Custom Stem
 

I need a custom handlebar stem for our tandem.

Does anyone know of a good builder with a reasonable lead time?

What needs to be custom about it?

Length and angle.

People don't like making stems for some reason. Although Paul Brodie's video where he measures one he made may hold some clues. Never sell anything to a metrologist.

I have made exactly two tandem stems. The first one was made using a cut up frame for the part that attaches to the captain's seat post. I don't recall what I used to clamp the handlebar.

How much length and what angle of rise? Standard 28.6 steerer and 31.8 bar?

No, it's for a Santanna, so the steerer meeds to be 1.25" (31.8), about 130mm long with a 18º angle (roughly). Standard bar clamp. I can provide exact measurements.

You need a wedge style stem? You may end up having to go back to Santana.

It is threadless. I’ve exhausted all of Santana’s options.

A quick search around the web yields some 1-1/4 x 120-130mm stems, but 6 deg not 18. Can you use something like this and get your desired hand location using a riser bar of some sort?

I've never found such stems and I've looked extensively. Do you have a link?

A 130mm might work.

I'm not aware of a riser stem for a 1-1/4 steerer tube, and given the 400#(+) weight of the bike, I'm pretty sure I wouldn't want to use one.

The Zipp Service Course SL stem shows as available with a 1.25" steerer in various lengths including 130mm on the SRAM/Zipp web site. So far I've only found up 120mm for sale at typical online bike stores but I've only looked briefly.

Thanks!

I'm surprised I didn't find those, as I've done quite a bit of searching (the SRAM website has come up in other searches). What search query did you use?

Nothing fancy. I just Googled 1-1/4" stem 130mm and saw some mentions of the Zipp Service Course stem. Then I Googled Zipp Service Course to get to the product page I linked to.

I'm sure Dave Levy, TiCycles, could do it. Don't know lead times or cost. Probably not cheap but he could certainly build you exactly what you want.

He's building me a fork for the tandem and the due date is December/January. I'd love to have him do it, but I need it sooner.

Does anyone have any experience with Duane Draper @ Draper Cycles in Seattle?

Duane is a long time contributor here on BF. I can't remember any posts from him that made me shake my head:) I think he'll do you well. Andy

Great - thank you!

I follow Duane on Flickr, where I've seen in-process shots that show him to be careful and skilled. I've also been to his house and seen his work IRL. I would trust him to make a stem without any scary shortcuts taken.

He's not a full-time pro, he's got a day job, but sometimes a talented hobbyist can beat a full-time pro, by virtue of not needing to make everything profitable.

Thanks! So far, working with him has been great!

Hi all, I feel like I owe the group an update. First off, thanks Mike PromptCritical for your patience and thanks for the support from the group here.

Tonight I finished up the stem for Mike. It turned into a bit more of a project than expected but I'm really happy with where we ended up (aside from the 'reasonable timeline'!). I really enjoy taking on challenging projects like this.

After talking with Mike about his needs, we determined that the best way to approach this was an adjustable stem that I could send to him. He could ride around on it and find the right fit, lock it down and send it back to me. Then I can take measurements and make a real stem. I get the bonus of ending up with an adjustable stem for the future. I figured I'd do a quick drawing. This was an earlier version but you get the idea.


Since we wanted it to be adjustable, I didn't want to paint it. I wanted it to index so that when tightened the bars would be flat so I went with a square tube extension. I wanted it to slide nicely so I created brass shims to grip the extension inside a larger square tube clamp. I used stainless for all of the parts.


Getting the clamp square and brazed together so the binders were square and symmetrical, milling the brass shim and all the other steps to get the clamp completed went pretty well other than being time consuming. I used 50n silver fillet for this part.


I expected the extension part to be easy since it was really just a simplified standard stem. Some will be wondering about the propensity for stainless to stress crack when brazed. Yeah. I can confirm it does. I wanted the joint of steerer clamp and extension to be strong as the extension is quite long. At full extension it will exert some force on the clamp and joint. I used Nickel Silver and didn't consider the stress cracking until it was too late. I was using pretty thick-walled 0.125" square tubing and .065 stainless tubing for the clamp and the combination of heat required to heat the thick-walled extension and the copper-zinc filler just didn't work.

I had to call Mike and tell him that his 'reasonable timeline' was being extended. I offered him an option to cancel the project. He decided to proceed so I ordered 4130 square tubing and we agreed that I would gun blue the extension to protect the finish from rusting. Apparently due to weather that was delayed another few days.

The 4130 arrived Monday and I was able to get all of the fab work done Monday night and then some quick finish work and applying the bluing finish tonight.


I didn't spend as much time getting the fillets as smooth as I normally would since this will live a working life as a tool once Mike has returned it.


This is the start of the real stem made from the measurement of the adjustable stem.

Thanks Mike for your patience.
Duane

Beautiful work! Can't hardly wait to see it!

Nice work.
I wasn't previously aware of an issue with copper/nickel/zinc fillers and stainless. How did you notice it?

Thanks.

The clamp cracked almost immediately upon cooling. I had heard of someone having a hard time with KVA or 953 or some other stainless tubing and had the same problem - cracked when it cooled.

I had a few things working against me:

• I used pretty thick material for the extension since stainless is a bit weaker than 4130
  • It took more heat than stainless likes apparently to get filler to really soak into the joint
  • the flux didn't burn and it flowed fine and I got a nice inner fillet
  • there is a suggestion that even heating of the whole part might have prevented it.
• nickel silver melts a bit higher temp even than brass
  • After it happened, I read up a little and it mentions copper/zinc fillers don't get along with stainless. I assumed it was something about the filler getting into the grain structure of the stainless or something.
  • The more I read, I think they just take higher temps to melt and stainless doesn't like that; there are suggestions to anneal the tube before brazing but then strength goes way down so, I'm not sure if that's the solution.
• thermal expansion/contraction rates are different for the filler and stainless steel which adds stress
• The clamp had already been through one heat cycle to attach the bosses with 56%.

I think the combination caused the clamp part to crack. The clamp had already been through one heat cycle to attach the bosses with 56%. I think if I had just used Fillet Pro, It would have been fine.

I may see if I can make it work now that there isn't a time crunch. Having 2 extensions would be handy.

This is good intel. We don't know all the answers yet but these are clues. Thanks for sharing.

What flux did you use? So far I have only used it on lawn sculptures made from silverware, but the Cycle Design nickel silver flux made things so much easier. I will never use Type B on nickel silver again, unless it's after the zombie apocalypse and I need to make something to survive.

Gasflux blue that I have used with nickel silver for ages on 4130. I have some of the Cycle Design. I might try that when I get around to experimenting.

The third frame I ever made was for me. Talking about a whole frame from start to finish, not counting the hundred or so tandems I had worked on, as the apprentice at Santana in the '70s. It was a lugless touring frame made with "regular" 531 DB, not superlight but not Tourist gauge either. As in .9 DT and ST, .8 TT, decently light for back then. The first two frames were lugged racing bikes and I was ready to try something different

Instead of doing as I'd been taught (where's the fun in that?), I looked at the filler rod catalog and just ordered the strongest stuff, Allstate #11, which is nickel-silver. Let's call it NS for short. I just used the normal paste flux for brass, whatever we used back then. The fillets were a bear to file smooth because the stuff is very tough to file. I did some multi-day tours, up to a week with full camping gear, often enough on dirt roads, a decent strength test. Then a few years later I sold it to a guy who was going to ride it around the world. I never heard from that guy again, so maybe he died when the frame threw him in a ditch? But I did tell him I'd fix it if it broke, so I hope he'd have told me. I like to think that frame is still out there, being ridden. ;) I can dream can't I?

I've done a bit of brazing with NS since then, and in all that time, I've never heard of cracking while cooling (or at other times).

Paul Brodie, in his Youtube channel, has showed us how he made lugless MTBs BITD, and unless he only recently started using NS, it sounds like that's how he did all of them. What's that, hundreds, or is it thousands? I dunno how prolific he was. But he didn't make the fillet with NS, he only brazed the tubes with NS (some call it "tinning") and then followed that by fillet-brazing with brass. (He calls it bronze, same thing.) Same flux, and I don't think it's NS-specific flux he's using. Obviously he wasn't using SS tubing, so brass was an option. Why then wouldn't he just do the whole joint in brass? Why 2 different fillers on each joint? You'd have to ask him. But I doubt he saw any cracking after the NS brazing step, or he wouldn't have kept doing it.

Yes this is long-winded and somewhat irrelevant since Duane's problem was with thick-wall SS, not thinwall Cr-Mo or 531. I just wanted to point out that NS has been successfully used to make bike frames, and they didn't crack while cooling. So Duane's experience must have more to do with the SS, or maybe the thick wall, or both.

At Trek in the '70s, we used either silver or nickel silver. Never on stainless though. Tbh, I never knew nickel silver took more heat until I started building again 15 years ago. I don't think the extra heat is apparent unless you are working with stainless. It's within the upper range of normal brass flux, which is why Paul Brodie can use his gasfluxer. Stainless seems to have a property where it's easy to overheat. Maybe it's easier to notice just because it's shiny, IDK. But unlike more normal steels, it gets a cruft on it when that happens that makes it hard to flow out filler. I didn't see that behavior when using the Cycle Design flux, but that also helped the filler flow out more easily at a lower temperature, so that also probably helped.

When I worked at Trek, I developed symptoms of what the internet now tells me is a sensitivity to nickel silver. So I don't use it unless I'm feeling cheap and working with stainless. You can go through a lot of fillet pro ($) making lawn sculptures. I also wear a mask now because of Mr. Bulgier.

On the subject of gasfluxers, doesn't the same flux work with brass and silver? That would be nice. I have a drawer full of flux jars.

All of the gas fluxers I have used (4 IIRC) had only one type of liquid flux in them, good for either brass/bronze or silvers. But I found the need for paste flux too and in the end decided that the gas fluxer was doing far less of the work flux is suppose to do, compared to the paste and sold off the fluxer.

I had thought that the basic foundation chemistry for silver and brass/bronze paste fluxes is the same but for additives that vary the temp the flux is most active at and influence for how long it is active. Andy

FWIW, Trek used nickel-silver and Gasflux Type B for their dropouts. I don't know how many thousand I must have brazed, but I never really had a problem.