So, I acquired a coveted "Huffy Bicycle". I had actually been looking for an old Raleigh 3 speed or something similar to ride to the bus stop - and then THIS bike was dumped in a pile of "Free" stuff nearly at the end of my driveway. Of course, I had to take a look, and despite the Huffy brand, it has a Sturmey Archer 3 speed rear hub. Great! Just what I'm looking for, and the price is right. All I need is a seat and seat post.

In my parts bin, I have 7/8" seatpost - it is too big. So I order a 13/16 Wald Seatpost off of Amazon . .. and it is too SMALL!!

I've looked online, but I can't find any chart with showing any intermediary sizes between these two seat post sizes. Of course, I can wrap the smaller seatpost with a beer can and make it work, but that doesn't sit well with my latent OCD tendencies. Anyone know of a seatpost size BETWEEN 7/8" and 13/16"? Pics show actual measurement's in mm.






Huff

AdventureManCO can probably find your something Italian that will fit

Inches MM
0.8125 20.637
0.82677 21.0
0.834644 21.2
0.842518 21.4
0.850392 21.6
0.858266 21.8
0.86614 22.0
0.875 22.225

60 years ago, Huffys weren't that bad.

The First Step is to Confirm that the frame is not bent at the seatpost clamp area... Is the Slot in between the two clamp ears straight or does it taper at the top of the slot?

Next Step... Is the seat tube hole in the frame Actyually Round or is it ovalled? Measure it with the digital caliper to check.

Is it Round? then what dimesion did you read three or four times in a row?

straight slot? round hole in the frame? you now know your seat post OD...

Bent seatpost frame clamp? Oval Hole in frame? Contact a good Bike mechanic before you further damage the bike.

FYI.. 22.2mm seatposts are fairly common to many BMX bikes and older bikes like yours... 22.0 is available, but kinda rare... anything smaller is Hen's Teeth with gold fillings... Ebay shows Exactly ONE 21.8mm,as an example... there are Dozens of 22.2mm....
i'm thinking the frame clamp is crimped in too far.... and that your free Huffy may actually be a Murray in Huffy clothing... Murray used a 22.2mm Seat post sometimes... as per Sheldon Brown's Seatpost database and my personal experience.

Some folks make shims out of old pop cans by using heavy scissors to cut the cans... and well stocked Hardware Stores (ACE, not Home Despot) carry a stock of Shim Materials in various thicknesses... Aluminum is easy to work with and plenty adequate for the task...

check that clamp slot first, etc.

Well, seat post sizes are normally taken in metric measurements? I would most likely bet that a 22.2mm is the size you need. but you don't show any pics of measuring the seat tube ID, just ones of measurements all the wrong seat posts.

I think we have a few (used) ones in the shop and can mail one to you. if you can't locate one locally. Check with any Co-op or volunteer shop to see if they salvaged some..

Is that a "C" clamp at the top of the seat tube?

That is a C clamp I was just testing/confirming that the seatpost clamp will not close far enough to hold the 13/16"/20.7mm post. It won't. The clamp area at the top of the seat tube was spread open pretty good, so the larger 7/8" / 22.3mm post drops in an inch or so to where the seat tube split stops, then it won't go in any further.

I guess it may be a oddball size between those. The "correct" size is definitely somewhere between the two measurements I have pictured. There is no way that larger post is going in, and the smaller post is way too loose. Despite the age, the bike is in apparently great condition. My calipers won't go into the frame far enough to actually measure the ID of the seat tube.

I was just surprised that a Huffy would have an oddball seatpost size - I would have guessed it would be the same as an old school BMX/Schwinn Sting ray. And I would have thought if there was a size between 7/8" and 13/16" it would have been listed on Sheldon's site. But I was also surprised it had a Sturmey Archer rear hub.

The 13/16" Wald I bought seems to be a half millimeter thinner that specs suggest it should be, but I'm pretty sure that wouldn't make the difference.

The 21.8mm post you referenced seems like the the right size, and I guess if it exists, it was made for some bike at some time!! But a shim will do the trick.

A seatpost 0.5mm undersized will definitely be far too loose when inserted. But I don't think that's the issue here.

A 13/16" seat post should be 0.8125" or 20.6375 mm in diameter. If it's measuring 20.72mm, then it's around 0.1mm oversized - not undersized - IF that measurement is accurate.

However, you also might want to check your calipers. A 7/8" seatpost should be 0.875" in diameter, or 22.225mm (22.22mm to the limits of your caliper's scale). Instead, you're showing it as measuring 22.32mm - or about the same amount oversized as the other seatpost. To me, that suggests the possibility of a systemic measurement bias of approx +0.1mm.

FWIW: I find that my digital calipers often tend to show off by about 0.1mm (e.g., register -0.1mm or 0.1mm when fully closed) if I don't zero them before taking a measurement.

I was going off the millimeter specs on Sheldon's site, rather than actually doing the math:

BMX bikes Better models
22.2 .875" (7/8") BMX bikes Cheap models
21.15 .833" (nominally 13/16")

0.833" is 5/6" to 3 decimal places, not 13/16". That (0.833", or 21.15mm) also happens to be the size of the old (and hard to find) stems used on a few vintage bikes - post-1965 Chicago Schwinns, if I recall correctly, along with some others.

I believe this is a rare case of an error (probably a typo) on the late Sheldon Brown's website. But I guess I could be wrong.

Missed this one. Coveted indeed!

Here is what I'm seeing:





.821" or 20.85mm on an 80s Huffy, although yours maybe be different.

If this is what you need, let me know and the seatpost is yours. Just PM me and I'll get it sent out to you.

One thing that might help confirm is if you take an inner diameter measurment of your seattube where the seatpost is inserted, and I do the same, and see if they are equal. If that is the case, then this one will fit!