Bob Brown Cycles, Custom framebuilding in St. Paul, MN

Truly Custom

At Bob Brown Cycles, custom means more than just sizing. I do custom work that other framebuilders won't or simply can't. Basically, if I can't find the parts I need to build your frame exactly as you desire, I'll make the parts, including lugs, crowns, tubes, and even components. If you're looking for something that you just can't seem to find, give me a call, I can probably help.

Below are a few examples of some of my really custom work. Take a look at the tandem gallery for many more examples of custom crafted lugs.

Very Custom Lugs

From time to time I build frames with exceptionally custom lugs. Usually the customer gives me an idea of what they'd like to see, then I take that and run! I tailor the shape to fit the natural shape of a lug, and keep the bike design flowing and smooth. These are all hand-carved, as you can imagine they are also quite time-consuming. Take a look at the single bike gallery for some pictures after paint.

Custom Lugs for Carbon?

Yes, you read that right, but don't worry, this one is just an experiment. More than likely anyone reading this knows I'm a lugged steel guy, but I also believe that I can't complain about another material unless I at least give it a shot. With all the hype about carbon fiber rear triangles these days, I decided I should at least try one out, and give it the Bob Brown Cycles touch. So I built one for myself as an experiment. Here's what may be the only fully lugged steel/carbon fiber rear triangle bike around.

	The BB shell started out as the steel connecting shell that is supplied with the Columbus Super-Muscle rear end kit. I added the sockets for the seat and downtubes, then machined out the shell. As you can see, the front deraileur cable has to go right through the mono-chainstay port. It's kind of a neat look. I was pleasantly surprised by how much tire clearance was available with the carbon stays. Both the chainstays and seatstays would easily fit a 27c tire. The countours of the BB shell really show off the Chrome-illusions paint.
The main lugs on the frame started off as Pacenti Slant six lugs. I shaped the headlugs quite a bit to reduce the amount of steel on them and make for a clean minimal look. I like the amount of headtube extension cast into the upper headlug. I carved out quite a bit of material from the front portion of the lug though. The frame tubing is a mix of Columbus Spirit, and True Temper S3. It's light, about 17lbs with a full stock Campy Record group including pedals.
	The seat-lug was actually the most difficult part of the whole frame. I had to add a long extension to the back of the lug, then braze on the connecting tube for the carbon mono-stay. The tube in raw form is uninspiring, so to make it match the lugged frame, I carved it up with a couple points and shortened the length quite a bit. There's still plenty of overlap for the epoxy bond to hold, but it looks a lot better.
The paint came out fabulous. It's not at all a traditional type of paint job, but it's actually quite understated in real life. I deliberately kept the color pretty dark and kept the translucent color-changing coat thin. I left all the carbon parts bare until the translucent coat and blended that in very lightly. The result is the carbon weave comes through the color-change coat in a very unique effect.

Custom Fork Crown

For this project, the customer really wanted a fork with clearance for a 2.35" wide tire with a fender, with a 1.125" threadless steerer, and with a crown. A fork crown fitting those criteria simply did not exist (these days I'd use my new BBC crown!), so I made one. This fork is for a fully loaded touring frame and a heavier rider, so there was no room for a flimsy crown here. Below is my procedure for the build.

I began with some existing crowns and fork parts. I cut the fork blade sockets off an Everest crown and mounted them on my fork blades (which had already been raked and cut). I put the assembly in my mitering jig and used a 3/4" end mill to bore a hole thru the socket and blade. The hole only goes thru the inside of the socket and blade, the outside is left as-is.
	Next, I machined the connecting rod which would go between the two blades and pass thru the steerer. On my first fork I machined this from 3/4" solid rod stock, but later changed the design to 1" tube 4130 tubing with a 1/4" wall. I turned the ends of the tube down to fit the 3/4" hole I had bored in each socket. Then I machined a 1" hole thru the steerer tube with a re-enforcing sleeve mounted on it. Here is a picture of all the parts prior to jigging.
Next, the dropouts are fully brazed into the blades and cleaned up. Then the fork is ready to be jigged up. Due to the design of the crown pieces, the jig holds everything nicely in place. Once I confirm that everything is a perfect fit, I take it all apart, flux it up and re-assemble it in the jig for brazing.
	Brazing this was a big job. That connecting tube is 1/4" thick steel and the steerer is about the same at the point where it's being brazed. I used the largest, hottest flame my torch can produce and began heating the whole crown area evenly. Once up to temperature, I was able to feed brass in at each socket and flow it completely thru the joint and into the fork blade. This took a large amount of brass, but I wanted to be sure I had the absolute safest joint possible.
Above is the result after a little clean-up. I used extra brass around the crown sockets to get the final shape as I wanted it. After final clean-up, and paint, the customer had a very strong, fully crowned fork to match his custom frame.

Headshok Singlespeed

This is a single-speed mountain bike frame built specifically for a Cannondale Headshok fork. Here's a pictorial review of how I modified this Headshok fork. My goal was to reduce the overall fork height as much as possible without reducing travel or tire clearance. The Headshok fork is a complicated fork, and I don't recommend you try this at home, it required substantial machining work and knowledge in suspension systems.

Here's a close-up of the steerer/blade assembly as I was removing the steerer. I heated up the aluminum blade assembly until it expanded enough to remove the steel steerer. The steerer slides right out, but the fork blades are ruined as this destroys the heat-treatment of the aluminum.	This is a close-up of the steerer tube once removed from the lower blade assembly. The steerer is 4130 steel. it appears to have been turned then ground from tube stock. I was able to machine down about 3/8" from the bottom end to reduce the height a bit here without losing travel. I also reinforced the lower portion of the steerer to make it suitable to braze the new unicrown fork blades directly to this steerer.
Here's a shot of all the components inside this particular headshok. It's an elastomer sprung system, which I changed to a coil spring system to accommodate my height modifications. On the upper right is the fully serviceable hydraulic damping cartridge. Shown in the center bottom are the 88 needle bearings the fork rides on.	Here's the fork in my jig ready for brazing the blades. I used Columbus Nivracrom unicrown mtb blades which are much thinner in wall thickness and diameter than the original aluminum blades. The smaller diameter of these near the steerer allowed me to lower the height of the fork more here without sacrificing any tire clearance. The tapered blades look much better and weigh less than the original straight walled blades.
	Finally, here's what the fork looks like on the frame after paint and re-assembly. I machined the headset to fit the press fit bearings on the fork and the custom headtube on this frame. I turned the headtube on my lathe as well, it's fully butted and relieved on the front face to reduce weight. The finished fork and headset weighed in at about 1380g which is just about 3 lbs exactly or the same weight as a Rock Shox Sid SL and Chris King headset.

Headshok Soft-Tail Travel Singlespeed

With the success of the first Headshok singlespeed, I decided to take it a step further. The entire rear triangle of this bike separates from the front triangle. Then with the fork removed, the entire bike fits inside one 26" x 26" x 10" airline legal hardshell travel case. The weight of the complete bike is 21 lbs, which when combined with the weight of the case, packing material, and tools for assembly brings the whole thing in at about 47 lbs, just under many new 50lb weight limits on major airlines.

The bike features about 1.25" of rear wheel travel, fully adjustable via the Cane Creek Air shock. Up front I did a little more headshok modification on this one. The fork began as a Cannondale Fatty SL with 70 mm of air-sprung travel and a damping dial (which does not fully lock out the fork). I lightened the fork up a bit similar to the first headshok bike, however I then went a step further and machined my own internals for the Fatty cartridge damper to provide a true on-the-fly lockout. This fork has 20mm more travel than my first modified headshok, full lock capability with fully adjustable hydraulic damping and an air spring, yet weights only about 20 grams more than the first fork.

	I had to machine my own custom crown to fit the Cane Creek rear shock and the seat-stays of the frame. It's machined from 6061-T6 billet aluminum. Just for a nice touch I machined up a cantilever cable hanger for it so I could run my favorite brakes, Control-tech canti's. The shock and crown together weight about a pound.
The longer travel fork isn't as aesthetically appealing to me, but this fork is much more plush than the first one (which had 50mm travel). I machined the headtube from oversize tube stock 4130 with relieving in the center to save some weight. I was able to save a few more grams with the carbon fiber handlebar, and of course the famous cork grips!