The best seatpost for klunkin?
- Thread starter IRMB
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Please explain as it looks interesting !
Mark
Mark
I'm building a clunker from a 1938 Schwinn and havent found a good strong seatpost for it, yet.
I bought this cheap chromoly one, which is known to bend and decided to try and reinforce it with carbon fiber.
I keep carbon pre-preg in my freezer at home as it's a great tool for fixing stuff. I've repaired everything from mountain bike frames, carbon handlebars, remote control airplanes, etc out of carbon fiber. I developed some techniques to be able to DIY carbon fiber at home.
So I basically filled this cheap chromoly post with unidirectional carbon fiber pre-preg, compressed it as well as I could and heat-cured it in my oven.
I won't be able to test it out for a little while, as I'm still collecting parts, and my frame is still in paint.
I'll post pics of the bike when done.
Solid 13/16 post, Made in USA....This is what I use....
http://www.genuinebicycleproducts.com/parts.html
http://www.genuinebicycleproducts.com/parts.html
mine's a solid 13/16th, too. and made in my kitchen. For a total of $7.00
klunkin aint easy!
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Yours isn't exactly solid, IRMB, so much as it's filled. That seems like a good idea, and I'm curious as to how it will work out for you, long-term. Every klunker's seatpost is doomed to lead a short life, but I bet your method will extend your post's life considerably.
MAny folks have used tubular seatposts with a smaller-diameter solid rod inside to bolster it; i'm considering that option.
The aluminum posts that Atomic Paul sells on the GBP site are just solid 6061 stock, but they're given a lot of love-- it looks like they start with 7/8 rod, and turn it down to 13/16" to fit Schwinns but leave the top at 7/8" for seatguts. The transition from the 13/16" to the 7/8" is tapered, and looks smooth. Of course, good ano ain't cheap, and those posts look good. I think $37 is fair, considering what you get.
Budget-minded folks might want to consider doing what the original klunk guys did: solid 13/16" diameter 6061 rod, cut to length, with a Wald shim up top to take guts. http://www.discountsteel.com/items/6061_Aluminum_Round_Bar.cfm?item_id=138&size_no=55 Pretty cheap. Wald shims are less than $2 each; I like to have a few kickin around the parts box, just in case.
MAny folks have used tubular seatposts with a smaller-diameter solid rod inside to bolster it; i'm considering that option.
The aluminum posts that Atomic Paul sells on the GBP site are just solid 6061 stock, but they're given a lot of love-- it looks like they start with 7/8 rod, and turn it down to 13/16" to fit Schwinns but leave the top at 7/8" for seatguts. The transition from the 13/16" to the 7/8" is tapered, and looks smooth. Of course, good ano ain't cheap, and those posts look good. I think $37 is fair, considering what you get.
Budget-minded folks might want to consider doing what the original klunk guys did: solid 13/16" diameter 6061 rod, cut to length, with a Wald shim up top to take guts. http://www.discountsteel.com/items/6061_Aluminum_Round_Bar.cfm?item_id=138&size_no=55 Pretty cheap. Wald shims are less than $2 each; I like to have a few kickin around the parts box, just in case.
Yah, I'm going to force additional epoxy through the gaps to make sure there is contact between the carbon and steel, the whole way.
This is probably one area where resin transfer mold would work better than pre-preg. But that's what I had.
What about a @slowriderz solid post? Surely they would be plenty strong enough?
Very impressive seatpost treatment IRMB!
Luke.
Very impressive seatpost treatment IRMB!
Luke.
Danke. I know there are others out there making posts from steel and aluminum. - But it's always cooler to DIY and the juxtaposition of modern carbon on a 1938 clunker is humorously ironic - so why not?
Well I have one of his seat posts that I decided not to use on a build. Thankfully he turned both ends
so I'm going to cut them and bam I have two seat posts one of which will go on my klunker build.I LIKE BIKES
Well, I should've taken pics, but I was in a rush to try the thing out, but I got my latest klunkin' seatpost concept in the post yesterday..... it's a 12" section of 7/8 316L stainless--316 is "marine grade" and extra resistant to corrosion-- with 1/8" thick walls. Yes, it's heavy, but lighter than a slowriderz solid post (obviously--- just using that as a comparison) and only a bit heavier than the thinner-walled "chromoly" (I used quotes b/c I'm doubting the authenticity of the chromoly claim from Black Ops) 7/8" posts I'd been using--and bending under my weight.
But yeah, I'm gonna run it all weekend, try to bring a shine out on it (it's very dull right now, with "ATSM A269" printed on it)... my plan is to sand it a little with some fine grit, and then use whatever polish my buddy Harry suggests for SS. If this works out, I'll be swapping all of my 7/8" posts for these things. I'm feeling really optimistic as of right now, but 245lbs of rider perched atop a 7/8" post is a recipe for failure, so I'll have to do some "testing" before I can be truly confident.
But yeah, I'm gonna run it all weekend, try to bring a shine out on it (it's very dull right now, with "ATSM A269" printed on it)... my plan is to sand it a little with some fine grit, and then use whatever polish my buddy Harry suggests for SS. If this works out, I'll be swapping all of my 7/8" posts for these things. I'm feeling really optimistic as of right now, but 245lbs of rider perched atop a 7/8" post is a recipe for failure, so I'll have to do some "testing" before I can be truly confident.
