seat post sizes

[galleta loco]

Good Lord,how many different size seat post are there.

 

[Bicycle808]

soooooooo many, often with just 0.1 or 0.2mm between sizes....

 

[ctaccruiser]

My favorite: is it a 1"(25.4mm) or 25mm, ran into that one a couple weeks back.

 

[mikeeebikey]

A bunch!
American made frames, usually use s.a.e. sizes, usually.
Imports are metric.
You really need a caliper, and remember the conversion factor, 25.4

 

[galleta loco]

LOL I've got 4 bikes with 4 different sizes who knew?

 

[Bicycle808]

A bunch!
American made frames, usually use s.a.e. sizes, usually.
Imports are metric.
You really need a caliper, and remember the conversion factor, 25.4

The old American bikes tended to be metric, but most of the new US-made road/mtn/'cross bikes are metric. I also recently picked up a made-in-Florida Trailmate industrial bike-- probably early 80s vintage-- that had a 22.0 post. That's a common French size. The stock post was just straight 22.0, so a regular saddle gutset didn't take, so i tried regain composure, and ended up running a 13/16" post with a "7/8" shim; it's working fine so far, even riding off-road.

Better than a caliper, if you can justify the price, are the stepped rods that quickly/easily/accurately determine what size the frame needs:

My usual method is to buy a frame where i either already know the specs or the original post is still in it, so there' no guesswork. MY "plan B" is usually to cuss and fidget and test-fit different sizes until I get it right. Haven't had to try that method in years, thankfully.

 

[ifitsfreeitsforme]

ha. I just went through this last night. I measured my Berkshire I.D., and it was .800". Measured all my seatposts, and I had, .81, .84, .86, .87... and up. I ended up sanding the .81 post on the belt sander.

 

[Bicycle808]

ha. I just went through this last night. I measured my Berkshire I.D., and it was .800". Measured all my seatposts, and I had, .81, .84, .86, .87... and up. I ended up sanding the .81 post on the belt sander.

That's pretty grim. 8/10". What's wrong with these ppl? Of course, that's a pretty old frame you got there, buddy. Times were way different back then, I guess.

 

[Uncle Fide]

Had issues with Indecision and it's seat post, got a nice 26.4mm layback post and what I thought would be correct tapered shim only to find the shim too thick at its thinnest size. Turns out the seat tube is 27.2mm! Now I have a pointless post to get rid of :-(


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