Kona seatpost sizes

[S8-Tom]

I've done a search and there's no definitive answer. What size post would a 1994 Kona Cinder Cone need?

From what I've read it could be 26.6 or 27.0. The current post (not original & not long enough) measures 26.6. It's loose in the seat tube above the top tube but gets tighter when inserted below the level of the top tube. I've tried a 27.0 and it feels like it'd go but don't want to get it stuck.
Should I go for something in the middle? 26.8?
What are you using?

 

[Anthony]

I think it's a 27.0 and that seems to be confirmed if a 27.0 will go in down to the area of the top tube weld. From what you say, it could be that the welding has caused a slight swelling on the inside of the seat tube at that point. That should have been reamed off in the factory, but if not I would ask the LBS to do it.

Seat posts should be inserted well below the top tube weld (regardless of what it says on the post itself), so Konas, Rocky Mountains etc need quite long posts.

 

[S8-Tom]

Thanks Anthony, that's what I wanted to hear as I've taken the gamble and ordered a 27.0.
I understand what you mean about the insertion requirements. Although the current post is very short I've made sure there's still about 100mm below the top tube junction.
Hopefully I'll be commuting on a correct length post next week!

 

[S8-Tom]

:cry: 27.0 didn't fit. Went to just above the bottom of the slit and stopped. Definately won't go any further. Having checked the existing 26.6 post (really should've done this sooner) it's a very good fit.

Wonder why this frame is 26.6 when it appears most are 27.0? Could a seat-tube from a previous years model have been used? Could the frame actually be be from a previous year?

Who know's. 26.6 purchased from ebay.

 

[taffy]

I had this issue with my Kula - advice given to me was it's a 27.0 dead.
After getting one it was the same story goes in a tiny bit then stops - 26.8 fit's perfectly.

 

[hamster]

The reason is deformation of the tube from the heat of welding. The tube goes slightly oval...hence a nice round post doesn't fit.

Most bikes have exceptions, caused by the usual tolerances in manufacture. All they usually did was slip in a smaller post. My Dawes tandem (531 Tandem tubeset) takes a 27.2 in the front, 26.8 at the back... :shock: A really carefully brazed 531 tubeset will take a 27.4 post.

Poorer quality bikes probably just fitted undersize posts, full stop.

 

[S8-Tom]

The reason is deformation of the tube from the heat of welding. The tube goes slightly oval...hence a nice round post doesn't fit.

Most bikes have exceptions, caused by the usual tolerances in manufacture. All they usually did was slip in a smaller post. My Dawes tandem (531 Tandem tubeset) takes a 27.2 in the front, 26.8 at the back... :shock: A really carefully brazed 531 tubeset will take a 27.4 post.

Poorer quality bikes probably just fitted undersize posts, full stop.

Could be. Just that I know that previous years used 26.6 seatposts. Surely if the internal diameter of the seat tube was so different to the 27.0 specified it wouldn't pass quality control?
I know a guy who was involved with Kona in the UK right at the start, I'll see if he knows.

 

[Baulz]

:cry: 27.0 didn't fit. Went to just above the bottom of the slit and stopped. Definately won't go any further. Having checked the existing 26.6 post (really should've done this sooner) it's a very good fit.

Wonder why this frame is 26.6 when it appears most are 27.0? Could a seat-tube from a previous years model have been used? Could the frame actually be be from a previous year?

Who know's. 26.6 purchased from ebay.

Kona must have got a good deal on odd sized tubing as many of their frames use 26.6 seatposts. I also have a 94 Cindercone and that is the correct size.

Was helping a friend rebuild a 93 Fire Mountain. A 26.8 post fit nicely to about where the top tube weld was, but would not go down any more. Swapped for a 26.6 and it fit perfectly.

26.6 is soooooo frustrating. I know Control Tech and Syncros made them, but seem to be impossible to find. Also looking for a 31.4 for a stupid Mongoose. :evil:

 

[hamster]

Don't get me wrong, there are all kinds of odd sizes out there, and Konas are one of them (early 90's Marins have a lot of 26.2, with the same problem). All I am saying is that seatpost fit also depends on tube distortion, so don't be surprised if you find the occasional oddity.

I gave up and went with USE post plus shim, but again it worries me on Konas where they have the long protruding part of the seat tube - a long shim is definitely preferable!

 

[Baulz]

I gave up and went with USE post plus shim, but again it worries me on Konas where they have the long protruding part of the seat tube - a long shim is definitely preferable!

I thought about doing that. How far down does the shim go? To the toptube junction or not that far? I worry as I have long legs, so use a 400mm post close to min insertion.