Bicycle Mechanics - Cutting an aluminum steerer tube?

I should be getting my new aluminum Cinelli Experience frame this week (carbon fork / aluminum steerer). Can I use one of those tube cutters that rotate around and around the tube until it's cut?

http://www.google.com/products/catalog?q=tube+cutter&rls=com.microsoft:*&oe=UTF-8&startIndex=&startPage=1&um=1&ie=UTF-8&cid=10168043035945891257&sa=X&ei=MMiQTcfYKsTZgQedraTXBQ&ved=0CFQQ8wIwAw#

sure can

Tube cutter Will raise a Burr around the inside of the tube,

as said measure many times , before you cut..

You can always run with spacers above the stem, so as to get the low position..

I'll install the headset and stem first, measure to get the best saddle to bar drop, then cut. I'd rather use a tube cutter to get a perfectly straight cut, then de-burr if I must.

Correct tool for the job http://www.parktool.com/product/threadless-saw-guide-SG-6

When you know how high you want it, measure twice cut once.

If it's a new build, and have no reference to how long you want it, would leave it very long, play around with spavers for a few rides, and re-cut when happy with length.

If you already have the tubing cutter then fine. If you don't you can get great results from using a wrap of masking tape around the tube set so it meets itself exactly. That provides a true guide line to cut the tube with a hacksaw. Cut it about a millimeter away from the tape and then file off the end down to the tape line and deburr the inside and outside edges to leave you a nice square, clean and perfect job.

I don't like tubing cutters because then often tend to swage in the last 1/8 inch of the tubing so you end up with a taper over that much length. But much of this depends on the sort of alloy that the maker used in the steerer tube.

Already had this discussion with a shop owner that thought using a hacksaw and guide was passee and a waste of time. I actually decided to let him `educate me` with a demo on a new fork, LOL

A tube cutter doesn`t cut metal - it DISPLACES it. Which means that the outside diameter within 2 to 3 mmof the `cut` areas will be too large for the stem to go onto, and the inside dia will be too deformed and small to insert a star-nut.

Of course if you insist you can always check and see for yourself!

Since I don't own a vice, I guess I should just bring it to a shop to have them cut it after figuring out the right height.

Starnut, Id say, is only a good piece to use on steel fork steerers . scratch becomes aluminum stress riser
becomes crack, becomes a break, too easily.

No starnut??? I thought they are fine in anything except carbon steerers?

Using a expanding fitting to secure the nut under the adjustment cap will do the task just fine.
and not score the aluminum steerer tube.

It's your Neck , do as you wish.

I never thought of the sharp steel edges of a starnut cutting into the alloy steerer tube. I guess I'll see what the headset included with the frame comes with. Maybe it will have both a starnut, and expander. If not, I'll get an expander.

Thanks for the heads up!

Andy in theory Fietsbob is absolutely correct. In reality - there are lots of alloy steering tubes out there with star fangled nuts in them. The wall thickness can vary considerably depending on the quality of the fork, and of course the forces on it will depend on how you drive it. From a practical point of view the nut will be above or within the area clamped by the steering stem so any real danger is minimal.

I use compression plugs myself but mostly out of principal. The notion of paying a large sum of money for a precision suspension item and then using a hammer on it just goes against my grain. I put out the extra $10.

While I've read of several posters who have reported successfully using a tubing cutter on aluminum or Cr-Mo steerers, in general I agree with Burton. A tubing cutter tends to leave a raised ridge on the outside of the cut and a sharp edge inside. If you are willing to file off the burrs, ok, but a fine tooth (32tpi) hacksaw with a cutting guide works much better.

As BCRider recommended a wrap of masking tape can be a suitable guide but I prefer a stainless steel radiator clamp. It provides a well defined and solid edge to guide the cut.

Finally if you leave the steerer a bit too long and add a thin spacer above the stem, having an absolutely square cut isn't as important since the spacer will provide the needed square edge for the top cap to butt up against.

Already had this discussion with a shop owner that thought using a hacksaw and guide was passee and a waste of time. I actually decided to let him `educate me` with a demo on a new fork, LOL

A tube cutter doesn`t cut metal - it DISPLACES it. Which means that the outside diameter within 2 to 3 mmof the `cut` areas will be too large for the stem to go onto, and the inside dia will be too deformed and small to insert a star-nut.

Of course if you insist you can always check and see for yourself!
Well damn. Glad you're here to tell me this.

Will someone please tell my bike it didn't work?

Will someone please tell my bike it didn't work?
Glad to. What's its e-mail address? :)

While I've read of several posters who have reported successfully using a tubing cutter on aluminum or Cr-Mo steerers, in general I agree with Burton. A tubing cutter tends to leave a raised ridge on the outside of the cut and a sharp edge inside. If you are willing to file off the burrs, ok, but a fine tooth (32tpi) hacksaw with a cutting guide works much better.

As BCRider recommended a wrap of masking tape can be a suitable guide but I prefer a stainless steel radiator clamp. It provides a well defined and solid edge to guide the cut.

Even with a fine-tooth hacksaw, you're going to have to take a file to the steerer tube anyway.


Finally if you leave the steerer a bit too long and add a thin spacer above the stem, having an absolutely square cut isn't as important since the spacer will provide the needed square edge for the top cap to butt up against.
I didn't think the top cap should be touching the steerer tube - no matter what.

Even with a fine-tooth hacksaw, you're going to have to take a file to the steerer tube anyway.
True, but just to smooth up the cut face but not to remove a ridge of raised metal. The problem with a tube cutter is most users adjust it too tight, particularly if the cutting wheel is a bit dull and that is what causes the displaced metal.


I didn't think the top cap should be touching the steerer tube - no matter what.
Good point. So, a very highly accurate 90° cut isn't critical in any configuration.

Already had this discussion with a shop owner that thought using a hacksaw and guide was passee and a waste of time. I actually decided to let him `educate me` with a demo on a new fork, LOL

A tube cutter doesn`t cut metal - it DISPLACES it. Which means that the outside diameter within 2 to 3 mmof the `cut` areas will be too large for the stem to go onto, and the inside dia will be too deformed and small to insert a star-nut.

Of course if you insist you can always check and see for yourself!

I had always used the tube cutter method on the forks I've had over the years with both aluminum and steel steerers. Never had a problem until I did the last one, a Surly 1x1 with a cromoly steel steerer. Measured, cut, filed and installed the star nut then went to assemble on the bike. The stem didn't want to slide onto the steerer, it was tight. I had to use a rubber mallet to get the stem on the steer tube. The stem can spin on the steer tube once installed but it's taught. Another steer tube and stem combo may produce different results. My experience based on Surly 1x1 rigid steel fork and older Synchos stem.

Now I see what you say about the tube "cutter" not really being a cutting tool. The diameter growth at the end of the steerer may be slight, I didn't notice it just by eyeballing, but it's significant enough to prevent my stem from smoothly sliding on.

Tube cutter Will raise a Burr around the inside of the tube,

as said measure many times , before you cut..

You can always run with spacers above the stem, so as to get the low position..

The burr on the inside isn't too much of a problem. Even if you use a hacksaw, you'll need to dress the inside of the tubing. Get a deburring tool like this (http://www.amazon.com/Empire-Level-27783-Deburring-Swivel/dp/accessories/B0015YPI16).


Already had this discussion with a shop owner that thought using a hacksaw and guide was passee and a waste of time. I actually decided to let him `educate me` with a demo on a new fork, LOL

A tube cutter doesn`t cut metal - it DISPLACES it. Which means that the outside diameter within 2 to 3 mmof the `cut` areas will be too large for the stem to go onto, and the inside dia will be too deformed and small to insert a star-nut.

Of course if you insist you can always check and see for yourself!

A tubing cutter works but, as you say, it displaces the metal rather than cuts it. However, it's easy to file the raised ridge off. Even a saw cut will need some cleaning. If you really want to make the tube nice and smooth you should use a pipe reamer like this one (http://wylaco.com/index.php?route=product/search&keyword=reamer&category_id=0). This one is a very good one but you can find them cheaper

http://wylaco.com/image/cache/data/Ridgid/34965-120x120.jpg


Starnut, Id say, is only a good piece to use on steel fork steerers . scratch becomes aluminum stress riser
becomes crack, becomes a break, too easily.

I've never used anything but a starnut on steer tubes. I've got lots of aluminum steer tube equipped forks that have starnuts in them. Most of those are mountain bike forks too which take a lot more abuse than road bikes. Haven't had one crack yet. The top of the steer tube doesn't see all that much stress anyway. I don't think it's an issue.

And generally aluminium steerer tubes are a lot thicker walled than steel ones. Only perhaps on some light weight road bikes would the alloy used be so thin that I'd worry about a scratch from a star nut causing a stress riser and eventual cracking.

I'll definitely check out the steerer tubes' thickness, and see what Cinelli included with the bike as far as the headset and parts go when the frameset arrives.

Thanks for all the opinions and advice.

I'll definitely check out the steerer tubes' thickness, and see what Cinelli included with the bike as far as the headset and parts go when the frameset arrives.

Thanks for all the opinions and advice.
I believe star nuts come in various types and there is a specific size for aluminum steerers to compensate for their greater wall thickness.

I believe star nuts come in various types and there is a specific size for aluminum steerers to compensate for their greater wall thickness.

just use a 1 inch star nut for al 1 1/8 steer tube, it is not necessary only if the walls are really thick

Well damn. Glad you're here to tell me this.

Will someone please tell my bike it didn't work?

I`m never one to pass up on a chance to learn something new so lets trade experiences. Personally (and every shop I`ve worked in) use a guide, a fine tooth saw and a chrome file and/or 320 grit wet sandpaper to cut and finish tubing. If there`s a way to accomplish the same level of quality faster - I`m very open to suggestions.

Every pipe cutter I`m aware of thats readily available to the general public is intended to `cut` soft, thin walled copper, brass and PVC tubing. Thats why they`re in the plumbing section. I`m also well aware that tubing cut commercially for precision applications is done using very expensive motorized equipment with saw blades.

But I`m seriously interested in knowing exactly what you did youself so here`s a chance to show off that job of yours. I have three different pipe cutters here - all virtually new with cutting wheels in excellent shape, so I`m going to cut a tube using one of those pipe cutters, and cut the other end using a guide and saw, and post pictures with details of both the overall time and the level of precision.

Really don`t know what you installed your fork on or what stem you stuck on it. I do know that Thompson, Ritchey and any BMX stem I`m aware of has tolerances so tight that you`d have to remove any deformation caused by a pipe cutter. And personally I hate to have to do any more work than necessary to achieve the results I`m after.

So I`ll have photos and details up within the next day or so and people can make up their own minds. And like I said - if you actually did get superior or equivalent results faster - I`d like to SEE it. Otherwise, in theory - you could also use a hammer and chisel too if you were prepared to do all the rework necessary to recover the situation afterwards.

If you don't have much use for a deburring tool, you can use a large flathead screw driver. Run it around the inside and outside of the hole at a 45-degree angle and it will remove the burrs.

But I`m seriously interested in knowing exactly what you did youself so here`s a chance to show off that job of yours. I have three different pipe cutters here - all virtually new with cutting wheels in excellent shape, so I`m going to cut a tube using one of those pipe cutters, and cut the other end using a guide and saw, and post pictures with details of both the overall time and the level of precision.

So I`ll have photos and details up within the next day or so and people can make up their own minds. And like I said - if you actually did get superior or equivalent results faster - I`d like to SEE it. Otherwise, in theory - you could also use a hammer and chisel too if you were prepared to do all the rework necessary to recover the situation afterwards.

Awesome idea! I look forward to SEEING how using a pipe/tube cutter fairs vs. the file/saw method!

Every pipe cutter I`m aware of thats readily available to the general public is intended to `cut` soft, thin walled copper, brass and PVC tubing.

All tubing cutters work the same way even ones that are designed for harder material. They don't really 'cut' the tube as take advantage of the ductility of the metal to displace it. Dressing the end of the tube isn't all that difficult and you have to do it when you use a hacksaw anyway.

A tubing cutter is better is than trying to cut the steer tube freehand. I'd take the hassle of dressing a tubing cutter cut over a crooked saw cut.

If you don't have much use for a deburring tool, you can use a large flathead screw driver. Run it around the inside and outside of the hole at a 45-degree angle and it will remove the burrs.

Aw, come on! It's another tool. Go get a deburring tool. You know you want it! ;)

The issue isn't JUST that you get a sharp burr. Depending on the material ductility and wall thickness it can also result in the material being formed or "swaged" inwards to produce a smaller diameter over a few mm's either side of the cut. So you end up having to remove both a burr as well as file open the inside diameter for a short ways. Granted USUALLY bicycle metals are of a grade that'll resist this sort of nonsense but it could possibly happen if the cutting disc is a bit dull and excess pressure is used to force the cut.

It's also interesting to note that the LBS where I used to hang out a lot in the shop area had a tubing cutter on the wall as well as a pair of block jigs with a saw cut guide on them for 1 and 1.125 size steer tubes. All the forks I saw them cut were done using the guide block and hacksaw followed by some filing to remove the roughness and chamfer off the outside and inside corners instead of using the tubing cutter which hung right by the saw. Could it be that they found the odd time that they ended up swaging in the diameter one too many times? I strongly suspect so.

Or you COULD cut them the way I cut mine. I chuck up the part I want to lose in my lathe and part off the rest of the fork.... Mind you the lathe cost a little more than a tubing cutter. But it's nice to use the right tool for the job..... :D

Years ago, I worked for a pipefitter. My job was to cut and thread steel pipe. When my pipe cutter left a ridge so high that it was difficult to start the threading die, I changed the cutting wheel on the pipe cutter. I recently installed a carbon fork on my bike. I put a new wheel on my pipe cutter and it cut the aluminum steerer straight and with almost no ridge.

I cut an Aluminum steerer for a friend with a tubing cutter and cleaned the upset with a file. He has had no problems with it.

The comparison is as I understand it, the suitability of using a pipe cutter to cut steering columns or handlebars instead of the conventional means _ a fine tooth saw, guide and a file to finish things off.
195679



Because I want this to be as practical and as representative as possible for other members of this forum, Ive used some specific bicycle components and realistic examples.

The tubing cut in this example is 22.2mm dia 6061 T6 alloy from an ITM Dual Aero bar set up. The T6 is a heat treatment and that reduces the ductile properties of metal. The photo shows both the raw cut made with a hacksaw as well as the finished end. The cut took less than one minute to separation and excess material at the separation point was minimal.Finishing was done with a chrome file and took another minute as in 60 seconds. Breaking edges is optional but easily done just by dragging the file around the perimiter at a 45 degree angle and takes less than 30 seconds.
195674

I will also on occasion use 320 grit wet sandpaper and a rigid backing. wet because both carbon and aluminum dust are health hazards.

This is the steering tube for a Marizocchi DJ fork that was cut today. Saw and files only.195673

This is a DT Swiss HR RIGID carbon fork with carbon steering tube that was cut yesterday. Saw and files only.195676

OK So how did the pipe cutter make out

This is a cut made on the same 22.2mm 6061 T6 alloy tubing but using a tube cutter. Actually the larger one shown in the photo.The pipe cutter took 10 rotations and a series of graduated adjustments and about 3 minutes to achieve separation. Because of the heat treatment, the metal eventually fractured and left pits as well as excess metal.
195682
Finishing was deliberately left incomplete because Im interested in comparing practical alternatives. Therefore the amount of time and equipment and technique was limited to exactly what was used to finish the tubes cut with a saw. The pipe cutter had already taken longer to achieve separation anyway.

This is simply to emphasize the extra work needed to dress the top surface (optional and cosmetic) and to clean up the casting fin and any dimensional issues around the cut interface. Necessary to facilitate the fitting of controls on handlebars and stems on steering tubes.

OK so this is a direct side by side comparison of the two techniques.195675
This is to illustrate that pipe cutters dont cut - they simply displace material. the process produces some local dimensional distortion and what is called a CASTING FIN. In this case the casting fin is 1.5mm in width on both sides of the cut. Thats a much larger area that needs to be cleaned up than is produced by a saw. In fact a saw cut just needs to have rough edges cleaned up to avoid cuts. The diameter is already OK.

So unless someone came come up with another process thats as efficient, uncomplicated and effective as a saw and file, I can't see considering anything else myself. Time is money.And a saw and file are still the only ways I know of to deal with carbon fiber.

Thats my 2 cents.

You weakling! I can hacksaw through a steerer tube in less than 15-seconds! ;) Great write-up and photos!

The shop where I worked at for 10-years made extensive use of the pipe-cutter. But we only used it to shorten flat-bars which didn't need clean-up anyway. Just put the end-caps and grips on and that was it. For steerers, we used a combination clamp & saw-guide. Put the steerer in between the blocks and clamp in a vise, then slide a hacksaw down the slot and saw through. We had a guy that must've been a lumberjack in a past life; he could cut a steerer in less than 10-seconds. Wipe a file around the outside once or twice, de-burr and that was it.

Great examples and photos! Did the pipe cutter also distort the INSIDE of the tube, or just cause the mushrooming on the outside? Also, was that pipe cutter new, or was it well used?

Since I don't own a vice or bench clamp, is it possible to have someone hold the fork while I saw? If not, by the time I get to a shop, and wait for them to cut it, it may be easier to dress the rough end a tube cutter leaves.

AndyK if you don't have a vise then you REALLY owe it to yourself to get one. Any surface area that wants to be legitimely considered as a workbench can only lay claim to the title with any seriousness if it has a sturdy and good quality vise. Go forth and go shopping. Once you have it for a very short while you'll wonder how you ever did without it. Even if you live in an apartment and your "workbench" is merely a B&D Workmate that comes out of the closet for bike work I would suggest a block of wood with a 15 to 20 lb steel vise that clamps into the wooden jaws of the Workmate so you can grab stuff like this. You'll quickly wonder how in blazes you ever managed without.

As mentioned already a pipe cutter doesn't cut anything. It pushes metal away under great pressure until the last bit gives up and it snaps apart. A pipe cutter leaves no shavings so it removes no metal. So sharp or not the metal is still all there. Just that a new one needs less pressure to displace the metal. But the outer ridge will still be there. But a new one will be less likely to swage in the wall and pinch the diameter as easily.

My cutting guide is a Performance "Spin Doctor" knock off of the Park guide and it handles 1" and 1-1/8" steerer tubes, any size seatposts and any size handlebar tubing. It does require a bench vise or other firm fixture to hold it in place.

It and a hacksaw with good quality 32 tpi blade have been used to cut Cr-Mo and carbon steerers and several seatposts (to shorten MTB-length seatposts for road use) with excellent, very accurate results in both hitting the exact cut line and producing an accurate 90° cut. I needed minimal post-cutting cleanup.

I recall I got it for about $15 during one of Performance's many sales events.

Great examples and photos! Did the pipe cutter also distort the INSIDE of the tube, or just cause the mushrooming on the outside? Also, was that pipe cutter new, or was it well used?

Since I don't own a vice or bench clamp, is it possible to have someone hold the fork while I saw? If not, by the time I get to a shop, and wait for them to cut it, it may be easier to dress the rough end a tube cutter leaves.

Hi Andy - distortion on the inside of a tempered aluminum tube is not much of an issue and on this tube there was almost none. A non-tempered aluminum or alloy or steel tube is much more of a problem. However its fairly easy to clean up with a deburring tool and some pipe cutters come with them built in. The one in the photo has a flip-out deburring tool but its not hardened steel so would only be appropriate for PVC or copper. Since the only thing likely to go inside is a star fangled nut - tolerancing isn`t critical anyway.

The condition of the pipe cutter I expected questions about so went out and bought a brand new one but not a really expensive commercial grade model. I wanted this to be representative of what most people would be likely to have around the house. Basicly I figure that anyone with a commercial grade pipe cutter wouldn`t be posting this kind of question.

There were a few comments made about straightness of a cut. The most basic guid I can think of would be a couple wraps of electrical or masking tape which will give a near perfect guide. Since the end will be by necissity a couple mmm below the top cap a perfectly square cut isn`t critical and is really only for finish and personal satisfaction anyway.

The outside dimensioning is really the most critical area. I doubt you`ll even need anyone to help you hold the fork while you cut it. I would suggest you protect the lowers with a blanket but the rest should be a snap. I overestimated the times required just to be more representative of what someone with no shop experience should be able to do.

Yeah - you could alternatively use a pipe cutter and do a lot more filing afterwards. I guess the question is why would you want to make the job any more complicated than it has to be?

Yeah - you could alternatively use a pipe cutter and do a lot more filing afterwards. I guess the question is why would you want to make the job any more complicated than it has to be?
I didn't think of this until now but i've used the following technique on non-bicycle jobs.

1. Use a tubing cutter to score a line around the steerer exactly where you want the cut to be. A couple of turns at light pressure will leave a noticable and easy to follow groove.

2. Using the groove from the tubing cutter as a guide, cut the steerer to length with a hacksaw.

Some of you are making mountains out of molehills. I have used pipe cutters to cut steel, aluminum, and titanium (handlebars) tubing. The burr was easy enough to clean up. The best tool is a specialized steer tube cutting guide and hacksaw. If you have pipe cutters those are good enough but you'll have to do some finishing. If you don't have either then get a $3 miter box and use that to guide the hacksaw blade.

AndyK if you don't have a vise then you REALLY owe it to yourself to get one. Any surface area that wants to be legitimely considered as a workbench can only lay claim to the title with any seriousness if it has a sturdy and good quality vise. Go forth and go shopping. Once you have it for a very short while you'll wonder how you ever did without it. Even if you live in an apartment and your "workbench" is merely a B&D Workmate that comes out of the closet for bike work I would suggest a block of wood with a 15 to 20 lb steel vise that clamps into the wooden jaws of the Workmate so you can grab stuff like this. You'll quickly wonder how in blazes you ever managed without.

Good points! I have a small garage, and a carpeted basement. So, one of those B&D Workmate benches would be great to un-fold in the garage, and do all of my bike work without having stuff on the floor! I have to buy me one of those! Then, I could get a vise, and saw away instead of crushing the tube with a pipe/tube cutter.

Andy, you will NOT regret such a purchase.

Another option would be a wall tool cabinet with a very solid door that hinges downwards to land on swing out 4x6 legs made from construction lumber. Here's a quickie sketch. I'm taking the time to do the sketch because I'm sure others will also find it useful and I know that a couple of buddies locally were asking about similar "compact garage" work areas. Hopefully it gives you some ideas to work with. The whole thing could be done with nothing more than a skillsaw, carpenters square and the usual implements of torture and destruction found around the house for tools. Enjoy.... :D

It's obviously quite a bit more work than a basic workmate so I won't be TOO upset if you choose to go the easy route. But if you have longed for a small spot you can set up and use more easily yet doesn't take up a lot of room this could be the answer.

Very creative BC! I already have a large storage cabinet in the garage, and the doors have stuff in them (car cleaners, chemicals, etc.). The workmate type folding bench should be fine! I can probably find one on Craigslist if I'm patient.

@BCRider Good points on the tape, have used it for years. Nice sketch for the fold-up, and hang mounts on the fixed wall for all the portable electric tools.
Ever build any SPADS?

No SPADs (Simple Plastic Airplane Design for those reading in. It refers to making models from the corrugated plastic sheet you buy in sign shops and better hardwares stores) for me. I like my balsa and other more "natural" materials better since for me building is at least half the fun.