SF Cyclotouring

Ride reports and other ramblings from a San Francisco cyclist.


Introducing...The JimG™ Rack Fixture

Today I built a fixture to locate a rack deck relative to a bicycle. The idea behind this design is that the fixture fits onto an assembled bike and will work (hopefully) whether the bike is right-side-up or up-side down.


Tube bending

Tube bending
Originally uploaded by Gino

Mitering a Tube

Mundane details
Originally uploaded by Gino

MAPP Gas Brazing

Too-hot low-fi torch
Originally uploaded by Gino
Gino took the video while I was brazing a joint on his forthcoming rack...


Rack Building Tips

Second Bend

Someone over on Flickr asked me about getting started with rack-building. Here's what I wrote to him, which I'm reposting here for posterity:

Here's where I learned about building racks:

1) Alex Wetmore's "Rack Building Basics" series of blog posts:

2) Alistair Spence's Flickr photos:

3) Pat S's blog:

Spend a few hours/days reading those, and you'll learn a lot.

On tubing choices, Alex has recommended that 5/16" tubing is the best all-around choice, because it's beefy enough for a lightweight porteur rack, but svelte enough for a small front rando-bag rack. The other two tubing choices are typically 1/4" for small racks and 3/8" for heavy-duty cargo racks. I've been working with 5/16x0.35" tubing, and the first porteur rack I built holds 40 pounds with ease.

Benders are specific to your tubing choice. There exist low-cost "tri-benders" with three grooves for 1/4, 5/16, and 3/8" tubing, but those won't bend chromoly steel -- don't bother with those. The bender I bought is a Ridgid 405 for 5/16" diameter tubing, which runs about $60-65:


I've been buying my tubing from Wicks Aircraft Supply:

They aren't the cheapest, but it's easy to order online and there's no minimum order. I buy tubing from them in 4-foot sections so avoid oversize shipping charges. It works out to roughly $3/foot, including shipping.

I just use a hacksaw to make cuts. If I want to be precise about it, I'll use a fork-steerer cutting guide to ensure things are perpendicular:

I use 1/8" thick mild steel sourced from a local hardware store to make rack tabs.

Other helpful tools:
1) Power Drill and a variety of bits -- you'll need this to drill vent holes in tubing, and holes in rack tabs

2) Bench vise

3) Tubing blocks -- you'll need to make these. Pat's blog has good tips on doing so.

4) Hand files, particularly 10" & 12" double-cut flat bastard files, and 10" & 12" round bastard files

5) Hack saw. Get one with long blade pins so you can double-up blades for slot cutting.

6) Tape Measure

7) Cheap bubble level

8) Cheap square of some sort

9) Lots of emery paper/production cloth -- sold in rolls in the plumbing department of most hardware stores

10) A "tube cleaning bit" for your drill. See

11) Lots of old leather toe straps, plus various small clamps, for jigging/fixturing pieces during brazing. Leather is important because it won't melt like nylon straps will!

12) A torch, brazing rod, and flux. I'd love an oxy-acetylene setup, but for now I'm just using a Bernzomatic handheld MAPP torch, which I bought at Home Depot years ago. Get filler rod and flux from Henry James:

GASFLUX C-04 BRASS ROD 1/16” Diameter

Let me know if there's anything else you're curious about...