Gare777

New build Im 5'8" or so I am building a Cannondale Synapes a 58cm so I have bottomed out the seat post and would like to bring it down an 1" can I cut it? Or should I look for shorter seat post??

SquidPuppet

Shorter sentences, for sure.

fietsbob

Door #1 or door #2.. you have 2 choices..

If you opt for cutting, I recommend the bike shop's Park saw guide unless, you are skilled enough to cut straight.






..

SkyDog75

I think you might want to consider looking for a smaller frame. I'm 2" taller than you and 58 is too big for me.

...but to answer the question you asked, yes, you can cut a seatpost to reduce its length.

Kontact 

Sorry for all the crummy responses - it is a reasonable question.

Personally, I wouldn't cut the seat post simply because carbon seat posts are at least a little valuable, but no one is going to want one that has been sawed through. I would just buy a basic alloy post and set the carbon one aside for when you move on from this bike to one that fits better.

fietsbob

Health and Safety note; carbon fiber dust , as far as your lungs are concerned , is like asbestos.

FBinNY 

Go ahead and cut it since excess length never makes a difference.

I prefer to use a top quality fine tooth bi-metal blade, but others prefer abrasive blades.

One trick is to wrap the post at the cut with a turn or two of tape, then position hose clamps (gently) above and below the cut to act as guides. The actual cut should be done with faster strokes and a light touch letting the saw do the work. Excess pressure causes more tearing, so take it easy.

Lastly, CF dust isn't good to breathe, so vacuum up all the dust, or have a friend hold the vacuum to pick up the dust as it exits ahead of the cut. I prefer to cut CF wet, so I use a mister to keep it misted but not drowned. That also keeps the dust down.

Kontact 

Dust is a concern, but a vacuum isn't going to address the risk unless you have a hepa unit. You're just going to breath it later when you change out the bag.

The best way is to cut carbon wet. I usually just use Windex and give the inside and outside spritzes as I go. When I'm done cutting I wipe it all up while it is still wet and throw away the paper towel.

My favorite blade was a well used fine toothed saw blade. It takes longer but tears out the fibers less. Tape is a must, and a place to mark where you are going to cut.

FBinNY 

I see that Kontact and I basically use the same methods.

As for the vacuum, a HEPA filter helps, as it does for fine dust in general. These days most decent vacuums seem to have them.

In any case, the reasonable care standard for something like cutting a single post is very different than for someone doing it regularly, or in an industrial setting where there's plenty of CF work going on.

So, use some common sense, don't put your face right near the cut, better yet use a paper mask, and if you use a vac, use some care with the bag. CF is hazardous, but with some common sense, a single exposure isn't going to be an issue.

cpach

Don't breathe the dust. This is a very normal thing to do. Ideally use an abrasive blade or a fine toothed blade. Taping the cut with scotch tape can reduce any splintering of the carbon. If there's a little splintering you can almost certainly just sand the end clean. Getting an exactly even cut is not particularly important. Hose clamps are an inexpensive way to get a reasonably even cut. On my personal bikes I measure from where my seat post is when fit to me to the minimum insertion line, then cut that amount off plus about a cm (for some minor adjustment for different cleats/saddles) from the bottom to maximize weight savings because why not.

Also, 5'8" on a 58? This seems questionable to me to be honest. It's totally possible that this is the correct frame for you but just a reminder to be sure before you hack that post short.

SquidPuppet

It doesn't need to be straight....at the ,, bottom = = [[ think....

Kontact 

Shut up.

SquidPuppet

Classy.

Kontact 

Yeah, like posting nonsense and grammatical criticism on seat post thread.

Don't you have a video game forum to bother?

SquidPuppet

I know that you have only been posting here since December, so maybe you don't know this, but it's kind of a running gag for everyone to give Feitsbob a hard time for his punctuation and grammar. It's meant in jest, friendly banter, not mean spirited.

Kontact 

That doesn't explain post #2 in this thread.

SquidPuppet

Yeah, it does. Friendly jabbing. Not mean spirited. Tongue in cheek. Shorter seatpost/shorter sentences.

Where you come from, don't guys tease each other and give each other a hard time as a way of being friendly and bonding? Playful sarcasm? Bench racing? Towel snapping?

I know you are a very serious guy, but I like to smile and have fun. Look at my screen name and avatar.


Relax, if you can, and in the meantime, please allow the administrative staff to police me.

Kontact 

It was the OP's first post, and you're not actually funny. Do you harrass new members on a bike forum because you were kicked off the comedy forums? How about sparing the newbies your intoxicating wit and save it for your many fans?

You and Fietsbob are the same sort of forum noise, but he might be funnier.

Cuyuna

Sometimes you just have to ignore the forum noise.

IrishBrewer

This was my thought. OCD aside, if it's not exactly straight, who cares?

Bike Gremlin

The video should start at the 19 minutes (if I did it all correctly):

HillRider

Let's get back to our originally scheduled programming. First, the OP says his seatpost is "bottomed out". Does that mean he can't lower it anymore because 1) an obstruction in the seat tube such as a water bottle mount boss or 2) the seatpost is already fully into the seat tube and can't go down any further because the saddle clamp is sitting on the to of the seat tube?

If 1), then yes, shortening the seatpost by cutting it is fine and the way to do it is adequately described in some of the above posts.

If 2) than shortening the seatpost won't help and only a smaller frame will fix the problem.

DrIsotope

Yes you can cut it, yes you should use a cutting guide, yes probably smarter to buy a shorter post and sell the longer one.

I just wanna know how long the arms and torso are on a 5'8" guy that somehow fits on a 58cm Synapse. I test-rode a 58cm Synapse and I'm 6'2". Fit me just fine.

ThermionicScott 

Maybe the OP likes a French fit? We're the same height and ride the same size frame (and will cut seat posts to get what we want.)

Kontact 

Someone 5'8" is only riding a bike 2 sizes too big on a 58. No, he's not sitting on the top tube trying to stretch to get to the bars - the difference in TT length is only 2-3 cm. Not ideal, but certainly not some sort of yoga pose.