Cutting down an overlong steerer on a new bike

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Airsporter1st
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Cutting down an overlong steerer on a new bike

Postby Airsporter1st » 8 Jan 2019, 10:52am

Saw this link on another thread:

https://www.spacycles.co.uk/m1b0s21p3866/SPA-CYCLES-Wayfarer

Is the handlebar stem protrusion normal and is it then ridden like that - or is it intended that the shop or new owner cut it down to size? I'm guessing the latter, but have seen some people riding bikes with that 'feature' - though perhaps not so pronounced.

fastpedaller
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Re: .... a burning question!

Postby fastpedaller » 8 Jan 2019, 10:58am

One of the useful cost saves for manufacture is that the same length of (non-threaded) steerer tube can be used for all size frames. This means that it can then, indeed, be cut to suit what the rider wants. Most people (I've done it myself) will cut it down a bit, but leave it a little higher than we anticipate we'll need 'just in case'. Once cut, it can't be made longer, so worth erring on the side of caution! The one in the photo link does look somewhat extreme.
I left about 1.5 inches 'extra' (ie above where I'd spaced the stem to) on mine - I can always trim it if required, and it's short enough that it's not likely to impale me if I fly off!

JakobW
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Re: .... a burning question!

Postby JakobW » 8 Jan 2019, 11:04am

That looks like it could be rather painful in an abrupt stop!

Pretty sure Spa have just left it long on a test bike so that the bar height can be easily changed for different riders. The fashionable thing to do would be to cut it flush with the top of the stem clamp, but unless you're using a stem with a lot of negative rise it's probably sensible to leave a cm or two of spacer above the stem to allow for potential height changes.*

*You may need to watch out if using a carbon steerer - the bung needs to support the stem clamp area inside the steerer, and lots of spacers above the stem may mean you need a longer bung. Not sure what the recommendations are for Alu steerers.

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

Postby PH » 8 Jan 2019, 4:41pm

If the owner wants the bars at that height, or lower, then yes it's intended to be cut down. OTOH the owner has the option of having the bars higher than the photo should they wish to. It's pretty common on bikes intended for enthusiasts, even from mainstream suppliers like Surly. It's a simple enough job, either with a hacksaw or pipe cutters.

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Mick F
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Re: .... a burning question!

Postby Mick F » 8 Jan 2019, 5:02pm

fastpedaller wrote: ...... Once cut, it can't be made longer ...........
Yes it can.

In the old days of quill stems, I would agree, but A Head systems clamp on the outside of the tube. This means that you could insert a substantial sleeve inside and weld on an extension.
Mick F. Cornwall

Airsporter1st
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Re: Cutting down an overlong steerer on a new bike

Postby Airsporter1st » 8 Jan 2019, 5:57pm

Thanks for the response folks and to the mods for changing to a more relevant title!

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foxyrider
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Re: .... a burning question!

Postby foxyrider » 8 Jan 2019, 6:03pm

Mick F wrote:
fastpedaller wrote: ...... Once cut, it can't be made longer ...........
Yes it can.

In the old days of quill stems, I would agree, but A Head systems clamp on the outside of the tube. This means that you could insert a substantial sleeve inside and weld on an extension.

Not sure how you weld carbon!
Convention? what's that then?
Airnimal Chameleon touring, Orbit Pro hack, Orbit Photon audax, Focus Mares AX tour, Peugeot Carbon sportive, Owen Blower vintage race - all running Tulio's finest!

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

Postby Mick F » 8 Jan 2019, 6:06pm

:lol: :lol:
Araldite?
Mick F. Cornwall

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

Postby robgul » 8 Jan 2019, 7:28pm

I manage a bike shop and quite a few of the bikes at the quality end do come in new with lots of steerer tube on them - what I normally do is adjust the spacers/stem height to what the rider thinks he likes and tell him/her to ride it for a bit - coming back for adjustments up and down - until the optimum steerer length/stem height is acheived.

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. Note: metal or carbon steerers need different saw blades to cut them.

Rob

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

Postby PH » 8 Jan 2019, 7:35pm

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.

tim-b
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Re: Cutting down an overlong steerer on a new bike

Postby tim-b » 8 Jan 2019, 9:00pm

Hi
An overlong steerer can be a cause for concern:
Many CF steerers are only intended to be around 80mm above the headset
An overlong CF steerer with a low stem height won't coincide with the bung length as demanded by many manufacturers
Regards
tim-b
~~~~¯\(ツ)/¯~~~~

fastpedaller
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Re: .... a burning question!

Postby fastpedaller » 8 Jan 2019, 11:06pm

Mick F wrote:
fastpedaller wrote: ...... Once cut, it can't be made longer ...........
Yes it can.

In the old days of quill stems, I would agree, but A Head systems clamp on the outside of the tube. This means that you could insert a substantial sleeve inside and weld on an extension.


I meant in the context of 'home shed' repaired. It would be possible to replace any steerer by brazing in a new one, but again it's a lot easier to cut a bit extra off than it is to add it on! :wink:

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

Postby robgul » 9 Jan 2019, 8:42am

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

- yes the cap does butt up to the stem/or spacer if you have any above the stem. The risk of cutting way out of square when cutting a tube freehand is high ... and good practice says that the space above the steerer tube and the underside flange of the top cap should be minimal within the amount to allow for pre-load.

Rob

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

Postby pwa » 9 Jan 2019, 8:52am

I have always cut steerer tubes freehand with a hacksaw, tidying up with a file afterwards. I put some tape around the tube as a guide. A safer alternative might be to put something solid like a jubilee clip around as a guide to the blade. Cut a smidge above where you think you need to be then file down until the tube is a little below the top of the stem or, my preference, the thin spacer above the stem. The top cap, when clamped down, should be close to but not touching the cut tube.

Samuel D
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Re: Cutting down an overlong steerer on a new bike

Postby Samuel D » 9 Jan 2019, 9:13am

To have the cap as close as possible to the top of the steerer tube while not touching it, the tube does need to be cut (or filed) square. But I saw them freehand too for want of a guide. The result has always been good enough for me. You cannot fine-tune the gap infinitely anyway, since spacers are only available in discrete heights (and since the spacers do need to be square to load the bearing cups evenly, freehand cutting or filing of them shouldn’t be attempted. You’d need a lathe or something to do that job).

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.