A bike that defeated us....

Some time ago a visitor bought a steel frame road-bike to do up – nice bike, in good condition, maybe 30 years old. However the seatpost was too low , and stuck.

Seat posts fit frames snugly – 0.2 mm - but usually are adjustable. The trick is bolt a saddle on top, and use that to get leverage. Once you can get the post twisting – you can then adjust height. Seat posts sometimes get stuck if they're not greased, or they're the wrong size and hammered in, or someone has bent them. But this one, seemed straight. It was however not original - an aluminium post in a steelf rame.

Aluminium and steel (iron) are reactive metals and rust (oxidise) readily. if you make a bike out of one or the other, it should last – specially if painted and kept dry. A bike of one with parts of the other, is OK if the metal surfaces arent in contact (ie they are greased or painted etc or otherwise sealed).

But here, the bare aluminium of the post was close up against bare steel frame, probalby damp between, helping ensure good electrical contact.

As most of you know, when two different metals are in contact, corrosion can speed up. Electrons flow between the metals, and oxidation (corrosion/rusting) speeds up.

The 0.2 mm space between post and frame, was now jam-packed with aluminium oxide. Looks like talc, but is also used as an abrasive on sandpaper.

We did give it a go. We tried RP7, oil. We tried the saddle trick. We tried a large wrench,on top of the seat post, an even larger plumber’s stilson to get leverage . Two of us tried. Not a mm of budge.

Dave S – who understands a lot about metals and metal work – took one look, then said, cut the post, file the aluminium out from the inside..

But volunteers and owner, wanted a last try. They took the bike into the workshop, turned it upside down, and clamped the seat post in a vice. Two people held the work bench, 2 more tried to turn the bike - using the frame to get leverage.

There was an awful silence .. then an awful grinding screeching noise …. then another awful silence. But the bike had turned; the post must have loosened. So we worked it to and fro, then stood back, to think what to do next…

It then became very clear, why the bike had turned. The steel and aluminium had stayed firmly stuck, and when we turned the bike, the steel tubing of the frame, had simply torn, about 3 cm below the top.

Moral:if you're looking for a bike to do up - most things can be repaired - but things rusted solid one inside the other, is going to be difficult!

4 members like this

Comment by Matt Jones on June 27, 2012 at 15:00: Would it not have been more prudent to first try to break the join by hammering the post down vertically a little bit ?

Comment by Gus K on June 27, 2012 at 16:54: I don't underestimate how stuck it was for a moment. When alloy and steel bind it is like a weld and I know. I had have a Ricardo that had a very stuck seatpost and your final method was exactly what we did after freezing it, heating it, RP7 and other lubricants even a can of Coke (all the options Sheldon Brown offered)

we finally put it upside down in a clamp and pushed and pulled. We almost gave up too and we gave it one last big shove and 'crack' - we thought the frame had snapped. It was the bind breaking and we could move the frame back and forth and slowly pushing the frame upwards it came apart.

Read my story here part 1 http://gusk.posterous.com/the-ricardo-and-the-frozen-seat-post and part 2 (success) http://www.adelaidecyclists.com/profiles/blogs/my-stuck-ricardo-sea...

Comment by Jilden on June 27, 2012 at 20:51: I have a steel frame MTB I bought new in 1996, retired in 2002, that has an aluminium seat post. Because it hasn't been stored in a damp shed the seat post still moves like new. Way it goes, I suppose.

I would have cut off the seat post short, cut it down through the clamp, then cut the post internally with a suitable saw blade. Same deal with any rusted pipe joint where the outer section has value.

Comment by dialysiscyclist on June 27, 2012 at 23:17: We had the same problem with an old Daccordi in the late 80s, fluted seat post would not have helped the cause, my dad got it out at his work place {tool shop}, can't remember exactly how, probably the cutting vertical technique...We kept the top of the 3TTT seat post and mounted it on a bit of wood, still got it here...

Comment by Mike Brisco on June 28, 2012 at 14:11: Interesting to read of others experiences. Thanks for the tips - especially cutting it with a saw blade, inside as we did have hacksaw blades on hand. faster than filing.

Matt - we didn't consider that - depending what makes it stick, might have worked. People tend to say "welded" but I'm not sure if they mean , here, its actually a metal to metal join (ie an actual weld) , or merely it is stuck fast - which might be other means, e.g friction, or some sort of glue. If the first - should have worked, it would have broken the join spots. But if it's not & is due to packed aluminium oxide thus friction - might not have worked. Still, something else to try in future, worth a go. Thanks!

Comment by Trevor Hill on June 30, 2012 at 18:18: I one spent $150 at my LBS to have a seat post that had been hammed in removed. They spent quite a few hours on the job. They ended up heating up the steel frame. The bike is now my wet weather bike, have ridden it a lot to try and get my monies worth out of it.

Comment by Rob (Chewbacca) on July 3, 2012 at 8:27: I bought a real nice Colnago Titanio with an aluminum seat post but when the previous owned tried to disassemble the bike to package it up to send he found the seat post was seized. He tried everything to remove the seat post but no go....sale cancelled and money refunded.

Comment by Vincent Coleman on July 12, 2012 at 10:39: Can you use a blowtorch or welder to melt the seatpost? Alu has a lower melting point that steel, right? Will it weaken the frame though?

In my case it's a stem, and cutting through a stem is going to be a lot harder that a seatpost...

A bike that defeated us....

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