As in the title really. I have a carbon Scott Genius with a 34.9 seatpost, but i've put my 31.6 Reverb on it with a shim.
I intend swapping my Reverb for the correct size asap, but in the meantime should it be OK?
Can you get 34.9mm Reverbs??
Use a long shim (140mm long) -Syntace make one, because 34.9 is Liteville seat tube size.
You can get 34.9 reverbs
Specialized were shimming the 2017 enduros from 34.9 down to 30.9. I have a USE shim in my 2018 so I can run a 30.9 reverb.
I cracked a carbon frame because the seatube was slightly too big and the clamp was the only thing holding the seatpost in place. The seatpost would move and eventually cracked the seatube in line with the bottom of the seatpost. Unless the shim is very close to the full length of the seatpost within the frame, I would not risk it personally.
Ran one on my 456 for a couple of years, no issues just use a sensible length one. As above with such a big difference in size I’d want a shim longer than the seatpost personally.
The Ransom used to ship with a 34.9-31.6 shim.
I ran a few seasons with that V2 Genius shimmed for a Joplin. No dramas.
IIRC I believe Scott would only warranty frames if there was 100mm insertion depth.. needless to say, my ransom branded shim was 100mm.
The USE shim i'm using is 100mm long,i would have liked longer really - as the reverb obviously finishes below the shim.
I might have a look for a Syntace one - or try and get a 34.9 Reverb asap,although they seem a bit more scarce than other sizes.