Is it possible to get a 13-32 8/9 speed cassette?
 

I'm currently running a 11-28 8-spd cassette on my old road bike but I'd really like to bump it down to a 13-32. I'm seeing 11-32 cassettes available but I don't think my RD can quite handle that, I'm pushing it as it is. Closest I can find is Nashbar's 12-32. I'm wondering if I can buy an individual 32t cog and a spacer, remove my 11t cog from the outside and make my own 13-32? Would that work?

google fu shows this: https://www.amazon.com/SunRace-8-spe.../dp/B001GSQL6W
but it is a FREEWHEEL. So not much help.
Your plan would require a 32 cog that was splined, most 32 cogs are part of trimounts rivetted onto a splined carrier.
There have been cassettes which were built up of all single cogs, no carrier and all splined but they seem to be evaporating.
I keep a sort of eye out as I need such for my recumbent mid-drive cassette rebuilds every 5 yrs or so. A 6-7 spd cassette
might be the best donor for such a cog, in an off brand (eg Sunrace). Nashbar used to have such but not now.

The lockring assumes notches on the 11t, which may not be present on the 13t. Whether this would be a problem is
unclear.

I thought about the spacer built in on the 11t cog but this is handled by a spacer between the 28 and 32, if a 32 could be found.

The smallest cog has a built in spacer.
Only that type cog can be used for the end cog.
So, no.
You'd have to get a 13x?? cassette AND an 11-3? cassette and use parts of both.

Will your RDER handle a 32T cog?

Yes.

A poster from Wisconsin and I, have both built up 14-32 8 speed cassettes from:
* Shimano 8 speed 13-26 cassette.
* cheap Shimano 8 speed 11-32 cassette just for the 32T cog - I get mine from Amazon, looking at all the low end Shimano, and search for a used one, which is usually 30% less expensive.
* a Miche 14T first position cog.

Process:
* take apart the 13-26 cassette, put aside the 13 and 14 cogs and the spacer between the 14T and 15T cogs for another project.
* take apart the 11-32 cassette, keep the 32T cog and the spacer next to it; put aside the balance for another project.
* Assemble new cassette with 14T Miche first position cog next to the 15T of 13-26 cassette parts, and the 32T cog and spacer next to the 26T.
* put on freehub, re-using the lock ring from the 13-26 cassette.

The resulting 8 speed. 14-32 has very nicely spaced ratios over the whole range.

For 9 speed, Shimano offers a 13-25 and 11-32;
https://www.amazon.com/Shimano-CS-HG...GQO?th=1&psc=1
https://www.amazon.com/dp/B003EQB36W?psc=1
13-25 - 13.14.15.16.17.19.21.23.25.
11-32 - 11.12.14.16.18.21.24.28.32

I would mix and match; from the 13-25 use 13.14.15.16 and the 18.21.24.28.32 from the 11-32. Note that the two 16T cogs are different. One is designed to be next to a 15T cog and the other next to a 14T cog. Us the lock ring from the 13-25 cassette.

What are the following specifications on your RD:
* maximum cog size?
* maximum chain wrap?

What size chain ring(s) do you on your crankset?

If your RD can handle a 13-32 I'd expect it to work ok with an 11-32 as well. Yes, in theory the latter needs a couple more teeth of take-up capacity, but it's unlikely to make a difference in practice since you'll probably never shift into the 11t cog while on the small chain ring in front. If you ever do the chain may hang a bit slack but won't damage anything and you can just switch to a more appropriate combination.

OTOH, I can see the appeal of starting with 12 or 13t instead of 11t if the former cogs give you an adequately high gear already.

You can easily make an 8 speed 13-32 from the Sunrace 8 speed 12-32 by removing the first position 12 and replacing it with a first position 13. Simple, quick, relatively cheap (that first position 13 is around ten dollars and will probably last forever, moving it from cassette to cassette over the years) and shifts very well.

If you do the math, 11-28 and 13-32 have similar ranges (254% and 246% respectively). It might be much simpler to switch to smaller chainrings.

...and tolerate the faster drivetrain wear.

Entirely dependent on how much more, if any, the OP ends up using the 11T and 13T cog.

If the OP still has a standard 53/39 crank (to say nothing of 52/42), it seems kind of silly to me to orchestrate a Frankencassette and rear derailleur swap to accommodate it for lower gears. But there are many ways to Dublin. :)

I did not quantify the increase in wear, but it is inevitable, for at every gear ratio there will be fewer teeth (front and rear) engaging the chain at any one point and per crank rev.

There's a difference between what's important, and what's merely true. I don't concern myself with how much faster a 19T cog might wear the chain than a 21T. :lol:

Again, I made no judgment about to what degree the additional wear would be a factor for any individual, was merely pointing it out.