Peugeot PFN 10 Stuck Seatpost – Conclusion ( Video )

The Impossible Task

When I took possession of this rather beaten Peugeot bike I could have never envisioned the problem I was about to face. This seatpost, after hours and hours of attempted removal, never even budged a millimetre in the end. Even if I’d seen it move just a tiny bit, if it had just given me the slightest concession, I would have felt a bit better about being defeated. However, this greyed and forlorn SR seatpost wouldn’t give me anything but painful arms and a ton of frustration.

 

 

 

 

The List of Methods We Tried

 

1. We started out with a large Pipe wrench, with two of us taking turns trying to rotate the seatpost. Because this particular model of post had a square head, it was possible to get a good grip on it with the wrench for a lot of torque. No luck.
2. Penetrating Oil. And lots of it, but it had no effect and many believe it doesn’t work.
3. Heat. We had access to a professional blowtorch, and we heated the post and then dipped it in ice water, hoping to break the bonds of the aluminium and steel tube. We repeated this for about an hour, but no movement.
4. Coca-Cola. After reading some stories about the effectiveness of this drink for breaking down rust and frozen parts, we thought we’d give it a go. I let it sit for two days inside the seat tube, but no luck.
5. Flash heating the steel. On a morning of sub-zero temperatures, I put immersed the seat lug area in freezing water and then poured boiling water over the steel tube. The idea was to expand the steel instantaneously, thereby breaking some of the bonding inside the tube. It didn’t work.
6. Cutting out the Seatpost. The last resort was to try cutting the post out with a hacksaw. I was more optimistic with this method, and it started out quite well. The top of the seatpost was easily removed, and then I began sawing downwards to break the post in two or three parts. The idea then was to break it up into pieces with a screwdriver and chisel. Even this method failed, and the seat tube ended up taking too much damage from the hammer and chisel.

 

 

Conclusion

 

Galvanic corrosion. The definition of this occurrence is: “an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte.”  The aluminium seatpost and steel seat tube bonded together in the presence of water, forming a new chemical bonding that was very strong. I’d be interested to know what methods this expert uses to remove seatposts, he states he has removed over 700 with his own specialised set of tools. One can only guess, but its none of the methods I tried above.