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#11
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De-rusting Bike Seat-Post
On 2 Mar, 19:00, * Still Just Me *
wrote: On Tue, 2 Mar 2010 10:07:41 -0800 (PST), N8N wrote: What are you using as a penetrating oil? *IME lots of people recommend WD-40 which I've found to be marginally more useful than tap water. *I like PB Blaster, Kroil, and Wuerth Rost Off, although I'm sure there are others that work well Agreed. Unlike WD-40, I've seen PB Blaster actually work to loosen some very stuck fasteners. Sometimes multiple applications over several days helps. Whatever release agent used, it is helpful to encourage the bond to break using shock. This is an absolute with something which is guenuinely stuck. Use a big hmmer. |
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#12
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De-rusting Bike Seat-Post
On 3 Mar, 03:45, AMuzi wrote:
Rick wrote: How much too low? Not all seats are equal in height above the mounting rails. Try a taller seat. *Seats with excess padding or springs (or both) are usually taller. I have had to saw out seat posts before. *Days & weeks of soaking with penetrating oil don't always work. I've never had any luck with heat. The last one was a bugger. *I removed the bb, cut the top of the seat post off, inserted a long threaded rod, added washers and a nut to the bottom of the threaded rod thru the bb shell. *Pull up. *I used a large socket (1 1/16") to allow the seat post to slide up inside and provide a pulling point against the top of the frame, with washers and a nut on the top. *Lots of obstacles to that process like curved in seat tube at the bottom, water bottle mounts sticking in too far, curved top of seat lug, etc. but It worked with lots of effort but minimal damage to the frame. "I've never had any luck with heat" http://www.wolframalpha.com/input/?i...point+aluminum The melting point of aluminium exceeds that of some spelters so re- brazing of the seat stays may be necessary if more than minimal heat is used. Thinking on, the use of soaking with cola then rapidly heating the post will make the cola boil and could be enough to split the bond without resort to heavy hammers, melting, reaming or grinding. Seems like the lowest risk of damage. |
#13
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De-rusting Bike Seat-Post
On 3 Mar, 18:26, " wrote:
On Mar 2, 11:18*pm, LF wrote: On Mar 2, 11:40*am, Veganeric wrote: I've acquired a bike that unfortunately has a seat post that is rusted in place. Like I told Ray: (I hope yours is alum post in a steel frame.) On Mar 2, 10:30 pm, Ryan Cousineau wrote: I have a nice frame (steel) with a fairly nice (aluminum) seatpost stuck in it. Before I resort to cutting it up and pulling it out, I'd like to try saving the post. So far heat (tried by someone else) didn't work, a few days of liquid wrench and banging on it didn't work, either. Ray, I've loosed several very stuck aluminum seatposts in steel frames. Here's a few thoughts: 1. *COLD is GOOD. *The alum contracts greater than the steel when cold. *I have waited till a cold New England winter day to free a few. *I take them outside to cool down, then bring them in, Turn the bike upside down and put the seat post in a bench vice. *Use the leverage of the bike, twisting and turning the frame, to free the seat post. It can be a two person job; take care to not over torque (I worry about damaging the frame). *The whole thing heats up with friction. When it gets hot, I bring it out to cool down, and then bring it in and start again. 2. *AMONIA is GOOD. *The culprit might be aluminum oxide; amonia disolves it. It's fast acting. So, if it is going to do any good, it's very quick -- no need to wait for it to soak over night. 3. *It's hard to get liquid into the seat tube/ seat post area. Remove any water bottle cage bolts, and try to pour some in there. Removing the BB, gives other possibilities. 4. It might be just luck, but I like Krell (I hear it's alot like transmission fluid) as a lubricant for freeing stuck seat posts. Good luck. Keep us posted (no pun intended). Larry Here's a possible solution from 1995: Tom Noll View profile * * * * *More options Sep 14 1995, 2:00 am Newsgroups: rec.bicycles.tech From: Tom Noll Date: 1995/09/14 Subject: Stuck Seat Post Reply to author | Forward | Print | Individual message | Show original | Report this message | Find messages by this author Here's how I freed my seatpost after I tried everything else. I went to the local grocery store and purchased about $6.00 worth of dry ice. *I packed the dry ice around the extended seat post and let it chill for about 45 minutes. *When the seatpost was sufficiently cool, I twisted the post with a large crescent wrench, and *presto* the seat post released. *It is important to chill the seatpost and not the seat tube on the frame. Some caveats, this was on a custom mountain bike frame and there was enough of the seatpost extended (several inches) to put a good chill on. I performed the operation on a summer day when the air temperature in the garage was above 90. Lastly, I really had tried everything else; oil, penetrating lubricant, gentle heating, strong twisting. *The frame builder suggested that I return the frame and they would remove the seatpost with a torch, check the frame for trueness, and repaint it after severe heating. *I was at the end when I thought of the dry ice technique. The dry ice worked for me, and I still ride the bike. Tom Noll give it a go? Cheers, MD Also shock chilling method which relies on the greater heat conductivity of aluminium to contract faster than the steel. Heat up with a torch (dont smoke the paint). Insert hot post into cold water to boil off. When water stopped boiling, move post. |
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