every now and again, i come across something so great i wonder how i had missed it before.

buildyourown's blog, NW Cycle Machine, is a perfect example.

a lot of great stuff there, especially for a blog that just started in December and hasn't had a lot of posts since.

he uses a serrated roughing end mill to cut miters, and it sounds like a CNC setup. this sounds like a great alternative to bi-metal holesaws for CNC mitering.


he made the bullet-shaped pieces himself to mate the dropout to the stay.

now that is some fine fixuration.

powered by performancing firefox break

frame construction has to be put on hold for a couple of weeks while i put together a portfolio and application for next fall.

meanwhile, i got a flickr account to make it easier to upload photos. see the ST-DT joint photos here. also see the weird torch holder/helpful shop gremlin thing i made here.

also i have a chance to get some sweeeeet stainless rear drops from an exclusive overseas supplier...which would be perfect except that they're for a 64° CS-SS angle, whereas i've got a 68° or so. so i'm thinking of bending the seat stays up to make up the difference...kinda like an old Hetchins or a Lyon.

braze-on list and schedule

before main triangle assembly:
prep new HT: drill vent holes
drill bottle boss holes, braze ST bosses (done)
prep lugs (bevel edges, ream out to fit)
drill 1st (outer) pin holes
manipulate lug points to fit, determine clamping method
do a practice braze

DT shifter bosses...eyeball position (12-13 cm from HT center), secure with file tang or vise-grips
TT cable stops...
CS cable stop...
over-BB cable guides...make hold-down

modify file

the frame's mom is in labor

it's going to be born soon.

i'm just arriving home at 12:45 am. went to work at 10am, started frame work about 3:30 pm. so worth it.
the front triangle is all mitered and almost ready to braze. it looks sorta like a bike, finally!
the only bad news i encountered was that i cut my head tube too short, so i'll have to make a new one from some 4130 i have around. this is obviously a good sign: i had some of my 4130 practice tubes stolen a while back, and the only one i have left is 1.25" diameter, .035 wall thickness...perfect for a head tube. actually that tube is currently part of a project for school. so tomorrow i'll cut it (leaving a lot more extra this time), drill vent holes in it, drill all the lugs for pins, and see if it's ready to braze up.

i've got a quote of $160 for powdercoating the frameset from American Stripping in Manassas, VA, assuming i use a stock color. their color matching fee is over a grand, so Gios Blue is out.

also on the horizon: braze-on centerpull pivots. Mark Stonich, of BikeSmith Design and Fabrication, has been kind enough to post a set of fairly simple instructions on how to make these out of a little mild steel using a drill press, a few bits, and an m6 tap.

i got a really cheap tubing bender on eBay and tried it on the 3/8" .028 wall 4130 rack tubing. the bender bit the dust, putting only a small kink in the tube. i'm on the lookout for a Rigid or Imperial bender.

rack research

i'm having trouble finding a suitable front rack at a cost i like. i want something like the Nitto M12 (pic of Alex Wetmore's here) and the similar, more versatile Nitto Mark's Rack, which is in turn based on the Gilles Berthoud adjustable front rack. i like the smallish platform, just enough to support a randonneur's front bag, but i don't really need all the adjustibility and mounting options, and i don't plan to put canti mounts on the fork. i favor the idea of a front rack that attaches at some point along the fork blade as opposed to at the dropout (like the lovely stainless Velo-Orange Constructeur rack) seems the latter might impede the flexing of the blades, and i'd like to keep the amount of steel used to a minimum. well, i don't wanna make it sound like the V-O rack isn't great, cuz i'd bet it is, but it's just not quite my style.
made from auto brake line, seems like a great way to get some practice
Mike Flanigan's bone-crushingly badass "rising sun" rack
also, his take on a front bag rack:
gorgeous homemade "art deco" rack

and now the grand master of homemade cro-mo racks, BOB list and Framebuilders' list contributor, and former DC bike courier (!) Alistair Spence:

the email below and the two links above are quite helpful in considering materials. the 9/16" he uses must be really strong stuff, but the tubing benders i've seen haven't been compatible with it. i'm not building for the kind of punishing loads he was, so i think i'll likely stick with 3/8", 5/16" and 1/4" 4130, in no small part because i'm bidding on a tubing bender just like the Rigid Alistair mentions and it only accepts these 3 sizes. they've been going for under $20 including shipping on the 'bay.
the Paterek Manual has a chapter on rack construction, but i've lent it out, so i'll have to post some more info later.
and maybe i'll find a Mark's Rack for cheap at the Westminster Swap tomorrow and this'll be a moot point (for a while anyways)

Date: Mon, 23 Jan 2006 16:34:18 -0800
Subject: [BOB] Porteur rack

JimG wrote

>Super nice! Can you provide details on what tubing you used, where you
>got it, how you bent it, etc?


The rack is made of 4130 chromoly. I ordered it from Aircraft Spruce

Mostly made from 3/8" x 0.028" (9.5 mm x 0.7 mm) except for the truss that
connects the rack deck to the fork crown, this is 9/16" x 0.049" (14.3mm x
1.25mm) .
I made "eyelets" from 8 mm long or so pieces of 1/2" x 0.083 (12.5mm x
2.1mm) and brazed them to the lower fork leg and apex of the "v" made by the
rack support legs. An M8 bolt holds the rack to the fork at this point.
The tubing was bent with a Rigid tubing bender kindly loaned to me by Steve

Asher Miller wrote

>So.... stainless tubing mit brass fillet brazing?

> --Asher


not stainless but 4130 cro-mo, fillet brazed with brass. As I understand it,
to fillet braze stainless you must use silver, preferably one with a lower
silver content than would typically be used for lugs ie. 56%. Seems like 50N
(50% silver, 2% nickel) or 45% work well.
Obviously, since I've used plain old steel, I'll have to coat the rack in
some fashion, paint, powder, chrome etc.

Hope this answers your questions.

Cheers, Alistair.


From: dr john
Subject: Re: [Frame] Re: [BOB] Chromoly tubing (for racks)
Date: Sun, 11 Jan 2004 07:22:05 -0700

Jan 11 02

Dear Joshua,

When I was in the Coast Guard a friend of mine had a Dutch touring frame
with steel racks weldd on. Years later the memory of that bike inspired
me to try it myself.

I make racks for my Muttonmaster and custom models out of 5/15' and 3/8" x
.035 tubing from Aircraft Spruce. Tubing in those sizes bends quite
easily, which is a good thing because I make the top frame out of a single
piece. If you misplace your bends by even a little, it will be
quite obvious to the eye once the rack is welded/brazed onto the frame.

Even a 5/16" steel rack will securely carry over a hundred pounds.
Eliminating the attachments at the frame makes the rack stiffer, less
floppy and I feel, more secure than a conventional bolt-on model.

good luck



Date: Thu, 15 Sep 2005 13:55:49 -0700
From: "Bill Rider"
Subject: Re: [Frame] wall thickness for chromoly rear rack?

If you use 0.028 wall tubing and 3/8-inch for the main tubes, you can use
5/16", 1/4", 3/16", etc, in
1/16" increments and they will all fit OD to ID as you go up in size (or ID
to OD as you go down). Makes fabrication a lot easier.

Charter Oak Cycling
Best Newcomer at the 2005 North American Handmade Bicycle Show


Date: Thu, 15 Sep 2005 11:32:56 -0600
Subject: Re: [Frame] wall thickness for chromoly rear rack?
From: Harold Bielstein

I recently built several racks and I'm here to tell you that unless you
have a commercial grade tubing bender you'll have a hard time bending
3/8" x .049 wall thickness tubing. I think you'll find that 3/8" x
.028 will be more than strong enough for a rack system and is much
easier to bend.


Date: Thu, 03 Mar 2005 20:42:40 -0800
From: "Bill Rider"
Subject: Re: [Frame] On brazing touring racks, advice please.

I recently finished my first rack using 3/8"x.028 tubing from aircraft
spruce. Was a new experience, but came out good. I had it powder coated,
since that seems to be a common painting method, especially if you want it


Date: Thu, 15 Sep 2005 19:08:12 +0200
From: M-gineering
Subject: Re: [Frame] wall thickness for chromoly rear rack?

"L.J.Shields" wrote:
> I need to build a custom rack for the 20" demountable that I just built
> (posting and images about this project soon). The local aircraft repair
> supply house (they mess up a lot of small airplanes here in Alaska) a great
> selection of chromoly tubing including 1/4 " and 3/8" tubing in .028, .038
> and .049 wall thickness. I am inclined to make the main part of the frame
> from the 3/8" tubing with .049 wall thickness and the cross pieces from the
> .028. Any suggestions would be appreciated. Remember that this rack is for
> a bike with 20" wheels and that the main "struts" will be shorter than for a
> large wheeled bike. The method of fastening will be brazing. Any
> suggestions or ideas on racks for this bike will be greatly appreciated.
> Cheers,
> Smiley Shields

tubus racks are mainly constructed of 10 x .5 and 14 *.8


Marten Gerritsen


Date: Tue, 25 Jul 2000 13:03:20 -0700
From: Matt Houle
Subject: Re: [Frame] homemade racks?

I've never made a rack before, so I may not be the best person to answer
this for you. However, I would suggest using 5/16" x .028 or .035 cro-moly.
Both are available from Dillsburg (717-432-4589). I'm not sure that I've ever
seen a conduit bender small enough to bend 5/16" tubing, and most of the small
tubing benders out there may not be strong enough to bend cro-moly without
using heat to soften the steel. I would use a mapp/air or propane/air torch
to heat up the tubing while bending. But like I said, I've never made a rack,
so I might actually be very wrong.


Design notes:

Nitto M-12 top surface is 8.5" x 4.25" (see here)
Nitto R-10 top surface is 15" x 5" (see here)

suggested tubing size combos:
5/16" x .028" or .035"
Tubus: 10 mm x .5 mm / 14 mm x .8 mm (just over 3/8" x .020" / ~9/16" x .031")
3/8" x .028"
5/16" x .035" / 3/8" x .035"
3/8" x .028" / 9/16" x .049"