How does any one feel about drilling a nitto technomic stem for a bell mount? DO or Don't, Safe or not. I am finishing off my rando bike.

I would not drill an aluminum stem

Stems have been drilled for years for different reasons. Just the same i'd beg off. Andy.

i Drilled my Cinnelli 1R, to use it to eliminate the cable hanger on my CX bike.

they had a bored hole from the front/

here are other ways to mounrt a bell without drilling into the quill shaft..

Check out the drillium pages to see examples of the extremes people have gone to with perforating components. https://www.flickr.com/photos/78285412@N00/5033678647

drillium used to impress me. That was before I started collecting pictures of broken Campagnolo cranks and before my Cinelli stem broke. Now I'm more protective of my teeth than that.

The other thing about modern drillium that bothers me is that cnc mills are affordable to people of limited means. But the drillium practitioners are still just drilling holes, which seems blasé.

I gave the OP the benefit of the doubt that this bike will be ridden, hopefully many miles and many years. If that assumption is not true, and this is a bike that will be ridden for show, drill away. Fatigue cracks grow slowly and do not reduce the strength of the item significantly until they are quite large, and then failure seems to be precipitous. But that is never the case, evaluation after the fact always shows that the majority of the fracture surface has been exposed to the elements for quite some time.

There are alternatives...

The beginning of my racing career coincided with the tail end of the drillium craze. The joke was that you could walk a criterium course at the end of the day and find enough bits to make a complete drivetrain, if you could figure out a way to glue 'em all back together. That was an exaggeration, of course, but I did once find a very nicely worked bit of aluminum inside my flattened tubular.

I was a junior racer when the drillium/pantograph craze was at its peak. I saw the most amazingly tricked-out weight weenie bike owned by a kid in my race. He hit a rock on a descent, and parts went everywhere, I had to dodge one of his shoes. I didn't know you could actually do that much damage to a bike. He came out of it ok, but the bike was a total loss.

Ok no drilling the stem. I do love drillium though, nice examples. By the way my crank is a Zeus 2000, Brakes 2001 Lots of Holes. Ill put a braze on for the bell some where on the frame or us the clamp it came with The bell is brass from BELL and from Walmart , to nice, puzzling

I think that if you have a simple hole (not tapped) and manage to fit a nut inside the quill it might be okay. Or a riv-nut? Aluminum quills are pretty thick, around 5 mm. But if everybody else thinks it's a bad idea...

I mount my bells on drilled headset spacers. I think Velo Orange sells them pre-drilled.

And of course Compass Cycles offers chromed Nitto stems with a hole already drilled, if you have a couple of hundred bucks sitting around unused.

drilled spacer is a great idea if there is room. I was going to mention a custom stem

I keep considering the Nitto stem from Compass, but that's a lot of money. Then it's another $200 for the custom decaleur (which seems outrageous no matter how you look at it) and then, because the new stem and decaleur have limited adjustment, I probably will have to replace my Berthoud bag too.

IOW I can get rid of the slightly bodgy drilled bell spacer for just under $700. So I probably will keep considering...

Nitto Technomic stem? Just clamp it around the stem like you would a handlebar...

In the old days we referred to some shops as "Boutique Stores" -- pronouce the OU as a long ooh. In was not meant to be a positive connotation. It basically mean the store only carried a very few select items which were targeted to extreme shoppers and basically those folks with way too much money.

I saw one store near Pittsburg that had a matching set of a Porche, a Harley, a golf cart, a crazy drillium Colnago racer, an enormous elephant gun, and several other oddities... Marketing point was that all were modified to the extreme and all were plated in real gold. Several buyers were reported to have practically fought over the collection and it was all sold to the winner in less than a week...

Somervillain, who, I think, sometimes posts on BF, did it nearly tree years ago. he blogged about it here: https://bostonretrowheelmen.blogspot....-mounting.html
Not an endorsement, but it has been done before.

Thats the set up I was going to do. My question who drill the nitto stems that are sold at compass bicycles. Factory or after market? M5 tap for bell bolt.

I use An Incredibell , nylon band is part of the Bell ,https://www.mirrycle.com/original_bell.php.
why do it the hard way?

On My Rohloff hub trekking bar bike, I have this one on the left side, https://www.mirrycle.com/gripbell.php

The Compass stems have a reinforcement brazed in around the hole prior to chroming. Also, they're steel.

I don't understand why a 5mm threaded hole in the side of the stem is such a bad idea. How does it comprise the stem, does the hole, or edges of the hole, create stress risers or ...? By the time the torque loads created by pulling on the bars travel to that portion of the stem it seems like they would be dissipated a lot(excuse my ignorance of mechanical engineering). Looking forward to enlightenment.

thanks, Brian

I don't know if it's a bad idea or not. I just know that aluminum has a tendency to fail without warning, which could be annoying in a stem. So I personally wouldn't intentionally do anything to weaken one.

a threaded hole is just about the worst stress riser you can put in a piece of aluminum other than an actual crack. Like I said upthread, if the plan is to put a significant number of miles on the bike, it's a really bad idea.

The whole issue with fatigue failures, and particularly fatigue failures in aluminum, is that the stresses required to start and propagate a crack are much lower than the yield stress. So your mental model of the strength of a component doesn't really do you much good in trying to decide if something will ultimately fail. We know that un-threaded stems have failed, so it is certainly possible.

To further what unterhausen said, unlike most all metals, aluminum doesn't have a "fatigue limit", a stress under which the material has basically infinite life. Meaning that, no matter how low the stresses are on aluminum, it WILL fail eventually. Higher stresses simply make the time to failure shorter. Adding a stress riser to aluminum is just asking for a crack to start.

So all the existing bazillion al handlebars and parts will fail? And al frames? I don't have any data(maybe some here does) but the failure rate of al parts/frames seems pretty minuscule, if not litigation would most likely be running rampant if this was the case. Just asking.

Brian