The mountain biking season is entering it’s second phase, summer. The first rains in the late fall mark the first phase, the racing season marks the second. The Sea Otter Classic is just around the corner and the 1st National Series Race is even closer than that and the Pietermaritzburg UCI WC is this weekend. … Read more
You never know anything unless it’s been measured. That’s the rule any engineer lives by. Most people think of suspension systems and tuning them as some sort of voodoo or black art. The #1 problem with these folks is that they really never understood the role that springs play in the system or how springs work in a … Read more
When a spring in a shock is compressed two things happen; the spring twists and the spring cocks. When this happens, the spring needs the freedom to do this otherwise the restriction results in mechanical friction in the shock, slowing it down in an uncontrolled and unpredictable way. In motorsport, you would use a hydraulic … Read more
Hey folks. Here are my pictures from the 2012 North American Handmade Bicycle Show in Sacramento California. Enjoy!
***THIS ISSUE HAS BEEN RESOLVED – SEE THIS POST*** I like my Santa Cruz Butcher. It’s a fun, solid, no-frills trailbike. I got it for that reason. I didn’t want to mess with it and I wanted solid.A creak had developed in the main pivot. I hate that. I hadn’t taken it apart when I … Read more
Today I stumbled on the proverbial pot of gold for bike folks, an early Wicked Fat Chance at a local pawn shop. The bike apears to be a late 80’s or very early 90’s frame. It’s still got the pressed in BB bearings that were phased out in 1991. Honestly, I don’t need it but … Read more
Mary was re-gearing her Nomad this morning. Putting a 26 tooth ring up front to give here knees a break climbing on the, now heavy, bike. We were checking the ring spacing when we found something off. I really hope that this is the only one that slipped through QC. #Y1LR26000, Chainring 26T-AH, FC-M980 It’s as if … Read more
***Update 2017-02-23*** Time has proven that the spike configuration seen below is one of the best ways of accomplishing the goal. The importance of the fender washer stack can’t be emphasized enough. It spreads the load of the spike and reduces failure. Very long spikes are hard to justify. Most often, the result in a … Read more
This is a pretty special bike. A juvenile DH race bike for my friend Bryan Harrell’s son Jake. Jake has been racing ABA BMX (ranked 4th district CA04) for the past two seasons and is absolutely killing it. As mountain bikers and living in the best place you can for riding trail, it is only natural … Read more
I’m getting a 29er type bike built for me this winter. All I needed to do was design it. I’m looking for it to be a nice tight fire roadie/crosser that can still ride real singletrack quickly with tires maxing out at 1.9″. Special attention is going to be put into getting the largest chainrings possible … 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
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
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
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