Hey! It's a second hand steel bike frame, probably from the 80s or 90s. It came with a 25.4 mm seatpost clamped to hell. The gap on the seat tube had to be completely closed shut and screwed even tighter beyond that for it to hold in use. I spread it open a little with a flat screwdriver. It's currently at 26.2 mm, and I think it could go a little further to 26.4 mm. Is that the most likely intended seatpost diameter? Or should I look for some uncommon 26 mm posts and leave it at that?
Some more measurements:
Seat tube diameter: 28.6 mm
Tube thickness at the top: 3 mm
Likely tube thickness is 1 mm due to the lug "protruding" from from it by 2 mm
Cheers!
by anotherbazyl
3 Comments
Here’s the list of seatpost sizes on QBP. You’re probably looking for a 26.4 or 26.8. Call ahead to any shops you’re planning on going to – the odds of them having those exact sizes are slim.
25.8
26.0
26.4
26.8
27.0
27.2
is it just me or is there a shim in that seat tube?
Well there’s nominal and then actual when it comes to seatpost diameters. Whatever fits and clamps well is what we go by. Everything else is just semantics IMHO (unless you’re determined to use a specific seatpost for some reason- then you have options to make that fit work, i.e. reaming, shimming, sanding, etc.)