SF Cyclotouring

Ride reports and other ramblings from a San Francisco cyclist.

12/17/2008

Rack Building - Requirements Summary

In 2009, I want to try to build a custom front rack for a bicycle -- something small, to support a handlebar bag or similar. Alex Wetmore has a great series of blog posts on custom rack building, which I've read and re-read. They are a valuable resource!

First, I really would like to find a local source for tubing. You can order steel tubing online from various sources (check here and scroll down to "Tubing Sources"), but I've found that mail-order is often a hurdle to getting things done, especially if this is going to be a continued endeavor. But, what tubing do I need, and how much of it? Alex provides some guidelines:

* Handlebar Bag Rack - 1/4 x 0.028"; ~4ft needed

* Porteur Rack - deck: 3/8 x 0.028", stays: 3/8 x 0.035", cross members: 5/16 x 0.028"; ~12.5ft needed

Locally, I've found some metal-supply houses to check out, including Bayshore Metals, Metal Supermarket in Redwood City, and J.C. Metal Specialists, Inc in San Francisco.

Next, I also need a means to bend the tubing. I have a cheap Harbor Freight tubing bender, but I've heard this isn't beefy enough for 4130 steel. I'll try it (maybe with a cheater bar over the handle?), and if it doesn't work, I'll figure something else out (I have some ideas for a home-built bender). Alex recommends the Ridgid 405 5/16" bender for the first-time buyer, since 5/16" is a good compromise between the lighter-weight 1/4" and stronger 3/8" tubing. I'm wondering if my cheap bender might handle thinwalled 1/4" tubing well enough...

Finally, I need a torch to braze with. I've got an old Bernzomatic handheld MAPP torch that I've done some lightweight brazing with, and I think it'll be fine for rack building. The trigger start is broken, but I have a flint lighter for it. I haven't lit the torch in about 4 years, so it might not even work. I have some old paste flux (needs re-hydrating) and some brass rod. That should be enough to start with.

[And just so I can find it again, Alex has a great tutorial on calculating tubing bend lengths]

1 Comments:

Anonymous alex wetmore said...

Go for it!

I'm working on a rack at the moment which I'll post some photos of soon. It is interesting because it has more bends and less brazing. It might be a good first rack. It can be made with exactly 4' of tubing if you are careful with the bends, although I'd have spare on hand.

Your HF bender might work for 1/4" tubing. Alistair uses a cheap bender for 1/4" and it works okay. I have a cheap bender which is as useless for 1/4" 4130 as it is for all other 4130.

7:55 AM  

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