Damaged steerer tube

[Grumpyoldbiker]

Hi
I'd be grateful for advice on some damage I have discovered on the steerer tube of my bike. See attached photos.
I think the steerer tube is damaged at the top, probably due to over tightening?
Any thoughts, advice?
Safe/unsafe to ride?
Regards
Peter

[Grumpyoldbiker]

Forgot to say, the bike has an aluminium frame with carbon forks.

[Brucey]

I'm guessing that we are looking at a stem with an eccentric shim in it (a specialized stem or bike by any chance?).

Yes that steerer is damaged.

I would have the steerer professionally inspected; if the damage extends (or is soon likely to extend) towards the bottom of the stem clamp, then you may experince what is often referred to as ' a sudden and complete loss of control of the vehicle' as the handlebars part company with the rest of the bike.

If you are in any doubt about the integrity of the part, stop using it immediately.

cheers

[Grumpyoldbiker]

Yes it is a Specialized Allez. Thanks for the advice.

[tim-b]

Hi

Is the expansion plug supposed to be at the top of the steerer as shown here (scroll down the page past the star fangled nut section)?
http://www.parktool.com/blog/repair-hel ... stallation
(I may be misinterpreting your photo)

The expansion plug provides some support to the steerer tube and stem

As Brucey says, if in doubt don't use the bike until it has been professionally assessed

Regards
tim-b

[iow]

also note in the link provided by tim-b above, the steerer is cut long so that it extends past the top of the stem (reducing the clamping force on the cut end) and an additional 5mm spacer is added on top of the stem to enable aheadset adjustment.

[tim-b]

Hi

Specialized installation instructions for some fork models here
http://service.specialized.com/collater ... lized.html

Regards
tim-b

[Brucey]

IIRC specialized often use a non-projecting steerer, and an extra-long expanding plug which has a lip on the top edge so that it cannot disappear inside the steerer. The plug helps to prevent the steerer from being crushed, and if the stem is done up too tight I think it may even clamp the top lip of the plug directly, tbus avoiding damage to the steerer top.

cheers

[meic]

How much does a professional inspection cost and where can you find a quality expert?
What incentive is there for the expert to say anything other than "it is damaged replace it."?

How are CF steerer tubes cut to length or are they never cut as that will expose fibres and damage the matrix.

How much load is on that bit of the steerer, will the forces and damage have progressed past the bung?

Can the remainder of the steerer tube be considered safe and that damage bit be left on and remain but not as a loaded part of the structure?

Meanwhile any forum members can only recommend that you replace it with a new fork as that absolves us from any responsibility and we dont take the financial hit.

So replace the forks.

[JohnW]

There are those of us - you know, anachronisms, boring old ffffffuddy-duddies - who stick with steel.

We do have our reasons.

[meic]

Like Gentlegreen

for example?

[Valbrona]

As per previous responses, the top of the steerer is damaged and this runs the risk of sudden failure.

This break hasn't been caused by over-tightening of the expander. Instead, and as you are probably aware, it has been caused by over-tightening of the stem bolts. There is a simple way to prevent such damage, and that is to use a spacer above the stem. This positions the stem lower down the steerer tube so that it clamps around the steerer tube for the whole of the length of the stem. Position the stem in the uppermost position and if you over-tighten you run the risk of damaging the very top of the steerer, like in your case. The spacer above the stem only need be 5mm or so.

The fix is simple. No need to have your stem 'professionally examined'. If you have spacers below the stem then one/more of these could be removed and the broken part of the steerer simply cut off. Depends how much space for adjustment you have. But your bars will end up lower.

Carbon paste should be used during assembly of carbon parts. And a torque wrench comes in handy. And don't cut a carbon steerer tube unless you know what you are doing.

[JohnW]

Like Gentlegreen

for example?

OK meic. Whilst I don't suggest that steel is 100% perfect, steel frames have been in production and use for generations and a failure is still rare. All down those years steel frames have lasted and lasted - they have a proven track record. Gentlegreen's experience notwithstanding, most of the frame fracture/other defect problems which find their way onto this Forum are with alu.

This is particularly so for carbon/alu composite forks.

If a defect does appear on an alu/carbon/titanium frame, we can't take it down to the nearest framebuilder and have it put right. The frame is knackered and has to be replaced. A steel frame can be repaired - and that's particularly beneficial when on a lengthy tour.

A steel frame can be built to your requirements, and updated with extra braze-ons if you change your mind after receiving it - and even altered.

We hear of claims of longevity with alu frames, and of life-shortening defects with steel, but I and several riding colleagues have steel frame which continue to gather high mileages, and have done so since being built before alu/carbon/titanium frames were ever available.

I have known steel frames/forks to break - I can't deny it - but very rarely and even then they were repairable. Generally, even if a steel frame does "break", it's a progressive phenomenon, whereas alu/carbon very often fail suddenly, spectacularly and without warning.

From experience - my own and generations of cyclists - and accidents apart - I know that a steel frame will last me a lifetime. I don't know how long the other materials will last me.

Every prang is different from all others, but generally a steel frame will fail progressively and offer some (albeit minimal) cushioning.

I could go on meic - and there will be posts of dissention, but one of the reasons is the lessons of the years.

And before anyone starts - the claims that eventually the other materials will catch up are most probably right, but they haven't yet.

Finally - and perhaps someone in the know could comment - in recent times failures of steel frames that I have heard about suggest that modern, welded jointed, off-the-shelf frames are less reliable than properly built, brazed-up frames.

[Brucey]

.....And before anyone starts - the claims that eventually the other materials will catch up are most probably right, but they haven't yet.

-and there are quite good engineering reasons why they may not, too.

Finally - and perhaps someone in the know could comment - in recent times failures of steel frames that I have heard about suggest that modern, welded jointed, off-the-shelf frames are less reliable than properly built, brazed-up frames.

well I think this may be the case too. And this is despite the fact that many of the current generation of steel frames are built heavier than older ones.

There are several reasons why this might be. I quite like lugged steel frames myself.

cheers

[meic]

If a defect does appear on an alu/carbon/titanium frame, we can't take it down to the nearest framebuilder and have it put right.

I know that you said frame but the thread here is about forks.

I have some steel forks on my Holdsworth that I dont like that much, I bought some scrap steel forks for the price of their postage, then I went to a frame builder to see how much it would be to replace the steerer tube. £90.
I bought a brand new pair of 531 steel forks from Thorn shortly after for £100.
Carbonfibre forks are a similar price. On-one sell forks at around £40

I dont think that I will ever take advantage of steel forks repairability paying a frame builder, though I am not above a bit of work with a crowbar.