How precise are seat post measurements?

[661-Pete]

Sorry, didn't read the thread properly

Of course, at Cyclemagic we make these magic shims that reduce the size of the tube.

This is the shim made of anti-matter - check?

I would think, 'try it and see' might be an option but not for that sort of difference, and I'm not sure I would trust the result. To gain 0.7 mm in diameter the 'jaws' of the seat post clamp would have to be pi * 0.7mm ~ 2.2 mm further apart: even if you could prise open the seat tube to that extent it will now be curved to the 'wrong' radius possibly putting damaging stress on the frame.

For seat posts which are (fractionally) too small, I seem to recall Richard's Bicycle book recommended drilling through both seat post and frame (after setting post to correct height!), and inserting a bolt or two. Messy and I'm not sure I'd recommend it, but it might get you going.

 

[marzjennings]

I say sell you're old gravitydropper and get a new one that fits. Unless you've knackered the old post you should get a couple of hundred for it used which will go a long way to getting a new one.

 

[fossyant]

Let me guess, the bike manufacturer is French...... why not stick to the standards eh ?

 

[allen-uk]

Bit further east I'm afraid - China.

A

 

[RecordAceFromNew]

I want a different bike.
c) The device is $300+.

Keep your gravitydropper and put part or all of the $300 towards a better/alternative bike? 27.2mm is a very common size.