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. On Thursday, November 6, 2025 at 4:34:15 PM UTC-5 GAJett wrote: > 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/ > > On Thu, Nov 6, 2025, 12:08 PM Dan <[email protected]> wrote: > >> 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? >> >> On Wednesday, 5 November 2025 at 23:18:25 UTC+11 Conway Bennett 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. >>> >>> On Tuesday, November 4, 2025 at 8:07:00 PM UTC-6 Ed Fausto wrote: >>> >>>> 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 >>>> >>>> On Friday, April 29, 2022 at 8:35:57 PM UTC+8 lconley wrote: >>>> >>>>> 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. >>>>> >>>>> [image: Seat Tube Reamer (2).jpg] >>>>> >>>>> Laing >>>>> Delray Beach FL >>>>> >>>> -- >> > You received this message because you are subscribed to the Google Groups >> "RBW Owners Bunch" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> > To view this discussion visit >> https://groups.google.com/d/msgid/rbw-owners-bunch/e4b451c3-2881-4ca0-a1fc-1ed0ab7b3a9bn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/rbw-owners-bunch/e4b451c3-2881-4ca0-a1fc-1ed0ab7b3a9bn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > Guy > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/rbw-owners-bunch/e3d3a631-abc1-4a8b-a514-2c478041bb9bn%40googlegroups.com.
