Alex Wetmore is always busy with something…

I find the combo of vice grips (or other clamps) and spokes to be really useful for holding small brazeons in place. Today I installed mid-fork eyelets onto a fork, small guides for headlight cable routing, and a headlight mount.

Another favorite tool is the flat stainless stock that is used to secure Blackburn-style racks to bikes. This stuff is really handy for making temporary fixtures.

I used a fender stay here instead of an old spoke, but a spoke really is superior. Brass won’t stick to it and it bends more easily. These guides are cut for 1/4″ tubing, but you can also pull the rollers out of used chain.

Watch out for the vice grips, they can distort tubing pretty easily. Used with care they are very handy for temporary clamps.

Most racks have some sort of cross member, straight tubing that goes across the rack platform. They are pretty easy to build.

One of the tricks is getting the two miters to be parallel to each other. I find it simplest to put some scrap metal in the miters and then eyeball them for parallel. You want to check early and often because you do want to be parallel when you have the tube the correct length. In this case you can see that I’m a little off:

It is important to clean the inside and outside of the metal before brazing.To clean the inside of the tubing I make a simple bit for the drill. This is a piece of 1/4″(or smaller)tubing with a slot cut in it to hold a small piece of shop cloth. Scraps of shop cloth are always somewhere on the workbench.

Support the tube in a vise and put the bit inside of it. The sand paper will remove any deposits on the metal and make for better joint.

Once you have the cross members cut, mitered, and cleanedyou need to lay them out. I find that it is best to number which position each one is in and draw alignment marks on the cross members and the rack. I measure to get even spacing across the rack, but use my eye to determine when they are parallel to each other and the sides of the rack. The rack platform may not be a true rectangle and it’s more important that everything look good than that everything is perfectly measured and square.

The rack is parallel to the ground and held in the vise after the last step. With everything laid out I tack each of the joints with a small blob of brass. I don’t use any clamps or fixtures for this, the cross members stay in place on their own. This isn’t the only possible option — Alistair likes to position the rack vertically and use clamps to prevent the stays from sliding down. Once everything is tacked I rotate the rack in the vise and make sure that the valley of each miter is pointing down. This lets me use gravity to flow the brass where I want it to go and to get the best fillet.

Once you’ve brazed everything on one side you flip the rack and do the other side.

In this entry I’ll show how I build the fork crown mount for a rack. This is the part that goes from theback of the rackthrough the fork crown.

On a rack that is designed for very heavy loads I would recommend connecting the rackto the fork crown using two stays, one over each fork blade. This single stay setup is not as good at resisting high lateral loads. It does work with almost everyfork though, where thetwo stay method only works with forks that have extra eyelets on thetops of the fork blades.

I don’t have a lathe, so I use a bolt as the threaded stud that runs through the fork crown. This is a M6 bolt that I’m removing the head from:

The bolt will be held inside some larger diameter tubing. First I need to cut the tubing square. Note that to make sure that it is square I need to check the cut in two orientations 90 degrees from each other.

This is an exploded view of what is going on. I have a 6mm (close to 1/4″) threaded stud that will be inserted into some 5/16 x 0.035″ tubing. This is then inserted into some 3/8 x 0.035″ tubing. The 3/8″ tubing is bent and will be brazed into the fork crown. The 5/16″ tubing is pulled out from the 3/8″ tubing in this view, but when brazed together the 3/8″ and 5/16″ tubing will be flush. This creates a nice face to sit against the fork’s crown.

Everything is loaded up with flux and ready for brazing:

A view after the three parts are brazed together.

Here is a shot showing how I hold the piece in place while brazing it to the back of the rack. I’m using vice grips on the rack and a piece of scrap metal (PCI slot cover from a PC) to hold the piece in place. I checked with a square to make sure that the threaded stud is square with the back of the rack.

Here I am checking the angle. The bike that this is going on has a 73 degree head tube angle, so the face of the fork crown is also 73 degrees. I want it to sit flat (or close to it), so I need to angle my mount at 17 degrees (73 + 17 = 90). I’m using a simple engineers protractor to check the angle. My reference is one of the stays on the rack. I’m a little shallow here, but that is okay. It will make the front of the rack slightly higher than the rear, and that is acceptable.

The other option for doing this is to mount the fork crown mount into a fork and then use a fixture to hold the rack in place. The advantage of this method is that you can see how everything will look before it is brazed together. Alistair designed this nice little jig out of a test tube holder for holding the rack in place while brazing. I like the jig, but find that things are a little more secure using my method. Give both a try and see what works best.

The fork crown mount is half brazed onto the rack. I flipped the rack over to finish the brazing on this side.

All done

This is mitering for a basic 90 degree joint with 3/8″ tubing.

The tube directly after cutting with a hacksaw. It’s a little messy:

Make a notch in the centerline of the tubing using a file or hacksaw. This keeps the file centered in the next step:

File. A handy hint is that a 12″ Nicholson bastard file has a 3/8″ diameter, so it makes a nice miter into 3/8″ tubing. A 10″ file works for 5/16″, a 8″ for 1/4″ tubing.

Once filed you have a miter, but it’s pretty ugly:

Clean up the inside of the miter with production cloth wrapped around a piece of tubing:

Then clean up the outside with production cloth:

Check the miter. It looks pretty good to me:

This will be the first in a multipart set of blog entries with some basic information on rack building. I’m going to start by discussing tools. If you have any requested subjects please let me know in the comments and I’ll concentrate on them in future entries. The next entry will be about mitering tubing. I don’t plan on doing any entries around the use of a brazing torch, I think that you should learn that hands on from another person who is skilled in brazing.

My existing toolkit already had some of what I needed, such as a good vise and a hacksaw. However I also needed to buy a number of more specialized tools such as files, clamps, and machinists squares.

My most used tool is the vise. It supports tubing when I’m cutting it, mitering it, and brazing it. I have a pretty basic Japanese made vise that has 4″ wide jaws. I haven’t found the need for anything bigger yet when building racks, but this one is probably too small for mitering larger tubing used in frames. I often clamp rack sized tubing directly into the jaws of the vise, but it is better to make tubing blocks. You can see a homemade behind the vise. I have my vise mounted in front of the workbench so that I can access it from three sides. Framebuilders often have a vise mounted on a pedestal for 360 degree access.

My torch kit started out as a Victor Superrange II, but I quickly replaced a number of the parts. It would have been cheaper to buy a kit from scratch. I use Oxy/Propane (Oxy/Acetylene is more common). My welding shop swapped the stock acetylene regulator for a propane one. Propane doesn’t burn as hot as acetylene, but it is hot enough for brazing. It’s nice being able to use the same fuel tank as my propane BBQ. My oxygen cylinder has a 55 cubic foot capacity and that seems to last me about 6 months (maybe10 racks?).

I’ve upgraded the hoses to the Smith Kevlar hoses (around $50) and replaced the torch with a smaller and lighter Victor J-28. I primarily use a W-1J tip when making racks.

A great early project is a torch stand. This one is made from pieces of a BMX frame that I found in the trash. The stand lets me keep the torch turned on when I need to put it down for a minute and also holds short pieces of brazing rod andmy striker.

A lot of small tools are involved in making racks. I laid out some of them on my workbench. From left to right we have:

• Drill and bits
• Tubing bender
• Clamps (Kant Klamps are the specific brand)
• Pliers
• Shop cloth or production cloth. This is sandpaper on a roll and 1″ or 1.5″ wide. I buy 80 grit shop cloth and a roll seems to last a long time. Enco has it pretty cheaply.
• Sharpies are really useful for marking on steel.
• Machinists squares in a couple of sizes are useful for keeping things square. Enco has a small kit for $20 with 4 sizes.
• Vise grips are useful for clamping fixtures.
• Round files are useful for mitering. More on this in a future entry.
• A welding magnet can also be useful for clamping.
• A center punch makes drilling holes in tubing much easier. You need to drill small vent holes in most of the tubes that you braze.
• Sitting under the center punch is a deburring tool. It cleans up the inside of tubing nicely after you cut it.
• Brazing flux and a flux brush.

You need to wear some sort of eye protection when brazing. These safety glasses are special in that they have didymium lenses with a flip-up #3 brazing lens. They are large enough to fit over my regular glasses (yup, I look like a dork with three pairs of lenses on my eyes). You can get them from Sundance Art Glass. Without didymium the flame and flux produce a bright orange sodium flare that is very difficult to see through. It makes it hard to see the underlying metal,which is necessary to know when the flux is getting hot enough (it turns glassy) or the steel is getting too hot (it turns orange). Here is an example without the glasses:

Can you see anything under that huge orange flame? I can’t. This is what happens when you put the glasses on:

Whoa. That tube is too hot.

The glasses are expensive and a luxury,but they are a really useful luxury. I think that they help my brazing quite a bit.

Kent, Mark and I met at the top of the I90 bridge this morning for some socializing and bike geeking. The toys of the day were my Bike Friday Tikit and Kent’s Dahon Curve. Mark brought along Jan Heine’s Alex Singer — normally one of the most interesting bikes of the bunch, but today it didn’t get much attention.

Kent’s Dahon is really nice. For $400 you get a bike which folds up to a tiny package (not as small as a Brompton, but smaller than the Tikit) and which rides nicely. Contrasting the Dahon and Tikit was fun. The Dahon is very simple in comparison. The fold isn’t as slick, but it is fast enough (Kent says it takes about a minute). The Dahon folds into a small package partially because it is a small bike to begin with — both Mark and I felt that it was undersized than us. Kent said that if you think about it as the fast alternative to walking then you’ll have the right mindset. I was impressed with the parts spec on the Dahon. For $400 it includes some nice features like Schwable Big Apple tires and a simple and effective Sturmey 3sp drivetrain.

Kent and Mark were impressed with the fast folding of the Tikit and Mark liked the riding position (which is pretty similar to my other bikes). The Tikit has some handlebar flex that I’m still working out, but once you get used to it the ride is pretty nice. The Tikit is closer to a normal bicycle in ride and fit, but it also has a much more complicated design and is much more expensive.

The ride also gave me a chance to try out my newest rack. I built a second rack for the Tikit that fits into the folded bike more nicely than my original design. There is clearance for the saddle to fit into the rack and it doesn’t get in the way of the rear tire when the bike is folded. I think that I came up with a solution that is asthetically pleasing and functional.

I’ve been very busy and haven’t updated the blog in a while. Click on photos for more, I’m limiting myself to one or two per project.

My IvyCycles Rohloff Custom is on the road. I’ve put about 100 miles on this bike in the last week and it’s fantastic. Everything that I hoped for. John Speare wrote a blog post about how cool it is, so I don’t need to.

A couple of weeks ago I bought a minibike for Rollo (minibike polo). I still suck at polo, but I’m having tons of fun showing up every Friday and playing a game or two. Bikes like this are about $5 at Goodwill. A carbon fiber golf club (used to make my mallet) cost $2. I spent more money on the steel for making my extra long seatpost than anything else. I carry my Rollo bike there on my Kogswell Porteur — bike on a bike. Aren’t porteur racks great?

Speaking of Porteur racks, I made a new rack this weekend for the IvyCycles bike shown above. I call it the MiniMax. The platform is about the same size as the bottom of a Ostrich Handlebar bag. It’s small enough to work nicely as a handlebar bag rack without having tons of extra metal and large enough to carry my messenger bag. I originally built the rack with the decaleur at 73 degrees back (to match the angle of my headtube) but the bike’s stem and handlebars got in the way. So it is vertical (for now). The rack needs some stays to the rear corners and a headlight mount, but it’s done enough to ride.

Rory and I built a rack for his new bag. He is going to have a small run of similarily large bags made. This one uses Cordura, but he is thinking about canvas for the production run (and the colors will be more muted). He used a unique and wonderful mounting system for the bag — Ortlieb hooks mounted to a bar on the front of the rack. I’m going to buy one of these bags from him for the MiniMax rack and setup Ortlieb hooks too, except that they’ll be on the bottom of the bag instead of the front. Click the photo for more photos that show the mounting system.

Last week I settled my insurance case from getting hit by a car while riding on Seattle’s streets. I’m glad that the whole ordeal is over with and I’m happy with how everything was resolved.

Next weekend I’m taking the IvyCycles bike camping and I’m sure I’ll report back with more at that point. It’s been a busy and great June and I expect the rest of the summer to keep pace. I hope everyone out there is having fun too.

Alistair showed me photos of his rack jig a couple of months ago and I finally got around to building one myself. The core piece is some sort of holder that we got at “Science, Art and More”, a fun science oriented store in Seattle. It consists of two tube clamps with a center pivot that can be rotated 360 degrees. Alistair added two other tube clamps on stalks, one for the frame or fork and one for the rack top. Using this you can position the rack top while you braze in the stays that will hold it in place on the bike. Click the image for more photos.

After building the jig I added the fork crown mount to one of my rack tops. I like how this one came out:

The bolt that goes through the fork crown is just a standard steel M6 bolt bought from my local hardware store. I cut off the head and brazed it to some 1/4″ tubing. Finally I put a 5/16″ sleeve around the bolt to provide something for the nut to compress against.

Nothing groundbreaking, but it is a little smoother looking than the similar design on a Nitto M12.

Yesterday I made my second small front rack top and it was the second time that I had trouble with the measurements for bending tubing (using a lever-style bender). While sitting down with a piece of scrap and the bender I figured out an alternative way to compute bends.

Swagelok has a the best manual for lever benders that I’ve seen. The information is good for any brand of lever bender (I have two benders, neither is made by Swagelok). Starting at page 13 there is a discussion on the gain calculations for figuring out where to place bends for making a polygon.

I’ve had problems with the Swagelok method ofcomputing gain because asmall mistake anywhere in the process can cause problems elsewhere. Yesterday I made either a computation or measurement error and madeone bend 1/2″ earlier than I should have. I ended up splicing twopieces together to recover. Since the Swagelok method has you map out all bends before you start any small errors at end bend will compound.

I figured out an alternative that is easier for me to use.Instead of marking only the end of a bend I’m marking both the start and end of each bend and measuring the straight section of rack between the bends. Using the bender radius I can compute the desired lengths of the straight sections.

In this example I make a roughly 5×7 rectangle (good for a handlebar rack) out of 1/4″ tubing using the Ridgid 404 bender. It has a 5/8 radius.

For a 5×7 rectange the long straight sections would be 7-(5/8)-(5/8) = 5.75″ and the short sections would be5-(5/8)-(5/8)=3.75″. To make life a little easier I rounded these up to 6″ and 4″. The rack will be 5 1/4″ by 7 1/4″, which is still a good size.

Using the radius of the bender I can compute the circumference of the bend that I’m making. For a 90 degree bend it is (pi*2*r)/(360/90). r is 5/8, so this gives me .98″.

The Process:

In this example I’m going to put the seam along in the center of one of the ~5″ sections.So I measure 2″from the end of the tubingand draw a line. .98″ from that lineI draw a second line. To bend I align the first line with the 0 point on the bender. After a 90 degree bendthe second line will mark the start of the new straight section.

I continue this process working around the rack. This photo shows us at the halfway point.

At the final bendIdo the same thing, but I also do something else to check my work. Using a square aligned with the center of the first piece of tubing I draw a third line in between the two normal ones. I put a S through it (square) making a $ sign. You can just barely see this in this photo, but it is clear in the next one.

The $ line will line up with the 90 degree mark on the bender:

I cut the tube to 2″ past the last line and bend:

Here is the final product:

It is about 5 1/4″ across (center to center). We used 4″ straight sections and the bend radius is 5/8″. 4″ + 5/8 + 5/8 = 4 10/8″ or 5 1/4″.

You’ll notice that I never had to measure any fractional numbers except for the bend circumference. I set your calipers up to the bend circumference and locked them in place. This let me use the ruler for the straight line measurements and the caliper for the bend marks.

The same technique should work for non-90 degree bends, you just need to figure out the circumference of the bent area. The formula is simple: (pi*2*r)/(360/degrees). So a 60 degree bend with a 5/8″ bender would be (pi*2*(5/8))/(360/60) = .65 (or 21/32nds). I’m going to be building some front lowrider racks with trapezoidal shapes next and will use this technique there.

I spent some time on Saturday experimenting with different headlight mounts on my bike racks.

This is the first attempt. It is just a M5 eyelet on one of the rack stays. Nitto uses something like this on the M12:

It’s a basic but functional solution. The small piece of flat stock gives one a lot of options for where to actually put the light. It looks pretty ugly though. The best part about the light mount on this rack are the three loops for managing the front cable. No zipties here! They are made from rollers pulled from a worn out bicycle chain.

On my convertable Porteur Rack I played with two different options. The first (no light mounted to it in these photos) is a pretty basic design that is easy to make. I just used some 5/16″ tubing with a perpendicular piece at the end for the light’s mounting bolt.

I also need a mount on this bike which is farther back so that it doesn’t interfere with the front wheel hook on a Sportworks bus-mounted bicycle rack. I thought of a nicer and more simplistic option here. I used the shaft from a nail (about 3mm in diameter) and put a 5mm eyelet on the end of it. Minimalistic and functional, I like it.

While I had the torch out I filled in all of the vent holes on my front rack with small nails and brass. That was a lot of work, but now there is no way for water to get in: