2 Seat post questions

[jgspin]

There is an insert in my titanium frame seat tube about 75 mm long. My seatpost extends about 50 mm beyond that. I gather the seatpost does not contact the seat tube past the insert. Do you think it's ok for me to cut the seatpost up to the end of the insert?

I know it's better to just buy a seat post with a set back, but has any of you put a set back on an aluminum seat post with one of those tube benders?

[Mike748]

Yes, should be ok.

No way. Good chance you'll crack the aluminum trying to bend it. It will break eventually.

[salem]

For question two: even if you managed to not damage the post (unlikely), there is a good chance the clamp would not have enough adjustment range to avoid a nose-up saddle angle.

[fourflys]

There is an insert in my titanium frame seat tube about 75 mm long. My seatpost extends about 50 mm beyond that. I gather the seatpost does not contact the seat tube past the insert. Do you think it's ok for me to cut the seatpost up to the end of the insert?


I assume you'd be doing this save the weight? If so, you might want to think about how much this would really save you and is it worth the possibility of screwing it up? I mean really what would it save you, 20 grams?

BTW- just noticed you're in Poway... me to pretty much, I'm in Sabre Springs...

[Bob Loblaw]

There is an insert in my titanium frame seat tube about 75 mm long. My seatpost extends about 50 mm beyond that. I gather the seatpost does not contact the seat tube past the insert. Do you think it's ok for me to cut the seatpost up to the end of the insert?

Why?

I know it's better to just buy a seat post with a set back, but has any of you put a set back on an aluminum seat post with one of those tube benders?

A seatpost is machined very precisely. If you start bending it (assuming it doesn't break) you will almost certainly run into horizontal and lateral alignment issues.

Used posts are inexpensive. Just replace it. You may even have success with an ad in the Serotta Classifieds offering to trade for a setback post.

[Louis]

I know it's better to just buy a seat post with a set back, but has any of you put a set back on an aluminum seat post with one of those tube benders?

There is almost no chance that this would work. I say it will destroy the shaft.

If you do cut off the bottom of the post be sure to note how far from the bottom the min insert line was so if / when you use the post in another bike you know how far down it has to go.

Overall, it's probably not a good idea to cut off the bottom of the post. If your % body fat is less than say, 7%, then OK, you can go on a weight reduction crusade and try to get a lighter bike. Otherwise, leave the seatpost alone and loose some weight yourself.

Happy riding.
Louis

[oliver1850]

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[fogrider]

wow, it's past april 1! why stop with cutting the seatpost? drill some holes in your crank arms and brake calipers. you should also bend your stem down for better aerodynamics!

[jgspin]

Overall, it's probably not a good idea to cut off the bottom of the post. If your % body fat is less than say, 7%, then OK, you can go on a weight reduction crusade and try to get a lighter bike. Otherwise, leave the seatpost alone and loose some weight yourself.

Happy riding.
Louis

Ok..nix the tube bending.... .was just curios if anybody's done it and survived.

There is a pronounced lip at the bottom of the sleeve insert where it ends so I'm almost certain that no part of the seatpost contacts the seat tube beyond the insert. Yup..I'm an aspiring weight weenie going the cheap route. Alas, I've been trying to get rid of my little pot belly going on 3+ years now and my body fat is more than 7% I am certain of that. But I'm small and this morning weighed 124 lbs; plus I don't generate much power so any bike weight shed would help me out...even if it's just in my mind.

[rice rocket]

Aluminum will bend w/o cracking if you torch it. You'll screw up the heat treat though, so if the part was engineered to low factors of safety w/ a heat treat in mind, you might not survive.

Hack the tube, you'll be fine. If there is an insert, the bottom part of the seatpost isn't doing anything anyways. Just remove the burrs so you don't muck up your frame on reinsertion.

[jgspin]

BTW- just noticed you're in Poway... me to pretty much, I'm in Sabre Springs...

Hey fourflys, good to know. Maybe I can tag along on one of your rides one of these days. Make sure it's your recovery ride cause I'd feel badly for you to be constantly slow pedaling and waiting.

[Kontact]

Many frames have an "insert" like you describe in your frame. Cutting seatposts is an old and relatively common weight saving trick. Make sure the post is cut longer than the bottom of the frame insert, though.

I tend to avoid doing things like this because it limits where that post can be used in the future, and makes the minimum insertion warning line a fiction.

But if the post you have doesn't give you the right position, there is no point in spending any time trimming it. Go get a seatpost the works, and maybe it will come appropriately short.

Someone your light weight deserves light stuff. Just be sensible about it.