Tubing questions for threadless stems

[Vincentsavary]

Hi everyone,

as a first step into the world of framebuilding I would like to start by welding chromoly threadless stems, in different clamp diameters. I made some research and think I have kinda figured out the tubing selection, but I would need some reassurance.

1. What is generally the O.D of the extension tube? From what I have gathered it seems 1-1/8" is the way to go, independently from handlebar clamp diameter.

2. The most suitable tube I found for a 25.4 handlebar clamp tube was 1-1/8" (28.6mm) O.D, 1.009" (2.62mm) I.D and 0.58" (1.47mm) thickness. My question is, what dimensional tolerance do I have for the handlebar clamp diameter? Could that extra .22mm cause problem? Other option I found was 0.995" (25.27mm) I.D with .065" (1.65mm) thickness.

3. Is .058"-.065" (1.5mm-1.6mm) thick enough for stems? Would .049" (1.25mm) be suitable for the handlebar clamp tube only? I would like to make 26.0 clamp stems too, but the only option I found is 1-1/8" (28.6mm) O.D, 1.0270" (26.08mm) I.D and 0.49" (1.25mm) thickness.

4. Where would one order tubes and binders? I did manage to find tubes on Aircraft Spruce and other websites, and M6x1.0 binders on Nova Cycles Bike Fab Supply (althought I'm not sure they would work for every handlebar clamp diameter?), but I'm still curious if you have other resources.

Thank you for the help

[progetto]

https://www.framebuilding.com/Llewellynstemlugs.htm

[Rody]

Hi everyone,

as a first step into the world of framebuilding I would like to start by welding chromoly threadless stems, in different clamp diameters. I made some research and think I have kinda figured out the tubing selection, but I would need some reassurance.

1. What is generally the O.D of the extension tube? From what I have gathered it seems 1-1/8" is the way to go, independently from handlebar clamp diameter.

The extention tube diameter and wall thickness will be determined by your performance and design needs. I've used everything from .875 - 1.5" in every wall thickness. You need to determine the structural needs.

2. The most suitable tube I found for a 25.4 handlebar clamp tube was 1-1/8" (28.6mm) O.D, 1.009" (2.62mm) I.D and 0.58" (1.47mm) thickness. My question is, what dimensional tolerance do I have for the handlebar clamp diameter? Could that extra .22mm cause problem? Other option I found was 0.995" (25.27mm) I.D with .065" (1.65mm) thickness.

In short, yes, sloppy fitment is dangerous. Structural interfaces MUST be precise...there is no room for poor fitment. I would suggest looking at a thicker wall tube and then turning down the internal diameter on a lathe so that there is no question to the fitment.

3. Is .058"-.065" (1.5mm-1.6mm) thick enough for stems? Would .049" (1.25mm) be suitable for the handlebar clamp tube only? I would like to make 26.0 clamp stems too, but the only option I found is 1-1/8" (28.6mm) O.D, 1.0270" (26.08mm) I.D and 0.49" (1.25mm) thickness.

Is it thick enough is not the question...is your fabrication skills up to using thinner wall dimensions with less room for error? Start with thicker material than your structural design requires as you learn the process and refine your skill. You can then reduce wall thickness and evaluate. You need to define the specifications for the parts and machine them to fit...rarely will you find ready to use materials.

4. Where would one order tubes and binders? I did manage to find tubes on Aircraft Spruce and other websites, and M6x1.0 binders on Nova Cycles Bike Fab Supply (althought I'm not sure they would work for every handlebar clamp diameter?), but I'm still curious if you have other resources.

Again, there is not going to be many ready to weld options. Learn how to leverage the materials you have access to with proper machined tolerances to achieve your design and fabrication goals. I make many of my binders and clamps from solid rod/bar, this allows me to have exactly what I need for each application. Nova, Paragon machine, Ceeway, and bikefabsupply are all options for ready made parts for this application.

Thank you for the help

Stems, handlebars, forks, etc... often seem like a simple first step into bicycle parts fabrication, but in truth, bear much higher cost of consequences if a failure occurs. I would encourage you to burn through buckets of cut material practicing coping and welding/brazing before even making a functional part. Best wishes,

Rody

[Vincentsavary]

Thank you Rody for responding.

I am indeed starting to realize that there's a lot more to making stem than I originally thought, not only in skills but also in equipement. I'm in welding school right now and will definitely spend as much time as possible practicing on thin wall tubing before attempting any bike part. Thank you so much for your insight!

[Rody]

No worries my friend...please check back if you have further questions, I'm glad to help when I can.

Rody