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Internal seatpost modification

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Internal seatpost modification

Postby stw » Sun Oct 16, 2011 7:44 pm

Hi everyone,

New to posting here but I often read threads. I've got an idea for modifying my integrated seatpost (round) so that I don't have to use something like a Tune Cappy to hold my saddle on. I've heard that people have used the hardware from a regular seatpost, and then just put it on top of the integrated one and have it cut perfectly for your saddle height.

Has anyone done this and can share their experience? Some seatposts seem to be just a completely straight tube (just like the integrated one) with the top hardware inserted into it. Can you just bash the hole thing out of the top and then reinsert it to an integrated one?

Hope that makes a little sense, just trying to get an idea before I buy a new post. Thanks!
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Re: Internal seatpost modification

Postby FAQinc » Mon Oct 17, 2011 12:09 am

A novel idea but isn't that going to weigh the same/similar as a integrated seatpost Capp? It might work/make financial sense if you find a cracked carbon exotic/lightweight seatpost with the exact diameter needed and cut that to size/broken area.
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Re: Internal seatpost modification

Postby Fourthbook » Mon Oct 17, 2011 12:23 am

Not sure how that would save either weight or $. A Ritchey WCS Stubby costs ~$75 and weighs ~125 grams; or for $120 you can get lightweight seat masts like the Tune Cappy or Woodman that weigh 75-85 grams. Given the hassle of cutting down a similarly light seat post and then jerry-rigging a clamping mechanism, what's the point...???
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Re: Internal seatpost modification

Postby stw » Mon Oct 17, 2011 10:12 am

Ah that is certainly a good point. I guess it is more for the super clean look, but I would need a 34.9 post and it's not easy to come across a nice/not too expensive one that would work. If I do it I'll post some pics here though because I do think t would look great!
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Re: Internal seatpost modification

Postby Ypsylon » Mon Oct 17, 2011 11:49 am

I've seen it done on a Scott Spark or Scale and it does look cool. I'm fairly certain it does save a tiny bit of weight, too.

The problem is that you know nothing about the cf lay up of your ISP. If it's able to support a clamp one could guess that it's able of supporting a seatpost head, but you wouldn't know. You'd have to somehow reinforce the holes you drill for sure.

You could try and contact the manufacturer and ask them if it would work or not, but if I were a manufacturer I'd not have an engineer answering my e-mails and if I was answering e-mails for a manufacturer and was not an engineer who knew the part in detail I'd just flat out say "no".

Light-bikes.de has a bunch of very educated people with experience in working with cf and it has an "English section" as well. If you told people what you were up to and to what specific model you wanted to do it to they might be able to give some advice. Maybe someone could even provide a piece of cut off ISP to check out. At the end of the day, if they say it's possible, you'd have some advice from a couple of complete strangers and you pay with your health (and frame) if you trust them, so that's only helping to a point. But if they say it's completely nuts you have one less thing to worry about.

BTW, you do realize that you'll have to stock up on shoes, pedals and saddles, because you won't be able to change those to a different model?
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Re: Internal seatpost modification

Postby Kniprode » Mon Oct 17, 2011 4:48 pm

Hi, It's my Addict seatclamp since 2007. Important is quite large passing thru tube, for lower stress. And tight hole.
100gram saved against original seat clamp. Not bad for so small detail - it makes more than 10% weight of frame.
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Re: Internal seatpost modification

Postby stw » Tue Oct 18, 2011 2:05 am

Thanks a bunch for the advice, I'll check out that site for sure.

That modification looks incredible! I'm not sure I would be brave enough to drill a hole for that style seatpost, was hoping to find one with a removable insert on top and just glue that into the top. Yours looks great though, thanks for sharing!
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Re: Internal seatpost modification

Postby TheRemery2 » Tue Nov 15, 2011 9:50 am

I've done this mod too. It saves about 100g. The "bitsa" one I built weighed about 37g in it's lightest form....I later shifted to an aluminium U-cradle and that increased the mass (but my behind had become heavier so that was appropriate).
Link:
http://weightweenies.starbike.com/forum ... =scott+isp
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