I was looking for an unintrusive place to mount a bell or perhaps a headlamp and i came across this solution from velo orange: https://www.velo-orange.com/spbemo.html

Unfortunately, I don't have enough room for a headset spacer, but he mentions old french builders used to tap the stem and screw the bell directly in. This seems like a much better solution, and a decent weekend project for my Nitto Technomic.

I called my LBS in brooklyn and they basically said we're not screwing with the stem. If it cracks because of vibration, etc. they don't want the liability. Good old Sheldon B makes tapping sound pretty easy, but what do you guys think? Am I entering a world of potential hurt? I imagine it would only require drilling a 5/32" hole less than half an inch deep. Would this compromise the structural integrity of the stem?

i wouldn't mess with my stem. especially one made of Al. even a scratch deep enough can be a potential stress riser.
you can find a bell that would clamp on to the quill portion of your stem, and headlamps that mount to fork crown.

Yeah, I wouldn't, pavement probably tastes pretty gross. Why not zip tie or clamp (using one of those plumber-style clamps) the bell to the stem?

Besides, unless you have experience tapping, and know how the material will handle it, it takes a little skill (I've never tapped on bikes).

Also, if you have a Technomic, I'm assuming you are a big(ish) guy (I mean height and frame wise, not trying to imply anything), thus the stem integrity would be most important.

Lol, compromise one of the most important items safety wise on a bike, to mount a bell? I think I just got dumber.

That bell is for a threadless steerer, so it wouldn't work on your bike anyway. They make a "retro-mount" that will fit your headset, or you can get one that attaches to the bars themselves at any bike shop.

I use this but instead of bolting to the H-Bar I bolted it to the the quill stem. Problem solved.

All makes sense. I got the retro mount anyway, but thought it might be a fun project. I'll steer clear.

The only question remains, if it's so dumb and dangerous why did the French builders ever do it in the first place?

2014 - we see Nitto also made a threaded solution - GrandBois (Compass) sells them, picture is HERE. Note the added material built up around the threaded hole - likely to assure the skeptical !

It's also steel. IMO there's a big difference between putting a threaded hole in a steel stem vs. an aluminum one.

A Threaded Boss was brazed in before the custom level hand made stem was Plated .




These work Fine no tapping needed https://www.mirrycle.com/original_bell.php

Because their stems were made from steel.

VELO ORANGE makes a cool threaded option as well:

I wouldn't worry about it excessively. There's quite a bit of metal in the shank of a Technomic stem. That's one of those things that I might do on a personal bike but I'd never do it on a customer bike.

The French make the Peugeot and Renault autos, both withdrawn from the US auto market because of poor design/reliability issues. They also make the Citroen which never even made it in to the US market...

Didn't you know it was Click and Clack, the car talk guys that got Peugeot kicked out of the US? Morley Safer said so.

You can buy a tap and drill set at the hardware store for a few dollars. This includes the tap & the correct size drill bit.
8/32, 8/24, 10/32, 10/24 would be common SAE sizes, or metric sizes a bit less common at the store.

Sheldon's info is all you need. Vice-grips can also be used for makeshift tap handle.

Tapping aluminum is pretty easy, and putting a small hole in your stem is not likely to shorten your life or ruin your smile IMO.

I would make the hole on the side of the horizontal part of the stem.

I've had 3 Peugeots and considered them great cars. Of course, 2 of them did not make it past 50K miles, but I don't blame that on the French. Rather it was the American-grown hundred year old ice-laden Loblolly Pines and gravity that did them in. I do believe you are incorrect about Citroen as well. I recall a dealer in Gainesville, FL in the late 60s.

I suspect drilling and tapping an aluminum stem is one of those things that usually comes out okay. I also suspect that higher-than-average failure rates were a lot easier to keep quiet back before the internet.

Personally, I'm not comfortable with "usually okay" on important bits like my stem. If I drilled and tapped one, I'd spend every ride thinking about it. What anyone else does to theirs, of course, is not my business - as long as they're not in front of me in the paceline.

Sorry, I saw the opportunity and was taking a cheap shot...

I searched for broken bicycle stems- a broken clamp, a carbon stem failed at a joint....

any of you nervous nellies have any information about an actual broken stem??

<Edit> Never mind. I just realized this thread is in the Bicycle Mechanics hell hole, where there can be no positive outcome.

Haven't any of you ever had your one control hand bounced off the handlebars when you were drinking or eating? You have maybe a moment where you dive a bit and think, well, I might be going down. Except you don't, because your wheels are still under you and you're in your saddle.

Breaking a stem isn't necessarily the end of the world if you're comfortable on your bike. Your wheels are still rolling along and keeping you up and you've got working brake levers right there if you didn't panic and drop the bars.

Plus, I bet that won't fatally damage the stem. Especially if your handlebars are near or above your saddle. It's hardly even under much stress in a lot of riding positions. If you're worried, epoxy the screw in. That should ease the fear of stress risers.

I'll take the lack of response to mean that, in spite of high concern over stress risers, safety items, etc.,

stem breakage is very rare from any cause, and that drilling a small hole is unlikely to make a difference.



(If the OP was attempting to change a 7 degree stem to 12 degrees by heating with a propane torch however, that would be different)

And the good Crane bells have an adjustable clamp that fits perfectly to a quill stem,

With one big if. If you ride in an upright position. If my hands come off the bars, bad things happen. Many years ago, I entered a downhill intersection lying on my stem after I hit a rock I didn't see with my hands loosely over the hoods. Impaled my sternum hard on the famous qull bolt on the UO-8s.

Ben

I wouldn't say that's a fair shake for Modern French engineering. Renault has powered Formula One winning cars and Citroen won the WRC Title many, many times.