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Need Advice for Rack Tubing Sizes and Sources

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Need Advice for Rack Tubing Sizes and Sources

Old 09-02-20, 06:15 AM
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Need Advice for Rack Tubing Sizes and Sources

Hi everyone. I have a nice O/A setup, and middle-of-the-road brazing/soldering skills. This winter I would like to get into building some bike racks. Could some kind soul here give me a push in the right direction? I need to source tubing and a suitable tubing bender what sizes of tubing do I need? Should it be all stainless tubing with bronze filler rod? I know I have a lot to learn, but I am a quick study. Any advice and help would be so appreciated!
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Old 09-02-20, 07:27 AM
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Stainless Steels generally don't accept bronze/brass fillers. Silver is the usual filler. I much prefer bronze/brass (Gasflux CO4) for most of my fillet/non sleeve brazing and have no issue with a painted rack, so I use 4130 tubing. 5/16" and 3/8" by .035" walls are pretty much all I use. 1/8" and 3/16" plate for the tabs and thin stuff for the tail light mounts. Online Metals, Stock Car Steel are two sources I've bought from but there are others.

I've used those simple muli stepped benders that auto shops sell, Eastwood's nicer version of the same, various pulleys as forms.

IIRC someone posted a nice "how to figure bend points and lengths" primer on this forum (orf was it another?) a while ago. perhaps someone has saved that link? Andy
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Old 09-02-20, 08:29 AM
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I usually build my racks with stainless because I don't have easy access to powder coating. I get the welded stainless from McMaster Carr because i"m lazy. 5/16 is good for most racks. It doesn't take a lot of silver to put one together.

I recommend getting Rigid benders off of ebay. Parker as well. I never liked the way Imperial Eastman benders worked, but they are a lot more plentiful on ebay. Just did a search and pickings are bad unless you get one of the Chinese benders, which I'm skeptical of. The larger radius bends can be done with any round thing the right radius. For example, a pulley
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Old 09-02-20, 11:52 AM
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Tubus uses 10 mm (3/8") ...
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Old 09-02-20, 11:54 AM
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Andrew and unterhausen, thank you for the help!
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Old 09-02-20, 12:06 PM
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Originally Posted by fietsbob
Tubus uses 10 mm (3/8") ...
That's pretty big stuff, but some racks for utility bikes go to 1/2" or even larger. Tubus makes racks for German tourists that bring everything on tour. It's not a horrible idea, but 3/8" can be fairly hard to bend. On the other end of things, I built some randonneur front racks out of 1/4" and I just thought it was too small.

There are some Rigid and Parker (possibly other brands too) benders that look like they have adjustable wrench handles. Those aren't really strong enough for anything other than copper. It's not unusual to see broken ones for sale on ebay.
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Old 09-02-20, 12:14 PM
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My Bike Friday uses 8 mm .. I have Ortlieb panniers .. 11 mm hook inserts on the ones on the bike with Tubus racks..
smaller insert in the hooks on the bags I use on my Bike Friday

Bruce Gordon's racks used a similar tube as Tubus.. it is a thin wall 4130 ..
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Old 09-03-20, 06:03 AM
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Old 09-03-20, 07:39 PM
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When we did the laser rack tab order, gugie got the same number of 1/4" tabs as 5/16" tabs. And half as many 3/8" tabs.

I got mostly 5/16" tabs and half as many 1/4" and 3/8" tabs. But I also designed a rear rack tab at the dropout that doesn't tab into the rack.

When I designed rear racks for my mountain bikes, I used 3/8" tubing. It's a valid choice, obviously.
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Old 09-04-20, 12:58 AM
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Alex Wetmore's blog has lots of practical advice including a section on tubing selection. He stopped blogging on bike rack building about 10 years ago, so there will probably be some details that are out of date, but luckily the technology hasn't changed much in the last oh 100 years...

Please don't pester Alex with questions -- don't make him regret leaving his blog archives up for all to use. He's a nice guy and all but he has a family and a life, so being everyone's rack mentor is probably not how he wants to spend his spare time. Any questions, ask here, or your mom.

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Old 08-12-23, 09:28 AM
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Use archive.org

Alex Wetmore's blog has lots of practical advice
alexwetmore.org no longer serves content, but the old content (minus most of the photos) are available from the wayback machine:
https [delete] ://web.archive.org/ [delete] web/20230320145015/https [delete] ://alexwetmore.org/archives/category/rack-building-basics.html
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Old 08-12-23, 04:49 PM
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Originally Posted by kjwkjw
alexwetmore.org no longer serves content, but the old content (minus most of the photos) are available from the wayback machine:
https [delete] ://web.archive.org/ [delete] web/20230320145015/https [delete] ://alexwetmore.org/archives/category/rack-building-basics.html
No need for the Wayback machine, it's here at Alex Wetmore is always busy with something? Rack Building Basics

Alistair Spence's Flickr also has lot of great rackbuilding pics.

Consider using 4130 Cr-Mo, it's stronger than commonly-available SS tube and easier to work with, especially since you can braze with brass. Recommended especially for beginners. Let it rust if you don't care about looks, it'll take a long time before sterength is compromised. Or hit it with some rattle-can Rustoleum. Yes the paint wil rub off and flake off, so not a solution for a fancy "looker" custom bike. Chrome plate it if you're rich.

That said, SS is kinda cool and you can make up for the lower strength with a bit thicker wall, if you're not a weight-weenie. Silver brazing is a lot more difficult though. Beginners often cook the joint and it ends up weak. Practice on scraps before attempting a rack.

Sand the oxide layer off the tube right before brazing, since it grows back, and be semi-fanatical about cleanliness.

Get better flux than whatever off-brand the local welding shop sells. Gas Flux brand or Cycle Design are good, Harris is adequate.

Fillet Pro silver alloy from Cycle Design is excellent for racks, lets you build up a little fillet at each joint, but of course the bigger the braze the more $$ you're spending on silver. For no-fillet joints (or minimal fillets), your miters need to be perfect. 45% silver is what I'd use if I didn't want to pay for Fillet Pro.

Though the SS won't rust, the silver will tarnish. Not too difficult to re-polish the silver if you hate the tarnish, but I just live with it.
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Old 08-12-23, 05:24 PM
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I wish it was easier to get 4130 finished.

I've been pretty happy brazing stainless with nickel silver now that I got some of the nickel silver flux from Cycle Designs.
Downside is you can develop an allergy to it. Flux for brass, like Gasflux type B, doesn't work very well in my experience.

On a side note, Framebuilder supply calls Gasflux C-04 "Nickel Bronze." I don't think it works like nickel silver on stainless. Granted, it will wet out, sorta.
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Old 08-13-23, 02:30 PM
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Ignore the wayback machine, go direct to the blog

[QUOTE=bulgie;22982516]No need for the Wayback machine, it's here at Alex Wetmore is always busy with something? Rack Building Basics

Weird, I am not sure why I had trouble accessing it the first time, but yes, that link works for me now!

So, ignore my post, keep on doing what you awesome guys keep doing!
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Old 08-13-23, 03:38 PM
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Originally Posted by unterhausen
I've been pretty happy brazing stainless with nickel silver now that I got some of the nickel silver flux from Cycle Designs.
Note for any newbies reading this, "nickel silver" has zero silver content. It's more like what I call brass (Cu-Zn), what the welding industry calls bronze, but with a high nickel content. Dunno why they call it silver, but it does have a silvery color. It has a little higher melting point than brass, unlike silver obviously. It's so strong (stronger than some steels) that you can use it to repair steel gears with broken teeth — build it up and machine the new tooth, good as new. It's difficult to file, not really due to the strength but more the slipperiness — the file needs to be very sharp or it just sorta skates off, So I don't recommend using it for joints that will get cosmetic filing, too easy for the file to slip off and thin the steel tube.

It's slightly less "runny" than brass, so don't try to make it flow a long distance in a tight capillary joint. It will flow, just a bit more reluctant, more heat and time needed. The higher liquidus is handy sometimes when you're going to brass-braze something right next to a previous braze and you don't want the first braze to re-melt, like seatstay caps.

Jig your stuff without large clamping forces because when the steel is that hot, it's weak and will distort under light loads. Other than that, an excellent choice for SS.

Great stuff to have in your arsenal. As unterhausen points out, you can use brass flux, but the stuff made just for nickel-silver is best. The higher heat will cook your brass flux sooner than you're used to.
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Old 08-14-23, 06:17 AM
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Originally Posted by bulgie
No need for the Wayback machine, it's here at Alex Wetmore is always busy with something? Rack Building Basics

Alistair Spence's Flickr also has lot of great rackbuilding pics.
Thanks for the links. I got a "Not Found" error for Alex's rack building basics, so went with the Wayback Machine version.

I'm contemplating building a replacement for my TA mini rack which has a way to cleanly connect it to the fender, and a mounting tab for a light. Pointers to examples of such a mounting tab would be appreciated.
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Old 08-14-23, 07:38 AM
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I have rack tabs laser cut. It's a very simple process.

I don't think I've seen a ta mini rack that attaches to a fender.
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Old 08-14-23, 08:17 AM
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For a single rack I would just make my own tabs and brackets.

The TA racks I have dealt with use solid and fairly thin rods. Very easy to bend to fit.

I agree with Eric in that I don't recall a TA rack with a fender mounting detail. Not that such would be wrong, I question the need with a fork crown fender mount point being so close by. Andy
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Old 08-14-23, 08:38 AM
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I like the idea of attaching to the fender, I just haven't seen a TA rack with that and couldn't find one in a quick internet search. And the TA mini racks I found that have light mounts just have a bent bar.
So apparently I have been looking for the wrong kind of rack. Maybe Skip can point us to a picture of it. The one on the bike with the frame he built doesn't have a fender attachment or a light mount. But that TA rack definitely needs to be replaced.
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Old 08-14-23, 08:49 AM
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Originally Posted by Andrew R Stewart
For a single rack I would just make my own tabs and brackets.

The TA racks I have dealt with use solid and fairly thin rods. Very easy to bend to fit.

I agree with Eric in that I don't recall a TA rack with a fender mounting detail. Not that such would be wrong, I question the need with a fork crown fender mount point being so close by. Andy
I wonder if I misunderstood the recommendation to provide a brace between the fender and rack over on internet-BoB (or the BoBs misunderstood my setup)? Here's what I have at the moment (V-O fender, direct mount RAIDs, TA mini rack):



In addition to the post and fork crown mounts for the rack, the frame was built with an attachment point for the fender under the fork crown. I wedged a piece of wine cork between the two, but it's not clear to me that it's necessary. (I didn't question the advice of the iBoB crowd, just silently scratched my head and went about seeing what I could do. Perhaps I should have.) The distance from the center of the head tube to the center of the cork is right around six inches.

Ignoring the matter of fender bracing, I still would like to mount a light. Perhaps I can create a bracket which straddles the rack proper and the curved brake post brace. In any case, I couldn't braze anything to the rack without stripping the chrome first.

Hence my pondering the possibility of building a new rack with suitable bells and whistles.
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Old 08-14-23, 08:50 AM
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Originally Posted by unterhausen
But that TA rack definitely needs to be replaced.
Because... Too weak? Too small? Too rare?
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Old 08-14-23, 12:05 PM
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It sits at a wonky angle and is too far from the fender. I guess I'm a rack snob. Of course, you can't see any of this when there is a rando bag on it.

I have only done a brace between a rack and a fender one time. It was a short piece of tubing sticking down from a cross brace in the rack with a threaded boss on the fender end. I copied it from Hirose, but I think everyone does it this way. I think his video channel has been sanitized, but there is still some useful info on it if you spend enough time watching. I built that rack in a big hurry, and I hesitate to post pictures of it. Someday I'll rebuild it. Comes apart because it's for my S&S bike, which was also built in a hurry.

I think it's worthwhile attaching the rack to the fender, especially if you are going to use the same mount configuration as the TA. It stabilizes the rack and the fender, which is a good thing. My future racks are going to attach to the fender. In my case, it's mostly for the fender.

The picture for the upside-down edelux on the RH site has a nice detail shot of the rack (2nd picture). You could always do the something similar for the light mount if you have a right-side-up light, but it would have to loop around underneath. https://www.renehersecycles.com/shop...light-hanging/
If you are going with dyno power, you could get an IQ-X, which also can mount upside-down. Note also the low amount of clearance between the rack and the fender, and the fender brace.

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Old 08-14-23, 12:17 PM
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Originally Posted by unterhausen
It sits at a wonky angle and is too far from the fender. I guess I'm a rack snob.
Ah, well, I did a bit of bending to get everything (mostly) to line up. For now, I can live with the TA rack being a bit off-center, particularly if I'm not sold on it as the final solution. (I don't even have a bag yet. Am thinking about cajoling my wife into making one.)
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Old 08-14-23, 03:18 PM
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TA made variants of their rack with a light mount, at least two styles:




The second one starts with a plain rod, not threaded for the nuts as shown in the pic. It's 5 mm, so I threaded it with a die to mount this light. It's intended for a weird Cibie lamp that clamps onto a plain 5 mm rod just by friction, what where they thinking? I would think, being chrome plated, the clamp would slip. Never had the "correct" Cibie lamp though so I threaded mine.

Here's a less-elegant TA light mount I made when I was a teenager in the '70s, don't judge:


​​​​​​​

About the height of the rack above the fender: Check out Weigle's racks that are so low, the crossbar is curved on its underside to fit the fender. F'in show-off! Curving the bottom of the tube (not the top mind you, just the bottom) got him maybe 2 mm worth of bragging rights. I'm jealous, wish I'd thought of it.



Later it seems he moved to a simpler rack with no crossbar, or maybe he still makes both kinds?

If I had to curve the tube to fit the fender, everyone would think it was a mistake, like I forgot to leave room for the fender. But Peter pulls it off!

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Old 08-14-23, 04:55 PM
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I think you can do better than that TA rack. I like them, but I like my racks a lot better. Since you know how to braze, it's obvious you should make one. I would plan on making 2 so you don't have to work so hard on the design.

I don't like the bent up crossbar on the Weigle rack. Maybe if it fit the fender better. I'm wondering if it was a mistake. In my rack-making journey, I have found that you can make a rack that's too low for some bags. It can be really difficult to strap a bag to them if they are too close to the fender. I figure if you have to put a dimple in the crossmember, it's not going to be easy to fasten one of those bags.

There are patterns for rando bags out there. I keep thinking about sewing one, I have the fabric. I have had the fabric for the last 10 years.
Here's a blog post via the wayback machine. https://web.archive.org/web/20180222...lebar-bag.html
You can still d/l the patterns.
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