Steerer tube cutting tips.

[quixoticgeek]

At the weekend I'm going to cut the steerer tube down on my bike for the first time. Initially just to take about 50mm off until I'm sure about taking it any further. I've got a hacksaw, and I've got a new blade for it (32tpi).

Does anyone have any good tips on cutting steerer tubes? What's your preferred method for getting the cut straight?

J

[Kim]

I've done it once, with a hacksaw (after discovering my pipe cutter was made of cheese and not even slightly up to the job), and nothing went horribly wrong.  I suppose the failed attempt with the pipe cutter made a usefully straight reference mark.

[Ham]

Jubilee clip as a guide, works perfectly.

[drgannet]

Plumbers pipe cutter.

[Torslanda]

I use a pipe cutter but it has a downside as the wheel raises the edge of the tube at the cut and the burr needs filing. Other than that it's quick and neat.

For marking use masking tape and practice keeping the tension even so that if you get the tape on straight the tube will be straight when it's been cut.

If you have any spare tube practice getting the tape wrapped straight and cutting with the hacksaw. WD40 or similar to lube & cool the blade. There's no rush, take your time cutting and make sure you work the blade backwards and forwards, not wandering side to side...

[Ripio]

You don't need to get the cut perfectly straight.
Your headset spacer or stem extends a couple of mm above the cut tube for the top cap to apply the bearing preload, so a precisely straight cut is unnecessary.

[Torslanda]

as long as it's just for you . . .

[sojournermike]

I presume this isn't a carbon steerer? That needs a bit of care both for cutting dust and making sure you don't separate the outer layers of fibre.

Mike

[quixoticgeek]

I presume this isn't a carbon steerer? That needs a bit of care both for cutting dust and making sure you don't separate the outer layers of fibre.

Mike

nah, good ole chromoly steel

J

[yoav]

I invested £8 in a Planet X tube cutting guide. As well as steerers (steel, alloy and carbon), I have cut seatposts and various non-cycling tubes with it.

[Brucey]

if you have minimal tools and are in no hurry;

 Wrap a piece of paper (with a straight edge, overlapping perfectly at that edge) tightly around the steerer, and secure it with tape, the edge of the paper will be exactly at 90 degrees to  the length of the steerer.  Next mark out the line to cut to (eg by carefully filing a notch and/or using a marker pen, or lightly spray painting the piece that is to become the offcut), remove the paper and cut to the line (s) you have made.

You may find that the cut tends to wander once it gets a fair way into the tube. To guard against this possibility, you can start many shallow cuts instead of making a single cut. The resulting cut face may be a little raggedy but only to the tune of ~0.5mm if you start each of the cuts carefully. It is arguably 'good enough' as is, or can be fettled with a file.

 Obviously you can check the squareness of the end by using the paper technique again.

cheers

[quixoticgeek]

I invested £8 in a Planet X tube cutting guide. As well as steerers (steel, alloy and carbon), I have cut seatposts and various non-cycling tubes with it.

alas €13 to ship it to the Netherlands...

[giropaul]

An old, sacrifice, stem works ok as a guide.

[andrew_s]

I use a pipe cutter but it has a downside as the wheel raises the edge of the tube at the cut and the burr needs filing. Other than that it's quick and neat.

since I happen to have last weekend's un-filed offcut to hand, the pipe cutter increases the outside diameter by 0.18 mm for 1 mm below the cut, and reduces the inside diameter by about 0.5 mm (less even since there were no rollers on the inside)

[Torslanda]

I'm not going to argue!

[Ham]

I'm curious, has nobody else tried using a jubilee? It really is a successful bodge, why bother with any alternative? (on the bodge front) Same as Brucey's paper, only gives you a sawing guide as well.

[zigzag]

i make a circle around the steerer with a stanley knife using a stem as a guide. take the stem off, then use dremel both to cut and to finish off the edges.

[citoyen]

Old stem works for me.

Ham - CBA to go to the shop to buy a jubilee clip when I've already got an old stem in the spare parts box...

[Ham]

I think you will find that jubilee clips breed in the bottom of old toolboxes.

[Kim]

I think you will find that jubilee clips breed in the bottom of old toolboxes.

*peers at bottom of old toolbox*

Mine's breeding jeweller's screwdrivers and 5amp choc blocks.

I went digging in my new toolbox recently.  That one was breeding wrong size allen keys and worn-but-not-completely-knackered junior hacksaw blades.

I suppose it depends what you seed them with...

[rogerzilla]

If it's threaded, put a steel adjustable race on first.  It will help to reform the last thread after cutting.

Also, cut with a hacksaw then finish with a flat file.

[robgul]

Old stem works for me.

Ham - CBA to go to the shop to buy a jubilee clip when I've already got an old stem in the spare parts box...

Actually two a-head stems work even better - place them back to back with a narrow gap for the hacksaw blade and you'll get a square cut - but the real guide is better for a modest investment.  Tip: stick a bit of masking tape along the length of the steerer tube to mark your cut - then line that up in the guide.

Rob

[slohill]

My dodge is to jam a spare spacer using masking tape immediately below the desired cut line.  Ensure spacer is aligned correctly by measuring distance from top of stem to spacer at about 4 places.  Then draw round cut line with a pencilor marker to give cutline reference.  Then cut carefully.
Advantage of this method is that spacer ring gives higher cutting guide than jubilee clip.
As said before, file across top after job and chamfer inside and out with suitable file.