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aluminum seat post...cut it?

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aluminum seat post...cut it?

Old 07-05-08, 09:44 AM
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celerystalksme
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aluminum seat post...cut it?

so i have a new bike...

i can't quite get the seat post low enough. can i just cut the easton aluminum seat post down about 3 cm? is that ok? i won't hurt anything?
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Old 07-05-08, 09:46 AM
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Hmm, your bike is probably too big for you then. You didn't get fitted at the LBS?
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Old 07-05-08, 09:49 AM
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Yes you can cut cut no problems.

Oh and the seat post is too long does not equal your bike is too big.

Last edited by rollin; 07-05-08 at 09:54 AM.
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Old 07-05-08, 09:51 AM
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First, if you need to cut a seatpost, your bike might not be the correct size to begin with. Try some of the online fit calculators to doublecheck. If you just bought the bike, and it's too large, perhaps the store would exchange it (you can always take it for a fitting there too, I just suggested the online sources as a way to avoid any LBS BS by having your facts together before you go back.)

That being said, cutting aluminum shouldn't be a problem, but I'd take it to someone who has the proper tools so you get the best burr-free cut you can. Cutting it slightly off perpendicular won't cause any concern because enough of the post will be within the seat tube to make that irrelevant, but you still want to shoot for perfection if you can.
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Old 07-05-08, 10:02 AM
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Originally Posted by crash66 View Post
First, if you need to cut a seatpost, your bike might not be the correct size to begin with. Try some of the online fit calculators to doublecheck. If you just bought the bike, and it's too large, perhaps the store would exchange it (you can always take it for a fitting there too, I just suggested the online sources as a way to avoid any LBS BS by having your facts together before you go back.)

That being said, cutting aluminum shouldn't be a problem, but I'd take it to someone who has the proper tools so you get the best burr-free cut you can. Cutting it slightly off perpendicular won't cause any concern because enough of the post will be within the seat tube to make that irrelevant, but you still want to shoot for perfection if you can.
well, the frame is a cyclocross frame. i compared it to my road bike...compared to my road bike, the seat tube is 3cm longer and the top tube is 2cm shorter. i was told those are the most important measurements.
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Old 07-05-08, 10:05 AM
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Originally Posted by Wested View Post
Hmm, your bike is probably too big for you then. You didn't get fitted at the LBS?
my first two bikes i got fitted at lbs. this one i got off of ebay. i was told it should probably fit well enough. the seat tube is 3cm longer than my road bike...but the top tube is 2cm shorter than my roadbike.

Last edited by celerystalksme; 07-05-08 at 10:22 AM.
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Old 07-05-08, 10:34 AM
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hmmm...so now i'm worried. do you guys think the bike is too big? the standover is acceptable...the top tube is shorter than my road bike. i just can't seem to get the seat low enough...

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Old 07-05-08, 10:47 AM
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Originally Posted by celerystalksme View Post
hmmm...so now i'm worried. do you guys think the bike is too big? the standover is acceptable...the top tube is shorter than my road bike. i just can't seem to get the seat low enough...

It may very well be the right size. I have shorter legs and a long torso and tend to use larger frames than what may be considered the right frame for my height. I seldom ever have more than fist length of seat tube sticking out.

As long as you don't feel like your stretching when trying to ride the bike and it otherwise fits you except for the seat height due to the tube problem, then its most likely the right size for you. Seat tubes are often longer due to the popularity of buying slightly smaller frames and using long seat posts and stems to make up for the size difference.
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Old 07-05-08, 10:57 AM
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Got a pic? I'm having trouble visualizing your situation. If it's a traditional frame and you have less than a handful of seatpost you might indeed be on the wrong size frame, can't really tell without looking at your setup.
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Old 07-05-08, 11:24 AM
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if you're using a really long seatpost it could be hitting the bottle cage rivets/bolts. cutting down an alu easton post is no problem, just make sure you sand down the edges before you stick it back in the frame.

Last edited by Surferbruce; 07-05-08 at 11:40 AM.
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Old 07-05-08, 11:37 AM
  #11  
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The fit of the seatpost in a frame has nothing to do with whether the frame is the correct size or not. It only means the post is so long it's hitting an obstruction inside the seat tube. Where do you guys come up with this stuff?

I ride size 57 in a certain brand. On one of them, and one only I need to use a shorter post because the placement of the water bottle bosses is such that a longer post will not go in enough to give me the same 75.5cm saddle height I ride on every other bike I own.

If you can't get it low enough, cut some off. It's not a big deal.
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Old 07-05-08, 11:59 AM
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Originally Posted by terry b View Post
The fit of the seatpost in a frame has nothing to do with whether the frame is the correct size or not. It only means the post is so long it's hitting an obstruction inside the seat tube. Where do you guys come up with this stuff?

I ride size 57 in a certain brand. On one of them, and one only I need to use a shorter post because the placement of the water bottle bosses is such that a longer post will not go in enough to give me the same 75.5cm saddle height I ride on every other bike I own.

If you can't get it low enough, cut some off. It's not a big deal.
Simple really. The OP never said if the issue is the water bottle bosses or not. The OP also never stated the length of the seatpost.
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Old 07-05-08, 12:03 PM
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If you got the post as low as you wanted it, how much post would there be between the top of the frame and the bottom of the seat clamp assembly? If it's less than 3", it's pretty unlikely that the frame is small enough for you.

Is your road bike a compact frame (sloping top tube), while this bike has a flat top tube? That would make the measurements different but the actual effective geometries of the bike pretty similar. A little shorter TT on a cross bike is fine.

As for cutting the post, yeah, no reason not to do it. Hack saw or pipe cutter will work fine, just make sure you deburr the cut with a file. But first pull it out and figure out what it's hitting, it's probably the bottle cage bolt.
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Old 07-05-08, 12:06 PM
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Hacksaw/then metal file.
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Old 07-05-08, 12:28 PM
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Right, so the first suggestion he gets is that the frame is the wrong size. And then on to firing up the online fit calculators.

As opposed to it's a 330 post, or the bosses are high, or the tubing is shaped or there's a clutch of naked mole rats clogging the tube or for whatever other reason, he needs a 250 or less post.

I'm assuming by "low enough" we're not talking about the saddle sitting on the top tube.
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Old 07-05-08, 12:34 PM
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tb i'm glad you're posting again. this place has been slowly going to crap.
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Old 07-05-08, 12:37 PM
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Originally Posted by terry b View Post
Right, so the first suggestion he gets is that the frame is the wrong size. And then on to firing up the online fit calculators.

As opposed to it's a 330 post, or the bosses are high, or the tubing is shaped or there's a clutch of naked mole rats clogging the tube or for whatever other reason, he needs a 250 or less post.

I'm assuming by "low enough" we're not talking about the saddle sitting on the top tube.
While I can't speak for the others, that's exactly why I wanted to see a pic. I don't know about you but I've seen some pretty humorous set ups. Hell even if his rails weren't touching and he was using a 215mm seat post I'd still want to see why the OP couldn't get his seat "low enough".
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Old 07-05-08, 12:39 PM
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Originally Posted by terry b View Post
Right, so the first suggestion he gets is that the frame is the wrong size. And then on to firing up the online fit calculators.

As opposed to it's a 330 post, or the bosses are high, or the tubing is shaped or there's a clutch of naked mole rats clogging the tube or for whatever other reason, he needs a 250 or less post.

I'm assuming by "low enough" we're not talking about the saddle sitting on the top tube.
This.

It occurred to me as I was reading the thread that if the OP were just short, and thus had a small frame and a long seatpost, this situation could easily occur, especially if this frame had reinforcements welded into the tubes in various places. Cervelo does this with their aluminum frames, and it wouldn't surprise me if other manufacturers do it as well.

I'd just hacksaw an inch or two off of that sucker.
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Old 07-05-08, 06:06 PM
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i'll try to post a pic later...right now, the bike is at the bike shop getting a thorough look over and tuneup to make sure it's good to go for riding and racing.

but post, right now, sticks up around 4"...i want to lower it by literally 0.5"...but it won't go down. i don't know why.
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Old 07-05-08, 06:23 PM
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I rekon Surferbruce got it right. You have a VERY long seatpost and its stopping on the EDIT:seat tube bidon cage bolt. Cutting it is not a problem. Too much WILD speculation on this thread and too little common sense.

Regards, Anthony

Last edited by AnthonyG; 07-05-08 at 07:27 PM.
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Old 07-05-08, 06:36 PM
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Originally Posted by AnthonyG View Post
I rekon Surferbruce got it right. You have a VERY long seatpost and its stopping on the seatpost bidon cage bolt. Cutting it is not a problem. Too much WILD speculation on this thread and too little common sense.

Regards, Anthony
I don't think it's lack of common sense that holds this board back, but rather not enough pointless use of French terms for cycling gear.

Also, I think you mean seat tube, not seatpost.
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Old 07-05-08, 07:00 PM
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Originally Posted by celerystalksme View Post
hmmm...so now i'm worried. do you guys think the bike is too big? the standover is acceptable...the top tube is shorter than my road bike. i just can't seem to get the seat low enough...

CX bikes have higher BBs than road bikes. Using your road size isn't always the best way to judge the fit of a cross bike. BTW, what kind of frame is it?
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Old 07-05-08, 07:16 PM
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I've had to cut the seatpost on an mtb because it was hitting a weld in the seat tube, and had to cut a long post on one of my road bikes because it was hitting a water bottle bolt.
A friend damaged a Kestrel Talon frame by forcing a too long post into it. The seat tube is tapered.
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Old 07-05-08, 07:28 PM
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Originally Posted by Landgolier View Post

Also, I think you mean seat tube, not seatpost.
Thanks, Fixed.

Regards, Anthony
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Old 07-05-08, 08:00 PM
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Originally Posted by sfcrossrider View Post
CX bikes have higher BBs than road bikes. Using your road size isn't always the best way to judge the fit of a cross bike. BTW, what kind of frame is it?
it's a blue cx6.5

cyclocross people told me to pay most attention to the top tube length...they said it should be about the same as a roadbike, maybe a hair shorter.
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