Will heating a Reynolds 653 frame to remove a stuck seatpost affect the tubing?
 

As per the title, I have a Reynolds 653 TT frame which has an aluminium Campagnolo seatpost stuck in it. A well regarded local framebuilder is confident that the seatpost can be removed, preserving both the frame and seatpost and only damaging the paint around the seat cluster. However, a material scientist friend of mine warns that doing so would affect the strength of heat treated steel. Though I'm not sure if Reynolds 653 is actually heat treated or not (I recall that 753 had some very special requirements)

So basically I want a third opinion so I can decide whether I'll remove the seatpost with heat or dissolve it with sodium hydroxide (admittedly better for the paintwork than heat, but also a massive hassle since I'd have to do it myself)

Thanks

Thanks for your quick reply. I can't find anything about 653 on the Reynolds site. Is it the same as 631?

More importantly, if it is cold drawn rather than heat treated, does that mean it can be heated to get my seatpost out.

Try other methods first. Go to Classic and vintage and search, tons of info there

Try Freeze-Off before heat

and for a good read http://www.bikeforums.net/classic-vi...c-victory.html

Cold drawing is about making the tube wall thinner, in steps, the heat treatment is done last.

not too hot .. and Chill the post with Liquid Nitrogen or Dry Ice ..


I have a Buddy, the stuck-friction force was stronger twisting, than the brazing of the tops of the seat stays to the frame ,

so after getting the post out the brazing was redone.

Tons in the FAQ Mountain, on stuck seat posts in the forum Archives .

+1 on this. Classic and Vintage has tons of threads on stuck seat post and stems. Most are able to walk away with an undamaged frame and post although some sacrifice the seat post or stem when really stuck hard.

Reynolds 653 is an odd duck. The stays are 753, but the main frame tubes and fork blades are 531. So, the seat tube is 531 (which is not heat treated), but the seat stays at the seat cluster are 753 which is heat treated.

Copied from another forum FWIW:

Reynolds 653 History

Thanks Jim. Reynolds have sent me a helpful reply so don't spend any more time on this one on my account. I'll tell you what they said as it's interesting and other folk might appreciate it too. In essence, 653 was invented following feedback from Eddy Merckx that a pure 753 frame was too harsh for certain stages. So Reynolds produced a 653 tubeset which combined 753 stays with 531 main tubes and forks. Not any old 531 though, but an even thinner gauge than usual - just for use in the 653 set. Eddy and other riders were very pleased with the result, which combined a light, ultra-stiff and efficient transmission with a more forgiving and comfy ride. Nowadays when folks are after a similar ride builders use 725 stays and usually 631 for all other tubes. I heard it from the horse's mouth.

"Cold drawn" has nothing to do with whether the tubes are heat treated or not; it's simply the term used to describe drawing the tubing through dies and piercing with mandrels to get the tubing to the specified wall thickness and butting.

http://i32.photobucket.com/albums/d7...ps0dcf37e4.jpg

I'm no engineer but wouldn't the AL post expand more when heated then the steel frame, therefore increasing it's stuck fit? Andy.

What have you already tried?

I'm not either Andy, but yes I suspect you are correct. The thing heat may do is to break down the corrosive bond and possibly help with removal. I'd fill the seat tube with muriatic acid, which is available almost anywhere. It "eats" aluminum. We used it to remove aluminum piston deposits (two stroke seizure) on chrome cylinder walls since they couldn't be bored oversize.

Well I am an engineer! (ok - i purchased a degree a REALLY long time ago, and now I'm an EXPERT at MS Excel and PowerPoint... yeeha....)
But I can google Coefficient of Expansion! And YES! Mr. Stewart, you are correct! Aluminum has an expansion rate of 22 (10-6 m/(m K)) and steel 12 (10-6 m/(m K)). So the aluminum will expand more than the steel. I believe this works (as long as ruining your paint is considered working for you) because the atomic bonds between the aluminum and steel are broken as they expand a different amounts, allowing things to move relative to each other once the parts are back to room temp.
This should work just as well as with the freezing as mentioned, without ruining the paint.

Hopefully the person who actually knows the answer will chime in.

Coefficients of Linear Thermal Expansion

I generally have had good luck heating only the seatpost**. Granted, that expands the seatpost more than the tube. But it works, probably because the expansion isn't really what is the mechanism by which the seatpost comes loose. I have an acquaintance that says "an inch of steel makes a foot of rust," and that goes equally well for aluminum products of corrosion. So what you are doing is breaking the bond formed by the products of corrosion.

**I have a bike in the basement next to the lathe waiting to have the seatpost bored out because heating it didn't do anything. I'd rather do that than ruin the paint

In my experience almost always a lot easier to cut out stuck posts (assuming you've tried the usual twisting methods).

OP may have some saving this too in mind.

nobody, AFAIK, has addressed how much heat. that would be first in my mind.

Dry ice on the aluminum, followed by boiling water over the steel, but not on the aluminum. Channel lock pliers to twist the seat post. Removed a stuck on steel track adapter off of the aluminum hub from a carbon disc wheel this way.