I went over a bump and....

[Samuel D]

My guess is the down tube cracked somewhere near the head tube.

Glad you’re okay.

[CREPELLO]

You bought another Pashley? viewtopic.php?f=5&t=76705&p=672079&hilit=broken+head+tube#p672079

[andrew_s]

steerer/fork crown joint cracking?

This happened to someone in the club, on a ride back to Cheltenham from Bristol. He eventually had to give up riding when the front centres had got so long that the BB height was less than the crank length. Fortunately he'd reached walking distance by then.

[geocycle]

The bump was a small bear that jumped on the handlebars making handling difficult..... come on put us out our misery!

[Brucey]

well, unbeknownst to me, the trail had decreased by about 1" and in addition the steering was now misaligned slightly sideways. It was the latter that I noticed first, because suddenly I needed to put some force on the bars when riding in a straight line. I wondered if the wheel had come loose in the dropouts, and checked that first.

The wheel wasn't centred between the fork blades... but the wheel wasn't loose, either.

When I looked at the forks, I found to my horror that both fork blades were cracked, just below the crown. Somewhat less than half of the circumference of each blade remained. When I'd gone over the bump the remaining material had suddenly deformed.

I had about four miles to get home, and after some thought I decided to ride slowly on the smoothest route I could manage. Being a roadster I could sit upright and well back, and not use the front brake, thus reducing the load on the fork. I reasoned that the fork would likely bend a little more before it actually broke, and then one blade would probably break before the other. I've had one fork blade break before now and the wheel rubs so badly that you know instantly.

So I pottered homewards, somewhat precariously. The fork didn't move much more; I had dismounted when the way was rough, and slowed down to a walking pace where it was a bit bumpy. I could however hear a faint, but rather ominous creaking sound from the fork at times.

I don't think I would have ridden the bike in the same way had the steerer been breaking, and/or the fork had been made of a material that wasn't obviously fairly ductile.

I suspect that the joints may have been overheated when the fork was built; also the forks are over 15 years old, and have had a hard life. I did inspect the forks about 18 months ago, and I guess I've done about 4000-5000 miles since then. In that time I've done little more than pump the tyres up (I also lubed the chain, once; it is inside a chaincase...) but various other parts have got to the point where they are in need of work and I had planned to do a major overhaul on the bike very soon; the BB is worn, the rear rim has a couple of small cracks in it, there are a few rust spots that need sorting out, the tyres are worn... you get the idea.

I wondered how it was that I'd missed the cracks until they got that bad. Well...the fork hadn't suddenly become a lot more flexible (I've had that before) also the cracks had been growing right next to the crown, and the crown is quite thick-walled, so I would have had to invert the bike to see them; they would have been quite invisible from above. In addition the bike is dark green, and cracks don't show well with this frame colour. Jobst Brandt was right; if you want to see cracks, better have a light frame colour...

So just in case it isn't obvious, I think that the lesson is that you can't take the integrity of any frame and fork for granted. In some other materials (with less ductility) I think that the fork may well have snapped suddenly rather than bent as it did.

cheers

[NATURAL ANKLING]

Hi,
Make of bike
Just so I don't buy one

Had it happen once....my fault tho.........used a file to remove the paint

Your rather good on finding frame related failures........


I'de of done the same but some hear would froun at that.
You'de of told use if it busted on the way home woud'nt you

Ah reminds me my No 2 skip trainer has started to creak and groan.....must be the cranks or something......

[MikeF]

Steel is real!
If the forks had snapped whilst you were riding it on those 4 miles home, it would have been even more difficult to get home.

[beardy]

I suspect that the joints may have been overheated when the fork was built;

As they were steel forks it does have to be down to a manufacturing fault. If they were CF forks then it would have been ....well.... because they were CF forks.

This is not in any way aimed at Brucey, just the general bias against the demon new material, so apologies for raising this at a sad time. But it was "necessary" in the cause of balance, somebody had to say it. We know what the comments would have been if it had been a pair of CF forks that snapped and a lot more comments than I expect in this case.

Probably with some comments that at least you can inspect steel forks and spot a defect unlike CF where it is impossible to do so.
Oops , I've done it again!

Sorry Brucey I know I shouldnt.

but can you get some nice CF forks that will fit that Roadster?

I promise that if my CF forks fail (possibly before they reach 15yo) I will post about it (if I can) and let you quote this back at me with lots of 's.

[mig]

i do tend to inspect my frame and forks when cleaning as far as that is possible. i did find a crack on the exterior of a pair of carbon forks once (after i'd had an off on diesel) and decided to replace them.

brucey's original post outlines that his forks had partly failed and thereby given an indication that they were on the way out. this is good.

flexing my carbon fork in my fingers (after noticing the crack) quickly gave rise to total failure in one blade. if i had been riding this would have been bad in a very rapid format.

my feelings are that if we remove the words 'steel' and 'carbon' from any debate and replace with "some warning of failure" and "no warning of failure" then maybe opinions may differ.

after the carbon fork incident i do know that the people dependent on me in my family prefer me to ride on the former. for me that's "nuff said."

mr brucey - glad to hear that you didn't deck it. hope you can find something to replace them and the time to attend to the other matters on your bike!

[andrewjoseph]

i win!

[Brucey]

.....So just in case it isn't obvious, I think that the lesson is that you can't take the integrity of any frame and fork for granted. In some other materials (with less ductility) I think that the fork may well have snapped suddenly rather than bent as it did.....

which, like MIG says, is why I won't be fitting a CF or aluminium fork to this bike anytime soon.

BTW the bump that bent the (already damaged) fork was me dropping off a kerb about 3/4" high; I figured that provided I didn't load the fork any more than that, it wouldn't immediately bend further or fail completely. Not that I can recommend that it would always be thus, but this turned out to be correct in this case. [I was lucky enough that I could do about three miles of my journey on well-surfaced off-road paths; I'd not have risked riding with a dodgy fork in and out of traffic...]

If it had been a single tube failing (eg a steerer), and/or had shown any signs of further movement whatsoever, I'd have been walking, not riding.

Good guess, Andrew!

cheers

[Valbrona]

Give me a welded unicrown fork ...

[NATURAL ANKLING]

Hi,
Got to admit that my Carrera MTB even says "Power Fork" on the leg, welded girder I think and I wouldn't even look for bad things there.

I had a frame down tube part company on the only bit of my journey home from work (parked car and used the railings to get wheel back so I could turn it ) where I ever stood up to get out the car park.
Rode it for three months with ripples in tube.
Felt rubbery and saw 1 " of daylight between tubes, grabbed tubes with one hand going round corners and a 45 MPH hill which I did at max every day but not that one

Not advisable of course.

Both skip trainers are alluminium frames so I must look often, ones a fiver and the other £20 so the fashion is over.
Still spying lots of situp Raleigh's at the tip with mainly chrome rims.......

[bainbridge]

Glad you got back safely, but disappointed you didn't wheelie all the way home.

[Brucey]

someone said that to me when I told them what happened... all I can say is that it would take more skill than I have ever had to do that for four miles on a 50lb+ bike.... and you still have to be able to 'land'....

BTW I'm not feeling so bad about not having spotted the cracks beforehand now, but rather more worried that this won't be the last fork that will fail in this way.

The cracks were largely hidden inside the brazed joint; in other words until the cracks opened up, they couldn't be seen at all. Where the cracks have opened up, in many places there is about 1mm of the brazed joint that has failed in shear, then a crack through the fork blade, leaving a stub of fork blade stuck in the fork crown, under flush.

I keep thinking that one scheme proposed, i.e. that the frame could be built with sealed compartments, that must leak when there is a crack, isn't such a mad idea. You could check that the frame and fork compartments were all airtight in just a few minutes, using soapy water and compressed air.

cheers