Cutting down an overlong steerer on a new bike

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Brucey
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Re: Cutting down an overlong steerer on a new bike

Postby Brucey » 9 Jan 2019, 9:32am

if you don't have a guide available and you want to do this job just once using simple tools (eg hacksaw), even if it takes a bit longer than normal, you can use the following approach;

1. take a sheet of paper and wrap it around the steerer tube, so that the overlapping edges line up. This will give you a guide to mark/cut to which is extremely accurate.


2. Start the cut by making a shallow groove with the hacksaw, all the way round the tube.


3. carry on making the cut deeper and deeper until it starts to break through nearly everywhere, then finish the cut off. The cut won't wander if you have made a groove all the way round like this first.

Dress the cut edges with a file/emery cloth so that there are no nasty burrs.

With a little patience (and not much skill) you can cut a steerer within 0.5mm of where you want the cut to be quite easily this way. There are lots of other options; some folk use a hose clip in a similar way to the paper, as a cutting guide.

As in many things, 'measure twice and cut once' is a good axiom. IMHO having one or two spacers above the stem is no big deal and allows you to fine tune the height of the stem if required.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

pwa
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Joined: 2 Oct 2011, 8:55pm

Re: Cutting down an overlong steerer on a new bike

Postby pwa » 9 Jan 2019, 9:49am

To my eye, having a spacer (I prefer a thin one) above the stem, in the same colour, looks a little neater than having no spacer. Not sure why but it does.

If I have ordered the right frame size I have only a small stack of spacers below the stem, so the whole ensmeble doesn't look tall. And I'm sure it must be better mechanically to have a longer head tube and less steerer tube above the top bearings, where that is possible.

mercalia
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Re: Cutting down an overlong steerer on a new bike

Postby mercalia » 9 Jan 2019, 12:00pm

before you do so consider the extra as somewhere you could put a bracket of some kind for a device like a map/gps

swscotland bentrider
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Re: Cutting down an overlong steerer on a new bike

Postby swscotland bentrider » 9 Jan 2019, 12:11pm

I cut steerers freehand. Use some masking tape and mark all round where the cut is to be. I then make up to three cuts at different points on the circumference. Once the cuts meet up any minor discrepancies can be filed out. Just make sure you measure twice / thrice and cut once!

slowster
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Re: Cutting down an overlong steerer on a new bike

Postby slowster » 9 Jan 2019, 1:14pm

I've been waiting for someone to point out that we never had this problem with threaded steerers and quill stems, but since nobody has, I will :wink: .

(And before any smart alec points out that the correct amount of the threaded steerer still needs to be cut to ensure that there are enough threads for the headset locknut to engage with, historically the norm was to buy the frame and fork with the chosen headset already fitted by the framebuilder or bike shop.)

PH
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Re: Cutting down an overlong steerer on a new bike

Postby PH » 9 Jan 2019, 1:43pm

robgul wrote:
PH wrote:
robgul wrote:Then, and only then do I take the fork out and cut the steerer tube - using a special clamp to guide the saw blade to get the cut square so that the top cap sits correctly.
Rob

Except of course the top cap doesn't sit on the steerer and although cutting square is good there's leeway for a little error.

I think you're being a bit picky there :D
Rob

Yes, but there's nothing wrong with picky :lol:
Your post could give the impression that being square is so critical that a special tool is needed, when all that's required is a bit of care.

pwa
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Joined: 2 Oct 2011, 8:55pm

Re: Cutting down an overlong steerer on a new bike

Postby pwa » 9 Jan 2019, 4:03pm

slowster wrote:I've been waiting for someone to point out that we never had this problem with threaded steerers and quill stems, but since nobody has, I will :wink: .

(And before any smart alec points out that the correct amount of the threaded steerer still needs to be cut to ensure that there are enough threads for the headset locknut to engage with, historically the norm was to buy the frame and fork with the chosen headset already fitted by the framebuilder or bike shop.)

The flip side of that argument is that the quill stem system just didn't give you the option of cutting the steerer to size. It was done for you. No tinkering at home. If sliding the stem up or down within its small range of adjustment didn't solve your problems, tough, the bike didn't fit. No great stack of spacers to play with or angled stem to flip.

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Mick F
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Re: Cutting down an overlong steerer on a new bike

Postby Mick F » 9 Jan 2019, 4:07pm

My 1986 custom Mercian frame came with a Tange headset, and many years later I fitted a Campag one that had a lower stack height. I cut off about a quarter of an inch ........ if my memory serves me correctly.

On my third Campag headset on it now.
Mick F. Cornwall

Marcus Aurelius
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Re: Cutting down an overlong steerer on a new bike

Postby Marcus Aurelius » 9 Jan 2019, 4:18pm

Measure twice, cut once.

andrew_s
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Re: Cutting down an overlong steerer on a new bike

Postby andrew_s » 9 Jan 2019, 7:48pm

Samuel D wrote:To make the gap size less critical, I use a single spacer (~5 mm) above the stem. That way the stem clamps the steerer tube along its full height for maximum grip and minimum compressive hoop stress in the tube, there is no twisting of the stem clamp from uneven screw engagement, and there is least bending stress in the steerer tube when the handlebar is pushed and pulled in use.

It's not uncommon for a minimum of 5 mm space above the stem to be required by carbon fork manufacturers.

pwa
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Joined: 2 Oct 2011, 8:55pm

Re: Cutting down an overlong steerer on a new bike

Postby pwa » 9 Jan 2019, 8:02pm

Marcus Aurelius wrote:Measure twice, cut once.

I must confess, cos I know you lot won't tell anyone, that in a dark corner at the back of my garage is a pair of carbon forks with ally steerer that I cut a little short after a failure of maths. The simplest of tasks and I messed it up. I used to show people how to make picnic benches and things like that out of green oak and I always told them, "measure twice and cut once", but I forgot to do it myself!