This category is a repository for information around the PVD Samantha Bicycle Frame Fixture and other associated work.
When we work in engineering and design, we refer as much as possible to ‘first principles’, those datums or facts on which the entire project rests. “A basic assumption that cannot be deduced any further”. Everything comes back to these. They are both our lighthouse and safe harbor. In bicycle design, there are many of … Read more
It’s been a while since discussing the SKYNET and WOPR frame fixtures. They are some of my most important work and I review them from time to time. I’m not going to go into too much about the fixtures as little has changed, aside from one important detail. Early in the designing of the Cyberdyne … Read more
For those familiar with my work, it’s known that I try to push my models hard in the design of my bikes and the parts that go onto them. Because of that, equation driven construction geometry for entire bikes and groupings of parts turn into hundreds of parameters and equations for any given configuration and … Read more
I tell people all the time that I’m not a very good welder. I know good welders. I am not one. Still, I need to get metal connected and I can use all the help that I can get. When welding a bicycle frame, it needs to be held in a lot of interesting positions … Read more
I think it was 1990 when I built my first set of bicycle wheels. I was a young man of 20, working at Fat City Cycles in Olive Square in Somerville, Massachusetts. We manufactured very fancy bicycles there. On the side, I had just constructed a fixed gear road frame for use getting around Boston … Read more
I develop a lot of equations for use in my designs. Math is behind most of what I make. Generally, I’m using MS Excel while going through the math and drawings to arrive at the system that I want to use. That gets added to master spreadsheets along with all my other calculations that I’ve … Read more
This is the holy grail of the plate style fixtures and is the third iteration of a bicycle fabrication fixture that has developed from modern bicycle design principles. The 2020 Cyberdyne System fixture changed everything. By building a fixture on a breadboard surface, precise fabrication could be done with a lesser investment in tooling. The … Read more
This is something interesting that came up in the shop yesterday. My friend, Tim Murko, has been working with wood in recent years. He’s been doing various furniture and wall art types of things. For a while, he was content with just wood and fasteners (along with some fun electronics as Tim is an electrical … Read more
Last week while in Santa Cruz for the Caletti Open House, I got to take a quick ride at UCSC before heading over to John’s shop. At the top of U-Con by the kiosk before entering Rock and Roll, I got to talking with a bunch of guys. They took interest in the bike that … Read more
Handlebar upsweep isn’t a thing. It never has been. Notice that this will be the last paragraph where that term will be written in this article. Don’t say it. Don’t repeat it. It’s an old punchline to a joke nobody remembers. It’s been a few years since I’ve discussed handlebars in general. It’s time again. … Read more
“Skynet IS the virus.” – John Connor Just over a month ago, the SKYNET chassis fixture project was announced. An open source bicycle chassis fixture that exceeds in capability over anything that can be purchased. It would be based on the PVD Cyberdyne System fixture but significantly more accessible and affordable. Since then the design … Read more
I have a feeling that there’s going to be some discussion about math on the internets very soon so I’m going to start with something fun and maybe useful for a lot of people in the current era. I was on a ride yesterday where so many of my ideas come from. I was thinking … Read more
Last March, early in the COVID-19 lockdown, I set out to design and build a new frame fixture for myself. This was need-based on many levels. I wanted something amazing. Something better than anything I could buy. A fixture for a new way of doing things. The result was the PVD Cyberdyne System. I still … Read more
I live in a world divided into small fractions of a millimeter. Often, I spend a great deal of time freeing up just 1/2 of one and feel like a conquering hero. It is my struggle. I was recently sourcing some forks for the all-road bikes that we are about to do. It had been … Read more
Here’s a cool modification to the Cyberdyne frame fixture. While I worked to make the fixture as best I could in the initial round, I wasn’t going to be able to do everything I wanted as the project would never end. Now, when I can focus on just finer aspects of the use and refinement, … Read more
I’ve been working on my suspension bike design for about five months now. There’s no rush and I’m trying to do it right. I can prototype as much as I like in the computer and it doesn’t cost me a thing. What’s expensive is wasting money or time once I start cutting metal. I’m nearing … Read more
The rise of the machines… TL;DR: This isn’t just another Arctos frame fixture clone. It’s a better solution and one you’ve never seen. The rules of the game have been re-written. If I were to say where this began, it would probably be back at the 2016 NAHBS show in Sacramento. I had spent the … Read more
A while back, I wrote a piece on recognizing expertise in those around us. It’s pretty good, you should check it out. In that essay, I talk about how an expert can recognize systems around them and build those systems into other systems, better, that they can explain all this. I’ve been doing just that … Read more
Back in November 2019, I posted a stream of consciousness, ending in an enlightening concept: PVD/RAD. It looked promising even in that primordial state. The problem with that post is that it was confusing and left folks with more questions about the process than the answers it could have. Six months later, I’m still excited … Read more
Today is my day to eat some crow. Attentive readers will know of my work on brake caliper mount locations and a tool for attaching flat mount caliper bosses in the correct location. I’ve been pretty proud of this work. It cleans up a big mess. Devin Bodony of Lichen Precision, a machinist bro that … Read more
In photography and filmmaking, the joke is often made that “it can be fixed in post” to justify doing very low quality work. It’s true that there are a several small issues that can be fixed after the image has been captured. Some colors can be shifted, a smudge removed, subtle white balance changes, the … Read more
This came up in a discussion the other day. I figured that I’d bring it up here as it is current in what I’ve done in a recent design. I’ve been working with my klunker platform enthusiastically and have just produced the Supermarine Spitfire which was building on the Sopwith Camel. It makes use of … Read more
The current trend in bicycle marketing is to talk about frame reach, the horizontal distance from the bottom bracket axis to the center of the top of the headtube. The ‘long’ in long/low/slack is for “longer reach” or “longer top tube”. Although this is just flagging that they don’t understand much about what they are … Read more
POST: 2020/02/15 – An attempt has been made to refine the content you see here in a newer post. This should help a bit as it is clearer and more straightforward. Last year, PinkBike published an article describing Lee McCormack’s concept of fitting bikes using his Rider Area Distance (LLB-RAD) method of bike fitting. McCormack … Read more
It’s time for the Philadelphia Bike Expo! I wanted to be there this year but lots of important work got in the way. The design for this tool was done a couple of weeks ago. The tool was supposed to be finished before PBE and show to folks in real life but thanks to late … Read more
The job of the handlebars, stem, and spacers on a bicycle is to place the hand grips above (or below) the headset and with the grips in the correct location for the rider’s body, style of riding, and goals. It’s a relatively simple task that is often screwed up by the user or technician. This … Read more
Talking with another framebuilder bro today. He seemed to not know about 110×12 hubs and axles for the front of narrow gauge bikes. I got a little bit mad. Everyone should know. The market is currently flooded with fancy 100×12 wheels and exotic forks for road and gravel bikes. Cheap and expensive bikes are the … Read more
Here’s a cool tool. It’s a replacement #745 Radial Centering Cone on the Park Tool #HTR-HS Head Tube Reaming and Facing Handle. It more optimizes use of the tool for bores from 41mm to 56mm without the need for a Park Tool # 750.2 Oversized Centering Cone Adapter (which doesn’t actually come up to a 56mm … Read more
Here’s another post in the never ending saga of the new FM140 mount I’ve been working on. I decided to go with a special variant to work better with SRAM calipers. SRAM calipers are shifted about 0.3mm outboard. Along with some manufacturing and tooling tolerances as well as paint and clear coat, the 1.omm slot … Read more
Flat mount has been the topic of the week in PVD land. I can’t wait until this is over. The flat mount specification was released a few years ago and had everyone pulling out their hair. It is a fine system but it was specified so poorly and in such a confusing way that it … Read more