Couple weeks back I bought this aluminium single-bolt seatpost .
Now, just 20 days later, the nut that tightens the the mechanism to fasten the saddle rails to the seatpost is skipping around and not tightening.
I was testing new saddles on this seatpost, so tightening/loosening. Then, after I got done testing, I tried to put in the chosen saddle.
When I tried to tighten and fasten it, instead of the bolt moving into the rectangular nut, it got stuck and the nut started to move along with the screw, causing the entire upper metal plate to spin and get stuck as I tightened. This had happened a couple times before too. So, I tried holding the metal plate in place with my fingers while tightening this bolt to keep the upper plate straight. Impossibly hard, and I wasn't able to stop the metal plate from turning.
So, I presumed lightly oiling the screw system should help, thinking it has seized. I went ahead and put a couple of drops of oil in there. Now beyond certain (very loose) extent, the nut and bolt would just skip and slide and rotate around but not tighten anymore. Frustrated, I though that the oiling was a mistake, so I removed the plates, bolt and nut assembly and degreased it thoroughly and properly with a brush and degreaser.
I reassembled the plates, bolt and nut but it's still skipping and not tightening.
I seriously doubt that the bolt is worn out from such light use.
What is the solution ? I'm so clueless and haven't been able to ride at all since days now...
Link to close-up, labelled pictures of the parts of the seatpost for your understanding of their condition and quality : Here.
I confirm through careful observation that the bolt's thread seems damaged, and , from the observation of others here , also that of the nut's.
This damage causes the skipping and sliding, and I will be going to a hardware store and getting a new nut and bolt or just one depending on which is needed.
I am not sure but AFAIK both the bolt and nut appear to be aluminium.
Over-tightening might have been the likely issue , since at sensibly tight levels, the clamps failed to hold the saddle which would slide noticeably under climbs . Hence, I had regularly over-tightened it (like a true Jeremy Clarkson gorilla-with-a-spanner) and these cheap screws & bolts just couldn't take it.