Jonatan F

Went in to town to get a seat post for the festive 500. unfortunately I forgot to measure my bike!!!!

What I know is that it's a Chimon, probably Cobra.
Probably Tange champion 5.
What do you think that will make in terms of seat post diameter? Would love to be helped out here!

Here's a google-translated info page.
Chimo Cobra

Merry christmas!

Ps. If I'm inte the wrong part of the forums, please do move my thread. I was not sure where to put this. Also if there's a more accurate thread already existing (did my googling beforehand though and found nothing)

2manybikes

Find someone with a caliper and measure it, or, take the old one, if you have one, to the shop. If you don't have a seatpost take the bike to the shop.

Jonatan F

Absolutely, problem is, I'm 100 km away from the bike *facepalm* – forgot to measure!

2manybikes

You're not the first one, or the last, to make that mistake . If you get one just a hair too big, it may get stuck in the frame. If you get one that is a hair to small you may not be able to clamp is securely, the seat may go down when you ride.

Jonatan F

Figured that it's *probably* 26.6 since it's *probably* Tange champion 5 :S
Yea, I use a too small seat post today that I've failed to shim sux!

The Golden Boy 

Jonatan- I've been trying to find a bike that's listed as being of Tange #5 that is listed in Sheldon Brown's seatpost database.

I'm not having a whole lot of luck. I'm sorry.

Sheldon Brown's Seatpost Size Database

Scooper

The Tange No. 5 seat tube (1454) is 28.6mm O.D. and has 0.9mm wall thickness, so should take a 26.6mm seatpost (28.6 - 2 x 0.9 = 26.8 - 0.2mm clearance between seat tube I.D. and seatpost O.D. = 26.6mm).

The problem is that the O.P. doesn't know for sure that it's Tange No. 5, or even if it is whether the framebuilder reamed the seat tube to take a larger diameter seatpost.

The Golden Boy 

Stan, just knowing where to look for that information is a knowledge and skill that few possess.

seedsbelize 

In a pinch you can use masking tape and aluminum can shims. I can feel the eyes rolling as I write this, but you DO want to ride it I'm guessing.

Jonatan F

Have tried shims, they were to thin, but i could build a hell of a shim with several layers using that method... it is a frankenbike for winter rides after all...

However, I've done some measuring with my plastik (sorry) calipers. Seatpost inner seams to be 27.6-28,2 mm (a 28.5ish seat post was to big) Though that seems to be a very rare size... Maybe it's a 27.2. I don't think so but I have to check again!

I couldn't find a sticker to indicate tubing but i measured it to ca 28,6 so should be italian/english.

My top question: where the **** is the original seat post! I know it was there when i bought the bike!

I'll get one of these! Seen on sheldonbrown.

Jonatan F

Oh, btw, probably the pipe isn't that round. Maybe that's why the measurements won't be exact.

Jonatan F

I figured it out, quite obvious really. The seatpost cluster was quite deformed (probably due to my shiming, use of to small seat posts, previous owner (who took very poor care of the bike) etc. The actual size is 27,2. Tried a seat post from another bike. Thx för help!

Edited to reasonable seat postdimension

2manybikes

You mean 27,2.