistaken–a skinsuit. It was tough to explain to the kids why I was waving a cowbell at the TV.
It’s been one hell of a busy few weeks. The 2013 NoTubes catalog looks to finally be ready to head to print. I’d written parts of that all across the country, including a Holiday Inn laundry room. Cyclocross.com, on the other hand, is just kicking into high gear in anticipation of a launch date that already can’t happen fast enough. It’s all been sufficiently panic-inducing to pull a guy off his pet personal project, which by necessity has to get whatever time I have left at the end of the day start of the next day.
Still, I was able to do a little reworking during my last round of PF30 conversion revisions. I wondered how short I could possible get the chainstays.
Now, there are a million and a half ways to cheat on chainstay length. My favorite is probably cranking up the bottom bracket height, but in Danzig’s case, that wasn’t an option. So the question becomes: how short can I get those chainstays for a bike with 29-inch wheels, a 12.77-inch bottom bracket height (can always go higher, but that’s as low as I’d go) and (let’s just figure) 130mm of travel. With some adjustments I went ahead and made, looks like Danzig might be able to drop chainstay length down below 17.4-inches.
That’s pretty short. It’s not a done deal, yet, but it’s close enough for me to say that’s now my target.
BikesComments Off on Thanks to Sugar Wheel Works and Digging into Axle Path
Jul302012
Thanks to Jude at Sugar Wheel Works, my old Independent Fabrications single-speed is slowly turning into a bike again. When NoTubes sent me some rims to help bring an old Industry Nine wheelset back from the dead, I was really looking forward to asking Jude to do the build. There’s just a great vibe to Sugar Wheel Works, which shares an enormous building with a bunch of other really interesting businesses. In addition to building wheels, Sugar Wheel Works also offers wheelbuilding classes. It’s a simple kind of business model–offer a service, plus classes on how to do it yourself–that seems to be growing. Only today I found out Carl Schlemowitz from Vicious Cycles is starting something similar with frame building and painting.
So the Indy Fab is on the way back to life. Now it’s down to sorting through boxes and trying to find the rest of the parts I need to finish piecing it together.
This weekend I also finished a pivot redesign on Project Danzig that relocated all the pivot points to allow for even more freedom of motion around the bottom bracket shell. The goal was to ensure ample room for PressFit 30 and similar bottom bracket diameters. In the process, I had to rebuild my main frame around the fresh pivot locations and recreate my axle path from the ground up (literally). Here’s an approximation of what it looks like right now.
We’ve looked at instant centers, axle paths and chains a bit, but one of the specific elements I’ve prioritized throughout all the iterations of this design has do with the relationship of the axle path to the chain. The drawing above illustrates my goal for the axle path.
How you arrange your pivots dictates not only how far rearward your axle can travel relative to its starting point, but at what point in the compression the axle is furthest away from the bike’s bottom bracket. As the axle travels upward, it has the opportunity to move rearward slightly. What I want with this design is for the point at which the axle is furthest away from the bottom bracket to be just past the sag point on the bike.
Why is that? Because chains aren’t elastic. Tension through the line of the chain will keep trying to pull the rear axle toward the bottom bracket shell. By designing a suspension system that needs to move rearward in order to keep compressing right at the point at which pedaling tries to pull the rear axle forward to counteract that rearward movement, the obvious goal is to cancel out pedaling forces. We’re talking halves of millimeters in some cases, but the objective is to turn the chain force into a positive when it comes to eliminating pedal bob.
Factor in the much larger wheels of a 29er or 650b bike, and it can become more challenging to align those two. It was a need to create a longer travel 29er that still had short chainstays that led me to design a frame in the first place. Going forward, I’ll try to explain a little more about the challenges of a bike with larger wheels, how axle path gets involved in all this, and how that led me to design this system.
BikesComments Off on Monkey-approved Kids’ Bikes and Danzig PF30
Jul272012
I have to come up with some bikes for my kids. Actually the girl child has a pretty badass little 24-inch Santa Cruz I concocted based on an idea I got from framebuilder and ultimate bike-for-the-kids-creator Jeff Jones. The boys need at least one new bike, though, and I wish I could find something that looks pretty much exactly like that monkey’s bike.
I’m serious. Why doesn’t anybody make like a kids bike with larger wheels, but small crank arms–like 145mm? That’s sort of what I did with the Santa Cruz, and it makes perfect sense. Bikes like that are ultra-stable thanks to the whole sitting “in” the bike with some bigger wheels up around you (you’re basically creating a scaled down 29er in that regard), but everything else is kid-size. So there’s that on the agenda, if I ever get my garage finished.
I spent most of yesterday writing product descriptions, put in what felt like my weakest ride all year to get home, wrestled Facebook in a professional capacity (just like wrestling it for fun, except for the company issued luchador mask), then wrote some javascript to help make a site compatible with iPads. That last one is positively insane, as I haven’t written any genuine javascript functions in over a year. It was a little like meeting an old friend who no longer speaks the same language, and trying to build an airplane together out of shit you found behind a Radio Shack.
Oh, what Javascript and I had been through together! And to think now we barely know one another. I’m so happy with it that way.
Anyway, I seem to’ve found a little extra in the tank to crank out this Danzig redesign. I’m happy to report that after obsessing about pivot locations on my ride into work this morning, and on my sorry excuse for a ride home, it occurred to me that I can generate plenty of space for a PF30, or a PF50, or whatever the hell massive oversized beast becomes the next standard.
The nice thing about the relocation is that it also makes the frame easier to build. The key was a proportional move up and back for the lower pivot. Here’s Danzig PF30.
Remember yesterday when we looked at instant centers and how their vertical position affected axle path? Maybe it didn’t sound like that yesterday, but the bit about the higher the instant center the move rearward the axle path would be–that stuff? It turns out that axle path is my guiding principle when I’m moving my pivot locations. Right or wrong, there’s a set of criteria I’m following that dictates my axle path, and that range is what dictates my pivot locations. Using more goofy graphics and animations, I plan to dig into that next week.
My own theory, based on his facial expression in that photo, is that this guy just really needed to use a bathroom and, finding no public toilet in the video store, stole the gun to put himself out of his misery.
So Danzig. When I started work on this frame, there was no such thing as BB30 or Press-fit 30. The original design was built around a conventional English bottom bracket. Though it looks like the original pivot configuration will work with an oversized bottom bracket, I’ve started to look at optimizing around a much larger diameter bottom bracket shell.
This means adjusting the lower pivot orientation, which is what I was up to late last night.
In case anybody’s curious, raising the lower pivot location kicks the axle path back further initially. This makes sense if you imagine your instant center–the middle of your pivots’ rotation–as the center of a giant circle. The higher up you move the instant center, the higher up you move the whole circle. And the higher the circle, the more your axle kicks backward during that phase of the travel. Here’s a better view of the same image that probably won’t make any of this any clearer, but what the hell. Everyone likes circles.
The red circle is our original pivot center. The blue circle is the revised, higher pivot. The green arrows represent how the height of those circles affects the shape of the axle path. Your axle path is only a slice of pie cut out of that circle. Where you cut it changes how the bike pedals and rides. Completely. Important pie.
So that’s what I’m pissing with currently. Axle path–our slice of the circle–is also directly related to the force of the chain that’s trying to pull the bike together. If I find some magic extra horsepower to stay up late again tomorrow night, and if I’m not arrested for robbing a video store or run down by a perp pulling a daring recumbent getaway in North Portland, we’ll add that force to our circles.
Pivot released images of some pretty wild new frames today, including the new Mach 429 Carbon (above) and the Pivot Les hardtail. Impressive as the much anticipated 429 Carbon is, the modular drops on the Les are really intriguing. You can click through the photos for more info.
On the subject of new pivots, I’m definitely back off the Solidworks wagon. After taking some time away from it, I’m definitely back in and I have to say, I love this stuff. I’m going to sound like an ad for the software, but Solidworks is just scary powerful. What you can do with physical spaces in this program is just incredible.
None of this is helping me out right now, though. I have what I need to complete this next phase and be able to create an entirely new 3D model, but I’m obsessed with optimizing the spaces between things here. And so I draw. And redraw, and redraw again.
I’m convinced there’s a way to simplify the new Crankcase (the bottom bracket shell/pivot box) even more. That’s what I’m working on right now.
