I have the IRD crank that looks like the old campy style (same as the velo orange but less shiny, which is the reason I got the IRD model instead). Something trippy about this crank is that the middle ring is a triplelizer; the granny ring is mounted on it. Right now have a 118mm bottom bracket that lets me run it as a double, but things are a hair too close to add the granny ring.

So anyways, on my last internet order I got a bag of assorted crankset/BB spacers. I figure 2mm will let me clear the granny ring and give me the flexibility of running the crank as either a double or a triple, as the whim may strike. What I got doesn't make sense to me. I figure a BB spacer would fit between the driver side cup and the frame. I basically got a bag of assorted thickness washers that are 25mm outside diameter, 19.5mm inside diameter.

a. Out of curiosity, how the heck are these supposed to be used?
b. Does anybody sells a bag of assorted BB spacers, the ones that would fit between the frame and the driver side cup? I see bags of 10 for a given thickness but not a mixed set.

Are you sure you received BB spacers and/or are measuring the diameters correctly? Measuring the BB spacers I have on hand they are 1 3/8" (a bit more than 35 mm) ID and 1 1/2" (about 38 mm) OD. The only source I know of for BB spacers is Wheels Manufacturing (in bags of 10) though the Sturmey-Archer 3 speed rear cog spacers will also work. When I've used BB spacers on the BB (you can also use them to space freewheels and single rear cogs) I put them between the frame and the right hand cup, remembering that the left side adjustable cup will move in the same amount, possibly not leaving enough threads for the lock ring.

The spacers you received are for the bb spindle on some bmx cranks such as those from Profile.
As for your second question, I don't think any companies sell assorted bb spacers as a kit, however, I am sure if you check with your lbs they will be glad to supply you with as many as you like for a nominal price. Good Luck!

Cheers
lverhagen

Bicycle Research still makes them. https://www.bicycleresearchtools.com/access.html and Bike Tools Etc. https://www.biketoolsetc.com/index.cg...rts&sc=Spacers stocks them.

They were more often used to trim the freewheel position and usually go by the term "freewheel spacers."

You may want to check the following before proceeding: 1. do you have more than 2mm of threads exposed on the adjustable cup (left side) beyond the lock ring; 2. is there more than 2mm clearance between you crank and the chainstay on the left side.

As a point of reference, triple bottom brackets were usually 5 mm wider (all on the drive side) than those designed for doubles. That's why you want to double check your non-drive side clearances before proceeding along this path.

BB fixed cups have a flange, adding a spacer under it will move the whole BB,
freewheels and the left adjustable cup use the same thread
Right one is same size, but CCW thread..

Bagged spacers were sent a number of same,
retailer could have ordered several bulk bags , and made up
a bag of various thickness , but sounds like they resold what they got,
a bulk bag of same thickness.
their wholesalers Just don't. not their job.