sjanzeir

What I'm really asking is: roller tube cutter vs. saw and guide?

So, I've got this new fork and I need to cut the steerer down to size. I could just take it over to the Trek dealer nearby and have them do it for me for a small fee (they'll probably even do it for free for a longtime customer,) or I could buy the tools I need and do it myself (which is... just better.)

I had some experience cutting piping when I worked at my late mechanical engineer dad's shop way back when, which is why I'd rather have the cleaner, rounder, more precise cut that I believe a quality roller cutter can produce compared to the rougher, less precise cut of a saw, even if it has been used with a guide.

That said, I can buy a quality roller tube cutter locally and use that, whereas I'll have to order a saw guide online if I go the saw-and-guide route.

The steerer in question is steel, which may or may not matter as to which of the two cutting methods is best.

So, could you fellow wrenchers give me guidance? (excuse the pun )

redlude97

hacksaw and file. steel, aluminum, carbon I've cut them all

'02 nrs

hacksaw + a hose clamp for a guide.turn the steer tube often so as to not cut in only 1 area.follow up with a file after cutting.

echelon3

Great idea. I saw a video where someone used a miter box with a carbon fork. I'm about do one soon, a hose clamp (or maybe 2 so I could have one each between the area where I make the cut).

HillRider

A tube cutter tends to leave a ridge in the tube at the cut which is why tubing cutters have built-in reamers. You don't want that in the steerer because it can interfere with the headset and stem. Also, you can't use it on any carbon steerer.

Use a fine tooth (32 tpi) hacksaw, don't force the cut and use a cutting guide like the hose clamps shown above. I've done steel, aluminum and carbon steerers and the guided hacksaw works every time.

If you are going to do the job often a dedicated steerer cutting guide is worth buying but not for one-time use.

santacruzbob

If it's carbon remember to put a couple wraps of gaffer's (or duct) tape around it to ensure you don't get any string-cheese like delamination

Mad Honk 

The old plumbing cutters may work, but aren't really a great idea for steering tubes. And they won't do anything but ruin a CF tube! A good metal cutting saw with a low cutting tooth count will work best. And for CF it is a necessity. And for CF the dust is problematic. I use an ultra allergen filtration system doubled to keep the dust out of the air and my lungs. Steel cutting dust can be cleaned up with a magnet. But if this is a one of a time job, pay the LBS and don't worry about owning the tools. they will be more than the LBS price. Smiles, MH

Rexhardy1

I just cut a steel one with the hacksaw/hose clamp. Worked like a charm for me. Just a slight cleanup of the edges with a file and all went together well.

Reynolds 531 

Use TWO hose clamps.

Smitty2k1

I just used a pipe cutter on my aluminum steerer last night. Need to clean up the cut with a quick touch of the Dremel grinding/sanding bit.

LV2TNDM

Look at Park Tools and at the tool board of any reputable LBS and you will NOT find a pipe cutter for steer tubes. They simply are NOT used. Think about it, pipe cutters are fast and make a nice square end edge, so shops would use them if they were the right way to do it. They are not. You MAY have cut yours successfully, but trust me, this is NOT the tool to use.

Pipe cutters do two things to metal tubes: They cut by pressure, manually manipulating the metal, which increases the diameter of the end of the tube as they cut as well as put a round protrusion on the inside edge of the cut. The pipe cutter cold works the metal as it cuts, so doing this to aluminum, and especially heat-treated aluminum is simply a bad idea. Installing a star nut, or other fastener will be difficult or impossible unless you re-size the inside edge. But more importantly is what a pipe cutter does to the top 1/4" of the tube. You may have difficulty fitting headset spacers and the stem over the top of the tube, which would require resizing the OD. This SHOULD be done on a lathe, but who would do that? Instead, the average mechanic would use a file to get the proper OD. This obviously introduces all sorts of inconsistencies to the tube diameter. Not what you want when depending on stem clamps to maintain headset bearing preload, and secure fit.

And obviously, carbon cannot be cut this way.

So to anyone reading this thread, the industry-approved way to cut tubes is with a sharp hacksaw blade, cutting oil and a guide. A file is then used to finish the end and chamfer the inside and outside edges. A Dremel can be used as well. A grinder can be used, but with caution because it's easy to remove too much material and affect your final cut length.

wsteve464

Put a couple wraps of duct tape at the cut mark and use a hack saw. Doesn't need to be perfectly even as nothing touches the top of the steerer if installed properly, the cap only sets the preload by pressing against the spacers.

HillRider

This is correct for a threadless headset and stem, particularly if you leave the steerer a few mm long and use a 5 mm or 10 mm spacer above the stem. For a threaded steerer you want the cut as close to 90º as possible so a good saw guide is really a necessity.

phughes

You asked for the best way to cut the steerer tube, so... If you like doing things yourself, do yourself a favor, and buy a steerer cutting guide. I bought a Park Tools saw guide and it made the job very easy. https://www.amazon.com/Park-Tool-SG-...s%2C142&sr=8-5

sjanzeir

With the possible exception of highly involved wheelbuilding (I probably can assemble a wheel correctly, but I'm still a long way from being able to true one reliably,) I'd like to do as much of my own bike work as I can. I'd even like to build the skill and the resources to eventually be able to build my own bike(s). And it was the SG-6 above (and the much more affordable - but still not cheap - Icetoolz equivalent) that I already had in mind when I started this thread. Being a little more realistic, though, whichever saw guide I get likely won't be seeing much use, if any, beyond the fork in question, which is why I'm finding it hard to justify investing in a rather pricey tool. I'm in no rush, through; taking the fork to the Trek LBS in my neighborhood is definitely the cheaper, more convenient way to go about it, but I'm also interested in the experience.

100bikes

One additional thought is for a threaded steerer tube - screw on a headset top cone before making the cut.

Use whatever method you like to cut the tube - a Park(or other ) guide and a very sharp hacksaw blade are my choice.

After the cut, remove any burrs, and burnish the top of the fork with a file.

Unscrew the the headset cone to clean up the threads.

The old adage of measure twice/cut once holds very true for this.

dedhed

I'm not advocating (or using) a pipe cutter for steerers, but if pipe cutters did what you said, they would not be in use every day in the trades where time is money.

JohnDThompson 

Maybe I've just been lucky, but a standard deburring tool has always worked fine for me.


https://www.amazon.com/AFA-Tooling-D...=fsclp_pl_dp_1

phughes

I completely understand that. If you do choose to do it yourself though, the saw guide makes it so much easier, and you get a much better result. Whatever you do, I would definitely steer clear of a pipe cutter. (Pun intended.)

mr_bill

With one exception that may or not be useful here. If you've never cut a steerer tube (steel, aluminum, carbon) - a couple of practice cuts well away from the final cut will boost your confidence that you can do the job right on the "cut once" final cut.

Park tool instructions for reference

-mr. bill

sjanzeir

Awesome advice - the blades for the basic ACE hobbyist hand saw that I've got could be iffy sometimes, so a practice cut or two may be in order to see if I'm going to need to buy me a better quality saw for the final cut. I think I've got plenty of room; the steerer is pretty long - probably 350mm, if I recall - and I'll be cutting it down for the 130mm head tube of my 17.5" 7.6 FX.

HillRider

One more bit of advice, cut the steerer a bit longer than you think you want and use say 20 mm of spacers above the stem when you first assemble the fork to the frame. That gives you the option to change the bar height after you have ridden it for a while until you are sure where you want the bars positioned. Once you have made that decision, then make the final cut to length. It's a lot easier to cut the steerer shorter than it is to cut it longer.

LV2TNDM

When you're cutting low-carbon, seamed pipes, time is of the essence and the OD isn't much of an issue, especially if you're cutting threads on the end of the pipe afterwards. OD issues are irrelevant. But with a higher tolerance product with higher-grade metals, oftentimes heat-treated, method of cutting actually does matter. Plus, the headset/steer tube/stem interface is one of the most crucial areas of the bike. High forces are transmitted through the front wheel from impacts, braking and both, as well as the forces generated by the rider's weight and input. Forces all acting through the stem, perched at the top of the steer tube. It's imperative that this area be properly machined. Not some hack job with a pipe cutter. Again, go visit ten reputable LBSs and ask if they use pipe cutters for metal steer tubes. I doubt you'll find one. And if you do find any, you know not to patronize them!

(You also won't find pipe cutters used by steel frame builders. They use band saws, hole saws, plasma, laser or high-pressue water cutters. "Time is money" applies to everyone running a business, but cutting corners (no pun intended) with a pipe cutter isn't acceptable.)

And since I mentioned pipe thread cutting... if you applied your logic and analogy to thread cutting, between the trades and bikes, you may conclude that it would be fine to cut threads on stainless steel spokes, right? Well, that would, of course, be wrong. Spoke threads are not actually cut. They are rolled. Cold working a spoke end and rolling threads is the way spoke threads are "cut." This increases strength at the spoke end (essentially forging it) as well as producing threads whose diameter exceeds the spoke diameter. Rolling threads eliminates the stress risers created when actually cutting threads into a metal surface.

So use a pipe cutter all you want on pipes. But use a hacksaw on steer tubes.

dedhed

My point was that I've never had an OD issue with pipe cutters installing miles of pipe a year. Mostly cutting hard tempered and soft annealed copper and all types of joints, soldered fittings, crimped fittings, flared, compression. It just doesn't affect the OD of the tubing to any degree that would require additional work beyond deburring the ID.
All of the stainless hardware I work with is rolled thread to help prevent galling issues. It does normally give you hardware with reduced OD on the unthreaded section though.

I always cut steerers with a fine tooth hacksaw. A quick file or emery cloth to knock off the burrs and good to go.

Camilo

Same here - it's not technically difficult. I don't even use a "guide" I just put some tape around the tube, make a nice squared line around it and then just cut carefully with a hacksaw. Then I give the edges a quick once over inside and out to smooth them. IF the cut is slightly off-square, I just use a flat file it to even it up. It doesn't have to be within a micro-meter of perfect, probably even 1/16 off perfect is fine. Yes, you want to get it as close to perfectly square as possible, but slight deviations are OK and filing a bit here and there to square it up is not a big deal.

I make it sound care free, but the first time I did it I wasn't so sure. I did do one or two practice cuts "above" the final cut as recommended above. Doing that should alleviate anxiety.

I've done three or four steer tubes and have yet to buy a real guide. In retrospect, it would have been worth it to do that at the beginning, but it's really not something I have done or will do very often. Maybe never again??