i need to cut 2 inches off the seating tube of an aluminium bike to lower the seat. How should I do it?

Question

I have a new bike that is mint. But I need to cut two inches off the seat tube in order to lower the saddle. The bike is just marginally too big for me. I have not cut aluminium (or anything) and would apprecaite any tips. I do not want to start the job without guidance as I might ruin the bike. What tools do I need? What technique should I use? What tips are there? Thanks

Answer 1

a pipe cutter, its easy to do.

Answer 2

There is a terminology problem here. The seat tube is the part of the frame that goes between the cranks and the saddle end of the top bar. This should never be cut.
The seat post is the part that is clamped inside the frame and attaches to the saddle. You don't normally need to shorten these just drop it a little lower and clamp it up again.
Some bikes may have a seat post longer than the seat tube. If this is your case then the pipe cutter is the first choice (neater). A hacksaw will do the job also. Run a file over it to tidy it up though.

Answer 3

Do you need to cut two inches off the seat post because you dont know how to lower it properly or is it still too long and hitting the frame when you lower it? There will be an allen bolt or quick release lever on the frame holding the seat post in position, loosen it and lower the seat to your desired height then tighten back up. Or you might have lowered your seat post and it is sticking through the bottom of the frame and fouling the frame somewhere when the suspension compresses if you have a cheap and badly designed bike. A pipe cutter would be best but since you are unlikely to have one a hacksaw will do. Just file off the edges after you cut it. The post just now will have a mark on it and writing saying something like "minimum insertion". Measure from the mark to the bottom of the post and re-mark the post after you cut it with the same size so you know the limit of the post. If yo udont do it then dont be surprised at the post popping out one day and you ending up with a bike up your bottom.

Answer 4

You shouldn't need to cut the seat post, just loosen it and lower it into the seat tube of the bike frame. Most bicycles these days have a quick release mechanism, but if not then it's probably a nut and bolt job or allen key fitting.

If you must cut the seat post then a hacksaw will do. Hold the seat post in place using a couple wooden blocks between a vice. Then saw away.

If you're unsure how to differentiate a hacksaw from a wood saw, just remember that a hacksaw looks like a Capital D with a thin blade and small teeth whereas a wood saw has a big blade and big teeth.

Answer 5

Personally i would not cut it if you are going to grow at all in the future (obviously depoendant on age) as if you have cut it then you can't extend it again, I can only assume as you need to shorten it you have an interrupted rear frame from ur rear sispension, if this is the case i would recommend purchasing a new shorter seatpost as these are not expensive. This way you will have the longer one if you ever need it. If not ajnd as you say this is brand new then most good bike shops would part exchange for a different part. If you must cut it then use a junior hacksaw but make sure you cut straight and that you file a slight chamfer around the cut off end to remove and flash and prevent damage to the bike frame

Answer 6

cutting anything off anything will make it lighter. That doesn't make it a good idea. If you are really asking about your seat tube, meaning the part of your frame that your seat post goes into, you will severely damage your frame. If you mean your seat post, you can probably cut it down a little but don't get carried away. Also think of the difference it'll make. You can probably spare enough seat tube to save you maybe two ounces. Two ounces is what a sixth of a can of soda weighs. Its a lot easier to lose that weight from your body than your bike

Answer 7

Use a pipe cutter. It offers a much cleaner cut than a hacksaw. Mark where you want the cut, align the cutting wheel on your mark and snug the wheel on the pipe. Now turn the adjustment a quarter turn to tighten and go around pipe a couple of times with the cutter. Tighten by 1/4 turns after a couple of revolutions with the pipe cutter (this will prevent pipe from collapsing and makes for very clean cut) and repeat tighten/turn until wheel cuts through.
http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemId=1611582058

Answer 8

You can cut it with a hacksaw but would need to secure it properly as tube has a tendancy to turn as you cut it. A better way would be to use a tobe cutter like plumbers use.

Alternatively why not just buy a shorter tube? would probably cost no more than a hacksaw which you would have to buy anyway idf you don't have one.

Answer 9

you mean the seat post will not lower all the way into the seat tube? that seams odd....

if thats whats happening then use a reciprocating saw. i have a Ryobi 18v cordless saw that i use for these sorts of things. you can borrow one from a friend if you dont have one. it should cut through in a couple seconds with minimal effort. worst comes to worst, use a hacksaw. use a marker to mark the line where you want to cut.

whatever you do, make sure you cut it straight. use a flat file to grind the edges down smooth afterward, so you dont cut yourself on anything sharp.

good luck

Answer 10

If you take it to a bike shop (at least most will), they'll do it for free and help you out a bit too.

I'm a mt. bike mechanic, and we have ppl come in all the time for that sorta stuff. The mechanic oughta use a pipe-cutter to get a clean cut then file it down and make sure there are no sharp edges.

Answer 11

Aluminium will cut easily with a hacksaw as the previous answer. Make sure you've got a good method of securing the tube (vice etc), and you'll be fine.