Tool Fool - 27.2 seatpost solution

[lconley]

Cyclus holder and handle and 27.2 seat tube reamer (very sharp). For when you really, really want to put that 27.2 lugged seatpost in your 26.8 or 27.0 frame. This will be first put to work on my 27.0 Guv'nor and then my 27.0 Bombadil (already honed, but still tight). Less than $100, shipped from Germany. This is my birthday present to myself for my 66th Birthday.

Laing

Delray Beach FL

[st nick]

Thanks Laing. 

I'm glad to know about this tool.

I'm wondering about the pros and cons of changing a 26.8 or perhaps 26.6 which most of my bike are to a 27.2.

Well, I can think of several pros...

I just wouldn't want to mess the seat tube up if there are cons.

Paul in Dallas 

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[Julian Westerhout]

Laing, 

Happy birthday!   :) 

I'd love to see a report on how you found the process once you've done it. easy to difficult, quality of result, etc. 

Thanks! 

Julian Westerhout

Bloomington, IL 

[Ed Fausto]

Hi Laing,
I also found a supplier from Europe and plan to purchase the Cyclus holder and handle and 27.2 seat tube reamer.

I plan to ream my 51 GBW from 26.8 to 27.2 so I could use Cane Creek Thudbuster ST Seatpost.
The Cane Creek Thudbuster has helped me continue cycling even with my chronic lower back pain.
Could you give some tips or techniques you learn when you reamed your bikes seatpost?
Thanks in advance.

Edgar

[Conway Bennett]

I called Dave wages at ellis cycles to ream my hunqapillar to 27.2 from 26.8, and he wouldn't be do it because of the risk of damaging the frame.  You may want to consult an expert before doing this.

[Richard Rose]

Certainly there are degrees of back pain. Mine required surgery. I installed a Thudbuster on my Jones SWB & it worked really good. When I replaced the Jones with long chainstay Riv’s (Clem & Gus) the need for Thudbuster disappeared. On a related note I was gifted a Redshift Shockstop stem which I have installed on my project bike dubbed “MTBuno” inspired by ROADuno. It works fantastically well. So perhaps the Redshift seatpost is worth consideration too.

Sent from my iPhone

On Nov 5, 2025, at 7:18 AM, Conway Bennett <captaincon...@gmail.com> wrote:

I called Dave wages at ellis cycles to ream my hunqapillar to 27.2 from 26.8, and he wouldn't be do it because of the risk of damaging the frame.  You may want to consult an expert before doing this.

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[Rusty Click]

I'll echo Julians request as to an update when done.  I would like to do the same to my Atlantis.

Rusty

[Dan]

I wonder the same thing. 

I can’t help but feel that 0.2mm (27.2 > 26.8 is 0.4mm or 0.2mm each side) is a lot of seatpost wall to be removed. It would be up to a 20% reduction in wall thickness of the seat tube, possibly more?

[Guy Jett]

What about finding a machinist with a lath to reduce the diameter of the seatpost.  I know of one in Alameda, CA, Who just did this to a fork steerer tube just before he repaired a broken right rear dropout for me. He's also a frame builder. http://www.mikkelsenframes.com/

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Guy

[Ed Fausto]

"When I replaced the Jones with long chainstay Riv’s (Clem & Gus) the need for Thudbuster disappeared."

Hi Richard,

That is a very interesting observation.
I have not yet tried using my Gus on long rides and will try it out first.
Because of the long chainstay, the seat is more centered and would reduce the direct bounce in the seat.
I took a quick look at Redshift but unfortunately, they only have the 27.2 as smallest option.

Thanks again.

Edgar

[Garth]

A  27.2 ID of a 28.6 OD steel frame is completely normal. Tons of steel frames are like that. 27.2 is by far the most common post. Not only is that .7mm enough, you also have the lugs that reinforce the top of the seat tube. I see many of the current Riv models are taking 27.2 posts now. So they appear to be moving away from seemingly everything taking a 26.8 post !  From my recent web shopping, most any of the steel frame designer/contractors/sellers like VO, Crust and Soma all use 27.2 posts.  Only the oversized ST models take a larger post. That said, any steel frame that takes a 27.2 post you wouldn't even know if it was reamed from the manufacturer or not.

The Cyclus reaming tool is self guiding. It's modular, the silver part being the cutter. The initial black portion is to guide and center it in the seat tube. Anyone who has tapped a BB or reamed a head tube can do it. Even if you haven't there's some YT videos of people doing it.

[Ed Fausto]

Hi Garth,

Thanks for the advise on the Cyclus reaming tool.  I did not know that the black portion helps guide the tool and help it center.
I have been assembling my own bikes but this particular procedure is quite intimidating.
Will search of Yt videos to learn more.
Thanks.