I absolutely love trigonometry. It’s how we come to understand circles and curves. I work at the Physics & Astronomy Department at San Francisco State University. Every semester a few students will express their unease, confusion, and problem doing trigonometric work. Over the years, it’s been shown that, all of them, have never been given … Read more
A long, long time ago (1998?) I designed the disc brake dropouts for Independent Fabrications. I knew the whole crew there as we had all worked at Fat City Cycles together. The reason for the design was simple, I needed a new bike and I use Shimano parts. That was the moment that Shimano had … Read more
Things went pretty wrong at the Tara Llanes Classic. I’m bummed. Not just because of getting injured but because I really thought I had a shot at 2nd place in Cat 1, 40+. Grrr. I even had a cool bike for MegaDH. I got kicked off a big jump really bad on my warm up … Read more
This weekend is the Tara LLanes Classic. http://www.tarallanesclassic.org/. It’s what is called a Mega DH. Mega DH is essentially Super D’s wicked brother. A very long DH race with no emphasis on real climbing but a bunch of pedalling at high speeds could be involved. The key is that the course will involve true downhill trails … Read more
Jake Harrell is the son of my friend and business partner, Bryan. Fairfax Cyclery!!! Jake and Bryan have been racing a ton of BMX lately and Jake is proving to be a seriously fast kid. He can’t wait to get out with dad and the bros for the downhill rides. Problem: There is really nothing … Read more
Simple leverage. Didn’t anybody else do the math? BB30/PF30 has proven to be a complete mechanical failure. It was obvious from the outset and I had made good arguments against it when it was first being rolled out. The Shimano system is clearly superior but for some reason cyclists thing that everything has to be … Read more
The proper setup of Downhill and long travel suspension bikes often requires the frequent removal of the shock as well as having the system in a topped out AND bottomed out state. These little dummy shocks allow the rear end to be easily fastend in place to adjust things like chain length, cable routing, chain … Read more
Ashland Super D, Cat 1 40-55 Men, 42:26, 14th. Super fun race. A poor showing for me. Ran with full fixed high post. I was a bit out of shape for the climbing and could have saved some time with a dropper post. Can’t wait until next year. I would expect at least a 39 … Read more
Thinking about this today. What about the area under the curve with regard to shock rate? Should the area be similar for differerent types of bikes? The shape can change, the duration and the magnitude but will in the end the area be similar? I’m going to think a bit about this… Here’s the curves … Read more
Cheap stems are rad. They do just fine holding the handlebar in place and come in many sizes. Most are even lightweight. What’s the problem? Tolerances. Most cheap stems are cast or use cast parts in a weldement. These parts have deviations that cause a problem. The issue is that the bottom side of the … Read more
I read an artical online about a guy that made a few eccentric reducers for shocks to use for adjusting ride height on bicycles. It was a great idea although his execution was rather poor. I instantly decided to add that option to my PVD Reducers. Pretty cool. 1mm offset at both ends of the shock … Read more
Mary Pralinsky wanted a beater bike to take to the jumps and to the pump tracks. She wanted something cheap and unbreakable. Nothing can touch a Specialized P3 when it comes to that. The bike is heavy and indestructable. She found someone selling a used one with 90% of the parts for $200 and picked … Read more
So…. My friend Matt gave me a call. He had purchased a basket case VW Super Beetle project car. The car had had a lot of work done on it but wasn’t completed and it needed an engine. Matt had a line on a Porsche 914 engine that would drop right in. He purchased both … Read more
A Super D bike is a very special kind of bike. 90% DH Trail with 10% Climbing. Super high speeds on smooth to aggressive surfaces. You need a light bike but something that works right when treated rough. 160mm frames tend to work especially well in this situation if set up well for pedaling and … Read more
Named for NASA Project Gemini, since it’s the bike after Mercury. This is the first of a pair of bikes, one mountain and one road. They will reflect a snapshot in both disciplines of my bike design techinque. They will share several design cues. They will proabably be painted the same color. Since these will … Read more
This past week has been all about Mary. Two of them in fact. Mary Pralinsky and Mary Moncorgé. Mary Pralinsky is a friend of mine racing DH as an expert this season. Mary Moncorgé is racing PRO in GRT and nationals with Santa Cruz Alliance. Both needed fully prepped race bikes for the season. They were nice enough to come to … Read more
My SC Butcher bike has some serious drive train issues that make it less than fun to be on. It functions, but it’s so floppy and loose that it ends up being something that I think a lot about on a ride. That sucks. Gonna fix that. I don’t want to strip the bike down … Read more
Hey folks, Juliana Gallin of How-to Night SF was nice enough to invite me to lecture on how folks can build their own bicycle frames at home. Of course! It’s easy. How-To Night at Bazaar Cafe Wednesday March 9, 2011 • 7 pm • How to Build a Bike From Scratch Bazaar Café 5927 California Street, between 21st & … Read more
Inspired by products designed and made by Magic Motorcycle in the early nineties. Some wild stuff. Probably not the best, but intriguing to say the least. Especially if you are a machinist type like me. So, 2×10 has taken hold in mountain biking. It has a place but certainly 3×10 does as well. Shimano has … Read more
The radar mount was installed today. I mentioned it in an earlier post. Very cool. It took some planning, lots of rope and safety harnesses but it was installed without issue. A 40 foot drop on one side and an 18 foot drop on the other. No screwing around on this job site.
I’ve been quite busy lately… The modular throttle project is just about done. Final testing takes place this weekend but this revision is assumed to be the last. Prototyping has been a long process for this. The engineering was quite a learning experience for such a simple little part. A 60 degree variable rate cam that … Read more
This is a neat project from work. It’s a straddle mount that will sit on top of a wall above the water treatment facility on Ocean Beach. It will support a 9′ rotating radar boom against anything the Pacific Ocean can throw at it. 0.375″ stainless steel, plasma cut and welded together.
These are the all new PVD headtubes for the 2011 Gemini bikes. A pair of bikes following Mercury. A road and a mountain. They should be completed prior to NAHBS for all to see. Show bikes made to be ridden hard, put away wet and taken out again and again. Top bearing is Cane Creek … Read more
Named for the NASA Mercury space program. Seriously rad! The 2011 PVD Mercury Trailbike. Tapered head tube, 2×10 designed, DMFD, ISCG05 w/slider, BB92, with clearance for 3.0″ tires. Like all PVD Trailbikes, this bike is designed specifically to completely dominate Marin California singletrack. The time tested and challenged design sets the standard for high speed … Read more
2008 GSX-R750 Tie Down Tabs for rear end. mounts under the passenger peg bracket. A nice feature for transporting or working on the bike.
Math and numbers rule! You can learn a lot from them. This weekend I put my nose to the grindstone and measured the weights for my bike and weight distribution. Bike weight (full of fuel) – 444.5 lbs. Ride weight (no gear) – 203 lbs. Gear weight – 18 lbs. Weight distribution – 49F/51R (note … Read more
Here’s a fun little project. Motorcycles have engines. We all know that. What few truely understand is that we use our throttles and gearing to access and make use of those engines. Asside from gearing issues that I will cover later, throttles typically need modification so that we can get all that power we have … Read more
Here’s the new bike. Soon you’ll be seeing a lot more tuning projects based on this. I’m super stoked.
It’s not easy making things and bringing them into this world. It takes a lot of time, energy, money, devotion, and lonely days in the shop. I’ve got so many projects started right now and many more that I’d love to start. Why not? Life. Lately I’ve been really putting a lot of energy into … Read more
It’s been a few months since I’ve build a bike frame. I needed to update my geared trail bike with a few new updates in my design but one issue was lagging. 1.125″ straight steerers are effectively dead. It’s all tapered now. The light carbon forked folks like it. The burly slopestylists like it. Everyone … Read more