Darth Lefty 

Death cone?

Robvolz 

Bad Leg wrote: Quill - The hollow stem-like main shaft of a feather.

A quill-shaped stem and expander can be used on a bicycle.


Holy cow, thanks, I never new the meaning behind it. I just figured it was invented by Peter Quill or something.

Darth Lefty 

The .833 stem is a very American thing, that you can find on all the Schwinn electro forged and fillet brazed bikes for example, and persisted on BMX. I see it some places listed as "13/16ths" but it's not satisfyingly close enough to that.

Here are a ton of them
https://www.bmxguru.com/collections/stems-quill

seedsbelize2

Thanks. It confirms what I thought.

bulgie 

I'm shocked to see this kinda dumb "standard" was still in use as late as '84, I thought by then it had been consigned to the dustbin of history. I have 3 older Schwinns with it, a '33, a '71 and a '73. Never expected to see it in the '80s, but by then I had stopped paying attention to Schwinn.

Nothing wrong with it functionally, just parts availability or interchangeability. Schwinn did a lot of good in the American bike industry, but some dumb stuff too.

Mark "22.2 FTW"

tiger1964 

I'll defer to your expertise on that. I would have thought the "desired friction" would have been the stem-to-steerer interface, the stem-to-expander interface less so. Time for me to ponder more deeply...

bulgie 

Well you can imagine, if the threads had more friction than the cone-to-stem interface, then the cone would just spin as you tried to tighten it.
That's why some stems had a key on the cone that rode in the slit in the stem, to keep the cone from spinning. Not exactly necessary, most stems got away without one, but I think it's a good feature.

Hondo6

It's 5/6". 5/6 = 0.833333333 . . . . " . Rounded to 3 decimal places, that's 0.833".

Darth Lefty 

Why standards take hold and persist is a funny thing. Reynolds using imperial Standard Wire Gauge for tubing thickness is pretty random too. So many bike "standards" are not just inch diameters but also four flavors of gauge thicknesses turned into metric

What looks weird to me is seeing it on a Le Tour. Maybe it was a Greenville, not Asian?

That's true but it's got to be a math coincidence. It corresponds to a US tubing gauge. That definitely feels like why it would be used on BMX bikes with their straight chromoly tubing or Super Sports or on 1930's bikes. Why on Varsity bikes, though? I thought their tubing was made in house out of strips of sheet and you'd think they'd be US sheet metal gauge

JohnDThompson 

FWIW, Arnold Industries made aluminum stem bolts and cones for the weight-weenie crowd:

jdawginsc 

Pretty elegant for a piece that no one ever sees.

79pmooney

I had a custom stem made to the usual English standard and hit fail! immediately when I tried to put it in my Schwinn LeTour of early '80s vintage. (Didn't come with papers and I wasn't yet very Google savvy.)

Stem bolt torque. The amount needed is very low. Unless you have heavy panniers or the like, a sudden real side force on the handlebars is gong to cause all kinds of bad stuff even if you stem doesn't slip. High enough torque to cause any kind of issues of stick later is far mor than you need unless you opted to go without grease. And that is a place where there is no such thing as too much grease. (Other than the mess you encounter later when you take it apart. )

I love quill stems because the quill bolt torque is so non-critical. On-the-road stem height changes are no big deal at all (providing grease was used liberally and muscles sparingly and a rock or the equivalent is handy).

tiger1964 

Now you've done it! Now I have to pull all the stems up on my bikes and inspect, as I do not recall. I had presumed all had the "keying".

Hondo6

It may or may not be coincidence. But math-wise, 0.833" is (to 3 decimal places) 5/6".

I've read that Schwinn was more concerned with reliability than weight for decades on everything except their extreme high end bikes. Thicker steerer tubes would have contributed to increased reliability.

FWIW: per multiple sources I consulted, you're correct in saying that 14-gauge steel tubing today has a wall thickness of 0.083" - or an ID of 5/6" for a 1" OD tube. If that were also the case "back in the day", Schwinn (and other manufacturers) could simply have ordered 14-gauge tubing in mild steel for their steerer tubes vice "rolling their own." Schwinn might have looked at it, decided that ordering tubing for steerers from an outside supplier was more cost-effective than making their own due to the smallish quantities involved compared to frames, and decided to use standard 14-gauge mild steel tubing from an outside supplier. Dunno.

Schwinn started outsourcing some parts to Japan as early as the 1970s bike boom. My guess is that you might see 21.1mm stems on some Japanese-made Schwinns because of standards inertia - e.g., Schwinn specified the same headset/stem/steerer standards there as on their lower-end US bikes for compatibility purposes with existing dealer spare parts inventories. Dunno for sure there, either.

Robvolz 

Hey Uncle x2

im at the co-op

you needed stuff

Text message me

uncle uncle

^ My stem looked like this, same manufacturer and model, except it was 70 mm in extension length. I was unsuccessful in retrieving any portion of it from the shop I left it at; they replaced it with a "no name" stem, with a bit short extension length (around 65 mm as I measure it).

dddd

I've learned to trust Schwinn's methods over many year's time, but hadn't much thought about the bmx diameter quill situation until now.

I conclude that it wasn't dumb at all!

Given that Schwinn made bikes that maintained durability over a longer-than-typical period of time and use, this quill diameter was completely consistent with that.

Consider that many riders ignore height limit lines, and that older stems had no height limit lines. Also consider that many riders in those days tended to severely over-tighten bolts on bicycles. The considerable added steerer wall thickness below the root of the threads would seem to dramatically increase the working life of this sometimes-fragile threaded portion of the steerer when the .833" ID was used.

Compare Schwinn's approach to a surprising number of other makers who used 22.2mm ID steerers that had threads extending far below the headset's mating threads, which is comparatively very weak/unreliable/unsafe when the stem is raised to only it's limit line.

Schwinn I think was exceedingly conscientious about durability and safety, which probably had lots to do with the frequency of liability claims in the US in addition to Schwinn's "last-a-lifetime" durability philosophy.

bulgie 

Agreed, a thicker steerer has advantages when the steel is weak and the manufacturing standards (like thread length) are unreliable. But on a quality bike with alloy steel tubes and the right number of threads, it's unnecessary and a bit infuriating.

When I replaced the garbage Schwinn Ashtabula fork on my '71 Twinn tandem, I used an MTB fork, coincidentally(?) off an '80s Schwinn MTB. The MTB fork takes a 22.2 stem like God intended, and it is nevertheless quite adequate, and I daresay probably much stronger. The Twinn fork was so flexible that we couldn't stand up to pedal without the tire rubbing on the fork blades — both sides, alternately with each pedal stroke. The tire also rubbed on the fork when making a tight turn, like a U-turn in the street at walking speed. The wheel would just flop over. Nothing was broken or loose, just incredibly flexible side-to-side. For those who don't know, those fork blades aren't even tubes, they are flat plates of solid steel, not hollow.

I'm a Schwinn fan, mostly (like I say, I own 3 of them), but there are things they did that make me say "hmmm...".

Mark B