Broken Femur - what happened?

[Herzog]

I was in England visiting friends last week and whilst there I borrowed a friends bike to keep to my training schedule. However, besides potholes and more traffic than I'm used to, the riding was going well and I was managing to balance a family holiday and some good sessions (Ditchling Beacon Hill repeats were one of the best).

However, the last session did not go as planned (is there an award for understatement of the year on CC?). After completing an AE interval session around the South Downs, I was returning home (Saddlecoombe/Devils Dyke Road) when I had a pretty big off!! On a slight decent, suddenlyI couldn't turn the cranks. As I was starting to brake, the rear wheel locked and I started to fishtail. The inevitable happened and down I went with a sickening thud. Knowing instantly that I wasn't getting up from this one, the hand went up and some choice expletives shouted!! Femur was broken, taking a trip 3 inches inwards, attempting to say hello to my naval. Amazingly, no road rash and not even a mark on my cycling shorts etc.

Fortunately, there was an off-duty A&E nurse in one of the cars behind and she managed the scene very well. I won't go into the pain (apparently the femur is the most painful bone to break…worse than childbirth…), but I'm interested in hearing opinions on what could have caused the accident.

I've included pictures of the bike after the accident. As is shown, the rear mech did not go into the spokes, but has shifted to the biggest cog (as I was going downhill, I was in the smallest at the time, therefore no reason to shift in this direction). Could it be a simple case of the chain shifting too far and getting trapped between the cassette and hub and therefore locking the wheel? As mentioned, I was in the smallest cog at the time going downhill, so presumably something failed in the rear mech causing it to shift towards the hub (I didn't change gear!).

After a rather shocking experience in an NHS hospital (surgery great, aftercare terrible - left to my own devices in bed with little physio/support), I was flown by private jet back to Switzerland (health insurance is a wonderful thing) and am in great hands here.


I'm interested to hear any opinions on the cause of the accident (guesswork I know).

 

[Easytigers]

Wow! That sounds incredibly painful!!! Hope is a quick and full recovery!!!

 

[Globalti]

Bad luck. It's a very odd incident; on most bikes the deralleur is sprung towards the outside and the smallest cog so if the cable snapped for example, the derailleur would just spring outwards. What can have caused the chain to get caught up behind the cassett like that?

 

[cbs]

Firstly, sorry to hear about such a nasty off - can't imagine how much that must have hurt. Worst bit is that you won't be able to get on a bike anytime soon!

As you say, we can only guess, but I do have a theory...

Maybe your foot, or something on your shoe, got caught in the rear gear cable where it is exposed on top of the chainstay. That would stop the cranks turning and the pulling on it would move the rear mech right across the cassette, towards the spokes. In theory, the lower limit stop would come into play, but maybe if the cable is pulled hard enough, and the adjustment is slightly out, it's enough to send the chain into the spokes.

 

[Herzog]

Many thanks for the input (and GWS messages)!

...the derailleur would just spring outwards. What can have caused the chain to get caught up behind the cassett like that?

That's my also opinion, the mech should return to a position away from the hub, not towards it.

Maybe your foot, or something on your shoe, got caught in the rear gear cable where it is exposed on top of the chainstay. That would stop the cranks turning and the pulling on it would move the rear mech right across the cassette, towards the spokes. In theory, the lower limit stop would come into play, but maybe if the cable is pulled hard enough, and the adjustment is slightly out, it's enough to send the chain into the spokes.

Thanks for the suggestion, though I think it's unlikely. If something had got caught in the cable and pulled it, the cranks would still be able to turn (the cranks definitely froze before the rear wheel locked - it felt like the chain was catching on something metal, either the chainring or a cog). Also, there's no indication that anything interacted with the cable (no grass/mud on cable, damage to shoes etc.). Thanks though!

 

[GrumpyGregry]

Chainsuck maybe? I've never had it on a road bike but it can produce symptoms of locking the cranks like those you've described.

Pauses to consider the phrase...

(Ditchling Beacon Hill repeats were one of the best).

before wishing that you get well soon.

 

[coffeejo]

Nothing helpful to offer, only more GWS wishes and gratitude that I managed to recover from my own 40mph fishtailing experience a couple of weeks ago.

 

[cbs]

Many thanks for the input (and GWS messages)!



That's my also opinion, the mech should return to a position away from the hub, not towards it.



Thanks for the suggestion, though I think it's unlikely. If something had got caught in the cable and pulled it, the cranks would still be able to turn (the cranks definitely froze before the rear wheel locked - it felt like the chain was catching on something metal, either the chainring or a cog). Also, there's no indication that anything interacted with the cable (no grass/mud on cable, damage to shoes etc.). Thanks though!

No problem, I saw this thread and was interested in the forensic aspect, so had a stab at a cause. I think you're right, if you were pedalling at quite a speed when going downhill, then catching on a cable would probably not have stopped the cranks. You would probably have been aware of them catching and then pinging free, but for them to stop completely would be a different matter.

What I can't see though is how the mech carried the chain from one end to of the cassette to the other. It must have been the chain falling into the spokes that locked the wheel.

 

[VamP]

Eeech, sorry to hear and happy healing.

Might the chain have chain have come off at the chainset first, creating slack that then got bounced by the spokes into wrapping around the cassette? It seems improbable, but then it is an improbable accident. Had you attempted any kind of shifting in the lead up to the crash? Can't tell from the pictures but is the FD cable intact?

 

[Crackle]

Agree with Vamp: It sounds like the chain shipped at the front, that would potentially jam the cranks instantly, what happened at the back is just the result of the accident.

What speed were you doing when it jammed?

And I have no wish to know how painful a broken femur is.

 

[Herzog]

Again, thanks to all for the replies and GWS wishes!!

Eeech, sorry to hear and happy healing.

Might the chain have chain have come off at the chainset first, creating slack that then got bounced by the spokes into wrapping around the cassette? It seems improbable, but then it is an improbable accident. Had you attempted any kind of shifting in the lead up to the crash? Can't tell from the pictures but is the FD cable intact?

Yep, FD cable still intact. I'd shifted onto the big ring and smallest cog about 10 secs before cranks jammed (so they were happily turning for a number of revolutions before locking).

I'm hoping the guy whose bike it is takes it to a decent LBS so they can try to piece together what happened. If I know why it failed, it'll be far easier to get back on the bike a bit less worry-free.

I may have to file it in the "one of those things" folder!

 

[Herzog]

What speed were you doing when it jammed?

About 50-60 kph (yet to check the garmin trace). Think I scrubbed a bit of speed off before coming off. Besides the femur, the only other obvious sign of impact was a dirty hand. I'm amazed that the force required to break the strongest bone in the body did little else. As written above, shorts a little dirty, but not damaged. I think I came off onto the verge, sliding a little before hitting the sole of my left foot on something (and forcing the femur to break upwards). Am yet to check my shoes, but if the sole is unscathed I may write to Sidi detailing the strength of their shoes (also no ankle/other leg injuries) - other than the one attached - shown after being pulled 3 inches out of hip.

 

[Rickshaw Phil]

and .

I'm sorry, I've got no clue what might have happened there but would like to wish you the swiftest possible recovery.

 

[Crackle]

I'm amazed that the force required to break the strongest bone in the body did little else. As written above, shorts a little dirty, but not damaged. I think I came off onto the verge, sliding a little before hitting the sole of my left foot on something (and forcing the femur to break upwards)..

I hadn't read that properly when I was looking at the X-ray and was just wondering where the force would have come from for that kind of break and up the leg pretty much covers it.

Hope that heals nice and cleanly.

 

[rich p]

It's the Bermuda Triangle of roads, Herzog. My buddy came off on that section at Saddlescombe and ripped the quadriceps off his patella last year.
Wishing you a good recovery.