Did I bust my fork ??

bungle73 · Post by **bungle73** » 27 Jan 2020, 4:06pm

Allez Sprint fork. Bought a longer expander bung so I could play with my position a bit. Tried to put it in, but it wouldn't fit, so I had tried to put the old one back. Tightened to to the recommended torque of 9 Nm, which seemed a bit much., but that was what it said. Then I decided I needed to take it out again, and when I tried I heard a bang and smelt a funny smell. First though that was that I'd damaged my steerer. On examination I find this.

I think I made two mistakes. I put grease on the thing the nut screws into because it looked like there was some there already, and I think that affected the torque, and maybe I shouldn't have gone to 9. I read somewhere recently that they tightened theirs up to that, even though that is what they were told, and it damaged their steerer. Why say that tight if it's too much??

thatsnotmyname · Post by **thatsnotmyname** » 27 Jan 2020, 4:09pm

Unless I'm missing something, that steerer looks perfectly ok. I don't see what difference a longer expander would make in any case.

bungle73 · Post by **bungle73** » 27 Jan 2020, 4:17pm

thatsnotmyname wrote:Unless I'm missing something, that steerer looks perfectly ok. I don't see what difference a longer expander would make in any case.

Because it gives support to a longer section of fork; therefore more freedom to position the stem.

What about the line running the length of the fork, and the bit near the base where it looks like it's coming away that I've circled in red? And the mark on the interior, that now seeing larger and clearer in the photo looks like it may be just a mark.

What about the bang and smell?

Maybe I should take it somewhere to be checked out? Where though? Halfords is the only place local. I assume they have the necessary equipment?

bungle73 · Post by **bungle73** » 27 Jan 2020, 4:18pm

when I run my finger over the line I can feel it.

thatsnotmyname · Post by **thatsnotmyname** » 27 Jan 2020, 4:51pm

bungle73 wrote:What about the line running the length of the fork, and the bit near the base where it looks like it's coming away that I've circled in red?

They just look like manufacturing marks, or part of the carbon wrap, tbh. Impossible to tell without either high-res images or examining the steerer for real.

bungle73 wrote:What about the bang and smell?

No idea. Can you describe the smell?

bungle73 wrote:Maybe I should take it somewhere to be checked out? Where though? Halfords is the only place local. I assume they have the necessary equipment?

I wouldn't bet on Halfords having any kind of test equipment, or having any knowledge which could be useful to you in this case.

NATURAL ANKLING · Post by **NATURAL ANKLING** » 27 Jan 2020, 4:53pm

Hi,
Thats a CF fork :!:

...Steerer...

If cracked then its toast I am afraid.

Do Not Ride!

bungle73 · Post by **bungle73** » 27 Jan 2020, 4:56pm

I've notice another very faint line on the opposite side that is smooth, and when I examined the inside of the steere, near the bottom there is a load of mess of something. I've no idea what that is? Damage?

No idea. Can you describe the smell?

Not really. It only lasted seconds.

bungle73 wrote:Maybe I should take it somewhere to be checked out? Where though? Halfords is the only place local. I assume they have the necessary equipment?

I wouldn't bet on Halfords having any kind of test equipment, or having any knowledge which could be useful to you in this case.[/quote]

They sell carbon fibre bikes don't they, I'd have though they would have. So where can I take it then? A Specilized dealer?

bungle73 · Post by **bungle73** » 27 Jan 2020, 5:03pm

NATURAL ANKLING wrote:Hi,
Thats a CF fork ...Steerer...

If cracked then its toast I am afraid.

Do Not Ride!

That's the point, I don't know.

The interior looks like this. What is that at the bottom??

Post by **slowster** » 27 Jan 2020, 5:21pm

bungle73 wrote:Tightened to to the recommended torque of 9 Nm, which seemed a bit much., but that was what it said.

The torque figures I've seen on steerer bungs have always been a maximum figure. In my experience it should not be necessary to tighten it anywhere close to the maximum amount: it only needs to be tightened enough so that when the top cap bolt is subsequently tightened to remove play from the headset, the bung stays in place and does not get pulled up inside the steerer.

I think what you can see inside the bottom of the steerer is not unusual. Fibre reinforced plastics manufacturing is often a fairly messy process, and edges and voids which are not readily visible or accessible after moulding and curing, and which do not compromise the strength of the structure, are often left with that sort of untidy finish.

bungle73 · Post by **bungle73** » 27 Jan 2020, 5:28pm

slowster wrote:
bungle73 wrote:Tightened to to the recommended torque of 9 Nm, which seemed a bit much., but that was what it said.

The torque figures I've seen on steerer bungs have always been a maximum figure. In my experience it should not be necessary to tighten it anywhere close to the maximum amount: it only needs to be tightened enough so that when the top cap bolt is subsequently tightened to remove play from the headset, the bung stays in place and does not get pulled up inside the steerer.

I think what you can see inside the bottom of the steerer is not unusual. Fibre reinforced plastics manufacturing is often a fairly messy process, and edges and voids which are not readily visible or accessible after moulding and curing, and which do not compromise the strength of the structure, are often left with that sort of untidy finish.

Oh, ok. I'm starting to calm down a bit.

I smelt the interior and there is a faint burning smell I think. I think that is what I smelt before.

The literature from Speclized actually says "recommend torque 9 Nm", so that's what I went with.

So is the consensus that's ok to put reassemble and ride?

thatsnotmyname · Post by **thatsnotmyname** » 27 Jan 2020, 5:58pm

bungle73 wrote:They sell carbon fibre bikes don't they, I'd have though they would have. So where can I take it then? A Specilized dealer?

You've not been into a Halfords store before, I take it. Don't take the fork anywhere - just put it back on the bike and go for a ride.

bungle73 · Post by **bungle73** » 27 Jan 2020, 6:09pm

thatsnotmyname wrote:
bungle73 wrote:They sell carbon fibre bikes don't they, I'd have though they would have. So where can I take it then? A Specilized dealer?

You've not been into a Halfords store before, I take it. Don't take the fork anywhere - just put it back on the bike and go for a ride.

Well yeah, to buy bits and pieces. I did take a bike to be fixed there once (for a freehub problem), but I don't think they understood exactly what the problem was. I couldn't get that seemingly simple thing fixed anywhere I asked, so I ended up buying a complete new set of wheels.

Halford are the retailer for Boardman bikes though, which are supposed to be pretty nice, and are cf.

bungle73 · Post by **bungle73** » 27 Jan 2020, 6:14pm

Someone told me to give it a tap, and based on what they described it should sound like I think's fine. Bottom sounded different, but I think that's because that part is thicker, and where the legs are attached.

bungle73 · Post by **bungle73** » 27 Jan 2020, 7:45pm

OK, thanks for the replies, I've been reassured. I'm putting it all back together. So what torque do you think I should tighten the bung up to? For reference when I undid it the first time, it didn't feel anywhere near as tight as after I tightened it following Specialised's directions. Most odd.....

thatsnotmyname · Post by **thatsnotmyname** » 27 Jan 2020, 7:52pm

bungle73 wrote:OK, thanks for the replies, I've been reassured. I'm putting it all back together. So what torque do you think I should tighten the bung up to? For reference when I undid it the first time, it didn't feel anywhere near as tight as after I tightened it following Specialised's directions. Most odd.....

The bung only needs to be tight enough to not pull itself up the steerer tube when the top cap is being tightened down on it. ie not that tight.

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